Inlay Accuracy and Expectation

II use VCarve Pro and I’m attempting a 1/4" deep by 1/4" wide inlay. It is a curved piece (I call it a ribbon) I’m placing in a cutting board. Because of sanitary concerns the ribbon needs to fit tightly. I want it 1/4" deep to leave enough material to resurface the board if necessary.

I know the problem isn’t the software. What I see when I measure the inlay piece is the top of the inlay measures exactly 1/4" but the bottom measures 33/128". Just the opposite on the pocket. I checked the squareness of the spindle to the wasteboard and it was off a little so I used a brass shim and squared it. There was no play in my square and I used 2 different squares. I was very hopeful and reran both the inlay and pocket with the same results. I’m running the spindle at 14k, 0.04 plunge, 40 ipm.

1/128" is about 0.2mm. The machine specs state 0.13mm is within tolerance. Are my expectation too high for an inlay this deep? Any ideas for improvement of accuracy?

Here is a cutting board I made before I had the CNC. I want the same results with less effort.

What size bit are you using?

If everything is nice and tight and working properly, one suggestion is have as little bit coming out of the collet as possible. Different size from top to bottom of the cut could be runout from a little wobble in the bit.

You can test on piece of wood to see how tight or how loose, then play with offset values on either male or female inlay. That’s your bit or machine tolerances. If you write it down for next job, you’ll be good. Also keep in mind that, different wood gives you different results. If it’s to tight you play with female inlay, if it’s to loose then male insert needs offset.

Thanks Eric I will try that.

Thanks Alan. I have an allowance offset configured but if I make it large enough for the inlay to seat all the way into the pocket then there is a gap at the top of the inlay. I’m going to upgrade to a DW611 because I’m just not happy with the spindle. Perhaps that will help.

That’s another offset, depth needs to be offset as well. Besides upgrading your spindle is good choice, but you will have thickness or depth differences on Dewalt as well. You must practice changing values for your equipment, like start knowing each other with the equipment you’re driving.

You may check to see this following post, what’s about fine tuning your equipment.

Hmmm. That didn’t link to a video. I would interested to see if I missed a calibration. I have squared everywhere ai could think of. I have adjusted steps/mm. Other than this inlay issue I am happy. I’ve been able to do some engraving using 1/16" bits. Very happy with that.

V-carve provides an allowance for both the male and female inlay pieces. I have tried adjusting the plunge depth as well as editing the depth steps. If I have more time to experiment today I will report back.

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Eric, I did as you suggested. It may have helped a little but I believe the spindle itself has more runout than it should. Oh well, I’m going to upgrade to a DW611 and hopefully the increased top speed and torque will helpwith a better cut. I added more shim to the z-axis and now when I cut two identical male inlays and stack them there is barely any difference between top and bottom now. I’m going to be satisfied with that. No sense in spending time on adjustments I’ll have to redo when I upgrade. Thanks for the response though!

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I did see the video and that is what I had already done. thanks!