MPCNC has the Jitters

OK, I found what causes the gap as shown in the picture. I had the conduit laying in the rollers and they were tight against the rail. As soon as I tighten the conduit clamp, the opposite roller shifts causing the gap. I can tighten the one on the gap side without any issues. It appears that the clamp might sit a little skewed on the roller and tightening the screws causes the shift. I shortened up this dimension by an inch so it is not quite as pronounced. Looks like I just need to sand the saddle a bit to prevent this.

One step forward, one step back. I got everything re-installed and my inner rails are very close to parallel to the outer ones now. When I was re-doing the wiring I noticed that on one of the Y harnesses the green wire had 2 bad nicks in it (I could see the wire). I tried to just tape it, but the servo sounds terrible when running. I switched cables with the other axis, and yep, it runs smooth. Grrrr. I am finished for the night but tomorrow will see if I can patch it up, otherwise it looks like I am in the market for a new Y harness.

Hey wondering what the latest is on this problem?

I set my machine up and mine has jitters as well not quiet as bad as yours but I did a sample of my machine drawing and got alot of squiggly lines I’ll see if I can post a picture.

The one extra line in the bottom of the crown is my fault i restarted the program so thats not the issue its the little jitters all throughout if you look close around the little circles you’l see them.

How big is that, and what kind of surface are you drawing on?

Its roughly 6" x 4.5" its just set up on my dinning room table at the moment while i try and get all the quirks worked out. so its not held firmly down. I’m hoping its just that i need to sand the rails a lil.

I have tried tightening and loosening the the bearingsm I have checked square. im within 1/16 everywhere. I even removed the middle Z parts and ran the program and watched the bars to see if they still had the jitters it wasnt quiet as bad but they were still there a lil.

as far as my hardware and everything i printed all the parts and bought the kit from you. I did feel the silver heatsinks on the ramps board while the program is running and they get pretty hot this might be normal tho but i thought i would mention it.

My machine is a lil on the larger side 4’x2’ so my next thing if after sanding if that doesnt work is to make it smaller and see if that helps.

I actually think most of that is just the texture from the surface below and probably a loose pen mount (I am almost finished with a mount). Sanding the rails helps if they are really rough but the average conduit texture doesn’t usually show through.

I can see the machine jittering/jogging around when the pen isnt on the surface tho, it doesnt appear to be super smooth. so i know there is a lil more to it then the mount and surface but will see.

the Allied conduit i bought at the homedepot has all these lines in it I tired to look at images of your machine to see if yours has the same but I cant tell.

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My conduit looked the same when I first built it (common look after the plating process) and I took some fine sandpaper (~400 grit) and lightly sanded all of the rails. The other thing to check is making sure you do not have a bearing riding on a conduit seam. I had one stick that had a somewhat pronounced seam so I made sure I rotated that away from a bearing surface.

I have not fully run mine after making the inner rail stay parallel to the outer rail on my Y axis. I nicked the wiring harness and it cut at least mostly through the green wire. I was hoping to try a repair on it today but my schedule did not allow. It will now be a week before I can get to it again.

I did find that I needed the belts “tight” to reduce the shaking as well.

I see that this is old but one way that I eliminated some jittering was by slowing down the stepper speeds.