We’ve been doing every Wednesday, but the number of changes is slowing down so we will probably switch to every other week soon
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Bar, would you think that #2 is also a bug? If there is no tension pulling the belt, the extra 1mm wasn’t necessary anyway. Why would the motor continue to run? I get that it possibly isn’t seeing the encoder move but shouldn’t the motor still timeout?
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Yes, we actually had a watchdog in there for that at one point but it was causing other issues. I think that there is a way to do it, it’s just a matter of tuning it just right. There is a fine line between “the machine catches and stops itself whenever there is an issue” and “the machine turns itself off all the time and it’s annoying”
Do you also have this incosistency when printing the belt guard? The side with the 3rd screw is touching the gear, while the other side is leaning out.
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It should be symmetric on both sides. Could the difference be caused by a little bit of play in the bolts attaching it to the arm?
How essential would you say it is to install belt guards?
Is a belt jam only a matter of time, and happens eventually, or are some users running fine long term without it?
I’ve never had my belts jam. Apparently they’re just not that musical
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It’s gotten way better because of software improvements. That being said I haven’t taken them off so I’m not 100% sure, but I think they aren’t nearly so critical now
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Rebuilt my Maslow with the new encoders and did my calibration and tried to run a program today. Got about 2/3 through and Maslow got stuck. Tried to reset and during the retract all, the bottom left belt said it was right, but didn’t move. I tried to extend all-retract all, but still stuck. I guess I’ll go through taking this thing apart again and see what is going on with it. The cut was going well until that happened.
Are these 3D printed guards an improvement on the guards that came with the latest M4’s? Or did the guards in the kit get added after this issue was raised?
Yes, the 3D printed version is an improvement on what’s currently in the kit. So if you have been seeing belt chomping, Id recommend printing some of those. The instances of belt chomping have fallen since calibration has improved, but it can still happen on occasion.
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I experienced this too on the weekend. Cutting great until it didn’t.
The Top Left belt in my case simply didn’t retract during a part near the end of a cut, the software stopped the job after a 15mm deviation was detected, saving my material and preventing damage to the machine. Then it wouldn’t retract fully during “retract all”.
Upping the retraction force to 2700 almost worked, but I still had about 10cm hanging out.
I took the machine and encoder apart and found nothing wrong except the belt roll was tightly jammed against the idler and the grub screw on the motor pinion was loose.
I slid the loose pinion off the motor, manually rewound the belt tightly and saw it was now about .5mm less tight against the idler.
I loosened the 4 bolts holding the motor and pushed that as far back away from the idler as I could and tightened the bolts back up.
I tightened the grub screw like heck, although i doubt this would make much difference.
Feeling silly, and wondering if I should solder the eoncoder board pin or 3d print a belt guard, I decided against it and put everything back together.
The machine worked perfectly once re-assembled, and I was able to “retract all” on all 4 belts with 1500 force. I was then able to resume my cut where it left off and still got a usable part after all that. 
Sounds like the improvements to the software over time have spared me a lot of issues.
Edit: maybe tightening the grub screw is important - to avoid the possibility of a jam on an unseated bearing, per this thread: All belts retracting but one
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Can we have a link to the 3d printed belt guard added to the Not Shop? I didn’t even know there were upgraded belt guards for quite a while.
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Yes! Sorry, I didn’t realize it wasn’t up there already. Bar just told me he made one more change so let me print that and test it and then ill throw it up there
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Sorry for the delay! Its been busy over here. I’ve just added the file!
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This build is kicking my butt. Looking for some advice. I built my first 2 arms - took me several hours - the belts don’t want to stay on the platters at all when you’re trying to assemble and the fact that the belts are way too long makes it really hard to assemble everything. Then I saw this post about belts getting ruined, so I downloaded the new guide from the Not Shop and printed one. I disassembled one of the arms and a small piece of plastic broke off where the belt has to go through the hole (so now I have to buy a new set of arms). Then, I installed the new 3d printed guide into a different arm. It is very wobbly on the 3 screw holes. Screwing it together and trying to re-assemble the arm promptly broke the 3d printed piece.
Are there specific print settings for this new guide? I printed mine with 15% infill and supports and that didn’t work out so great. Is the new guide really needed? Should I try completing my build without the new guides or is that just asking for trouble?
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@bar any ideas/thoughts on this?
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These parts are designed for injection molding so they have pretty thin walls, I would recommend printing at 100%
Do you have a picture of this? This part is concerning because those bits should be really quite tough
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