Zaxis problems with rerunning job

Ran a simple cutout of bigfoot in pine. Replaced finished work with second piece of pine from same board (blue tape hold down). Rezeroed X, Y visually, Z using probe. All appeared fine. Ran the outline in gSender, again appeared fine. Started job and Z went all the way to the top. Stopped run. Rezeroed, outline fine. Started job and Z drove bit into spoil board. Stopped run. Reloaded file incase something got corrupted. Z shot up to top again. Rezeroed. Drove into spoil board. Shut everything down and quit for the day.

Today, started up again and cut out fine. Have not tried rerunning on new wood.


BTW, I have updated gSlender to latest version before all this happened.

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@Graham First of all Hello and welcome to the forum. Great group of folks here, very willing to help without all the drama seen on many forums.

You said something about visually checking x and y axis, and zeroing z. Whenever I tried that, I had problems. Where is your starting point and are you zeroing off the piece or spoiler board? A friend of mine told me to zero off the spoiler board, yet the forum said off the top of the workpiece. I opt for the workpiece and zero everything every time. Knock on wood, I haven’t carved into my spoiler board YET, but am sure I will sometime. :grinning:

My experience is somewhat limited so hopefully someone else can chime in with some additional words of wisdom. Again welcome, can’t wait to see what you carve!


I zero Z to spoil board as per Garret’s recommendation. I want to make some edits to the file anyway so I will try zeroing to top of workpiece.

@Graham Did you get fixed up, Graham?

If not, do you have limit switches installed?

Just FYI, settinig Z0 on the top of the material or the bottom of the material = top of spoilboard is your choice. That choice will not cause the issues you are having so long as you use the same position in both your CAM software and in gSender.

@Jake Frequently, Jake, experienced users will set Z0 to the top of the material for pocketing since the pocket depth is referenced off the top of the material. When cutting through the material, some use the top of the spoilboard, since that equals the bottom of the material, and choosing it as Z0 can reduce the depth of cut into the spoilboard. There are no hard and fast rules, though.

FWIW, since I am cheap and don’t like to reduce the thickness and/or replace my spoilboard frequently, I follow Peter Passuello’s method shown here Don't spoil your Spoilboard - CNCnutz Episode 51 - YouTube.


Will redo my project to Z0 the top of the work and see if that helps.

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Good info in the video.

zeroing to top of workpiece doesn’t solve the problem. Can run a job once successfully but subsequent runs after re-zeroing Z goes to top and XY moves way off.

@Graham Since it’s been a while, have you updated to the most recent version of gSender?

Are you running limit switches?

Edit: Is this the same issue that you described in your post entitled, “project runs fine once but not second time”? If so, I’ll join them.

As I said in that thread, it appears that you may be using the wrong post processor.