Hi, After using my Workbee for months now, I noticed two rather disturbing issues: First, the X-Axis "skips" close to the origin - but only on the incoming journey. Jogging 100mm from the origin, for example - not issues at all. Returning to the origin, and the X-Axis does a mini-skip. This happens every time. I've tightened the anti-backlash screws, and loosened the screws. No change. Actually, if I tighten the screws too much, the X-axis movement just stalls. So loosening the screws a half-turn at a time finally frees up the X-axis movement, but on the return journey, still that little skip. I have also checked the tension on the wheels - in case there was a binding at that spot. But that made no difference. I can't see any physical impediment. I li ve in Australia, and our local Makerstore is selling a rack and pinion solution for their machines - except for the Workbee - this is still being tested, and won't be ready for sale till August. I'm thinking that this will at least get rid of the lead screw/anti-backlash issues I'm having. But at the moment, I'm stumped. The second issue is more serious. In order to determine exactly where my cut lines will be, I initially run the job with a diamond engraving bit set at .1mm depth. However, every time the job gets to about Y=400mm X= 1200 it needs to do a hairpin bend. And the system stalls. I'm not sure which axis is stalling, but it happens every time. I was hoping that fiddling with the anti-backlash setting might solve this, but no joy. What do I look for? Also, with the router turned off and just the diamond engraver running the job, there is an awful lot of squeaking. I've lubricated just about everything I can see. No change. I'm completely stumped. Anyone care to jump in an offer suggestions? Duncan
for 1. I'd say there is something stuck in one of the wheels that it is jumping over. does changing the job speed make any difference? does giving commands instead of jogging make a difference? for example, G0 X100 then G0 X5 for 2. assuming you are not engraving at maximum speed, you need to lower the acceleration on X and Y (a GRBL setting) so it can do the sharp corners. there is also probably some binding in that area....
No, because then it would happen every revolution. But there might be something on the rails at that point. I'll take a careful look. Good idea. I hadn't thought of doing that. I'll give it a try. Another good idea. Thank you for the ideas. Mmmm Interesting. Yes, engraving at a pretty speedy pace (6950mm/min) since it is a half sheet of plywood and I didn't want to be there all day. I'll drop that speed to a more manageable 3600mm/min (which I use for actual routing). And I'll check the binding also - but binding is so difficult to identify. Thank you for your help. Duncan PS What part of SA do you hail from? I'm an old Durban (school/university) and Cape Town (most of adult life) boy.
It is probably your acceleration settings for that 6950mm/min speed in a hairpin turn. It is trying to get up that speed in a short distance. Which goes back to this question" Try it at a slower speed. I recently had a similar issue.
A quick report-back: Changing the speed worked brilliantly. I had assumed that because there was very little resistance to the diamond stylus, I could go as fast as I wanted. WRONG. Dropping the speed to 3000mm/min worked great. I also dropped my cutting feed to 3000mm/min and the result was flawless. HOWEVER, the skip close to the origin (about X=40mm or so) persists. So I thought it might have something to do with a chip/deformity/blockage in the lead screw itself at that spot, but I can't find any. Commands vs jogging makes no difference. I ended up loosening the anti-backlash screws till the skip went away, but now my parts will all suffer from a larger backlash error. Mmmm. Can't wait for the local Openbuilds guys to get their rack and pinion upgrade ready. Goodbye lead screw.
The X-axis skipping has not been resolved. I'm tearing my hair out. I was mistaken in stating it only happened close to the origin and on the return journey. It happens everywhere just as the negative direction of travel begins. In a circle, the right-hand side has a big dent in it. Slanted cuts (like this / ) have a swerve to the right just after the cut begins. I'll do some demo cuts tomorrow, and you can see what I mean. I can't find any physical cause, so I'm wondering if this might be a software issue. Is there a way to go back a version or two just to check? Bottom line, I destroyed a half sheet of oukume plywood ($75) today thinking I had solved this. Duncan
check your Z axis, if it is moving a bit sideways you will see it on the X if the X skipped steps then it would not return to the correct path, all following cuts will be offset, but if there is flex somewhere then a cut and move off its line and return to the correct line, all depends on cutting forces. the rotating cutter moving away from you will try to go left because of the rotation. so which way it deflects depends on whether your outside cut are clockwise or anticlockwise. highly unlikely to be software, post the Gcode please
Did you check setscrews on shaft couplers yet. A jump after changing direction sounds like slipping coupler on motor shaft or leadscrew side
Hi, You guys have so much more insight into this sort of thing than I. Thank you. I'll check the setscrews tomorrow. It has to be SOMETHING...
I had a similar problem where about 50mm from the far extreme positive end it would stall when going back towards s the o point. In my case the motor was pushing. It also happened in a couple other spots. I noticed play in the lead screw. It could move back and forth slightly. If I accelerated to fast with a high speed, the lead screw would actually bend. I took the play out of it by readjusting the lock collars and it helped. This did not occur when the motor was pulling the axis towards itself in the positive direction.
FOUND the bugger! How the machine even worked at all is beyond me... But I had some spares, replaced it, adjusted the tension on the leadscrew (it accepted a fair deal of tensioning), adjusted the anti-backlash screws and finally dropped the max acceleration rates on both the X and Y axes. Each adjustment made an improvement (especially the first (ha ha), but it was only when I dropped the max acceleration rate could I tighten the anti backlash nuts to the point where there little or no discernable backlash, and the X-axis wouldn't stall when moving from X=0. I also checked the other flex couplings. All good. Then I re-lubricated all three lead screws, and ran everything back and forth a few times. I'm now a happy camper (I hope) and after a cup of tea, I'm going to give it all a dry run... Thank you so much for your help guys.
