18 Hour Print Failed

It was my first attempt at an overnight print. 18 hours (85mm OD x 25.4mm Thick - Solid - Adjustment block) The print was going for about 2 hrs then I packed up and went home. When I got in this morning...



Major Y-Axis Skip. I checked my belt it looked good. So I manually moved the bed in Repetier to see if there was an issue. I Home'd out, nothing. I moved it the other way and major skipping!!! Based on the time remaining on my part and the location of the skip, it happened around the 10-11 hour mark.

What was happening: As the bed was moving, the wires to heat the bed were snagging on the cylinder that moves the Z-axis so since these were stuck the bed would not move then skip once they got free.

Has anyone else had this issue?

Any suggestions to prevent this from happening again?

 

The y upgrade should help with the wire interference but until then, you might take a thin piece of plastic (I have a few failed prints if you need any...) tall enough and long enough to keep the wires from catching on the coupler screws. Check those screws as well; I have had one come loose and fall out. Geared linear motion axis all around would save a lot of wasted plastic from belt slippage... just sayin'.
Sorry about your print. Lost mine last night too on the same axis but from getting bumped off by a slightly raised bump of nylon in the way. Anybody need a 200 gram hunk of fused nylon?

 

Were you running a heated bed?

 

ya I was

 

So was I - but no cooling fan or support. Both might have helped, but it was doing so well without.. and nylon supports are a Major PITA!

 

That is caused by stepper stall. Your y axis has the most mass to move. try to move it rapidly back and forth and the stepper can't keep up. lower your acceleration values, slow down your print speeds,

 

I have a theory the belts are getting warm and slipping. I want to try putting some adhesive cork board on my kapton heater to limit the radiation to the belt.

 

Keep us posted, Mike! BTW, yours and Tesseract's multi-extruder is a thing of great beauty.

 

It's a tooth belt through a toothed gear. I could see a little gear lash, but it's not jumping teeth.
One of my drawer slides has a bearing block that will move around, in a very long print it sometimes will start to bind , the small stepper can't overcome this and I get stalls.
If I disconnect that draw slide, run it through it's full travel, it resets the bearing block and I'm good for another week. I've ordered the bed upgrade to cure this issue.

 

My experience seems to be a bit different than yours, Patrick. It definitely skips a few teeth when the extruder runs into a bump that impedes the travel of the bed. I am waiting for the new system as well and will make sure all is tight enough but I worry about over tightening the belt and overheating the stepper. They sound a bit "graunchy" when you do that.

 

If you don't do the upgrade kit...
The plastic wrap around the bed wires are a little stiff. You might consider using the flexible nylon tubing around them. That might reduce catching. I don't know what is being done with the new wire routing - so no suggestions there.

1 hour, 25 hours, it sucks to have prints die but it is the nature of the beast - with any of them! (I'm sure someone can say something more prophetic than that.... )

 

Mike Kelly - stepper motor insulators - pre-cut for Nema 17s:

http://tricklaser.com/Stepper-motor-insulators-3-pack-SMI-3.htm

 

I meant putting insulation on the exposed side of the kapton heater. Limits thermal transfer to the belt and improves heating to the boro.
Like this:
http://www.ebay.com.au/itm/Reprap-H...51440880998?pt=AU_Gadgets&hash=item3a8b0b5d66

 

With all that space between the bed and the stepper, I'm not sure it would be that effective. I'm sure it would help with bed heating times a bit. Steppers do overheat - but I think the best solution is one of two things:
a fan mounted to the stepper - I've seen some designs for this.
slower prints.

 

I'm concerned about the belt, not the steppers. I'm not convinced it's a stepper issue

 

Just tried again with only 40% fill density... 6hr Print. Turned out pretty good. Also as far as measurements go, it was supposed to be 85mm OD and 25mm thick

 

I don't see the belt slipping over time. These take TONS of abuse. Steppers gen a great deal of heat and can fail - even when they're out in the open. In terms of heat, we're only talking about less than 100C. That's not all that much for these.

 

If the steppers are getting hot they need their amperage turned down. If they need to be maxed out to drive the y axis they're undersized and should be replaced. Though I've never touched mine during a print to feel how hot it is.

100C is enough for a few mm of expansion that could result in slips. Steppers are only rated to run at like 80C so the bed is definitely pushing more heat to the pulley than the stepper.

 

After the 6 hr print i flicked my belt it did loosen a little bit. I didn't get the proper twang from it I am used too. I was able to adjust it by 3 more teeth without any problem re-attaching the bracket to the bed.