Help - Y-Axis belt being chewed up!

[atoff]

Well, I just finished wiring up the Rambo, installed my switch, placed the LCD on my Max V2 build... before turning it on, thought I'd check everything over... low and behold, I notice that my Y-axis is harder to move UP (by hand) then down. I notice it requires more force to bring the cheapskates up... I start checking the belt, tension is loose, I haven't yet tightened it, but tightening it doesn't help. I feel under the belt and notice that it's being chewed every time I lower raise the cheapskate. There's residue from the belt all over. I have no clue what the cause might be, as nothing seems off. I've removed the belt, and tried feeding it through and testing without connecting it completely, same issue. Whenever I withdraw the belt I see it being chewed up. Can anyone please help me figure this out? I haven't even had a chance to power my machine on.

[mhackney]

Does the cheapskate carriage on the Y tower move easily (but without slop) when the belt is off? It should move freely. Next, does the bearing at the top of the tower turn freely with no belt on it? It should. Then check the gear to make sure it does not have any sharp burrs that could harm the belt?

If all of these things are Ok, then install the belt and make sure it and the carriage can move freely.

[atoff]

Yes, it moves very nicely without the belt, bearings as well. When I tightened the belt from the top the cheapskate wouldn't budge... it wouldn't move at all. Installing the belt, same thing...belt is chewed up.

[mhackney]

Not exactly sure what you are saying. Do you mean that now that the belt is chewed up, when you install it, the carriage won't move? If so, you need to replace the belt. If on the other hand, the belt is in reasonable shape and you install it and the carriage won't move (when the steppers are not energized) then you may have the belt way too tight.

[atoff]

Sorry, no, the belt is perfectly fine... it's in good shape. The carriage couldn't move when I first tightened the belt. Tightened to the same level as the others, even loosened a bit. Unless the belt is loose, it's very difficult to raise the carriage.

[mhackney]

Is the upper idler cocking sideways with the belt on and binding. It seems like each of the individual comments are fine but when put together you get binding. You should be able to take your time and poke and prod until you figure it out. Try to focus on the top, the motor/gear and then the belt and carriage to see if you can find a bind somewhere.

[atoff]

Okay, I believe I know WHERE it's binding, but I still can't see why. I think it's being scraped along the edge of the bottom slot.

Here (though along the Y-axis):
[img]http://i.imgur.com/U0tQ2El.jpg[/img]

So, essentially that means that the belt is being pulled too far towards the center of the printer... though I can't see anything that would cause that. Nothing cocking sideways or askew. Everything looks as it should.

edit: I do need to test again with the belt completely on to be sure it's scraping at the bottom. Also, I hope there's a way for me to fix this without completely tearing the whole thing down. My back can't handle it.

[mhackney]

Ok, that's progress. Now compare it to the X or Z - what's different? Is the stepper on Y mounted in a different way or place.

[atoff]

Thanks for the help, I figured out the problem, and I can safely call myself an idiot. I kept routing the belt OVER the 1st idler for some reason... wow, I feel stupid. Now I need to try to get the tensions just right. What a relief though, I was starting to fear having to take the whole damn thing apart!

[mhackney]

No need to feel stupid. Hopefully you learned something in the debugging process - break it down into smaller, testable units. Verify that each unit does what it's supposed to do and then combine them (preferably 2 at a time) and test again. Look for anomalies.

Oh, and you got 2 out of 3 right!

Cheers,
Michael