12x36 repair

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Updated November 22, 2012 17:03

Obsolete! the gear is obsolete. Well it's a stinking gear so we'll just un obsolete it.

It just happens to be a 1.75 mod 16T gear. We have no suitable involute cutters for this pitch and no patience to order and wait. There is also a lacking of funds to buy the cutter and key way broach.

On close examination it had been brazed by the previous owners which explains why the QC lever was always bouncing a little.

The broken gear is indicated by the yellow arrow a on left. It is connected to the left hand quick change lever and was annoying even before it broke (again).

A 1 1/8" brass rod was turned down to size in the 7" 4 jaw on the 9x20. The chuck was removed from the back plate and mounted on the rotab (with dividing plates). It was setup on the mill/drill and the festivities commenced. We used an involute cutter that most closely matched the flanks of the gear but that left the root fillet a little (OK a lot) narrow. So we followed it up with a larger involute cutter to open the root.

Not perfect by any means but it runs well. If I hadn't shown the pictures know one would ever know of how cheasy it is. I got 3 gears out of the piece so it's all good. It was broached with a 3/16" which is a few thou loose but no problems there either. I honestly thought that I'd just end up ordering the right tooling to do the job right but this is working so well there is no need. It'll just run like it is.

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November 22, 2012