Hi John;
I designed and built, from petg, the loose belt version based on Sam idea but quite a bit smaller. I can drive it with a 1NM 3 phase motor which has an 8mm d-flatted shaft after grinding the dflat quite a bit wider. No metal in the hub, its just a press fit on the motor shaft. Consisting of a hub that about 1mm eccentric plus and minus. Two 3d printed ball bearings pressed onto the hub, useing crosman bb's for balls. They drive the inside of a toothed belt, printed in petg. The 60 teeth on the belt are triangular, facing outward. The belt is 19mm wide and is moderately thin to encourage its flexibility. Two rings with the same triangular teeth surround the belt, sized so the armatures eccentricity pushes to full engagement at the maximum measurement of the armature, but the triangular splines are disengaged at the amatures minimum measurement, 1 9.4mm wide ring has 60 teeth, the other has 62. One ring is pinned into the ID of the housing, the other is pinned into the face of the output shaft/disk, whose OD carries the groove of another similar bearing, with the OD of the bearing glued into the housing cup. I left it running on the kitchen counter for a month at about 500 rpm for the input armature, no breakage. Output is taken from a 23 tooth sprocket fitted into, and pinned and superglued into the output disk. Designed to fit on the A drive furnished with a 6040 Gantry mill when bought as a 4 axis. The existing motor and gear ratio has very low holding power, this does. Backlash is in the driving belt as its not quite tight enough and it will need an idler fitted to snug up the belt. On that drive, the spacing is not adjustable. Once you have a printer that can use petg AND survive, I've a room full of failed printers, it took an $800 prusa kit before it Just Worked, you can make this for around $15. Theory is if it breaks, print another from the leftovers. Announced much earlier this summer on the list, I have had zero enquiry's. You can have the OpenSCAD file when I get a working machine up again, or I can mail you one drive and the motor+driver for $200. Right now I'm in the recovery process of bringing this machine back to life after a 6 month old 2T drive failed totally in the night last Thursday. And debian bullseye plus a raid10, all from SSD's is being a PITA to get setup and running like the stretch install that puked. So I'm using webmail cuz its all thats working. Take care John, Gene _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
