12/18/2018 at 12:10 •
Since I changed the belt clamps, my steel core belts were too short to put back on the machine so I installed some Gates LL2MR09 glass core belts.
I originally chose steel core belts for the hoped-for minimal stretch, though there wasn't much information about them available. I measured the displacement of the bed surface with 4 kg piled on it, It worked out to 42 um per kg of print load, equivalent to a maximum of 1.2 um in any single layer of a print that covers the entire bed.
Yesterday I checked the glass core belt stretch. It was about 3.4 x greater than the steel core belt- about 150 um/kg equivalent to a maximum of 4 um in any single layer of a print that completely covers the bed. Probably still not an issue for most prints.
12/16/2018 at 14:15 •
New clamps and glass core belts installed and working fine.
12/10/2018 at 22:27 •
The Z axis was recently behaving strangely. I noticed the belts were flopping around so I retensioned them. In a couple days, they were flopping again. I took them off the machine to see what was going on and instead of finding that the steel cores had broken, I found this:
The polyurethane belt had slid/stretched over the steel core (of course it did!) inside the belt clamp.
I have redesigned the belt clamps so the ends of the belt will fold over and the teeth will interlock. That should prevent this sort of problem from reoccurring.
I have used this folded self-locking type of clamp for years in the XY stage and in SoM, my other printer.