The AltMill is the pinnacle of hobby CNCing, bringing industrial-level precision to a price point and ecosystem for both beginners and advanced users. The AltMill MK2 2×4 is your go-to CNC when time, performance and precision are crucial for production-level reliability.
The AltMill MK2 2×4 comes with a standard 80mm spindle mount only. It does not come with a spindle, which must be purchased separately.
Ontario, Canada Customers: Starting April 29th, we’ll be pausing sales for all sizes of AltMill. Please read further on specific plans for each machine – ESA Compliance.
Production level cutting speeds (approx. 600 inches/minute)
Closed loop motor system on all three axis to auto-correct positioning and auto-stop when necessary (reliable for production style work)
Requires little maintenance during project production
Advanced, production-style features including Y-axis auto-squaring; limit switches by default; and tram adjustment capabilities
Cuts materials ranging from hardwoods to plastics, foams, composites, aluminum – even steel
Support for 80mm spindles and routers
25″ x 49″ working area with a max Z-height of 5.5″
Footprint of 59″ wide and 38″ deep
Lead times This product has a potentially long waitlist, relative to demand and seasonality. For more info on expected shipping and delivery times, please see our Order Status page.
Additional information
Weight
76 lbs
Dimensions
38 × 11 × 12 in
Include Spindle and Dust Shoe Kit
Include Spindle and Dust Shoe Kit, Machine Only
origin-criterion
C
Lead time
1 week
What's Included
***Included with your AltMill MK2 2×4***
SLB-EXT controller and emergency stop
Partially pre-assembled rigid frame
Inductive sensors for homing
Sturdy metal legs with the ability to add 4ft wide shelving underneath
***Not included with your AltMill MK2 2×4*** Check out our recommended products tabs for an ideal set up, but note the following ARE NOT included with your order:
Computer or laptop
Spindle
End mills or bits
T-tracks
Waste board (e.g. MDF 2ft x 4ft sheet)
Set of metric Allen keys, standard bits or drill for assembly
***Some photos may contain items for illustrative purposes, such as spindles, caster wheels, t-tracks, or additional shelving. There may also be cosmetic differences between the machine in the photo and the production version of the AltMill.
Payment
Full Payment is required at time of purchase to get your order into the Queue. We ship on a first-come, first-served basis. If you choose local pick-up, you are subjected to the queue order and cannot get your machine quicker.
Power Requirements AltMill with the 1.5kW spindle. We recommend allocating 2x 15A, 110V/120V circuits — one for the spindle, the other for the machine and a computer.
The AltMill consumes 500W and runs off a 48V 10A power supply, 110-120 volt circuit
The 1.5KW Spindle Kit consumes 1500W at max load, 110-120 volt circuit
AltMill with the 2.2kW spindle. We recommend allocating 1x15A, 110V/120V & 1x 20A, 220/240 Circuit — one for the spindle, the other for the machine and a computer.
The AltMill consumes 500W and runs off a 48V 10A power supply, 110-120 volt circuit
The 2.2KW Spindle Kit consumes 2000W at max load, 220-240 volt circuit
If you live in a country with 220V/240V power you must use a transformer to convert to 110V/120V.
To solely run the machine, you need a rating above 500W
To run the machine and a 1.5kW spindle, you need a rating of 2000W
3rd Party Spindles – I would like to source my own spindle, what should I be aware of?
For spindles 2.2KW or above, you will need to install extra 220VAC wiring
The AltMill comes with an 80mm spindle mount, we do not have larger diameter mounts at the moment
The VFDs that may work with our controller are: Huanyang v1, Huanyang P2A, Yalang YL620, H-100, and GS20, however they are not plug-and-play — read this article for further information
Warranty
The AltMill has a 1-year warranty once it arrives at your door.
We want you to have a great experience with your machine, so if any parts are found to be missing or damaged, please email us. We will ensure that you receive the support you need to restore your AltMill to operating condition or provide a full or partial refund.
You may cancel an order if it has not shipped yet, please contact us if you wish to do so. We do not accept returns for AltMills that have already shipped.
General Warranty and Limits of Service:
Effective August 1, 2026
Throughout this policy the words “we”, “us” and “our”, or “Sienci Labs” will be used to refer to Sienci Labs Inc. herein and “AltMill” or “machine” will refer to Sienci Labs’ Sienci AltMill. Additionally, the words “you”, “your”, “user”, and “operator” will refer to the original purchaser/customer, user, or viewer of any of the products or media provided by or through Sienci Labs.
Sienci Labs Inc. (the “Company”) grants the AltMill (the “Product”) a standard warranty within Canada and the US to the original customer to be free from missing parts, defects in material, and defects in workmanship for a period of three-hundred-sixty-five (365) days from the date of receipt by the original purchaser. Sienci Labs Inc. will ensure that the appropriate support is provided to the original customer to restore the AltMill to operational condition or provide a full or partial refund under the sole discretion of the Company.
This warranty does not cover damage due to improper use or assembly, lack of maintenance, normal wear and tear, or modifications to the AltMill which are not produced or authorized by the Company. Consumables such as cutting tools and sample or stock materials which may have come with your AltMill are not included in this warranty.
This warranty will become void if the operator does not follow the Safety Warnings and Guidelines, uses the Product for illegal purposes, intentionally causes damage to the Product, or transfers the Product to another owner.
The original customer must contact Sienci Labs Inc. within three-hundred-sixty-five (365) days of receiving their order to make a warranty claim to be eligible for warranty service. Proof of purchase, tracking number, email address, or other material will be used to confirm the original purchasing date and the identity of the original customer. If damage was due to shipping, original packaging materials must be kept in the original received condition. Photos, videos, written descriptions, and other items may be requested to assess and validate a warranty claim.
In the case Sienci Labs Inc. requires the original parts to be returned, the customer is solely responsible for packing all items securely. Damage incurred during return shipping will not be covered by the warranty. A method of payment such as a credit card may be requested by Sienci Labs Inc. to cover shipping costs or damaged items if Products are not eligible for warranty service.
We will be shipping to US customers with UPS option only.
72 reviews for AltMill MK2 2×4
4.5
Based on 72 reviews
5 star
76
76%
4 star
11
11%
3 star
5
5%
2 star
2
2%
1 star
4
4%
Rated 5 out of 5
Paul K. (verified owner)–
Overall, I couldn’t be happier with what I purchased. Assembly went fairly well but I relied too heavily on the video and not the written instructions. The video wasn’t up to date with what needed to be done. It would have been good to know that ahead of time. Using the CNC has been very enjoyable. I’m relatively new to all of this and am self-taught but learning lots. I did get some initial experience on a smaller hobby CNC of a different brand that I needed to reconfigure for use in a woodshop where I volunteer. (We build hand-powered mobility carts for kids around the world that don’t have use of their legs or feet.) Working on that CNC got me hooked. I had to have one of my own. After doing tons of research, I landed on the AltMill MK2 2×4. I have done several smaller projects in the first couple of months that I have had this. It has exceeded my expectations in that I was sure I would have errors and problems that I couldn’t handle. That was not the case. I have only reached out to Tech Support for one issue which was simply “user error”. If there is anything worth suggesting, it would be to improve the search engine on the Sienci Community User Group Forum. There is tons of great information there but it can be difficult to find exactly what you’re looking for.
(0)(0)
Rated 5 out of 5
Vincent Briamonte Jr. (verified owner)–
Amazing machine. First time I made a cut I was giggling like a little girls I was so entertained by how well it worked
(0)(0)
Rated 5 out of 5
Michael Green (verified owner)–
Everything has been exceptional so far. Great details for setting the machine up. I had a few issues getting gsender and the spindle to link up but after about an hour and a half arguing with chat gpt, I got it figured out.
(0)(0)
Rated 5 out of 5
Anonymous (verified owner)–
Super-solid and well-engineered. A professional-quality setup, far exceeded my expectations!
The gantry in particular is amazing. Thick steel plate supports and a industrial-size extrusion means no flexing at all, and the linear bearings make it slide like glass.
My only recommendation for improvement would be to provide an extra 20-25mm of Z travel, especially for use with the rotary axis.
I used a local Makerspace’s ShopBot for many years, and it was a wonderfully capable machine, but I after a few months think I like the AltMill better.
(0)(0)
Rated 5 out of 5
Hans L. (verified owner)–
Machine arrived in perfect condition; setup was a breeze; and operation has gone smoothly.
(0)(0)
Rated 5 out of 5
dave panebianco (verified owner)–
The Altmill 4×2 is awesome..
The build was easier then I had thought, the tutorial made it incredible easy to follow along.
(0)(0)
Rated 4 out of 5
Guy S. (verified owner)–
Solidly built. Instructions were mostly clear and relatively easy to follow, but please keep iterating to make it even better! (For example, I had to re-do gantry installation because placement and registration marks didn’t seem clear until after I installed, so I went back and did it again.
Appreciate the rigidity, industrial-level design, and speed.
Areas I’d *really* want to see addressed in AltMill Mk3:
– Have y-axis chain run to back of machine so wires hidden better and cleaner finished product.
– Likewise, mount the computer to back left corner for same reason.
– Provide mounting points for the 48V power adapter (unless I missed them…)
– Redesign gantry so that lead screws are on backside, not front. They get dirty easily, especially when unable to use dust shoe.
– Have firmware/gSender natively able to turn off steppers when in-between jobs. My steps constantly hiss while it idles, so I either have to hit the e-stop button or turn off SLB to make it stop. Suspect this is okay for stepper longevity…but it’s just a touch annoying.
Overall, happy with purchase. Would just love to see some additional refinement and attention-to-detail for the next AltMill iteration. If some of these items could be driven backward into Mk2, that’d be phenomenal!
BONUS: Not called out here, but man, please really invest some engineers on gSender. It’s a GREAT piece of software, but FrancisCreation has made a very nice alternative. Could certainly be as easy as working in plug-ins so that adding new functionality and/or hardware accessories is very easy, and integrates into workflows. His incorporation of RTC products, for example, is great; as is his tools for many simple and repeatable jobs (holes, etc).
(0)(0)
Rated 5 out of 5
Bryan Boudreaux (verified owner)–
Graduated from a BobsCNC and could not be happier. Excellent build quality.
(0)(0)
Rated 5 out of 5
Michael Monzel (verified owner)–
Easy set up. Followed the video directions.
(0)(0)
Rated 5 out of 5
Rocco Orlando (verified owner)–
The machine has been flawless to date. Very rigid with impressive cuts.
(0)(0)
Rated 5 out of 5
Wayne J. (verified owner)–
Again I’ll say, I had no prior knowledge of CNC routers. Did my research and had decided on a MK3 LongMill, but impatience got the better of me so I stepped up the AltMill. I am totally pleased with my impatience . And the 4X2 fits my needs and space wonderfully. So far my only major complaint is the customer interfaces ie., the cheesy little switch on the SLB, it’s not convenient and seems delicate in the long run.
(0)(0)
Rated 5 out of 5
Frank C. (verified owner)–
A very capable tool with nearly unlimited growth through software.
(0)(0)
Rated 5 out of 5
Ralph D. (verified owner)–
This machine is turning out to be an amazing purchase. It has been a solid and reliable machine to work with. So far, every problem I have encountered has been because of “user error”. I couldn’t be more pleased with this machine.
(0)(0)
Rated 5 out of 5
Michael (verified owner)–
Love my Altmill!!
(0)(0)
Rated 5 out of 5
Christophe (verified owner)–
Excellent experience. The machine is fast, efficient, and easy to use.
The assembly experience was also simple, well-documented, and enjoyable.
Thank you Scienci Lab for this fantastic CNC machine.
(0)(0)
Rated 5 out of 5
Hamilton G. (verified owner)–
Replaced my Shark with the Altmill 2×4. Absolutely love it, a big step up in functionality.
(1)(0)
Rated 5 out of 5
steve (verified owner)–
well thought out design not cheap —-low priced high quality .My background owned cnc router for 15 years and ran-programed cnc machines for 40 years
(0)(0)
Rated 5 out of 5
Scott M. (verified owner)–
Great CNC. No difficulties in assembling or getting to the first motions and cuts. It would be nice to see some of the loose wires such as those from the stop sensors have covers so that their not hanging out ready to be snagged and broken. The same holds true regarding the power plug to the SLB. It’s not a great look on an otherwise well thought out machine. Also, offering a simple pendant would put you head and shoulders above the competition. The game controller options is sort of lame.
(0)(0)
Rated 1 out of 5
Robert Schoenfeldt (verified owner)–
I still never got it to home properly
(0)(0)
Rated 5 out of 5
Kris I. (verified owner)–
Great Pricing for what you get.
(1)(0)
Rated 5 out of 5
Anonymous (verified owner)–
The machine is built well and pretty straight forward to assemble if the instructions are followed closely. I will say the only thing that was a bit cumbersome was getting all the proximity switches set up. The guys in my shop had a tough time with them. I come from an industrial maintenance back round so I am familiar with them and their acute tolerances so it wasn’t a big deal we got it sorted out. for someone who has never worked with them and doesn’t understand how fickle they can be and process of getting them all queued at the same time it could be a struggle but nothing that cant be figured out. As far as I know there weren’t any specific videos supporting this potential hang up. Other than that this machine is awesome and we will purchase another in the near future.
(0)(0)
Rated 5 out of 5
gary hill (verified owner)–
Love it! Fits perfectly in my confined space.
(0)(0)
Only logged in customers who have purchased this product may leave a review.
Paul K. (verified owner) –
Overall, I couldn’t be happier with what I purchased. Assembly went fairly well but I relied too heavily on the video and not the written instructions. The video wasn’t up to date with what needed to be done. It would have been good to know that ahead of time. Using the CNC has been very enjoyable. I’m relatively new to all of this and am self-taught but learning lots. I did get some initial experience on a smaller hobby CNC of a different brand that I needed to reconfigure for use in a woodshop where I volunteer. (We build hand-powered mobility carts for kids around the world that don’t have use of their legs or feet.) Working on that CNC got me hooked. I had to have one of my own. After doing tons of research, I landed on the AltMill MK2 2×4. I have done several smaller projects in the first couple of months that I have had this. It has exceeded my expectations in that I was sure I would have errors and problems that I couldn’t handle. That was not the case. I have only reached out to Tech Support for one issue which was simply “user error”. If there is anything worth suggesting, it would be to improve the search engine on the Sienci Community User Group Forum. There is tons of great information there but it can be difficult to find exactly what you’re looking for.
Vincent Briamonte Jr. (verified owner) –
Amazing machine. First time I made a cut I was giggling like a little girls I was so entertained by how well it worked
Michael Green (verified owner) –
Everything has been exceptional so far. Great details for setting the machine up. I had a few issues getting gsender and the spindle to link up but after about an hour and a half arguing with chat gpt, I got it figured out.
Anonymous (verified owner) –
Super-solid and well-engineered. A professional-quality setup, far exceeded my expectations!
The gantry in particular is amazing. Thick steel plate supports and a industrial-size extrusion means no flexing at all, and the linear bearings make it slide like glass.
My only recommendation for improvement would be to provide an extra 20-25mm of Z travel, especially for use with the rotary axis.
I used a local Makerspace’s ShopBot for many years, and it was a wonderfully capable machine, but I after a few months think I like the AltMill better.
Hans L. (verified owner) –
Machine arrived in perfect condition; setup was a breeze; and operation has gone smoothly.
dave panebianco (verified owner) –
The Altmill 4×2 is awesome..
The build was easier then I had thought, the tutorial made it incredible easy to follow along.
Guy S. (verified owner) –
Solidly built. Instructions were mostly clear and relatively easy to follow, but please keep iterating to make it even better! (For example, I had to re-do gantry installation because placement and registration marks didn’t seem clear until after I installed, so I went back and did it again.
Appreciate the rigidity, industrial-level design, and speed.
Areas I’d *really* want to see addressed in AltMill Mk3:
– Have y-axis chain run to back of machine so wires hidden better and cleaner finished product.
– Likewise, mount the computer to back left corner for same reason.
– Provide mounting points for the 48V power adapter (unless I missed them…)
– Redesign gantry so that lead screws are on backside, not front. They get dirty easily, especially when unable to use dust shoe.
– Have firmware/gSender natively able to turn off steppers when in-between jobs. My steps constantly hiss while it idles, so I either have to hit the e-stop button or turn off SLB to make it stop. Suspect this is okay for stepper longevity…but it’s just a touch annoying.
Overall, happy with purchase. Would just love to see some additional refinement and attention-to-detail for the next AltMill iteration. If some of these items could be driven backward into Mk2, that’d be phenomenal!
BONUS: Not called out here, but man, please really invest some engineers on gSender. It’s a GREAT piece of software, but FrancisCreation has made a very nice alternative. Could certainly be as easy as working in plug-ins so that adding new functionality and/or hardware accessories is very easy, and integrates into workflows. His incorporation of RTC products, for example, is great; as is his tools for many simple and repeatable jobs (holes, etc).
Bryan Boudreaux (verified owner) –
Graduated from a BobsCNC and could not be happier. Excellent build quality.
Michael Monzel (verified owner) –
Easy set up. Followed the video directions.
Rocco Orlando (verified owner) –
The machine has been flawless to date. Very rigid with impressive cuts.
Wayne J. (verified owner) –
Again I’ll say, I had no prior knowledge of CNC routers. Did my research and had decided on a MK3 LongMill, but impatience got the better of me so I stepped up the AltMill. I am totally pleased with my impatience . And the 4X2 fits my needs and space wonderfully. So far my only major complaint is the customer interfaces ie., the cheesy little switch on the SLB, it’s not convenient and seems delicate in the long run.
Frank C. (verified owner) –
A very capable tool with nearly unlimited growth through software.
Ralph D. (verified owner) –
This machine is turning out to be an amazing purchase. It has been a solid and reliable machine to work with. So far, every problem I have encountered has been because of “user error”. I couldn’t be more pleased with this machine.
Michael (verified owner) –
Love my Altmill!!
Christophe (verified owner) –
Excellent experience. The machine is fast, efficient, and easy to use.
The assembly experience was also simple, well-documented, and enjoyable.
Thank you Scienci Lab for this fantastic CNC machine.
Hamilton G. (verified owner) –
Replaced my Shark with the Altmill 2×4. Absolutely love it, a big step up in functionality.
steve (verified owner) –
well thought out design not cheap —-low priced high quality .My background owned cnc router for 15 years and ran-programed cnc machines for 40 years
Scott M. (verified owner) –
Great CNC. No difficulties in assembling or getting to the first motions and cuts. It would be nice to see some of the loose wires such as those from the stop sensors have covers so that their not hanging out ready to be snagged and broken. The same holds true regarding the power plug to the SLB. It’s not a great look on an otherwise well thought out machine. Also, offering a simple pendant would put you head and shoulders above the competition. The game controller options is sort of lame.
Robert Schoenfeldt (verified owner) –
I still never got it to home properly
Kris I. (verified owner) –
Great Pricing for what you get.
Anonymous (verified owner) –
The machine is built well and pretty straight forward to assemble if the instructions are followed closely. I will say the only thing that was a bit cumbersome was getting all the proximity switches set up. The guys in my shop had a tough time with them. I come from an industrial maintenance back round so I am familiar with them and their acute tolerances so it wasn’t a big deal we got it sorted out. for someone who has never worked with them and doesn’t understand how fickle they can be and process of getting them all queued at the same time it could be a struggle but nothing that cant be figured out. As far as I know there weren’t any specific videos supporting this potential hang up. Other than that this machine is awesome and we will purchase another in the near future.
gary hill (verified owner) –
Love it! Fits perfectly in my confined space.