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Posted by Steve W. on April 22, 2008, 11:29 pm
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John L. Weatherly wrote:
> My father-in-law has well broken in drill press that he wants me to repair.
> He told me it was built in 1918. It says "CANEDY OTTO MFG CO" on the side
> of the column. Flat belt driven. Has a counterweight inside the column
> with a chain attached to the quill. Has all kinds of open gearing on it.
> Has been retro-fitted for an electric motor.
>
> The problem is the gear that engages the rack gear on the quill is stripped.
> That means no feedy up or down. The shaft the gear is machined on is in
> good shape. It looks looks like they machined the entire shaft and
> shouldered up to the gear. Weird.
>
> Two questions:
>
> 1) Should I build up the gear with weld and machine it down, or machine the
> gear separately & silver solder it on? I have lathe capabilities as well
> as a 25" Smith & Mills shaper with a dividing head on the way (generous
> payment [gift] for the job.
>
> 2) How the hell do I reverse engineer the worn gear? I can count the teeth,
> but that's about it. The rack gear on the quill is in decent shape. I'm
> sure there is an equation three pages long for it, I'm just ignorant about
> gears.
>
> What do y'all think?
>
> --
> John L. Weatherly
>
> please remove XXXs to reply via email
Dress a cutter tool to the root shape of a pair of teeth on an unworn
area on the rack. Now count the teeth on the gear and measure the
diameter. Layout a circle to that diameter and layout the teeth to match
the old gear.
As for how to attach it. I would machine the current gear down the a hub
in a standard size. Machine the new gear in that size minus a few
thousandths. Attach the new gear by heating it in an oven and pressing
it on the hub. Once it cools it will be solid, no key or solder involved.
--
Steve W.
Near Cooperstown, New York
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> He told me it was built in 1918. It says "CANEDY OTTO MFG CO" on the side
> of the column. Flat belt driven. Has a counterweight inside the column
> with a chain attached to the quill. Has all kinds of open gearing on it.
> Has been retro-fitted for an electric motor.
>
> The problem is the gear that engages the rack gear on the quill is stripped.
> That means no feedy up or down. The shaft the gear is machined on is in
> good shape. It looks looks like they machined the entire shaft and
> shouldered up to the gear. Weird.
>
> Two questions:
>
> 1) Should I build up the gear with weld and machine it down, or machine the
> gear separately & silver solder it on? I have lathe capabilities as well
> as a 25" Smith & Mills shaper with a dividing head on the way (generous
> payment [gift] for the job.
>
> 2) How the hell do I reverse engineer the worn gear? I can count the teeth,
> but that's about it. The rack gear on the quill is in decent shape. I'm
> sure there is an equation three pages long for it, I'm just ignorant about
> gears.
>
> What do y'all think?
>
> --
> John L. Weatherly
>
> please remove XXXs to reply via email