Union Stars

The clamping might be causing your stock to be lower on the edges. You might try super glue and tape if your stock is flat. If it’s not flat, then do what @EthanKinney said.

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Neil, I have changed my clamping set-up, still with no success…


Have you checked the dust boot? If its to to tight against the material it will raise the Z height a little. I wouldn’t know what else to tell you other than your material isn’t level but you tried that so maybe its what Ethan said.
Good Luck

Are you sure your board is perfectly flat? I have had a few that the board is slightly warped (high in the middle) I added an extra clamp through the center section to pull it down. To fix the one I had that way I re-cut the stars that were to small by setting my probe in the general area of the incorrect star and rerunning just the stars needed to correct.

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Try a 60 degree bit and limit depth of cut.
60 degree bit is more forgiving on uneven material height.

Ethan - would you mind providing more details on the 2nd software program and what you do to generate the height map and g-code?

@BrianSkinnell I usually use bCNC to do the “autoleveling” like this.

The boards are flat. I’ve tried using less clamps and always get the same result. In my mind, if I get the same type result on different size unions, it seems like it could be a coding issue.

Hi Brian,

I’m using https://github.com/martin2250/OpenCNCPilot to generate the height map. I build my own “probe” by gluing a momentary button onto the end of a bolt and attaching that to the probe pin of my arduino.

My steps would be to:

  1. Locate the correct x/y position in easel
  2. Export the g-code from easel
  3. Close easel (to open the COM port)
  4. Start OpenCNCPilot
  5. load the g-code and create a height map probing routing (in the software)
  6. zero the work piece and then run the probing routine
  7. apply the height map to the g-code and save
  8. close OpenCNCPilot and open easel
  9. import the g-code and run

It adds about ~10-15 minutes to my carves, but I’m usually carving pretty fine detail over very large pieces. So the extra time for a good quality carve is worth it for me.

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oooohhhh Looks like I need to add my homing switches to the machine so I can use this.

I understand your switch placed in spindle for probing the surface and creating the height map.
How do you set Z height after placing bit back into the spindle?

Zeroing the probe is only for generating the height map and applying it to the gcode. You will still need to re-zero your bit afterwards and run the gcode.

The video at github did not show probing for bit length after height map was created. And of coarse it was being done on a circuit board with bit already in the collet.

I’ll be doing a carve on Sunday, I’ll post a video of it


So I installed OpenCNCPilot and was trying it out.
Jogging is not user friendly but could make do.
When I tried probing to create a height map the Z raised up to the mechanical stop and kept trying to go further. I had to hit the E stop.
Tried normal probing to set Z 0 and it probed in the correct direction but just stopped and alarmed when contact was made with touch plate.

Hi Mark,

I never got around to doing the carve yesterday, but I will be after work this afternoon.

Yeah, jogging in openCNCpilot isn’t very good. I do all of that in easel. You may have to go through the settings of OpenCNCPilot before you try and use it to verify that everything is setup correctly.

The program allows you to create “macros” and I have one specifically for doing the first “zero” before doing the probing operation. I’ll share that this evening as well.

Ok, I took a bunch of videos late last night when i was using the CNC.
Here they are. Don’t judge the shaky cam :slight_smile:

openCNCpilot Album

I’ll try and make a cleaner single video later, but for now this’ll have to do.

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Thanks for the videos and you do not need to apologize for them.
I did manage to copy the probe and set zero code from my preferred sender and past into the macros.
However when I import the project gcode it is large, way out of scale. I even tried it with metric code and had the same result.
And probing for height map only probed one location for me and stopped.
I am going to have to step away from this for a while as I need to be doing more productive things.
I may get back to you later on this.
Why do you not use OpenCNCPilot as your sender while you are right there ipo going back to Easel?
Thanks again for your efforts.

Hi Mark,

You may need to look at the settings for the program. Whenever i import, things are also way out of scale. Granted this program was initially designed by someone only wanting to mill PCBs.

I’m likely going to use OpenCNCPilot as the sender in the near future. I’m just more familiar with Easel. Jogging in Easel is far far easier than in the other software. I need to either figure out how to jog better in that program or write a few macros to raise the bit for changing bits and blanks. I just haven’t put the time into fully switching yet.

Once you get the process down, it really does produce a nice result. For instance I carved the two pieces below last nice that had some pretty fine detail and the wood i was carving on was pretty un-even to say the least.