Touch-Z approach: to Puck or not to Puck?

I noticed on the X-Carve, they use a metal block as a z-probe. To me, that’s a good idea because you can force a user to touch the 2 before doing the probe-for-zero…

OTOH, you do need a metal block of a certain thickness that is flat on the top/bottom… and it’s another thing to dangle on the machine (vs making a flush countersunk post using a flat Chicago screw that is at a known position). But for the countersunk zero, you need to move the sled to the right place before you say go and you need to have a way to always ground the router bit or you in the same dangley-bit situation as the puck…

To zero the Maslow all you need is a flat piece of metal that will cover the hole and be large enough to keep the sled parallel to the base. Since you don’t care that the sled is not touching your material doesn’t matter it only matters that the bit will touch where the bottom of the sled should be. I plan on using a piece of tin that is leftover from an HVAC project at work.


There has been some talk about it and it is actually built in (if I remember right) but it’s not as straight forward to implement and not a default feature yet. Automatic tool height

@Thormj has written a PR with some nice improvements to the Z-Axis control portion of GroundControl, and he has made room in it for the z-axis touch probe control. It’s getting closer… :grin::+1:t2:

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Awesome, great job. You’re truly wizards at what you do (to all those that help to contribute at making the Malsow what it is - and what it will become).


The reason I was liking the puck idea is that GroundControl could verify that it can sense the signal before plowing it it in:

  1. You pick touchZ, it says touch the pick to the tip of the tool (no motion)… waits for the signal.
  2. It says, put puck against material and press ok…
  3. when OK, then it does the Z probe

Pro: this means if you’re not aligned with the pin or you forgot to plug the probe in (hey, I ran without the z axis plugged in once :blush:), no motion happens.

Con: if GC is 20 feet from Maslow (say it’s on the other side of the panel to keep dust away)… you gotta say “Ok” and then run to the front and hold the puck in place if it isn’t held by your sled,

You can still do the above with sheetmetal (and that’s probably a great puck since the sled can hold it in place), but you’d have to have a tab on the sheetmetal that could touch the bit. Doing this with a flush Chicago Screw is right out unless you spring-loaded that sucker so you could tap it against your bit in step 1.

I could make it a configuration option…

I saw a link on hack-a-day or instructables or some such site where it appeared someone was using a metal plate to zero their z-axis. The interesting part was they were using a multimeter with one lead clipped to the bit and the other on the metal plate so the continuity beep would indicate contact between the bit and plate.

I’ll look for the link and add it here.

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That’s essentially what GC is doing when you connect up the Aux pin (1 I think) and run the Gcode for auto zero. Check out this thread:


That’s what happens when most of that hocus pocus electronical whatnot sails right over my head. :smile:


For those using the Ridgid router with the stock z-axis, you might be interested to know that the collet is electrically connected to the z-axis motor housing, thus providing a super simple connection point for an automatic z-axis zeroing setup. No clipping to the bit necessary! (unless, of course, your bit is somehow not electrically conductive)