[SEL] Re: Alamo piston pattern update

[Dave Otto]

Curt Holland wrote:

> Tell us more about this. How did you accurately center this? Because of
> the huge square corners there is no indicator that will back out of the
> way enough to allow the square corner to go by to indicate the flat on
> the other side. Did you just use a scale and some reference on your lathe?

Well I guess because I planed on turning the part around after it was round
I wasn't concerned about getting it Nat's ass on center. I centered the
blank using the chuck body as reference the best I could. I was more
concerned with getting the tail stock end centered properly. I figured when
I swapped ends and centered that end any little error would be removed. Now
each end has an accurate center for finial machining. My 3 jaw chuck is a
Buck adjust tru style, so when I chucked up on the core print end to finish
the piston end I was able to dial it in. This assures concentricity between
the two ends.

I machined the piston crown with the center inserted, cutting as close as
practical to the center. The finial step was to remove the center and take
very light cuts to get that last little bit.

The core print end was left long; and will be cut to length with draft after
it is split.

Obviously more than one way to skin a cat; this just seemed logical at the
time. My short term memory is so good that if I were to do this again in a
month or two I would probably do it differently because I won't remember how
I did it the last time. Happens to me all the time :(

> Unfortunately I have not documented this engine too well. A lot of the
> engine was in boxes when I bought it and my intention was to just put it
> back together and mechanically restore it later when I got some other
> project done. But to make this go together, that had to be fixed, then
> something else, etc., etc. 6 months later I've nearly done the whole
> thing. I just didn't take the time to pick up the camera and take many
> pictures. Sigh...

I know what you mean; I have to force myself to take pictures, I get caught
up in the work and don't want to stop and mess with the camera.


Regards, Dave

Dave Otto
Boise, Id
USA
Dotto at velocitus.net
http://community.webshots.com/user/otto1960