Two issues: "Skipping" and parallel pocket incomplete

Hi MPCNCers … It’s me again with another couple of questions:

My daughter is getting married in February and I though I might try to put my 3d printer and MPCNC to use for making some “lighted table numbers”. During the cutting of the prototype, I had a couple of issues and I wondered if you might take a look at things and take a guess as to what happened. Please refer to the photo tablenumber_poc_issues.jpg.

The idea here was 2 cuts. One to do a shallow pocket of the number, and since this is a lighted sign, I decided to outline the number a little deeper for greater effect. The major amount of trouble came when the CNC suddenly “skipped” out of the outline as it came down the right side of the “2” (I circled where this happened). It was off by that amount for the remainder of that pass (which was the last pass anyway). NOTE: I rewired my CNC recently, so it’s possible there’s a loose connection which was the fault here, but I’m thinking that’s probably not the case. I may be over feeding or have too great of a cut depth, but being very new to all of this, I’m unsure of nearly everything.

The other issue I’ve seen a couple of times, and that is not quite “filled” pockets using the parallel strategy, which I also circled in the image. I’m guessing I have a number off in my tool settings but not sure which one. The tool is this one:

Thanks for your help guys. Let me know if there is anything else you’d like to see and I’ll post it up.

Try 8-10mm/s and you can go deeper if you want. 20 is too fast. You can plunge faster though, also a finish pass is always a good idea.


Have a peek at the milling basics page.

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Thanks Ryan!

I could understand the speed being too high causing the skipping, but can that also cause the incomplete pocketing when using the parallel method ? I’ve discovered that with intricate lettering (which is ultimately much of what I am going to be doing with the CNC machine) that the peel strategy doesn’t really work out very well, and while the linear strategy does work, it literally shakes the entire table like crazy by rapid reversing on the X-axis.

Well, I would start with wood. The carve dialed in perfectly, they you can move to plastic and just adjust some speeds.

It is hard to give to much advice as some plastics are really hard to mill and some are super easy. The shaking could be build up on your endmill, CAM, or build size.

Your bit may be a smaller diameter than what you have typed into Estlcam. Or the bit didn’t get deep enough to cut its full width. In any case estlcam expected a bit that was wider than what actually cut the work piece.