Gantry "quake"

[johnm]

Folks -

God hates me. I was reading other posts about move speeds 3,4,6 12 ips... I've *never* cut anything at more than 2 ips, usu much slower than that - cutting mdf, wood, pb... using a 1/4 Onsrud spiral bit that came with the machine.

Anytime I have a small radius to cut I get a terrific amount of "quake" in the gantry and scalloping of the finished edges, regardless of bit. I have checked all of the guide rollers under operation, and everything seems "tight and bright" There is NO slop in the gantry at all, the steppers keep everything solid - but during z moves (at .2 ips) or arc moves, the gantry flexes and shutters - it seems VERY "jumpy" for lack of a better woid. I can't imagine cut moves at 5 or 6 ips, let alone 12... My jog speeds are 6, and that seems fast. Where do I find a "rule of thumb" for feed and travel speeds?

All of my SB files are arcs inch.... I'd sure appreciate some feedback on this, and another problem I'll post in a moment. Rose and I have a client coming over on Friday to give us the "sniff test" and I want everything to be fresh n minty... Halp!

TIA

John Moorhead

[glossy]

John,
I had a problem like that and it was the Ramping on the machine I dont know how they got changed but low and behold a call to shopbot and Bill said to check a couple of things and went through them with me on the phone. I checked several things before we found that some of the ramps had been changed (be Me or a ghost), anyhow a quick click on the reset button and all was back to normal. But I will tell you that the new upgrade to.19 software helped a GREAT amount. I hope you find your problem before the client comes if I can help just drop me an e-mail and I will do my best.

[carl_vallance]

John,
I had the same problem you are disscribing. In my case it was my computer. I was trying to be cheep and use an old computer I had lying around. 500 Mhz 512 Ram USB 1.1 port. It turns out the machine can move faster the the computer can keep up with. The computer would send out a signal to tell the machine it sould not be where it is yet and that gave it the jerky motion at higher feeds and rapids. I was maxed out at a feed of 3 and rapid of 6. When I bought a new computer for the Shopbot (3.2 Ghz 1 Ghz memory and USB 2 port) eveything worked fine. Now I can max out speeds and rapids with no problems. Don't no if this is your problem but it's somthing to look at.