Hey all I've had my Cbeam running sweet the past 2 years but all of a sudden all of my circles are coming out oval they seem to be short on the x axis about 0.5mm. I've done the usual make sure its all tight which it all is and there is no side to side movement on the x axis or y axis. I have tried to compensate by upping the x axis step/mm but it seems to push the circle out in between the x/y axis, I am running with 32 micro steps on my pro v3 board but have been for about a year now. Does anyone have any ideas why this is happening and what i can do to fix it? Cheers Jas
Check the shaft coupler setscrews (might be loose enough to slip under load, but look tight), and also stop collar setscrews, also making sure the collars are still tight against the bearings.
Hey Peter Yup all checked and all tight mate, just measured some parts and it seems to be the whole x axis that is short .... a 10mm square measures 9.8 Y --- 9.3 X
moomoo, if you eliminated mechanical issues, like Peter said, just for kicks do a calibration. Do it with the maximum distance you can. Don't use Caliper to measure, it's to short, use a measuring tape.
Cheers Justin with the steps/mm set for a decentish circle 290mm travel along x axis comes out at 296mm with steps/mm set as it should be with an oval circle 290mm travel along x axis comes out at 292mm just for giggles i did the y axis 250 travel (max) along Y axis comes out at bang on 250mm this is baffling me now mechanically wise its all nice and tight i can turn both the steppers by hand with no resistance on either motor so no binding along the bar...
Our leadscrews are hot-rolled rather than precision ground, so there are often tiny differences in the pitch of the thread. Divide the distance you told it to move by the distance it actually moved and multiply your current steps/mm value for that axis by the result. I would repeat the measurement a few times before changing your settings, to make sure you are getting consistent results. Alex.
Hey Alex Could this be wear in the leadscrew as it seems to have crept up the last month, but there is no play in it i have been playing around with the steps/mm but couldn't get close to a good circle so will try that method Peter is that in UGS or another program? Thanks for the help guys Jas
OpenBuildsCONTROL, ie the official OpenBuilds Grbl host for the last 3-4 years now, available at the "SOFTWARE" link on the menu right at the top on the menu Docs: docs:software:overview [OpenBuilds Documentation] Calibration Video:
Peter Cheers mate i didn't even know that was there I've been using UGS the past few years. Do you have any idea why it has just started doing this ? Jas
From our experience, an older machine, start loosing accuracy, is almost always either something rattling loose, or wiring (but wiring symptoms doesn't apply here) Calibrate, again (Using wizard in CONTROL, enter longer travel moves for even more accuracy, 100mm is good, but the longer the better) - then you know your "movement" is accurate. Next up, hold the end (router unplugged) give it a wiggle, see what moves that shouldn't - maybe while cutting the cutting forces are forcing the endmill to make something move that you don't anticipate (i.e not related to the leadscrew, but rather, say for example - something that rattled loose and the whole gantry is moving on you a little?
Hi Peter yeah I've had things work loose before and ruin hours of work so I check for loose parts pretty much every time I run a program with enough force i can move the router on the X axis but its the dewalt clamp that's causing the movement, but I am putting a lot of pressure onto it and I only cut acrylic so not sure if that would cause this I downloaded and manged to install control on my ancient pc and strangely the x axis when I measured with calliper's was only 0.4 out over 100mm, the Y and Z where bang on after calibration over 200mm its bang on going to try an acrylic circle cut now Jas
the calibration didn't solve the issue the circle is still oval by 0.5mm there is even a flat edge on the Y axis edges....this is baffling me now
That definitely sounds like backlash - starting at the bit wiggle things looking for anything moving that shouldn't - you can often feel things that you can't see. Alex.
You where both correct it was indeed backlash on the X axis.....as I was just checking I found the backlash adjuster locking nut in the X axis beam and i had about 0.3 backlash play Nut back on and backlash eliminated the circle came out spot on, I cant believe I didn't feel it the first time I checked Many thanks guys for taking the time to help solve this irritating problem Jas
