> From: Gene Heskett [mailto:[email protected]] > > I have noticed the 3D > > printed pulleys are noisier than the metal ones. But the noisy grind > > of the stepper motor is also gone. > > That's also worthwhile. I've also found the downloadable pulley making > code, like from thingiverse, generates pretty sloppy pulleys. Bound to > be noisy when the tooth fill is only 25%. But I don't know how to fix > the src code for those parametric composers. So after about 6 passes at > making pulleys, I ordered alu ones.
I have XML pulleys on the XY axis but those are 1.27NM motors. The Knee has a 3.5NM because that's what the 7.5NM Stepper motor dropped to at 300 RPM when it would skip steps. Especially with the bigger heavier vise and Rotary table. But the L type pulleys and belt were a gift from a friend so that's what I used. The issue I ran into because I didn't do my homework before I ordered the motor was the shaft diameter of 19mm (roughly 3/4"). The 12T pulley is just too small to also have a key and enough 'meat' for the pulley teeth. As it was I pivoted the key slot by 6 degrees from the imported STEP drawing so if I ran a set screw through the tooth there's bee enough material for threads. Anchoring the key from the tooth slot didn't create enough material. See attached photo. Fine if there's room for a larger diameter hub. Unfortunately I had to scrap that design because the belt didn't line up. Couldn't move the motor back. Couldn't move the upper pulley forward. Had to redesign with a 15T pulley so I can get a set screw through the tooth crest. John
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