Z zero changing by itself ??

[ken_rychlik]

I ran a simple part that I designed in partwizzard and made the toolpaths for. Just a simple push stick with a hole to hang it on a nail. Made with 1/2 inch material. The hole didn't quite go all the way through and the outside profile plunged to an inch deep. When I reset the zero and ran another one it did fine. Somewhere between cutting the hole and running the outside of the part, the z changed home base on me. Do I have a gremlin in the box somewhere?
Kenneth

[dauntless]

I don't know if you have a gremlin or not, but I do know that I occasionally have the same issue of the z-axis suddenly going what appears to be exactly a half-inch too deep. It happened again yesterday, perhaps 6 hours after running the z-zero routine and starting a 758,000 line cut. At 534,000 lines it suddenly dug in a half inch too deep. I got it stopped within seconds, but now half to repair the workpiece and run that section again.

[erik_f]

just a long shot but ask shopbot about running the usb hub they include and why.

[tkovacs]

Could it be that the tool slipped in the collet?

[ken_rychlik]

Erik, Why the usb hub when it has a serial cable to the controller? I didn't consider that it could have slipped. I'm going to have to watch for that. This is the second time I emailed shopbot support and they are not responding. ?? Thanks

Kenneth

[dauntless]

I do run the usb thingie that came with my machine, so that can't be it. I also checked the tool's depth in the collet and it had not changed...nor had the z-zero setting.

Also, I cut blue foam so there is no appreciable load on the tool that could make it "dig in". In fact, the run I was working on a few days ago was a refinishing run where it was trimming about 20-thou of StyroSpray off the pattern at 2 ips.

In the end I repaired the workpiece, reran C2 and C3 to make sure nothing had moved, and resumed work. The rest of the tooling path ran without incident.

[erik_f]

Could be grounding? Just tossing ideas out there.

[ken_rychlik]

Two different problems Stan. Terry hit mine on the head. The bit slipped in my collet. I was thinking about the grounding thing too on mine. I haven't decided exactly where it will be in my shop, so I don't have a ground rod driven for it yet. I need to get past the learning curve, to see if I will even keep it a all. lol Thanks
Kenneth

[CajunCNC]

Kenneth, please don't say ShopBot hasn't responded. :-)

You are scaring me !!! I haven't bought my CNC router yet . . .

And trust me, I will NEED support . . .

Steve

[ken_rychlik]

Steven, Actually I did get a response today. They have a different way to contact them instead of just straight email. Something about excessive spam. I understand that very well. From shopbots home page under contact there is a spot to send a message that is a little spam proof.

[myxpykalix]

Regarding grounding what i experienced due to a faulty grounding was not that the tool plunged or did anything eratic but when it experienced static shock it just stopped. So i'm not sure that might be the problem.

RE; emailing support. I thnik you are far better off calling them direct and talking to someone who will guide you thru the issue. In email you might get a "shorthand" direction and won't be as complete as talking to a human. That's not meant as a criticism of them, I just think you will get a better understanding of the problem by talking to them.

Stephen...don't worry about support. They do an excellent job 9-5 of taking care of you then WE take over and fill the gaps. I just happen to be on duty at 4AM (lol).

[butch]

Kenneth
I had the same problem when I started. Expecially when I was running a 1/2" x 3" long bit in oak. What a tech at ShopBot had me do is mark the bit at the point it went in the arbor. I did and found it was slipping. I did two things..Made sure I was placing the bit in the arbor far enough and tightend a the arbor better better....and slowed the feed rate and rpm. I also ordered a new arbor and replaced the old one. But I haven't had any Z change due to bit slippage since.

[cabnet636]

at a minimum the bit shank needs to be encased in the collet length! on a futher note to run the bit in so deep as to not leave a 1/4" of shank exposed is asking for broken bits.

jim

[tkovacs]

Kenneth,
If you have a spindle, be sure that the collet is snapped into the collet nut:

http://www.youtube.com/watch?v=6gMezORPi8M

Terry

[dauntless]

Thank you Erik and Kenneth. I currently have a 12-ga solid copper wire grounding the table to the controller case as outlined in the assembly instructions. The controller case in turn is grounded to a ground-fault-interrupt 15 amp 110v circuit. Do I need more than that?

Thanks! Stan