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| Cutting timing belt gears with a slitting saw (and cnc) |
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| stefang:
Hi folks, got something new (at least I have not seen it so far): Cutting a timing belt gear only with a slitting saw. Main setback is, that it only works for trapezoid gear tooths, and requires cnc with a rotary axis. Make one cut in the centre, rotate, cut the lower flank of the tooth, rotate, cut the upper flank of the tooth, rotate to next tooth...sounds pretty simple :D Gcode was done by hand, suitable for Emc2. Video of the process: Looks like a nice timing belt gear, except that I had litte problems on the lower half of it :palm: But issn't anything close to a fit :lol: Problem was, that I messed up the angle between the teeth... Another attemt after correcting the Gcode: Now it's a nice fit: It's not perfect as it misses the radiuses on top and bottom of the gear tooths (so it might shredd the belt after some time), but for lowtech-lowspeed-applications it should be adequate. Stefan |
| Bernd:
Nice. Sounds like you might need a round over tool to get that top part of the tooth rounded. Up oneside of the tooth and then down the other. :dremel: Bernd |
| John Stevenson:
Or get a copy of Gearotic. www.gearotic.com then you cam cut gears and timing belts with off the shelf end mills. John S. |
| geoff:
This pulley gear designer will also do timing pulleys using a 4th axis: http://svstuff.com/gears/ Only $12; haven't used it myself but it looks the part. From my understanding, gearotic only does 2.5d cutting for timing pulleys which doesn't strike me as optimal. |
| sparky961:
An excellent idea for using CNC to get this done. I wish that I would have had a CNC 4th axis while I made a bunch of timing gears. Instead, I had made up a spreadsheet with each angle that I needed to stop at, and painstakingly dialed in each one. It isn't hard to grind a suitable form tool to single point cut. I don't remember how many teeth my 5" diameter gear had, but I know my back was sore after bending over the machine for so long! Results were great though. A bit of fine sandpaper (with aluminum) cleans up the sharp edges quite nicely. All rammed up and ready for casting, using an open mold: After cleaning up the castings on the lathe: Single point cutting of teeth using rotary table: A few operations (and many hours) later, one finished custom pulley: |
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