Axis Binding

So somewhere my X and Y axis are binding. It’s driving me crazy.

I can get 1hr+ into a print and it’s perfect and then BAM, usually the Y axis will skip a few steps and the print is ruined.

If I move the axis back and forth by hand every now and then I can feel a little resistance, like there’s some imperfection on the tube that it’s trying to roll over - but there’s nothing wrong with the tube (and it’s only every now and then?).

My roller blocks aren’t quite square (damn you PrintrBot you POS), so the Y axis pipe is slightly off square, could that be the issue? It just doesn’t make sense that it only happens occasionally.

Thinking of filing out the rollers by hand to square up the pipe see if that fixes it, just thought someone might have a better idea of where to start?

make sure your drivers are set correctly, you could just be under or over powered. run it and see how the motors feel, if they are cool to the touch = under powered, too hot to touch = over powered. Either case will miss steps. I can’t imagine your print being that far off square, but definitely reprint when you get some free time. Solid base gets you better results.

Seems you weren’t far off, I’ve already been testing different current settings and just never found the sweet spot, eventually I did some research on the drivers and realised they are just garbage (chinese cheap crap), I have active cooling on them and heatsinks but it doesn’t help as most of the heat is actually sent out the bottom of the chip into the PCB, if the PCB is garbage then they will overheat no matter what cooling you place on top.

I had a couple of genuine Pololu DRV8825’s around that I then installed on my X and Y and the skipping steps went away (1/32 microsteps are nice too, smooth, sounds strange though :).

BUT the misalignment on my Y axis is still killing me. It’s so bad that one of the three bearings on the roller block on the left side of Y doesn’t even touch the conduit!

So frustrating, as you say a solid base is important and it seems in Australia it’s hard to get that sorted as our Conduit is utter crap, and the printrbot just isn’t good enough to print the parts either. Sooo more money down the drain as I pay to reprint the rollers. Wow it’s getting costly now.

Going to have to find some better 25mm tube also.

The chinese MK9 was garbage also, I’ve now replaced that with a E3d v6 and EzStruder and the extrusion is now sweet as, just can’t get the damn thing aligned good enough to print properly. Frustrating.

I have used both drivers and didn’t notice a difference. You shouldn’t need active cooling on your drivers if you are driving them too hard they will over heat and have a thermal shutdown and will miss steps instead of blowing. If your axis aren’t moving easily loosen all the bolts. Get it moving real nice and slowly tighten it up. Mine is very loose, the rigidity comes from the geometry of the design not how tight you have the bolts.

If you make it a little smaller your miss-alignments should go away. Triple check all distances X and Y and diagonal. just make sure the corner blocks are the same distance apart in the x and Y directions. Once those as good measure Diagonal across the middle those should be the same as well. Do that before reprinting parts.

Sorry to hear about your bad experience with the MK9. The 3 I am using are the most trouble free extruders I have ever used including an E3d I use at work. Did you see my walk through on some of the common MK9 issues? Most come pretty good out of the box, some need a tune up.

Sorry you are disappointed at the performance of your machine. I’ll do my best to get you up and running if you still have the desire to get it going.