Need Help Troubleshooting a Problem

[Steve Wonser]

I'm trying to cut a pocket in some cherry and for some reason the z-zero is changing on me. Here is what I'm doing:
- Have a 12" x 12" x 3/4" piece of cherry secured to the spoilboard with a vacuum puck.
- I surfaced the wood using a mortise bit on one side, after z-zeroing on the top of the wood. The wood was surfaced properly.
- Next I removed the wood and z-zeroed to the vacuum puck because I want to make the wood .70 in thickness. I put the wood back on and ran the toolpath. Everything worked correctly.
- Now I want to cut a pocket in the wood so I change the bit to a 1/4" up cut and reset the x & y zero. I also z-zero the cutter to the top of the wood.
- Because this happened to me yesterday as well, I did a M3 0,0,0 and made sure that the cutter was at the surface of the wood in the lower left corner. Then I did a MZ 3 to move the cutter up so that I could install the dust foot.
- I ran the toolpath for the pocket and for some reason the z-zero drops about .25 below where is should be and ruins the cut.

Anyone have any idea of what I should check? I checked the toolpath file for the pocket and it seems correct. The surfacing toolpaths worked as expected. I'm at a loss. This problem happened to me yesterday and ruined my last piece of wood. I got a new piece today and the same problem occurred.

I should also mention that the toolpath looks perfect in VCarve Pro's preview. I'm running v8.020 of VCarve Pro and the Shopbot software is 3.8.26.

The toolpath file is attached.

Thanks,
Steve

[Brady Watson]

Go back and check that each toolpath is referencing the material at the appropriate place. You mentioned Zzeroing to the top of the puck and Zzeroing to the top of the block. Check your material settings carefully in VCP.

-B

[Steve Wonser]

I actually have 3 VCarve files. One is used to plane the wood just enough to flatten the top. It uses z-zero from the top of the wood. The VCarve file to thickness the wood to .7 uses z-zero from the top of the vacuum puck, bottom of the wood. The third file is for making the part. It specifies a thickness of .7 and z-zero from the top of the wood.

This is for a baby cradle plan that I got off of the Vectric forum. It calls for two ends, headboard and footboard, that have pockets to fit the sides. I modified the files to make the sides slightly narrower. I cut the headboard and footboard on Saturday. Everything cut great, except I realized that I forgot to modify the pocket size on the footboard. I fixed the file, but couldn't cut it until the next day because I needed to glue up a piece of wood large enough. I used to ShopBot to plane the wood to thickness on Sunday and then tried to cut the part, that's when I ran into the pocket depth problem. I looked at the .sbp file and it seemed okay so today, after purchasing more wood, I tried it again and got the same result.

I should also mention that I first cut the headboard with pink foam to test the design before cutting any wood. It cut perfectly until near the end when I was cutting the profile. It made several passes without a problem, then it just stalled for a second or so while I could see the lines of code still moving on the computer. After that it just shot off to the left of the material cutting a groove and ruining the piece. Since it was foam I thought it may be static electricity, which is why I went ahead and cut the wood.

[Tim Lucas]

Then I did a MZ 3 to move the cutter up so that I could install the dust foot.

When you moved z to 3.0 did it top out?

[scottp55]

Steve,
I forget if you have 5.5"Z?
What is combined thickness of spoilboard,puck with gasket,material?
Just guessing 2.2" but maybe "On Board" gasket adds to that?
Do you have the upper Z prox switch and is it working? (Keypad up and it should simply stop---no noise)
A MZ3 puts you awful close to topping out, which can do that.
Just wondering.
I see Tim beat me out:)

[robtown]

Worn collet? Up spiral bit isn't lifting your material is it? Plunging too fast? (That would probably result in a shallow pocket...) how long have you run 3.8.26?

just getting the low hanging fruit out of the way here...

[Steve Wonser]

Thanks for the help everyone! I also submitted an email to ShopBot tech support and got a response within an hour or so on a holiday no less! Anyway they suggest stuff similar to what you guys have suggested. I updated the SB3 software to 3.8.36. That update also updated the firmware in the Desktop. After the update I tried the cut again and it worked properly. I ran three other part files after that to complete my project and all worked well. I'm hoping that I've seen that last of that problem.

Scott, I do have the 5.5" Z and must admit that I didn't think about raising the bit too high. I'll check the prox switch and keep the 5.5" limit in mind when I'm stacking things up on the spoilboard.

Thanks again,
Steve

[scottp55]

Glad it's working again Steve.
IF it was a hard stop on Z and it blew by the prox, then maybe clean the switch/contact/and connection before checking the wire.
It Should have just hit the prox quietly, and given you a "stop/hit".
I had mine work loose once by the DC hose working on it, and another time a fine coating of Padauk dust was the culprit. Check for your blue foam up in there.
scott