Maslow Home Maslow Community Garden

Automatic tool height


I won’t be able to make a video, but let’s see what we can accomplish.

The approach hasn’t been adopted by enough users to turn that on yet, the ‘greyed-out’ button is a place holder for now.

For now, I use one of the Macros to achieve the same thing. In Settings, down toward the bottom, find ‘Macro 1’ and ‘Macro 1 Title’
Click on ‘Macro 1’ and paste or type in this:

G20 G90 G38.2 Z-.15 F1 G20 G90 M02

Click on ‘Macro 1 Title’ and give it a name like: Z Axis zero

To test the rig before using it, attach the clip directly to the ground plate and try the macro. The z-axis should not move, and the line “z axis zeroed” should appear in the GC terminal if the wiring is correct. Watch out if the z axis does move - it will try to run until it arrives at -.15 inches. The ‘Stop’ button will be your friend if the travel gets too near the end stops. If the first test wash successful, then disconnect the clip and try it again, touching the clip to the ground plate after a second or two to simulate a bit touching down. The z-axis will move until the clip touches.

Here’s my sequence for zeroing before a cut.

  • unplug the router and install the bit you’re going to use.
  • rig the z-axis cable from the PowerControl board to the ground plate and the bit
  • use the ‘Z-Axis’ controls to move the router bit to within 0.15 inches above the ground plate, and ‘Define Zero’. This doesn’t have to be exact, just close, and if it’s too far you’ll get another chance without hurting anything.
  • Now, when you run the macro you created, the z-axis will lower until either the bit touches the ground plate and the z-axis is set to 0, or the z-axis reaches -0.15 inches and gives up, reporting “error: probe did not connect, program stopped, z axis not set”
  • if the z-axis is zero, unrig the cable and ground plate and you’re ready to plug in the router and cut
  • if the z-axis reported “error”, take a close look at the bit - is it still above the ground plate? if so, use the ‘Z-Axis’ control to set the zero here, and run the macro again. If the bit is touching the ground plate and lifting the sled, recheck the connections…

I hope this helps, ask any questions I’ve missed. If it works, you could do a video :smile:

Holey Triangular Calibration

Thank you for your in depth detail of setup. I hope to try this out tonight. I’ll let you know how this goes.


I can report a success yesterday with Auto-Z’ing and would love to see this fully implemented (as seen in the Z-Axis window) in an upcoming GC release.

I was able to use the indent for the orientating tab on the standard RidgidRouter, clipping the Ground clip to the base so that the outside of the clip contacted the router drum, and sliding my touch plate between the work surface and the sled.

3 cheers to everyone who helped get this running!!


Just as a follow up here; I followed the detailed write up from blurfl and the setup worked flawlessly. Thanks for your help @blurfl. @blurfl would you happen to know what Aux 1, 2, 3 can be used for? From previous reading I somewhat remember that Aux 1 can be used for spindle on/off. Is that right?

Thanks again for your help.



Glad to hear you had success!

That’s right. The others (don’t forget AUX5&6) haven’t been used yet.


We can use this simple Touch Off Plate.


I took a steel ruler scraped off the cork board backing and goo. Then put a bend it so it will hang off the top of the sled when I slid it underneath.

For now I use the continuity tester buzzer on my multimeter, until I solder in the aux port pins.


Ooh. I like this approach as it’s something I can possibly do. I’ve been having trouble with my z axis zero def, so I need to implement something. Are you just clipping the black lead on to the bit? Could you have just clipped the red/white lead directly onto the ruler? Or is the post just looking ahead for attaching the permanent wire to the aux pin?


Hey, Becca,

I am clipping the black lead with white alligator clip to the Z motor housing. Its kinda hard to see in the photo. You could also forgo the banana plug post as well.

One thing, I learned after making some small wooden boxes out of thin 5mm plywood, is after you get the bit to touch the plate, you need to slide the ruler out and drop in thickness of the ruler which in my case is around 1/64 inch or .396mm.

When I initially cut the box out I did not add this in and it threw off the depth for the pockets where the box top is supposed to slide in.

I used the box maker app on Easel to generate the gcode.


Thanks - now I see the black lead and white cable being clipped to the motor in the photo.:blush:

Do you mean that after you’ve made connection with the ruler, but before you “Define Zero” in the GC screen, you lower your z axis in the GC screen by this additional amount (in your case, 0.396mm)?


Yes, you are correct. Thanks for clarifying.


Well, I’m still new to this and I didn’t want to make assumptions (gets me in trouble) and with the number of accidental drag-cuts I’ve made, I would have felt foolish deliberately lowering my z axis more than what seemed necessary when/if it resulted in more accidental drag-cuts (by this I mean, my safety height for movement wasn’t high enough or I defined my z too low since I’m just eyeballing it now). Now, I’ve just got to find a metal ruler… Thanks again for your help!


This should not be the case, the touch-off is to the top of the ruler, which is
the bottom of the sled. When you then remove the ruler, the bottom of the sled
and the top of the workpiece are the same, so the thickness of the ruler should
not matter.

On other CNC machines, where the bit position is relative to the frame, you have
to have a known thickness for your touch-off block, but since the Maslow is
relatve to the bottom of the sled, not the frame, you don’t need to do this
added calculation.


I see your point, my ruler only goes a little past the midpoint and the bit. But it’s so thin, I dont think that not running the entire length of the sled is making a big difference, as far as being parallel.

I have some 2"x.125" aluminum stock that is long enough to support the top and the bottom of the sled, I can try. I also added a bungie and adjusted the collar over the weekend. I will try to make some test cuts in the next few days and see if I can get closer to the pocket depth I was shooting for.


Yes, if the ruler doesn’t go past the hole in the sled, things will be off.


I was testing and was able to drive the router onto my ‘Bezel’ off the workspace at dead center. Currently Ground Control 1.11 will stop responding in the direction once you are outside it’s perceived border as shown in GC.

My thought is to put a copper sheet attached to the shield top center. I would have a switch to let me know if it tried to extend too far North/UP to mechanically stop the sled. This serves 2 purposes. 1 I could incorporate a Home position. A known location that tells me I arrive where I thought I am ergo I’m in calibration, if I can return repeatedly to the same spot. A known starting point. 2 I can auto set Z zero before starting.

In the grand scheme of things the likely hood of needing to route at that 3 inch landing zone is pretty low.

Some software and hardware changes need to take place to accommodate this.



Thank you


The problem with ‘home sensors’ is that if you retract the chain too much you
can break the sled, and if you feed out too much chain you can have the sled
fall to the floor.

If you don’t know where you are starting, you don’t know if it’s safe to retract
or feed the chain on either motor.


That is the reason for implementing a hardware switch to know the sled is not going to far.

Process looks like this. I have the center of my work space marked and I always return to it to begin and end. If that is off I know something happened, I had a chain skip or the frame is warping. From there I’m moving straight up. I’m going to look for touch switch then run auto Z.

This is check and balance.

FYI - at the time I worked on the original Makerbot CNC it had no end stops. It’s starting position was the center of the work space and moved out. It was up to the operator to not go beyond the limits. I handled this by stepping until the system couldn’t go any farther in each direction I then drew a boarder 2 steps in from that. This became my work space. Anything that loaded had to fit this space. I think it would be a decent reality check once calibrated to allow the user to move the router to the workspace boundaries and check based on real world vs perceived world and how much difference there is.

Thank you


I like the way you think! I recently saw a 3D Printer that touched 4 sensors on 4 corners of the bed in a specific order. Not only did this confirm the travel distance was working properly, but it also confirmed where it was. If it ran into a problem, it would issue a stop command. I dont know if I would want to wait XX minutes for travel all across a 4x8 sheet, but you could even have a thin piece of metal overlaying just 1 corner of your work piece.


@ChuckC Thank you. I started out with it in the corner and realized I park and start in the center every time. It’s faster to go straight up.

I’m responsible for the term Bed Leveling on 3D printers. I used the phrase “level in relationship to the nozzle” back in the Original Maker Bot kit days in an article with a mod to allow adjusting the 4 corners with left over parts. The bed was less then 4x4 inches. It is not so easy when it’s over 16 inches in each direction to keep flat, lol.

Thank you