missing steps. (Page 1 of 2)

Is there any squeaking?  I had some trouble with the front pulleys rubbing against their printed mounts, hard enough to skip some steps.  A bit of lubrication fixed it.  Have you tried turning off the motors and moving the extruder back and forth on Y by hand?  Sometimes that helps things get back into line, or you can feel if there are any sticking places.

If you drive it back and forth with pronterface, does it skip?  Does it only happen in one direction?

no squeeking, I can tell you it's much harder to pull these around than I was expecting.

When my shapeoko motors are off, pulling it around is pretty easy.

I havn't seen it skip when driving it in pronterface.

Here's a picture of how a part will turn out sometimes.

That's the most severe I've seen it happen.  I don't have a video yet, and it doesn't happen all the time, so it would be hard to predict with without recording for a very long time.

There is a difference in the noise of the stepper, a stalled out noise that I'm familiar with on my CNC mill if you push too hard or fast when cutting parts.

The motor that seems to be in question stays cool since it's mounted to the steel case, so it's not overheating.

Here is a pic of the first time I noticed the problem.

I'm still having problems, I put a fan aimed at my board to see if it would help any, I think it does help some, but I'm still seeing this issue from time to time.

Check and see if the pulleys in the front are rubbing against their mounts.  I had some friction there that caused some missed steps, and fixed it with a little lithium grease.

I had the same issue, take a picture of the S/D from directly overhead and post it and I can tell you if it's is the same thing as I had.

Here are a couple more pics of problems.... same part, both jobs failed do to this problem.

Here's what I was talking about with the pulleys.  See if the sides of the front y pulleys are rubbing against the printed pulley mounts.

Hi. I am having the same problem as you do. Prior to this i was having a windows lockup. I had checked mechanical problems. But i giess its python related. I foumd worms in my conputer memmory. I hope it might solved our case

Mine is not software, but I wouldn't count on settings not helping with the problem either... Stepper motors give less torque when at higher speeds, and more likely to stall if then encounter some sort of mechanical or inertial resistance.

However with the motor off it feels heavy to me, but I have no other solidoodles to compare to...

Each axis is WAY harder to move than other machines I've worked with such as a shapeoko cnc router.   I suspect it's due to not as much rigidity required, and as a cost savings measure.   You end up with low cost bushings, linear slides that are just plastic rubbing on metal etc.

All that being said I wouldn't trade those things for a machine that I had to pay 4x as much for.  I would like a little less hardware tweaking though... The fact that there are no heat syncs on the stepper controllers puzzles me.  Having to add a fan to this is not an acceptable end user solution.  I feel like I'm on a witch hunt trying to track down this problem.

I think I have it figured out.... I don't think I have a solution yet.

I took the front pulley off one at a time.  First the right.  I was still having problems where it seems pretty stiff.  Then I put that back on and tool just the left side off and still stiff..

I removed both pulleys and the axis moves really nicely (as I would expect)

The problem is those bushings and the the back connecting rod...  It's pretty junky if your asking me.  It just doesn't turn very easily at all.  I slide the whole rod to the right, so only part of the left side of the rod was in a bushing, and it turned really easily, as I would expect.

I think my rod is bent some which is causing the binding.  I'm pretty sure a ball bearing instead of a bushing would be better here, as to the fact that it's being pulled against with some force with the tight belts.

I'm not sure how I'm going to fix this.  If I had a lathe I would turn this rod a tiny bit and I think that might help.  Maybe I'll just get some very find sand paper and sand down a tiny tiny bit. 

I didn't inspect the rod yet, but it feels like it might if someone were to grab the end with some pliers thus putting some tool marks in the rod where it contacts the bushing.  I'm not sure that's the case, but as far as the friction goes, that's what it feels like.

I'm glad I found  this, but... what to do, what to do?

If I could find some press ins bearings that fit exactly here to replace the bushings, I'd upgrade those in a heartbeat.