I’ve had many successful Retract All cycles.
All of a sudden, only one of the four arms would retraction force of 900.
Raising it to 1,000 caused a second to retract, 1,200 brought a third and 1,500 pulled the last.
So weird, I can’t think of anything that changed between my prior success and now.
Should I be concerned if I’m not having to use 1,500 to Retract All?
Can anyone suggest what may have happened to cause this problem?
Is there anything I should be doing to revert to the lower force numbers?
As you can see below, I think the controller dialog from 900 looks correct.
Retract All
[MSG:INFO: Retracting all belts]
[MSG:INFO: Requesting state change from Unknown to Retracting Belts]
[MSG:INFO: Succeeded]
[MSG:INFO: Top Right pulled tight with offset -0.011]
[MSG:INFO: Top Left pulled tight with offset 0.000]
[MSG:INFO: Bottom Right pulled tight with offset -0.011]
[MSG:INFO: Bottom Left pulled tight with offset -0.011]
[MSG:INFO: Requesting state change from Retracting Belts to Belts Retracted]
[MSG:INFO: Succeeded]
Sometimes the way the belt is spooled up on the arm can lead to it not retracting as smoothly if there is sort of a bump in it that is rubbing. You can safely ignore it, or you can try extending that belt all the way out and then letting it spool up again.
I had to modify gears on mine to resolve that, they had a lot of resistance spinning and there were not enough space for belt to spool. I used a spindle sander to surface the inside of the gear and belt sander to reduce its width on the teeth side just a tad.
Sanding the spools also worked to solve most of my issues.
My machine initially worked well and became more problematic as time went on.
I suspect that the temperature and humidity here in Florida caused the spools to swell which is why the gear side of the spool was tighter on the arm than the belt take-up side (more mass = greater expansion).
I wonder if the spools made of nylon, it’s know for moisture absorption and swelling. I reckon my did the same, pretty humid here in NC mountains as well. Although I just got a big dehumidifier for whole house, it’s crazy how much water it pumps out.
I kind of figured it was nylon or some kind of polycarbonate, both of which absorb moisture.
I run mine outside under a canopy and it gets to 94 degrees and 90% plus humidity here which is not ideal.
My 4.1 machine went from calibrating and running well to throwing position errors and e-stops and then having problems retracting. Trying to re-calibrate would result in endless looping due to very low fitness values.
I was very frustrated because I was on my second set of arms and spools.
It is definitely worth disassembling the machine to check the spool(s) fit if anyone is having similar issues.
I wonder if the spools made of nylon, it’s know for moisture absorption and
swelling. I reckon my did the same, pretty humid here in NC mountains as well.
Although I just got a big dehumidifier for whole house, it’s crazy how much
water it pumps out.
the 4.1 arms are delrin, I don’t remember what @bar said the initial injection
molded parts were made of.
Right on, derlin is great and don’t absorb water as far as I know, I usually use sheets of it for some laser projects, didn’t know you can inject mold it. It’s usually machined.
Maybe not a total remake, since it would only be a few thousandths of an inch (fraction of a millimeter), the mold could be welded and re-machined to increase the inside circumference of the spool.
That would probably be an option, but I would like to switch the factory for
that part so we would need to make the again anyway
If you head down this road, look at the spool design in my onshape account, it
flips the belt over so that the teeth go against the center, making it so you
need less wrap to be solid.
I also put an overhang on the teeth so that the belt is more supported and less
ikely to get into the teeth.
