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Originally Posted by sanddrag
I was just wondering how to make Technokat style dog gears in a CNC mill. I know all about the programming and tooling and stuff, but I'm wondering how to go about setting up the gear in the machine. Do you just clamp it in the vice with lead or aluminum jaws? How do you make sure the teeth don't get deformed; just don't clamp it too tight - but how tight is tight enough? Or do you machine a radius the same as the gear partially into the jaws of the vise to hold it? Would you make some sort of fixture to hold it? Also, once it is held in the machine, how do you go about centering the part because in the program I assume everything would be referenced from the center since it is round. I have only centered rectangular parts with an edgefinder before so I'm not sure how you would do this. Thanks.
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I would do it in one of two ways:
1. The easy method would be to make a shaft that fits perfectly in the bore of your gear, then slide this into the chuck on your mill to indicate the center of the gear relative to the spindle. Set your NC machine to 0,0 once you can drop the shaft into the bore of the gear. This should be accurate enough for making the pockets for a dog.
2. Using a dial indicator in the chuck of the mill you can indicate the center of the gear by rotating the indicator around the bore to find the center with relation to the spindle. This is more accurate but also more time consuming to do versus a shaft.
As for mounting the piece, I would probably not use a vice but instead hold the piece flat to a table with screw down clamps out on the edges, this would put very little stress on the teeth since you are clamping through the meat of the gear. You should be able to get far enough out that you can mill all you want.
Matt