Pulley quality tests?
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Anyone have any good methods to verify the quality of your pulleys? Installing each one into my delta is too much, but slapping a motor onto a spare extruder driver and testing them quickly seems reasonable to me. I just want more concrete ways to check things like eccentricity or how well the pulley teeth profiles are meshing with my belts (I got spare belt lengths to test with).
For eccentricity I've thought of just propping up the end of a laser pointer on the pulley and watching the amount the laser point travels on the wall across the room as the motor spins the pulley. My thinking is any eccentricity should show as a repeating vertical movement distinguishable from vibrations and it wouldn't be to bad to sort through my pulleys like that. One possible issue though is the retaining walls don't necessarily match the tooth for roundness although it should in a quality pulley...
I'm still stumped on a quick and easy way that is quantitative in some way to check the profile fit or issues.
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I tried to figure something out quite a while ago and just decided it was better to buy pulleys that were created to a tight tolerance in the first place.
The laser idea is interesting. Might be something to that.
Try shopping here: https://www.sdp-si.com/
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@Phaedrux Yeah I can't find anything obviously off with mine, so it really is just to write it off as good in my mind.. The $20 for an aluminum pulley hits some part of my brain that screams no, buy 30 for the same $60 and pick the best 3 and you'll have spares to play with, thats why I got so many spares.
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@lord-binky
gates idlers are good quality.
https://e3d-online.com/products/gates-powergrip
-2gt-idlers?_pos=2&_sid=12a86a93e&_ss=r
be aware they have an id of 5.alternative these are high quality
https://de.aliexpress.com/item/4000040551804.html -
So... I'm going to go ahead and eat my words here. I checked the profiles by squirting some hot glue into a section and pulling it when it cooled. This let me compare the tooth profiles much better than by trying to peer down in them and judging from a reflection. Overall they were shaped fairly right. Issues I found though: I measured one set (black anodized aluminum) they were about 1mm small on the OD for the belt and the lowest OD was often next to a set screw hole ( consistency suggests it's likely an issue in the manufacturing process). Even the ones that appear like gates ones in every way and had the proper OD, they had sections that when moving set calipers along the OD the calipers would catch near the flanges, basically a straight section was essentially a very squashed U shape only flat in the middle. This occurred among a few out of 3 different sourced pulleys.
I can handle the $13 for powergrip GT3 pulleys from misumi, so I think I'm going to do that for my sanity. This was a fun exercise in giving my gut instinct the bird though
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@lord-binky said in Pulley quality tests?:
they had sections that when moving set calipers along the ID the calipers would catch near the flanges
Same experience here. It was a bit maddening at the time actually. I still have a sack of pulleys I'm never going to use after trying to find a few good ones. I wish I had the good sense then to have just got good ones off the bat and moved on.
