Chewed Belts

[xnaron]

I decided to inspect the belts on my Rostock Max today. I've had my printer up and running for about 2 or 3 weeks. I've probably printed about 20 to 30 hours.

Look what I found on the X belt! The other belts were chewed but this one was the worst.

I've been using these belts on my cartesians and they last for years.

I've read other users were having their belts prematurely wear and I believe the suspected cause was the sharp pinion gears.

I will replace them but I want to make sure it does not happen again. Is it the pinion gear? Do we have a replacement option if so?

thanks,
Brendin

[Polygonhell]

I'm pretty sure the issue is having the head meet significant resistance and the drive pulleys eating the belt.

Almost all the failures seem to be about 1/3 of the way up on the front side of the pillars when the head is homed, that's more or less on the pulley with the head on the bed. Which to me implies pulley eating belt when head meets resistance, if it were just sharp teeth on the pulley I think you'd see more consistent wear.

Ideally you'd want the motor to stall in that scenario, but with the long belts and shallow teeth I think it's difficult to tune them to that level.

[mhackney]

I don't know if this is possible, but it would be good for those that have had chewed belts to post WHERE the chewing occurred - i.e. how far from the bottom of the carriage for instance. This might help us correlate the cause. I'm inclined to agree with Polygonhell and maybe starting to collect this info will help.

Recently, the pulley's were changed from the original 15 tooth to a 20 tooth pulley. It will be interesting to see if that has an effect.

One interesting thing about a delta printer - on a cartesian, the Z is typically a screw, not a belt, so head crashes aren't going to affect that. We have 3 steppers all pushing the head down into the bed.

I just checked my belts and they all look good. I have well over 300 hours on them. Heck, the four vases that took 14+ hours each were good for 56 hours themselves!

[Av8r RC]

Here's a measurement of where mine is chewed. On the Z-Tower a stretches between 16 and 16 3/8" below the U-Joint centerline.

(that's not my fingers thru the belt, just the reinforcement)

(Belt is chewed at the blue tape mark. And a sneak peek at my Budashnozzle mount)



Here's what it did to some of my prints.

First one I noticed something was wrong and thought my hotend was loose but it wasn't.
The slip occurred at 3.3mm high.
KISS, 0.35mm layer height, 50mm/s all around, white ABS @ 230, 1hr 15min. Needs a little more retract. http://www.thingiverse.com/thing:12278

And a Cheech bobble head. Both times at 29.25mm high.
Slic3r, 0.2mm layer height, 20mm/s outer perimeter, 40mm/s perimeter, 65mm/s infill, 25% fill. Still needs a little more retract.

[Eaglezsoar]

Is the Budashnozzle mount available on Thingiverse?

[Polygonhell]

Yeah that's pretty much where the wear usually is. try positioning the head on the table and move it away from the affected pillar, until the wear patch is on the gear.
If a pillar calibration point is high, then as the head moves in the area opposite it can rub on the bed which can lead to the pulley eating the belt.
Plastic pulleys would be less prone to do that.

[Av8r RC]

Is the Budashnozzle mount available on Thingiverse?

No not yet. I'll try to get it up tonight. Plus a couple other parts that many might find useful.

Are you going to be using the press to fit connector from the stock hot end?

[Eaglezsoar]

Is the Budashnozzle mount available on Thingiverse?

No not yet. I'll try to get it up tonight. Plus a couple other parts that many might find useful.

Are you going to be using the press to fit connector from the stock hot end?

That would be nice but not that important. I do think that a press to fit connector should be part of it,
which one is not important. I see so many developed around a 4mm nut which I believe is crazy when
the PTF connectors are available. I have them in about 6 different thread sizes and that's about all that
makes them different. I do appreciate your offer to put those files on Thingaverse, I have two of the
Budashnozzles and I would like to be able to use them.


Carl

[Craftgizmos]

I'm pretty sure the issue is having the head meet significant resistance and the drive pulleys eating the belt.

Almost all the failures seem to be about 1/3 of the way up on the front side of the pillars when the head is homed, that's more or less on the pulley with the head on the bed. Which to me implies pulley eating belt when head meets resistance, if it were just sharp teeth on the pulley I think you'd see more consistent wear.

Ideally you'd want the motor to stall in that scenario, but with the long belts and shallow teeth I think it's difficult to tune them to that level.

Yep, I bet that is what happened to me. Tying to get the leveling correct, and at times the head WAS dragging on the bed.

[truenorthtrader]

Hey I would STRONGLY suggest anyone get the upgraded gears if you have the original Aluminum belt gears that attach to the Stepper motors.

The new one's have PLASTIC gears touching the belts, the rest of the body is metal so it connects to the motors solidly.

I'd stop printing until you get them, especially if you have tiny pieces of belt under where the gears are on the Rostock body, if so you are slowly chewing away mass from the belts and it will eventually fail.

[mhackney]

100s of hours of print time on my printer with aluminum pulleys and no sign of failure. I don't think it's a simple as aluminum vs plastic gears as I posted before.

[MorbidSlowBurn]

I haven had any issues with mine either on the metal gears (not nearly as many hours as mhackney). But I do think the plastic gears will be a little more forgiving on slipping as there will be a larger contact patch to the belt versus the metal gears. Also due to the larger diameter they won't put as much "bending" stress on the belts.

[cassetti]

I noticed a bit of 'fuzz' after a week of printing with the printer in the same area on my belts as everyone else. I've cleaned up the fuzz, but the belts seem fine, I just checked again and they still seem good to me.

Could it be caused by overtightened belts? Maybe not because it's happening on every belt?

[mhackney]

I theorize that over tightening is the issue. People would tend to tighten all belts relatively the same so if one is too tight, they all will likely be too tight. The larger diameter 20 tooth gears would decrease the radius of bend and might help.

[cassetti]

That may be - because I have not adjusted my belts since I tightened them initially. I have over 60 or 70 hours so far of print time with no issue. Had a successful 13 hour print, and 2 hours into a 17 hour print

[jesse]

Is the force of the extruder pushing against the bed against the stepper motors trying to keep the layer at the right height?

Could that be causing the wear?

My Y-axis is opposite of the extruder and is accumulating black rubber dust.