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Everything you need to know about the AutoZero Touchplate

We’re excited to share a new product, the AutoZero Touchplate! This has been a long and complicated project that has been in progress for more than a year, with lots of design and manufacturing hurdles to get over.

Introducing the product

The AutoZero has one main purpose, to find the origin point of rectangular pieces of material. One of the main drawbacks of using conventional touch plates however is 1)the inability to use non-straight bits such as v-bits, tapered bits, and ball nose bits 2) needing to specify the size or diameter of the end mill you are using for the probing sequence.

Some higher-end touch plates can calculate the diameter of the bit to assist with probing by touching off the inner wall of the touch plate to find the distance traveled across two surfaces.

However, the AutoZero Touchplate is unique since it also offers a chamfered surface that allows the tip of v-bits, tapered bits, and ball nose bits to be used.

Lastly, we’ve made some general improvements to the new touch plates including:

  • Improved designs for touch plate wires, resulting in more reliable connection at the magnet and touch plate ends.
  • Nickel plating to help with conductivity and improved asthetic finish.
  • Integration with gSender, to make the set-up process super easy.
  • Cutout design to make removing the touchplate easy and to help visually confirm accuracy.

Pricing and availablilty

We now have around 600-700 units in stock and ready to ship. Pricing will be $120CAD/$95USD. Now to discuss the elephant in the room, these new touch plates are a lot more expensive than the original basic touch plate. There are a couple of reasons for this.

  • The cost to manufacture the touch plate itself is substantially more expensive
  • The product times for this item is very long and unpredictable
  • The AutoZero provides features not found on any other touchplates

In essence, the pricing decision for this product comes down to the fact that these are expensive to make and we can’t make a lot of them quickly.

To also make sure we’re transparent about our pricing, we’ve also compared our prices with some of our other competitors, and the pricing for this touch plate is in line with other high-end touch plates which lack the functionality of the AutoZero. In terms of a value standpoint, we believe that the AutoZero offers more than any other touch plate currently on the market.

We are hoping that we can continue to improve the design and manufacturing process of this product to bring prices down and make it more accessible to our customers. However, we feel that this pricepoint still allows us to be competitive and still provides enough profit for us to invest in research and development, as well as lowering the chance that we’ll run out of stuff (a common trend the past two years).

In terms of recommending this product, this is a very nice-to-have but absolutely not a need-to-have. The original touch plate offers a great value at $35CAD/$27USD, and has many of the same features and functionality as the AutoZero. The AutoZero is not needed for general use.

The engineering that has gone into creating this project

It’s safe to say that a lot of research, thought, and design went into this product. Here’s just a small peek at some of the things that we went through with creating the AutoZero.

Physical design and functional improvements

Here’s an excerpt from Chris’ design documentation:

Desired Functional Improvements for V2

There are many things that the current touch plate does well but there are possibly more features that we could integrate into a newer design while retaining the existing functions:

  1. Stabilizing the touch plate when placed on stock material before & during probing
    • This can be accomplished by moving the plate’s COM (center of mass) to be further overtop the stock material, placing more of the plate’s mass overtop the stock material, or increasing the coefficient of friction between the touch plate and the stock material
    • This creates a more reliable probing operation where the plate’s position is less affected by the movement of the wire harness, the small force imparted from the bit onto the plate during the probing procedure, or by other mishaps like the user grazing their hand past the plate before running the probe sequence
  2. Probing without the need to specify end mill diameter
    • Touching off two known surfaces rather than just one can allow for bit size compensation during probing, removing an extra step for the user
    • This can be done most easily by using a circular or square cutout or extrude
    • Need to ensure that enough wall contact exists to catch the mill flute at its greatest distance from its centerline
      • With our biggest mills being ¼” and having a helix angle of 30°, the largest span between peaks, P, would be = πD * atan(90-β) ≈ 16.13mm
      • The pitch on the ⅛” bits however is about = 8.17mm
      • Smaller ⅛” bits can have a cutting length of only 12-17mm so finding the right wall height to accommodate full contact on ¼” bits but not hitting the collet nut on ⅛” bits is a close game (collet nut furthest dia = 24.98mm)
  3. Probing non-straight-style cutting tools
    • This can include v-bits, round groove bits, and tapered bits (no straight edge bits)
    • Although these geometries can be unpredictable to probe, all these bits have a cutting edge that leads down to a singular conductive tip which we could leverage to locate their XYZ positions
    • Using a very shallow geometry, we should be able to make contact only with the tool tip while still being able to infer the XY location. V-bits would require a 45° minimum for 90° v-bits and below, but tapered and round groove bits would require and even shallower tangent geometry
    • Possible probing sequence
      • Touch the bit to a top surface to find the initial Z height 
      • Using the Z height and locating the bit near the shallow geometry, touch off the bit point in two X locations and two Y locations
      • Using these 5 probed coordinates, we can locate the zero point of the cutting piece
  4. Ability to measure angling in the stock material
    • Touching off at two or more points could allow us to compensate gcode to accommodate stock material which hasn’t be mounted square to the machine
  5. Coating the aluminum to avoid any future issues with corrosion or reduced conductivity
    • Openbuilds probe leverages 2µm nickel coating

Ideal design will maintain:

  • Thin profile to not reduce z-travel needed for probing
  • High side walls for straight bits
  • Low chamfered profile for tapers and Vs
  • Same starting point for all bits
  • Bit goes to zero point once probing is complete
  • Good weight and COM distance from material edge
  • Plate places to bit rather than bit placing to plate

Over 8 different design concepts were created before landing on the current design. Here are a couple examples.

  1. Hole block

    Rough dimensions: 60x60x20mm
    Total weight: 147g
    COM from edge: X & Y= 19.89mm
  2. Leaf plate

    Rough dimensions: 60x60x20mm
    Total weight: 127g
    COM from edge: X & Y= 20.12mm
  3. Hole block

    Rough dimensions: 80x80x20mm
    Total weight: 206g
    COM from edge: X & Y= 28.04mm

Manufacturing and supply chain challenges

The new design also proved to have some design challenges as well. First of the design challenges was in creating the chamfered edge. The AutoZero uses a 170 degree chamfer at the bottom of the plate. Initial prototypes used a ball nose based 3D toolpath strategy to create the angle, but because of the scalloping, the surface was not smooth and consistent enough for use with. This was then changed to custom tooling to create the edge.

The other challenge was to get consistent nickel plating thickness. Since we were working with fairly high tolerances, the thickness of the coating and the variance in thickness would impact the overall dimensions of the block. So this meant that the manufacturer would need to control the coating thickness AND the tolerance of the milled block underneath.

And lastly, even though these parts were shipped at the end of November/early December, due to lots of shipping delays, the touch plates finally arrived just a few days ago, meaning that the transit time for these were just about 4 months.