18 Hour Print Failed

Wow. They definitely don't loosen over time. My other (delta) has taken tons of abuse and never stretched. It doesn't get heated but still, I'm really surprised. Most of them have polyester - which start stretching until around 80C in a controlled environment and in general, at most 2%. To get three teeth worth (say 6mm) is, in a word, wild.

So, based on that, I'm wondering what happens when things cool down? How elastic is the belt?

And, is it worthwhile to shield the belt as Mike says, against heat?

 

His point was that after 6 hours it got warm and loosened. I agree, the belt should return to normal when it returns to ambient temperatures. I don't think you'll permanently deform the belt, but it could get soft enough that a teeth slip could occur. Just a hypothesis though as I don't have strong evidence to support this. I've just noticed similar occurrences during long prints.

If you've read stratasys's patents they do an interesting method of heat shielding the belts from the heated enclosure. I think there's some definitely advantages of heat protections. I've been trying to think of ways to do it for both x and y by an active cooled line or something. Basically I want my volume to be closer to 50-80C, if it's possible, but keep the belts around ambient. I kinda envision telescoping panels or accordian style surrounding just the belt.

 

I'm willing to bet that problem will be solved in one of the future Robo3Ds...

 

It's actually a problem with almost all printers due to stratasys's patent

 

Time for steel belted radials .

 

John the robo uses the gt3 belt which is the same belt used in our delta printers / Cartesian printers ... we've / I've printed on the delta for over 14+hrs.. no problem with so called heat creeping up the stepper shaft causing it to stretch (it doesn't get that hot..) if it does then.... configuration setup of the printer is what's causing the stepper to get hot... (it would have to be extremely hot to do that)

I seriously doubt that much heat will transfer through a 1/4" wood insulator also to cause and belt stretch.. the GT3 belt is designed for this linear motion purpose the grooves of the belt and the teeth of the pinon are design not to skip with proper tension..(provided you dont hit a wall of the sort) GT3 are also reinforced like john says.. unless the Robo belts are pure rubber...lol.. I wouldn't be surprised if they got some cheap knockoff GT3's that don't have the reinforcements....... anyone care to cut there robo GT3 belt and verify if it has the reinforcements inside..... actually you dont have to cut it.. you should be able to see the reinforcement string looking from the side of the belt....

 

Cambo, you animal! I nipped a little off of one end. They're reinforced. About ten strands of something.

The thesis put forth here was that the heated bed caused the belt to heat. I have to wonder since it's open and moving. I 'spose someone can glue on a little palm frond to generate some air current down there if that proves to be the case.

I doubted heat creep myself so.. In all honesty, maybe a loose belt to begin with or even maybe a little gear slippage. I've certainly had some over the course of this thread. LOL

 

yeah id look to tighten up the belt then... and also check you see if the stepper has a flat on it to keep the pinion from freewheeling..(due to a loose set screw)

 

What software you printing with?
The skipping could be caused by the hot end getting caught on the model as it moves from one section to another. I have had this happen.
Cura does not have a setting that allows you to lift the print head when navigating across the model ( I don't believe that MC does either). Repetier host supports this.

 

Great news, thanks. Was the main feature stopping me use it.

 

I agree with scotta. All my y axis failures were caused by warping of the model or something blocking the extruder from crossing, when this happens, the belt slips until the force is enough to either bump the extruder up enough, or the extruder melts through whatever was in the way.

 

Sitting here looking at the machine - belts....Ok, there's a tensioner on the X-axis belt, would one help on the y-axis as well?

 

shouldnt need a tensioner on the Y. You can adjust the tension with the stops that attach it to the bed. just slide the belt out, adjust a few teeth then slide it back in.

 

I watched the heat bed wires rub against the rails and the rods thinking that the routing didn't seem right. Unfortunately requests on the forum for a close up photo of someone's printer to compare went unanswered. In January the wires ripped off completely and I haven't used it since. I signed up for the upgrade expecting it in March, but looks like April before I get it fixed.