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View Full Version : Gear today, hold tomorow



Hexhead
09-12-2006, 11:05 PM
If you tell me how to do this today, I'll do it tomorow.
I need to make a small gear (for a belt sander). I have a rotary table and tailstock for the mini mill. My question is what are some ways to secure the gear material to the shaft to make the gear.

ASparky
09-12-2006, 11:18 PM
Not sure I understand the question, but if I do then. The way I hold gear like stock to a shaft is with two collets. Both with a grub screw to fix to the shaft. One of the collets with two threaded bolt holes parrallel to the shaft - with bolts in.

Jam the material losely between the two collets, tighten both to the shaft with the grubs. Then use the two bolts on one collet to force the material snug against the other collet. This provides more than enough grip to lathe the material, It may be enough to allow gear making.

Hexhead
09-12-2006, 11:41 PM
You understood correctly grasshoper. Thanks for the quick reply, this gear is small, the size of a nickel, so the collets are going to be pretty small. Do you think a tapered shaft would work or super glue.

Ps; anyone else who has ideas I'd like to hear them I need all the ways to do things I can get, I still have to wear a dunce hat when I work.

ASparky
09-12-2006, 11:56 PM
I am assuming holes are a no no. If not bolt to a collet and go for it.

You may also be able to get away with making a single collet with grub (or glueing) and superglueing the stock to the collet, if heat is not a no no then heat gently to unglue.

Oh and do keep cool while machining, superglue is wunderbar but really doesn't take any heat.

darryl
09-13-2006, 01:43 AM
What meterial will it be made from? My first thought was to press fit it to a stub which would expand more than the gear blank, thus the heat from machining on it wouldn't tend to loosen it on the stub.

If the material would be a brass, you could soft solder it to a brass stub, or conversely mill the gear teeth into a suitable sized shaft, then part the gear off after the teeth are made.

If you can do it that way, then you're free to select an alloy steel to make the gear from. You could drill the mounting hole in it, mill the teeth, then part off almost all the way, but not quite. Then you'd have a 'handle' on the gear to hold it for heat treating, if that's something you'd want or need to do.

J Tiers
09-13-2006, 08:27 AM
I just jam a regular "straight" (actually they taper) mandrel into it nice and hard, and go to work with it between centers.

One thing, the dog you use needs to be held so it cannot turn , a regular slotted dog driver isn't good enough.

In the picture you can see the gear on the mandrel, and kinda see the setscrews that tie the dog against rotation. I should have lightened-up the pic, but I already had it. The blocky thing is clamped on the straight portion of the center, and holds the setscrews that hold the dog steady.

http://img.photobucket.com/albums/0803/jstanley/gear1s.jpg

TGTool
09-13-2006, 11:02 AM
Yes, a tapered mandrel was what I'd always been told. And arranged so the cutting forces are toward the large end of the taper - that is, you don't want any force trying to loosen the gear blank.

Jan M