I just had a job go bad and found out that the machine is binding up in the X direction. When I move the boom back and forth it “stutters” in certain places. At first it would only move about 3 inches from home in X. I cleaned everything but I noticed that V pulleys don’t turn freely if I take them off, grab them in the center and try to spin them around like you would a ball bearing. They seem to be filled with sawdust. Assuming that they are supposed to spin freely (or at least without a lot of drag) how can I bring them back to working order?
Do you have to replace them?
Lube the heck out of them?
Griff
(Well crap, my hypometric precursor device is blown…)
2
Two sealed bearings per v-wheel with a precision washer between. You can pop them out to clean/replace, just don’t lose the washer/spacer.
I’ve never experienced a problem with bearings, I have replaced v-wheels, a quick search will provide a variety of sources.
Keep in mind that if you’re moving the gantry quickly you can generate enough back emf for the steppers to lock up - be sure this isn’t the “stutter” you’re feeling. A little friction in the v-wheels isn’t really a huge issue, but you should seem them rolling as the gantry moves. If they aren’t either 1) they’re too gummed up/bearing are worn or 2) they are tight enough against the rails. If you’ve been running for a while any they -have- been rotating against the rails, then you’re in the #1 camp. If you don’t know for sure, might be best to replace them and take note of how things are set up.
The central washer is very important, this should have a thickness of 0.99 to 1.00 mm. if it is not used in this thickness, there are displacements that take away better performance.
A little off topic, but…Just out of curiosity, has anyone, or has anyone heard of anyone replacing these bearings with ceramic bearings? I’m going back to my RC helicopter days and remember that ceramic is the way to go, but very expensive compared to the standard. Just wondering if anyone has tried it and if so was it worth it for anything other than to say “it worked before and it still works”.
Ok this is all helpful and I am able to get things back to what appears to be running order (not quite finished yet) by just manipulating them by hand. The one thing I couldn’t figure out was how to take them apart without tools like a press (not a mechanic). Since I bought a kit I think the pulleys were assembled when they came(?)
Any ideas on disassembly? Do I have to trot down to Harbor Freight and buy a cheap press?
@johnelle The V-wheel assemblies can be disassembled by using an M5 bolt as a handle/screw — just insert it partially so as to only engage one bearing, then wiggle back and forth until it comes out — repeat on the other side.
@DanoInTx If memory serves, the bearing quality thing was discussed quite a bit early in the project history — I believe the discussion is linked to from https://www.shapeoko.com/wiki/index.php/Parts#Motion — the consensus was that the better bearings would not be an advantage, but inexpensive enough that there was no point in going w/ less expensive ones.