I must have missed the designed size. Yes there is a minimum size. You need to have a minimum number of teeth engaged. So even if you have a 13T pulley, if it is very close to a larger pully it would not have enough teeth on the belt.
You CAN design a system that works if you move to different tooth size and shape. The specs on modern belts are better then the older L and MXL belts so you might be able to fit hat you want into the same space as the original. You do a recalculation from scratch. As to how to make the pulleys. Just buy them. But for testing you can 3D print timing gear pulleys. I make mine by printing a plastic ring with the teeth and then epoxying the ring to a steel pulley hub. Fully printed pulleys don't work well but the hybrids are nearly perfect and really easy to make To make a plastic ring, download the CAD file for the pulley from the vendors web site. I use SPD/SI and get the .step file. Then use yu CAD system to bore a huge hole (like 20mm or 30mm) in the pulley model. Print that. Then as the printer is working turn a 20mm or 30mm hub on your lathe and drill and tap for set screws. What makes this a quick job is that they provide CAD files or every pulley so you don't need to know how to layout the teeth. On Sat, Dec 26, 2020 at 11:57 AM andy pugh <[email protected]> wrote: > On Sat, 26 Dec 2020 at 19:34, John Dammeyer <[email protected]> > wrote: > > > Making a new lower pulley with 9 teeth is out of the question. It's too > small for only 9T and definitely won't fit on the 19mm motor shaft. And > that's the kicker. At almost 3/4" the pulley that goes onto it has to be > large enough to have a decent grip with set screws onto a 6mm key. > > I seem to recall that it is recommended to not go below 12T anyway. > > I don't know much about L and XL belts, all my machines have used T5. > T5 is available in widths from 8mm to 25mm. > https://www.bearingboys.co.uk/T5-Section-5mm-Pitch-1224-c > > I also have the correct hob for making custom T5 pulleys, so that is > one reason for _me_ to use them. > > You could consider ignoring the keyway, especially if the motor shafts > have a threaded hole in the end. > > I have several times taken inspiration from the Trantorque bushings: > https://uk.rs-online.com/web/p/keyless-bushes/7542545/ > However they require a huge central bore, so what I have done is > machine the pulley bore with a taper and then pull or push in a > sleeve. > At various times I have used a bolt in the end of the shaft, a nut > pulling the wedge through, or a ring of bolts to push the wedge in. > > Here is variation on the theme, with two tapers: > https://bodgesoc.blogspot.com/2017/01/gears.html > > -- > atp > "A motorcycle is a bicycle with a pandemonium attachment and is > designed for the especial use of mechanical geniuses, daredevils and > lunatics." > — George Fitch, Atlanta Constitution Newspaper, 1912 > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
