Subject: Re: Fabricating Crankshafts: questions!

From: Charles Lamont <[email-masked]>
Date: Wed, 24 Jan 1996 21:14:13 +0000

Edward Haas writes

>       Hello, all! I would like to make a "fabricated" crankshaft for a 
>3-cylinder engine. It will be built up of various sections of bar, etc. 
>and it will need to have 120deg. throws. What I'd like  to do is key the 
>various parts together, but I'm clueless as to how one gets the accuracy 
>needed to broach keyways to, say. plus or minus a tenth of a degree. Can 
>someone explain a trick or two?

If it is not too big then the loctite method seems to have a lot going
for it.

For a press/shrink or adhesive assembly, one useful tip is to make the
main shaft as on continuous piece from one end to the other, assemble
all the webs and pins onto this shaft, and then cut out the sections of
shaft between (the bits that would otherwise tend to bend the connecting
rods).

--
Charles

Turnpike evaluation. For information, email: [email-masked]

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From: [email-masked] (Orest Koroluk)
Date: Thu, 25 Jan 1996 19:58:44 -0500

In article <[email-masked]>, [email-masked] (Edward Haas) wrote:

>         "Steamboat Ed" Haas     :      

You might try making the whole thing without keys first and then aligning
the assembly (possibly in parts) then keying the crankpins by drilling
holes at the point where the pin and disc (throw) intersect. 

Also, as I mentioned in a recent post, Loctite works really well as long
as things don't get too hot ie. over about 300 deg F.

A number of years ago I helped my brother rebuild a couple of snowmobile
engines that used built up crankshafts. Granted they were twins but the
principles are the same. The crankpins were made with a taper (self
holding) and needed to be pressed apart and together with about 5 tons of
force, as I recall. When being reassembled I remember knocking the various
pieces into alignment using a lead hammer.

Orest