Z-axis cut depth is way off

Need some help with figuring out what could be going on with my X-carve. The Z-axis cut depth seems to be way off, but I’m not sure if its something with the cut settings too… I’m trying to conduct a very light carving around .001" deep, but the depth I’m seeing carved is closer to .02 or so, which is way off. I’m using a 30 degree v bit. My feed rate is 30min/in, depth feed is 5min/in, and cut per pass is 0.01". Not sure what could be going on. Is there a calibartion issue with my z-axis? Deeper cuts seem to be ok though…

Any help would be appreciated. Thanks.

How are you setting your Z0?

Z-probe. I think I may have found out my issue, or should I say issues.

First, since I am using a scrap board under my work piece I was not entering the total thickness correctly which I believe was most of the issue. I use the scrap board since after I do the carving I cut the final shape out of the work piece. Two separate steps since I don’t want to use the 30 degree v-bit to do a through cut. Another issue I found is that I think there are a few places on the waste board that are higher which is throwing off the carve depth. Not sure how to get around this and make sure the waste board is even. I’ve read on the forum that people have done a lot to correct this issue as far as milling the entire wasteboard to produce an even level surface… LOL I would have thought we wouldn’t have to do this!..

The scrap thickness underneath shouldn’t add to the problem for the engraving as you’re measuring from zero (stock top) down.
For something this precise, I’d highly recommend surfacing the face of the workpiece. As long as what you’re cutting is flat and perpendicular (to your machine / endmill) and zero is set correctly, you should be good.

Hmm, that is what I thought. Odd. it also seems to get worse as I go to thicker materials. I carved something that was 0.5" thick and had the carve depth at 0.005, and it came out as expected, fine carving and not deep. Then I used the same settings on a 0.65" thick piece. Ran the same setup with the Z-probe, etc… and for some reason it carved deeper… don’t get it.

How much clearance do you have to move up? Are you retracting too high and crashing at the top of your Z?

There is plenty of room to move up on the Z-axis. It’s not crashing at the top.

Just out of curiosity, when you set up your machine in the initial settings, what did you put your z-axis rod type as? Acme thread? If you don’t have the setting put to the correct type of rod you’re using, this will definitely throw off your depth of cut.