Rigidity Testing on the LongMill MK3

Posted on March 30, 2026March 30, 2026 by Andy Lee

Testing the amount of deflection a machine experiences at different loads, aka the rigidity, is a good way to predict the overall performance of a CNC machine. When it comes to using a CNC machine, two primary objectives are to make the part accurately and quickly. One major contributing factor to the precision of a part has to do with how much the end mill deflects away from the programmed path. The end mill on a more rigid machine will deflect less than on a less rigid machine given the same feeds and speeds, and thus produce a part that is more accurate. Alternatively, a user can run their machine faster while still producing a part of acceptable quality on a more rigid machine.

A diagram showing the effect of tool deflection and how it affects the geometry of a simple part

Perhaps a common example of how this affects a simple part of a CNCed design would be holes. Holes cut on a CNC machine tend to come out undersized, because the material on the walls of the hole push the machine and endmill towards the center.

It should be noted that deflection exists in all machines, it’s just a matter of how much. To improve tolerances, it’s common to do a “roughing” pass, which removes the bulk of the material, and then a “finishing” pass, which removes a small amount of material at the end, minimizing deflection to bring the part to final shape.

The state of the market & why we’re sharing results

As we discussed in one of our prior blog posts, there isn’t, as far as we can tell, a standardized method for testing machine deflection in the hobby CNC space.

We are able to glean general comparisons between our machines and other machines in the market by test results posted by other members of the community. As time has gone on, here are some of my personal opinions on why that is the case:

It’s hard to give context on what the rigidity numbers mean.

For most of the practical testing range, deflection is not visible to the naked eye. A lot of times, people will demonstrate standing on their machine as a demonstration of rigidity, maybe even standing on it while it’s cutting. This doesn’t really show how rigid the machine actually is, because you can’t see how much the machine is deflecting from a distance.

Additionally, just because a machine is bigger and heavier doesn’t necessarily mean that it has less deflection. Some areas of a machine’s design can affect the overall accuracy of the machine, even though it may seem insignificant at first glance. For example, from our comparisons between computer simulations and real life testing, we’re able to see that things like bolt tolerance and mechanical components shifting around under load can actually play a pretty big role in the overall deflection values. All this to say, you could have a super rigid machine, but have a weak or loose part of it, just that one part alone can have a major impact on the overall machine rigidity.

Rigidity is less important that we think it is.

Owning and using a CNC machine isn’t just about how rigid or fast it cuts. The whole experience is important, from the setup, assembly, software control, and overall reliability. For the average hobbyist, if a CNC project takes 45 minutes to cut instead of 30, does it really make a huge difference?

Return on investment in a higher degree of engineering requires high volumes to experience

Lastly, with us expecting to build a very high volume of CNC machines, a small design improvement affects a lot of users. For machines built at lower quantities or DIY machines, it’s cheaper and easier to over-engineer the machine rather than optimize it, since the cost of engineering time is higher than the cost of buying bigger or better components.

Testing process

We built a simple testing jig using old prototype parts from the LongMill MK3. We have a force gauge on the moving gantry and the dial indicator on the other. When we turn the lead screw to push the force gauge against the router, it moves the dial indicator some amount. The more that the dial indicator moves, the more the machine is deflecting.

Getting straight to the results & comparisons

As we can see from our results below, we have around 65-80% improvements in rigidity between the LongMill MK2 to the LongMill MK3.

(Past Data and writeup for the LongMill MK2 from 2022.)

These tables show the amount of force applied during the test on the X & Y axes.

LongMill MK3 48×30

Force Applied (N)	Force Applied (lbs)	Positive X (thou)	Negative X (thou)	Positive Y (thou)	Negative Y (thou)
25	5.62	4.5	5	8	9
50	11.24	10	10	11	12
75	16.86	16	15	17	18
100	22.48	22	21	24	25

AltMill 4×4

Force Applied (N)	Force Applied (lbs)	Positive X (thou)	Negative X (thou)	Positive Y (thou)	Negative Y (thou)
25	5.62	1	1	1	1
50	11.24	2	3	4	3
75	16.86	4	4	5	5
100	22.48	7	6	6	7

LongMill MK2 48×30

Force Applied (N)	Force Applied (lbs)	Positive X (thou)	Negative X (thou)	Positive Y (thou)	Negative Y (thou)
10	2.248	2.8	NA	3.2	NA
25	5.62	~7	NA	~10	NA
50	11.24	14.2	NA	20.7	NA

Comparison at 25N/5.62lbs
	Positive X (thou)	Positive Y (thou)
LongMill MK2 48×30 (extrapolated)	7	10
LongMill MK3 48×30	4.5	8
AltMill 4×4	1	1


Comparison at 50N/11.24lbs

	Positive X (thou)	Positive Y (thou)
LongMill MK2 48×30	14.2	20.7
LongMill MK3 48×30	10	11
AltMill 4×4	2	4


Comparison at 25N/5.62lbs
	Positive X (thou)	Positive Y (thou)
LongMill MK2 48×30 (extrapolated)	7	10
LongMill MK3 48×30	4.5	8
Difference (thou)	2.5	2
Difference (%)	64.29%	80.00%

Comparison at 50N/11.24lbs

	Positive X (thou)	Positive Y (thou)
LongMill MK2 48×30	14.2	20.7
LongMill MK3 48×30	10	11
Difference (thou)	4.2	9.7
Difference (%)	70.42%	64.29%

Expected Loads

To get an idea of what sort of loads a machine will experience in cutting:

Basic glossary

Axial engagement (AP) = depth of cut

Radial engagement (AE) = stepover/width of cut

Linear feed (VF) = feedrate

Transverse force = forces perpendicular to feed

Feed force = force needed to push the bit through the material

Axial force = up and down (in the Z axis) forces

Generic ¼” end mill

For a list of recommended feeds and speeds for our general selection of end mills, please see our guide here: https://resources.sienci.com/wp-content/uploads/2022/10/FeedsSpeedsMetric.pdf

Settings based on recommended feeds and speeds

Same settings as above but with a 6.35mm step down

Same settings as above but with 6.35mm step down and 6.35mm step over (full slot)

We will refer to some of these values in our discussion below.

Balancing machine performance and cost

Building a machine to be rigid and powerful is easy, but making a machine rigid and powerful on a budget is hard. To optimize the design of a machine, we take many factors into account.

Acceptable deflection

As my electrical engineering professor used to say, in science, 5 = 5, but in engineering, 5 = 5, plus or minus a tolerance, which is to say, whenever we cut out a part, we should expect some deviance in the size of that part, and we need to decide and understand how much deviance we can accept.

In the scope of woodworking, I believe anything under 0.005” (5 thousandths of an inch) to be “very very accurate”. For context, 0.005” is 6.25x smaller than 1/32”, or about a sheet and a half paper thick.

LongMill MK3 48×30

Force Applied (N)	Force Applied (lbs)	Positive X (thou)	Negative X (thou)	Positive Y (thou)	Negative Y (thou)
25	5.62	4.5	5	8	9
50	11.24	10	10	11	12
75	16.86	16	15	17	18
100	22.48	22	21	24	25

If we look at the range of deflection at different forces, we can determine that we should aim to keep forces to under 25N to be within the 0.005” deflection range.

Motor power

In our testing, we also measured the maximum force that the motor can apply to each axis. On the X axis (one motor), we measured the force to be around 600N, or 135lbs. On the Y axis, 256lbs.

Each motor must resist internal machine forces, such as the friction from the lead screws, bearings, and linear guides, as well as control the inertia of the machine itself. Additionally, the motor must push the end mill through the material at varying forces.

The mean and peak feed forces from Millalyser give us an idea on what those forces are (3.8N-10.4N). Based on these calculations, the motor forces are far higher than the expected loads from cutting.

A few notes:

We have 1.2NM motors on all axis, which will be the same as the ones used on the LongMill MK3 in production.
We used a 48V power supply, instead of a 24V power supply in production

Given how much more powerful the motors are, we believe that running the machines in 24V will not make a difference in overall performance. Because the 24V power supply and SLB-LITE designed specifically for the LongMill MK3 is significantly less expensive than the 48V architecture used on the AltMill, it makes sense to go down this route.

Spindle/router power

Through our AutoSpin T1 project, we did a significant amount of testing and research around spindle and router power, even going as far as building our own dynamometer to test true power output of different routers and spindles. Millalyzer also gives us an idea on the range of power draw needed from the router, ranging from 68.6 watts to 234.8 watts.

The green line shows that the Makita RT0701 can push around 1600 watts of power until dropping down to around 350 watts of power at 32,000RPM. A typical 1.5KW spindle progressively increases power output as the RPMs get higher.

We can ensure that the spindle or router used with the LongMill MK3 is capable enough by comparing the estimated power draw from Millalyser to our measured output line. In either case, both the Makita RT0701 or 1.5KW spindle is more than capable of producing enough power.

Our LongMill 1.5KW spindle kit costs around $650USD versus AutoSpin T1 is around $150USD, which is a 4x difference. Users can use either option, but we believe that the AutoSpin T1 is adequate for this application with the added benefit of the lower cost.

AltMill vs LongMill MK3 comparison

As it stands, the AltMill is approximately 2-4x more rigid than the LongMill. This is largely due to:

Thicker and heavier structure on the AltMill
Higher mass of the machine on the AltMill

If performance and rigidity is very important to you, the AltMill does provide much more in that way.

There are some practical considerations to make when it comes to actual differences in cutting, such as:

This is something I learned people call the “pucker-factor”, which is that people may not be so inclined to push their machine as hard as they can because of a lack of confidence.
Tools have a limit to how hard they can cut because they can deflect and break as well

Overall, I expect the practical cutting performance of the AltMill to be around 2x of the LongMill MK3.

If you’re cross shopping between the LongMill and AltMill, here are the prices to consider:

LongMill 30×30 ~$1390USD or $1870CAD

LongMill 48×30 ~ $1790USD or $2410CAD

AltMill 2×4 ~ $2790USD or $3890CAD

AltMill 4×4 ~ $3160USD or $4290CAD

…so between LongMill MK3 48×30 vs AltMill 2×4, which I think is the closest comparison based on working area, the price difference is around $1000USD, or comparing the 4×4, $1370USD.

We should also note that the AltMill also requires a spindle, larger tooling, and higher power dust collection to get the maximum performance, which can increase the cost difference when comparing between total setup costs.

Conclusions

With improvements to the machine rigidity and motor power, we expect users to be able to cut much faster and reliably compared to the LongMil MK1 and MK2. A significant amount of work and consideration has been made to improve performance overall while keeping the price the same as the older generation.

While this article only covered testing around rigidity, make sure to stay tuned on discussions of other improvements for the LongMill MK3, including easier assembly, maintenance, and electronics as well!

We hope you enjoyed this report on the LongMill MK3 design and performance!

LongMill MK3 Call for Beta Testers

Posted on January 5, 2026January 5, 2026 by Andy Lee

Hey there. We’re now looking for beta testers of the LongMill MK3. Interested in being a beta tester? Please check out the details below. A link to the application form can be found at the end of this article.

What does “beta testing” mean?

Beta testing involves the process of testing and using a product in a real world environment before mass production or general release. In our case, the LongMill MK3 platform is a new product that is actively in development. While we are confident in the performance of the new machines, we feel that it is important to get it into the hands of real users to obtain feedback and information about: how well the machine performs; how it works; and potential issues that may happen in manufacturing or production of the final product. We also want to identify users and use cases for the product to help us target our machines to the right people based on what you do during the beta testing period.

As a beta tester, your responsibilities are:

Putting your beta machine through the paces
Reporting back to us with feedback on a regular basis
Letting us observe and test your machine
Sharing your learnings and testing with the community
Optionally, participating in a video interview to share your experience

As the company providing the beta machine, our responsibilities are:

Providing you with one-on-one technical support for your machine
Helping you set up your machine (either in person or virtually)
Providing you with updated parts to ensure your machine aligns closely with the final production version

There are several differences that you may see between the beta testing machines and production machines:

Some parts will be uncoated, such as the gantry plates and aluminum parts
Machines will either be partially assembled or come in non-production ready packaging
Some parts may be off the shelf components not from our regular manufacturers

Pricing

We charge for our beta testing machines. We believe that is the best way in vetting between folks that are purely looking for a discounted or free machine and folks who truly need or want a machine. It is our top priority to work with beta testers that will find true value from owning a CNC machine and use it long term. We ask beta testers to ask themselves: “If this was a product I could buy now, would it bring enough value to me to warrant the amount I would pay?”

If you’d like to hear some interviews from our former beta testers, please check out some of our videos.

Final pricing for production units have not been determined yet. However we expect pricing to be around the same as the LongMill MK2/MK2.5, and thus beta testing pricing will be as follows.

30×30 working area= $1,950CAD

48×30 working area= $2,450CAD

What you get:

A full, LongMill MK3 machine
Secondary accessories like the dust shoe and AutoSpin T1
One-on-one technical support and set up assistance
Parts to upgrade your machine to production level spec at release

What you need to provide:

A space and bench to put your machine
A sheet of ¾” MDF to act as your wasteboard

What is the LongMill MK3?

The LongMill MK3 serves as the successor to the LongMill MK2 and MK2.5. Just as all of the LongMills that came before it, the LongMill MK3 aims to be a beginner friendly and affordable CNC machine with the capabilities to produce meaningful projects.

The LongMill MK3 comes with several key updates to its design, including linear guides and closed-loop stepper motors on all axes, allowing for a faster, more reliable and more rigid machine than its predecessor. A significant reduction in unique components also makes assembly and maintenance faster and easier. With all of these improvements, we believe that the LongMill MK3 is the ultimate starter CNC machine.

Timelines

We will select 3-4 beta testers in mid to end of January 2026. Beta testing units are expected to be shipped or hand delivered to you starting in mid to late February 2026. We expect the beta testing phase to last approximately 12 weeks.

Sharing with the public

As a beta tester, you may share details of your work and usage of your beta machines freely. You may provide feedback and information with the community without restriction. We may however ask you to sign a photo/video release form if you get selected (in case we use your footage for marketing purposes on our end.)

Application form:

Apply to be a beta tester

FAQs

Will the LongMill MK3 be compatible will your accessories?

With the exception of the LongMill MK2 generation dust shoe (the LongMill MK3 will have a new dust shoe), accessories like the AutoZero touch plate, Vortex Rotary Axis and gControl Panel Computer will be compatible. The LongMill spindle kit will also be compatible with the LongMill MK3.

Due to weight restrictions, the Automatic Tool Changer will not be compatible with the LongMill MK3.

Will I be able to upgrade my LongMill MK2 or MK2.5 to a MK3?

While some of the parts are transferrable between generations, the LongMill MK3 comes with significant changes to the rails, linear motion and electronics that are unique to the new machine. It is not cost effective to upgrade older generations of the machine to the LongMill MK3.

What’s the difference between the LongMill and the AltMill?

The LongMill is focused on beginner hobbyists. The AltMill is designed for more dedicated hobbyists and for low volume production use. There is a size, cost and performance difference between the two machines. However, with the LongMill MK3, we’ve integrated a bunch of AltMill components, closing the gap between the two machines.

April 2026 Production Updates

Posted on April 7, 2026April 6, 2026 by Andy Lee

It’s another month, another production update!

Notes on customer service times

First off, I just wanted to mention that the last couple of months have been pretty busy on the customer service and support side of things, especially as we were coming down from our busy winter season, which meant that response times were a bit longer than usual. I’m happy to share that we did bring on another support person to our team with a lot of hands on experience being a former customer, which means we now have five full time staff for customer support, plus, some of our engineers and product management team also involved in the customer service and resource development.

We’ve now caught up on tickets and replying back on our typical timely manner.

With the AltMill 4×8, ATC, and a bunch of other stuff going through our pipeline, we anticipate our demand for support to continue to grow, so if you’re interested in joining our customer service team, feel free to share with us here: www.sienci.com/work

AltMill 4×8

Mike presents the upcoming timeline in the company townhall

We have been full swing on AltMill 4×8 production, with a bunch of stations now set up for assembly of the new machines. However, we have been delayed a few weeks, and current first machine shipping date is set at ~~April 10th~~ April 17th. Due to some components being off tolerance and needing rework, we are putting extra effort to make sure that the first batch of machines don’t have early stage issues. Some things that are being addressed include:

Pitch error on the racks
Tooth profile tolerances on the pinons
Gearbox backlash

On the bright side, we have ordered enough extra parts so that even with a higher than typical number of QA rejects, we are able to fill a substantial number of the first batch. We are also working on remaking parts to ensure that we can complete the rest of the production batch. We are building and assembling as much as we can as we work through the process in the meantime.

We are also now in production of batch 2, bringing additional considerations and QA processes to reduce potential issues and delays.

In other news, the engineers and marketing team have been working on putting together the full assembly resources and videos over the last few weeks, getting ready to post once the machines start shipping.

Filming and creating content for the assembly process

Assembled units for the gearbox and swing arm mechanisms

LongMill MK3

A lot of work/progress so far with the LongMill MK3, with most of the work done around general testing and reliability.

We have now completed a round of rigidity testing to compare between the LongMill MK3, LongMill MK2, and the AltMill. Check out the results on our blog. (TL;DR) = the LongMill MK3 is between 65-80% more rigid than the LongMill MK2, signifying a big jump in performance.

In other news, we continue to work on the development and production of the LongMill MK3. We have now ordered the majority of the components needed, with the exception of controllers and power supplies which are still in development. Based on current timelines, we expect to open up pre-orders mid-May, and start shipping in and around July.

In other news, we’re clearing out of the last set of LongMill MK2.5s . We have around 50 of the 30×30 and 50 of the 48×30 in stock, so if you are looking to get one of those machines, they’ll probably still be available for the next few weeks before we sell out.

SLB-EXT V2 and SLB-LITE

We have made a few key decisions around the SLB family of controllers. First, naming:

SLB-EXT V2: The new successor to the original SLB-EXT currently used on the AltMill. The SLB-EXT V2 is designed specifically for the AltMill and power handling of 48V.

SLB-LITE: Designed specifically for 24V architecture of the LongMill.

Wire management with the new SLB-EXT case

Our first prototype boards have been produced! We will go through initial flashing and testing of the new board over the next few weeks in April, and make revisions as needed before going into production.

Additionally, new molded cable samples have been made with a nominal width of 7mm, over our current nylon sheath design with a width of 10-12mm. Why did we unify all of the cables into one mold? Because:

Simplifies wire management
Makes wiring of the machine during the assembly process more intuitive
Allows more space in the drag chain for additional cables and accessories

Auto Tool Changer

The ATC production is now in full swing as we get prepared to ship out existing orders. We have set up production stations to start with assembly and we are building our first units now.

Unfortunately we are continuing to work on a few straggling details in preparation for shipping, and we expect that we will begin shipping in the third week of April. Some outstanding tasks include:

Completion of the resources and installation guides
Completion of the new firmware testing

Otherwise the completion of the hardware production and assembly for the first batch of ATCs are scheduled to complete on ~~April 10th~~ April 17th, in tandem with the 4x8s.

I’m also excited to share that we’ve also implemented a new station with the ATC to machine some aluminum parts in house. We’re expecting to slowly integrate more parts over time that we can machine in house to give us an opportunity to stress test our machines and products, as well as give us more production flexibility or adjust designs more quickly as needed.

Ethan checking for Tool Rack defects with a jig

March 2026 Production Updates

Posted on March 10, 2026March 30, 2026 by Andy Lee

Hello there, welcome to our March 2026 Production Updates!

AltMill 2×4 and 4×4

Lead times for 2×4 and 4×4 machines are now fairly short, with most machines shipping out within 2 weeks. Lead times for 1.5KW and 2.2KW spindle kits may vary. 2.2KW spindles for the AltMill are expected to ship in approximately 1-2 weeks as well. 1.5KW spindles are backordered, and are expected to be restocked in mid-to-late April. We will provide a more detailed update on the product page once we have more details.

Orders for AltMill 2×4 and 4×4 will ship out separately, which means that users can assemble their machines ahead of time.

Office Expansion

We just expanded our office again! Mid-last year, our upstairs neighbours moved out so we took over around 6000sqft. There was also a part of the office with a stairway that lead to nowhere. Now, that stairway leads somewhere! We are knocking down that wall to take over a portion of our next door neighbour as well. This move adds another 2000-3000sqft, which will be used for some assembly work, especially for electronics, as it is more isolated to the larger office and we can reduce the amount of dust for those parts.

LongMill MK3 Development

LongMill MK3 development continues to chug along.

Setting up the first LongMill MK3 with Dave

We set up our first machine with our beta tester, Dave! Since he’s our first beta tester, we learned a few things, including:

Starting the Y gantries at the front of the machine makes it easier to put on the X rail, especially if you have limited access to the back of the machine.
Putting the X rail onto the Y gantry can be a bit finicky. We are potentially going to update the design of the Y gantries to allow the rail to drop in sort of like the AltMill.

Other changes and updates in progress include:

Redesigned Z-motor mount to allow the inductive sensor to sit higher up, allowing for more travel.

We are still looking to onboard and work with two more beta testers, which should happen in the coming weeks.

We are also slowly starting production on some of the major, long lead time components in the coming weeks.

Additionally, we are coming close to the end of the LongMill MK2.5 batch. Once we have sold out on the remaining machines, we will not have LongMills available for sale until the new batch of MK3 machines start shipping. We are currently checking inventory to confirm how much longer we have, but we estimate approximately 1-2 months of stock remaining currently. LongMill MK2.5 machines are shipping within a week.

SLB-EXT V2

The development of the new controller continues to be underway. For those not up to date, we are working on a new version of the SLB to be better optimized for cost and manufacturing, while still keeping the same functionality of the original SLB.

A ton more work done with the new SLB, including:

Updated layouts for the traces and components
Design and development of the advanced breakoutboard
Design of new plugs and cables to improve wire management

We will start the process of making a batch of prototype boards and conducting testing in the coming weeks.

AltMill 4×8

As of Feb 23rd, we have received all of the parts needed to start building 4×8 machines, with the exception of some screws and small straggler parts such as some allen keys, warning labels, etc. Much of the work is currently with testing and QA for incoming components, as well as working on the setup for the rest of the production area to get ready for assembly of major components in the next week or so.

Mike with the 4×8 AltMill Y rail assembly station

Closer look at the AltMill 4×8 rack and pinion assembly station

Automatic Tool Changer

We have now received the majority of the parts needed for ATC production and are currently putting together space for the assembly and testing. We are expecting to start shipping out ATCs at the end of March, which will be a few weeks delayed compared to our original anticipated delivery time. Macros for the ATC, which are programs for controlling the ATC functionality can now be found online here: https://github.com/Sienci-Labs/atci_macros. We are also expecting to have updated versions of gSender plus online resources complete by shipping time, so the small delay is allowing us to get some of those things polished up.

Clear Cut Dust Shoe

We’re excited to announce that the Clear Cut Dust Shoe is now available for sale! However due to higher than expected demand, the ~150 units we had stock were sold out within 24 hours, plus more with units that were sold with spindle kits.

We’ve put a pause on selling Clear Cut Dust Shoes individually for now, and we are currently working on ramping up production on that. We have a separate amount of stock for the spindle kits, so that we will ensure they are included on all of the spindle kits we ship on a 1:1 basis. We’ll have another announcement coming out soon to let everyone know the production schedule for the new dust shoes.

Informal Call for New Staff

I want to put some feelers out in the community for someone looking for jobs/roles in finance and HR. Up till now, we’ve/I’ve been managing this side of things since our company is not quite large enough to have someone fill this role full time, but given how things are going, I feel like we need to look in earnest for people to fill some of our company admin roles.

If you feel like you might be a good fit in a finance or HR type position at a startup or small company like Sienci Labs, feel free to send in an application here: https://sienci.com/work/

Oh also, we are looking for an electronics/embedded design engineer as well, so feel free to apply for that as well.

February 2026 Production Updates

Posted on February 3, 2026February 3, 2026 by Andy Lee

Hey everyone, welcome back to our February 2026 Production Updates!

AutoSpin T1 Has Launched

We’re excited to finally launch the AutoSpin T1! Learn more about it here: https://sienci.com/2026/01/20/everything-you-need-to-know-about-the-autospin-t1-router/

We received our shipment of approximately 2000 units on February 2 (it was supposed to be mid- February) and will get routers shipped out to customers shortly after.

AltMill 4×8 Production

We continue to wait and prep for the arrival of AltMill 4×8 components. Based on our schedules, the last remaining parts for the 4×8 are scheduled to arrive between Feb 20th to March 6th. Other parts are expected to arrive sooner, which means that assembly for the first units will start approximately mid-February, allowing us to make progress in advance before all parts arrive.

In other news, resources for the 4×8 assembly continue to be worked on, with filming for the assembly video scheduled for the second or third week of February in preparation for customers to start receiving their machines in March.

LongMill MK3 Development

Thank you all for the overwhelming response of applications for LongMill MK3 beta testing. We’ve now received the rails and started internal testing. We will be sending out beta testing units to selected individuals in the next few weeks.

First functioning prototype build of the LongMill MK3

As it stands, we’re super excited about the LongMill MK3 as we expect to bring a massive leap in performance over the LongMill MK2 and 2.5, while keeping it at a super competitive price point. Some additional work we’re doing to bring down BOM costs include:

An easier to manufacture, significantly improved dust shoe with easy to replace bristles. This means not only is the overall cost of the dust shoe less, but users can extend the life of their dust shoe by replacing just the bristles. We will provide users with extra bristle in each kit.
Integrated cables. With current cables being a combined bundle of motor signals, power, and inductive sensor signals sheathed in one nylon cover, we’re looking at molding a single cable to reduce the overall unit cost of the total cable.
SLB-Lite. With the SLB-EXT being a major cost in the total BOM cost of the LongMill MK3, development (see in the next section of the article) is expected to keep all of the core functionality of the SLB and SLB-EXT, in a smaller, lighter, and more affordable package.

SLB-Lite

In our discussion about the LongMill electronics, we mentioned, especially with the Closed Loop Stepper Kit, that the overall cost of the electronics currently makes up a significant portion of the LongMill MK3 bill of materials. This is primarily because the electronics were specced and designed for the AltMill. However, for the smaller and less power hungry LongMill, the AltMill electronics are functional but overkill for the application.

Peter and Daniel and have continued to work on the newest generation of electronics to act as the successor to the SLB-EXT used in the AltMill. We expect a number of improvements for the new controller, currently code-named “SLB-Lite”, including:

Lower cost, with the board expected to be around half the cost of the SLB-EXT
Improved wire management
Overall smaller footprint, allowing for lower shipping cost and easier integration into LongMills, AltMills, and other CNC machines.
Ability to use power supply voltages from 24V-48V and the ability to provide up to 100 watts per motor.
Ability to connect an additional board for added features and functionality beyond the SLB-Lite, while still being less expensive in combination than the SLB-EXT.

Lastly, by using the same controller on all of our CNC product lines, we expect to see savings through the economies of scale by essentially doubling the number of units produced. Plus we expect to reduce our inventory management costs with fewer unique components, and a more unified experience between the LongMill and AltMill lines.

Additionally, coming to all controllers is new SLB and SLB-EXT firmware, with overall performance and stability improvements, and specific features like faster and better handling of motor alarms and resetting, support for advanced plug-ins used for the Automatic Tool Changer, and unlocking of SD card features allowing for running gcode and files directly from the controller. More details on the new firmware and ability to have access to beta firmware before the wider launch available on our blog.

To coincide with SD card support, the upcoming gSender Edge (our beta version of gSender), will be coming out with the interface to communicate with the SD card. When both systems have been tested to be reliable, full support for the new firmware and all of the new improvements will come to the main version of gSender.

To hear Kevin talk about SD card support in the next gSender Edge release, check out this video here:

gControl Panel Computer Pricing Updates

Due to the recent RAM and memory shortages, pricing for the gControl has been increased. We are keeping an eye on the pricing for components as they change, and are hoping that pricing will come down soon. We will update pricing when RAM and memory prices come back to normal levels.

Certified VFDs are Now Shipping

After a long wait, certified VFDs have finally arrived and have undergone testing. Customers who are waiting on VFDs will receive them shortly.

ATCs Sells Out; New Batch Added

Due to higher than expected demand for the ATC, we have sold out of the first batch. Customers who place orders moving forward will be part of the second batch. The first batch is expected to start shipping in late March, and the second batch is expected to ship in June.

First look at production covers for the ATC.

Curious on how this whole ATC thing works? Check out Johann’s breakdown video here:

January 2026 Production Updates

Posted on January 6, 2026January 6, 2026 by Andy Lee

Hey everyone, happy new year! It’s time for a very exciting 2026!

Potential Resolutions for UPS Issues

We had some interesting visitors from UPS, including Sean Griffin, president of UPS Canada, Dean Tabakos, Director of Business Development at UPS, and Frank Perez, UPS President – Americas Region & International, Healthcare and Supply Chain Solutions (SCS) Engineering, and our UPS rep, Todd McCracken.

As we mentioned in our previous updates, we’ve been having some issues with UPS shipments, primarily with things getting stuck at the border. This meant that we were getting a lot of shipments being sent back without any reason. We were also being charged a lot of taxes and duties when we weren’t supposed to.

With all this going on, some of the high-level execs from UPS decided to stop by our office to take a look at what was going on and let us know some of the work they were doing to get shipping back on track.

Reducing issues with customs declarations

With the change in regulations requiring all shipments entering the US to have customs clearance (before it was just for shipments above $800), UPS and other shipping and logistics companies were slammed with a significant volume of declarations needing to be made. With a big part of this process being human-driven, many shipments were being held at the border or sent back for customs issues and errors. We were told that with the implementation of new systems and AI, they are now able to automate more than 95% of the processes, meaning that the error rate and speed have gone up dramatically.

Reducing border hold-ups

When a multi-part shipment is created, but all parts of the shipment are not in the same truck, every item in that truck is sent back. Initially, this caused a huge number of shipments to be shipped back. With the change in generating separate manifests, shipments are accounted for on a truck-to-truck level, which eliminates issues created when multi-part shipments don’t travel together.

This is expected to reduce the number of shipments being sent back from the border, but also reduce transit times and lost packages because prior to this change, multi-part shipments needed to be held in a facility until all of the parts of the shipment are ready to cross the border. This specifically impacts us because most of the machines that we ship must be shipped in several packages, which means that if all boxes for that shipment are not together, they will wait in a warehouse until they are. This creates more opportunities for damage as they get transported around the warehouse as they wait, or get lost if they are misplaced.

—–

It’s hard to say how much things are going to change in the short term, but we are obviously optimistic that as we get settled into the new normal of more complicated reporting and customs processes, we will have fewer shipping issues.

Tax Registrations for Nexus

Some customers may have seen us charge sales tax for certain US states. This is because we have reached Nexus in these states (usually $100,000 or $200,000 in annual sales, although rules and calculations vary by state). Taxes will be automatically calculated and charged, and we will remit them directly to the state to comply with US state tax laws.

Arizona
Colorado
Florida
Georgia
Illinois
Indiana
Maryland
Michigan
Minnesota
North Carolina
New Jersey
Ohio
Pennsylvania
South Carolina
Tennessee
Texas
Utah
Virginia
Washington
Wisconsin

Some of these states are new, some of them we have reached Nexus for some time ago and we have been collecting taxes already.

AltMill 4×8

Production for the AltMill 4×8 continues to move forward, with business as usual with:

More short and long term wear testing ongoing
Packaging planning and design
Resource development for the 4×8
Working with and gathering feedback from beta testers

Nathan with packaging planning for the AltMill 4×8

ATC

Auto Tool Changer work continues on as we wait for production to complete for parts. Some work done for December and ongoing include:

Continued testing for software and hardware
Packaging design and optimization
Testing of different compressor sizes and configurations

ATC production and development continue to move forward.

Closed-Loop Stepper Motors

First off, our closed-loop stepper motor kits are now available for sale! This kit allows users to install closed-loop stepper motors onto their LongMill.

In other news, we got a batch of closed-loop motors which had the wrong firmware onboard, which gave us a chance to reprogram and look into the tuning parameters for motors. Going through this gives us an opportunity to look at continual optimization of different aspects of our machine systems.

Certified VFDs

As we mentioned in some of our previous updates, we have certified our VFDs for the Canadian market. We initially certified around 100 VFDs in our first batch and are in the process of getting our next large batch of VFDs to ship to customers still waiting on their units. We were able to get around 40 units done early, so we will ship them to customers currently in the queue. We expect the remaining units to arrive in January to complete the rest of the queue.

LongMill MK3 Development

LongMill MK3 is in official development. Here are some design goals:

Reduce part count and variability

Reducing the number of parts reduces the amount of time needed to assemble the machine. Additionally, reducing the number of unique parts also allows the assembly process simpler by copying the same processes across different areas of the machine, plus reduces the amount of supply chain and inventory management we need to do. We expect the LongMill MK3 to have 30% fewer unique parts over the LongMill MK2.

We have a mix of parts that come from the LongMill MK2 and the AltMill, plus a bunch of new, unique parts that are specific to the LongMill MK3.

Improve reliability

The LongMill MK3 will use the latest family of SLB-EXT and closed-loop motors, self-adjusting anti-backlash nuts, and linear guides to provide significant improvement to machine reliability over the LongMill MK2.

Keep affordability

With improvements to our assembly and QA process, changes to the design, and larger economies of scale, the LongMill MK3 will have a target price with beginners and hobbyists in mind.

Lower the barrier to entry

The LongMill MK3 comes in conjunction with many new features and products, including:

The AutoSpin T1, which aims to provide spindle-like features and functionality at a lower price point
Inductive sensors included by default, implementing homing and other positioning checks

Currently our main focuses are in:

Producing and testing our first batch of prototype rails (expected to arrive end of Jan)
Producing and testing our first batch of laser cut steel gantry parts
Designing and developing a new set of electronics (currently code-named the SLB-lite), to bring down the cost of the electronics used in the LongMill to better fit the needs of beginners

AutoSpin T1

As mention in the last month’s blog post, we have now completed production of the AutoSpin T1 and are currently waiting on the arrival of the tools. We are expecting them to arrive mid-February.

AutoSpin T1 Router - Cord and Connection

10 Year Anniversary Party

Can you believe it’s been 10 years since we started Sienci Labs? We’re planning something to celebrate. Details are still percolating but this is what we have in mind.

Open House (afternoon): Shop tours, demos, and hang out/meet our team

After Party (night): Big, casual party and rave in our back warehouse

Everyone is invited, stay tuned on our social media for more details coming soon.

Our first Kickstarter video from 2014:

Everything You Need to Know About the Closed-Loop Stepper Motor Kit

Posted on December 15, 2025December 12, 2025 by Andy Lee

We’re excited to launch the Closed-Loop Stepper Motor Kit to the community. The Closed-Loop Stepper Motor Kit (CLSM Kit) is a complete kit including the motors, cables, controller and other hardware required to convert any LongMill MK2 or MK2.5 to use closed-loop stepper motors.

Order your kit here: https://sienci.com/product/closed-loop-stepper-motor-kit/

Contents of the kit

Each kit comes with all of the components needed to convert a LongMill MK2 or MK2.5 (any size) to a closed-loop motor system.

One (1) SLB-EXT Closed Loop Controller, plus:
- Independent e-stop with 3 customizable action buttons
- 2.5m e-stop cable
- 1m USB-C to USB-A cable
- Mounting brackets
One (1) 48V 10.4A Power Adapter
Four (4) NEMA 23 Motors and new motor covers
A drag chain (1000mm) to accommodate any size LongMill, plus drag chain brackets and holder mounts
Four (4) inductive sensors with mounts for Y-axis
Sixteen (16) 40 mm blue aluminum standoffs
Motor cable set (x1 long, x3 short)
M5x12 bolts
M5 washers, nylock nuts and t-nuts
M5x55 screws (for use with the LongMill dust shield)

Resources

Complete resources for installing the CLSM Kit to the LongMill can be found on our Resources site: https://resources.sienci.com/view/lmk2-closed-loop-steppers-2/

Specifications

Motor specifications: Nema 23

Motor (Frame) size: 57mm

Motor torque: 1.2NM

Motor max speed (RPM): Approx. 1500

Voltage: 48VDC

Length: 56VDC

Cable Lengths

X cable: 1.8 m

Y1 cable: 1.4 m

Y2 cable: 2.7 m

Z cable: 3.65 m

Measured from the 2×4 AltMill cables which we are using for this kit.

Changes to the Industry

In recent years, we’ve slowly seen a shift for hobby CNC machines to adopt the use of closed-loop stepper motors. We’ve also seen a shift in the price of the motors coming down over time as well, with the price for an open-loop stepper motor and external driver now at similar levels.

We still see open-loop steppers used in pretty much all budget and entry level CNC machines, but we expect this to change over time as the demands and expectations from the CNC community continue to grow. We also expect as the popularity of closed-loop steppers grow and prices come down, that most machines will start to use them.

Cost of Development and Open Source

We don’t keep exact tracking of how much time and money we’ve invested in this electronics ecosystem, but I would guess at this point we’d be looking at least a million dollars. This includes the development of the controller and electronics themselves, testing of the motors, and development of gSender. We recognize that for many up and coming CNC manufacturers and developers in our space, investing that much into development is not possible.

Pushing this ecosystem to a wider audience should allow CNC manufacturers and developers in our space to get a head start in pushing the ecosystem further and potentially scaling up where they can contribute to future generations of CNC companies.

A good example of this is Masso’s initial decision to move to a subscription model for updates, then a sharp retraction after backlash from the community (https://www.reddit.com/r/hobbycnc/comments/1jtfbkd/maso_reverses_course/).

While this situation changed course in the right direction, it does shed light on the fact that close source CNC control ecosystems reduce the control users and manufacturers have in a core part of their machines.

So why do the fact that our systems are open source matter? Well, it means that if we disappear from the face of the earth, users and companies can replicate and develop atop existing designs and code. We can’t make you pay more for what is already free and openly available.

Some folks may see allowing others to use and duplicate our designs as a potential danger to our business. However, the way we see it is if someone else can make what we already make cheaper or better, it would serve us to use this development for ourselves as well. The fact of the matter is that developing a CNC company is so much more than just the designs themselves. It’s also the resource development, customer service, community, and continued innovation that needs to be there in every company to succeed.

Closed-loop Steppers vs Open-loop Steppers

Closed-loop stepper motors are simply faster, more accurate, more efficient, and more powerful than an equivalent open-loop stepper motor, with the added benefit of being able to detect when it loses steps. This also adds another layer of safety, as our control systems automatically shut off attached peripheral devices like spindles and lasers when the machine loses its position.

How does this work? Well, with an open-loop stepper, you can think of the motor having a “cog.” When we want to move the motor, we send it a signal to move a single step forward or backward. In the case of most standard stepper motors, there are 200 “steps” in a motor (there’s also something called microstepping but we won’t get into that today.) By sending a specific number of step signals at varying speeds, we can control the angle of rotation specifically and the speed of the rotation as well.

When the system works without being overloaded, the system works quite well. However, when a load exceeds the amount that the motor can handle, the motor “skips a step.” This means that the cog goes out of line and the machine loses it’s position. However, because there is no feedback system in the motor, even if the motor loses its position, the motor will keep moving.

The reason why an open-loop stepper is less efficient than a closed-loop stepper is because not only do you need to move the motor forward, you also need to apply a force to keep it from overshooting its position. This is to say, if you wanted to move the motor a full rotation by sending a signal to move it 200 steps, it also needs to consume power to keep it in position so that the motor does not overshoot into the 201st step.

Closed-loop steppers on the other hand are structurally the same as an open-loop stepper motor, with the exception of having an encoder built onto the shaft that allows the microcontroller to measure the position of the motor continuously as it rotates. This means that the motor can act more like a bicycle, allowing the motor to coast in the position it needs to be, and apply a varying amount of power to keep the right speed up. By comparing the position of the motor using the encoder with the position the controller requires, it can adjust its position thousands of times a second.

When the motor becomes overloaded and the motor is no longer where the controller expects it to be, an error message is sent to the controller by the motor which allows the machine to emergency stop.

Since we use closed-loop stepper motors with an integrated driver, this also improves repairability and compatibility with many different types of systems as we can swap just the motor, and the driver and electronics inside the motor are specifically tuned for the motor itself. Using external drivers like on the SLB and the original LongBoard (used on older generations of the LongMill) it can be a bit trickier since different motors have different performance characteristics. This is why we tune the drivers to work best with the original motors, but when it comes to compatibility with other, non-Sienci produced motors, we can’t predict the performance.

Economies of Scale

One of the big advantages that we have is that unlike independent manufacturers of controllers, we already have an established volume of production (our machines) that allow us to get to higher economies of scale.

Offering the CLSM Kit for the LongMill is our first step in unifying the technology stacks between the LongMill and AltMill lines, and committing to closed-loop motors on all our machines. This allows us to leverage even larger levels of economies of scale, allowing us to reduce our production costs even further.

We’re also able to leverage economies of scale into the optimization of the motors themselves. In our first batches, we were using off the shelf motors with standard tuning. However, with a recent issue from a new batch of motors that requires us to reflash and reprogram the motors, we started delving into further motor tuning that will in the future allow us to optimize motor performance for our line of products. If we were dealing with a small number of motors, it may not be economical for us to focus on tuning those motors, but if we’re dealing with a large number of motors, we can spread out those efforts more, making the cost of tuning less per-motor.

Right now the CLSM Kit uses the same motors as the AltMill 2×4 and 4×4 (Z axis motors) and shares cabling with the AltMill 2×4. We expect to see some interchangeable use of parts between the AltMill and LongMill lines as we continue to develop these products into the future.

Future plans

The closed-loop stepper motor system and SLB-EXT systems are a great, feature-filled, proven platform for mid-level and semi-professional use. However, we do acknowledge that it’s expensive for entry-level hobbyists. One of the projects we intend to work on is to create a more affordable version of the SLB-EXT and peripheral electronics that fit better with hobby level machines. This will open up some new possibilities with developing more affordable, entry-level machines.

We also believe that opening up the use of our electronics platform and software will open up new possibilities for people looking to update and upgrade their existing systems, as well as supporting emerging CNC manufacturers to integrate our systems into their own machines, reducing their cost of development.

Pricing

The complete kit is available for purchase for $560USD/$795CAD. Kits are expected to start shipping out in around 2 weeks from time of purchase.

FAQs

What machines can I use this kit for?

We have specifically designed this kit for use with the LongMill MK2 and MK2.5. Each kit comes with all of the hardware and electronics needed to make this conversion.

We believe that this kit can also be used with non-Sienci built CNC machines, such as DIY kits and other hobby CNC machines. However, we do not have resources and guides to help customers on the assembly process at this time.

Does it come with software?

The CLSM Kit comes with the SLB-EXT which is compatible with our free, open-source, and powerful control software, gSender. This allows users to use the full range of gSender features.

Can I buy a LongMill now with the CLSM kit instead of the open-loop motors that come by default?

At this moment, no. We are planning to release a LongMill MK3 in 2026 that will offer the LongMill with closed-loop stepper motors as the default option. TBD on announcement and launch plans but news should come out sometime in the spring. Stay tuned for future blog posts and news via our socials.

If I have a SLB already, can I use that instead of the SLB-EXT?

Unfortunately, no, the SLB does not have the motor connections that allow it to interface with the closed-loop stepper motors and the power distribution circuitry to power all of them.

Why is the LongMill MK1 not supported?

Given that there are much fewer LongMill MK1s currently in the wild, and the mechanical structure of the machine is less suitable for more powerful motors, we opted to focus on only supporting the LongMill MK2 and MK2.5.

Do you have any drawings so I can adapt to another brand CNC?
Yes! You can download all plans here.

December 2025 Production Updates

Posted on December 2, 2025December 8, 2025 by Andy Lee

We’re now in the final month of the year! What a crazy year it’s been, especially with the growth of the AltMill platform, the launch of the ATC, new tools, accessories and more. We’ve seen significant growth in 2025, with our company and sales doubling from 2024.

Holiday schedule

Our offices will be closed for the holidays from Dec 25 to Jan 1, and we will reopen Jan 2, 2026.

We will continue to ship orders up to Dec 24th, however, we recommend placing orders in advance if you need them to be shipped out beforehand.

Customer service, shipping, and other company functions may be limited at this time.

ATC

The ATC has now launched!

Production is now underway, with our intial batch of parts ordered for the first 160 units. We are aiming to start shipping units in Jan 2026 based on our current schedule.

We also have a livestream scheduled on YouTube, so make sure to check that out.

Live Stream, Dec 4, 7pm

AltMill 4×8

AltMill 4×8 was just launched and is currently in production as well. Most parts have been ordered, but a few major parts such as the extrusion and gear racks are going through final sample checks before full batches are ordered.

Now that the 4×8 is launched, we’re mostly in a waiting game for parts. We are slowly starting set up processes to get ready for the assembly.

AltMill 2×4 and 4×4

AltMill 2×4 and 4×4 are continuing to ship. However, we’re currently waiting on more 1.5KW and 2.2KW spindles to arrive, expected in the second week of December. This means that the machine and spindles may ship for some orders at different times. Once the spindles arrive, we are expecting to clear out of the remaining queue fairly quickly.

AutoSpin T1

We’re excited to announce that the AutoSpin T1 is now in production. We received our first production sample at the end of October and started our final set of testing. Although the performance and function of the tool met our standards, we had to get a second unit built to ensure our text and logo matched our standards for packaging and silkscreening, since they were a little bit off. However, we have checked the latest version and were able to accept it for final production.

We now have the first 2,000 units in production. We are expecting production to complete around mid-December, and we should have them arrive at our shop around the end of January.

Closed-Loop Stepper Motor Kit

A few months ago we put out a post to test the waters for interest on a closed-loop stepper motor kit. Since then we’ve received quite a lot of interest for a kit for adding CLS motors to the LongMill, as well additional inquiries to retrofit the motor and control systems on non-Sienci Labs machines.

Otherwise, we are currently wrapping up the remaining ordering of parts and finishing the resources and documentation that will be available to help users do the installation at the time of launch.

We’re excited to share that we are reaching the final stages for supply chain, testing, and resource development for a kit. We are now working on figuring out pricing as well as the potential tie in with the LongMill MK3 in development. Keep an eye out for launch info coming out in the next 3-4 weeks!

Closed-Loop Stepper Motor - X-Axis Motor

Closed-Loop Stepper Motor - Y2 Sensor Placement

gControl Panel Computers

We’re happy to have received another batch of gControl Panel Computers, so we’re shipping out to folks who have been waiting first (roughly a month.) We are expecting to have stock until January or February. We have also ordered another batch of computers expected to arrive early next year as well.

We are experiencing a new potential issue. RAM and memory prices have skyrocketed in the recent months, with news reporting that demand for these parts have increased due to AI. Because of this, the newest batch of computers that are currently in production will ship to us without SSDs and RAM. We are hoping that the price of those components will go down early next year. If not, we will have to reconsider pricing for the computers.

Another production update for the LongMill

Posted on April 18, 2019April 14, 2023 by siencilabs

Hi everyone! I just wanted to provide a quick production update and let you guys know what we’ve been up to, as well as some things that you might see in your LongMill. Please note, we are working on making small changes that will improve the performance and ease of assembly of the LongMill. The changes mentioned in this post may or may not show up in the final production version.

We’ve been spending a lot of time the past week to get the parts prepared overseas and taking advantage of the economies of scale to make some small modifications to the hardware to improve performance and assembly for the LongMills. Here are some of those things:

Parts printing has started

We’ve been continuously been printing parts for almost two weeks now, fine tuning the settings on the parts and making adjustments if needed. We are starting with printing the middle Y axis rail supports and X axis rail brackets (Chris calls them “shoulders”), since the designs are finalized on those. Other parts that are being finalized for printing include the X axis motors mounts and the Z axis motor mount. We have asked our motor manufacturer to add threaded holes to the mounting face of the motors to make assembly easier, but we need to have the samples come in for us to make sure that everything comes together perfectly. Samples should arrive in the next week, so we should be able to see how that turns out pretty soon.

We are currently running our two Prusa i3 Mk3s about 16 hours a day. We have two Cetus printers that just went through some TLC so we will have those up and running soon. We are planning to grow the farm by an extra 4 to 8 printers once we finish up the calculations on print time and see how many we need to keep pace with orders.

Using an off the shelf aluminum router mount over a 3D printed mount

We’ve found a good option for an aluminum router mount to replace our 3D printed mount. This means that

We can save on printing time
Potentially secure routers better and with more rigidity (but we still need to test this)
Customers and builders can source the mount from multiple sources if needed

The exciting part of using this off the shelf router mount is that it comes in several sizes, making it easier and more secure to attach some of the larger routers and spindles. We will have to do some testing to see what the Z axis performance is like in terms of moving larger spindles (52mm to 80mm), but it is good to know that it is a possibility.

If we find that the performance isn’t as good, we will stick to printing our mounts. Test mounts are on the way and should show up in the next week and a half.

Taller Y axis plates and Y axis dust protection

We’ve gone and adjusted the height of the Y axis to allow for the LongMill’s Y axis to be flipped to the other side. This can help if you:

Want make the machine more narrow
Are worried about dust getting into the lead screws
Fit more stuff underneath the machine and cut thicker items

One downside of flipping the axis is that it is trickier to set up the drag chain along the Y axis. We’ve come up with another way to make a “shield” that works as well to help block dust. JUST A QUICK DISCLOSURE… all of the machines we’ve been testing and using have had no dust protection on the Y axis and have worked fine over all of the testing. We’ve concluded that this is just an optional precaution if you really want it.

Improved print quality, new printers

Posted on May 29, 2018May 29, 2018 by siencilabs

One of the key areas that we strive to improve on in our manufacturing process is with the quality of the 3D prints in the Mill One kits. Our 3D printed part quality is an area that has a lot of room to grow in terms of improving quality. We have worked with our customers and listened to their suggestions to improve print quality, and over the last couple of months, our prints have become stronger, more consistent, and more precise. Making these improvements have involved testing different print settings, nozzle sizes, bed surfaces, and materials.

One other step that we have taken in improving print quality has been to update our printer farm with two new Prusa i3 MK3 printers. This is to increase our print capacity, as well start replacing printers from our aging fleet. One of our longest lasting printers has close to 3000 hours of printing on it.

If you’re familiar with Prusa as a company, they build industry-leading printers known for their consistency and reliability. They are currently being used to print the ACME nut mounts and the angle mounts, which are parts that require good layer adhesion to provide high strength. Based on our initial tests with the ACME nut mounts, it appears that these new mounts are stronger and less prone to cracking than mounts made by other printers. We have one printer that has been working fairly reliably but still need to fix some things on the other Prusa to have it up and running properly.

Here are some other things that we have improved over the last couple months:

Reduce Z banding on the electronics holder and cover
Improve bed adhesion for the angle mounts
Adjust tolerances on the nut catches on the ACME nut mounts
Switch from using the Cetus printers for printing the ACME nut mounts over to the Wanhao i3 or Prusa printers to have a smoother bottom surface (the raft on the Cetus leaves a rough bottom surface)

We’re excited to be using these new printers for creating better parts and continually improving our kit!