"andy" wrote in message
...
Thanks all for the responses. Quick too! I ordered up a piece of 1144
(stress proof) 1.25" diameter.

Ok, if it's Stressproof(tm), and not just normalized 1144. Stressproof has a
yield strength of around 100 kips (thousands of pounds per square inch).
Ordinary normalized 1144 yields at 58 kips.

That probably will do the job, but if it isn't Stressproof, it's not what
you may think you're ordering.

1" would have been nicer, but I assume
tolerance= -0.006 means the piece is smaller than what I need. I
checked out all the other steels recommended and "fair machinability"
scares me. This shaft has three diameters, and is threaded in two
spots. Did I mention that i am a wood guy? I really like this saw
however, and will give it my best shot to get it running again.

I took the old shaft to the grinder, and the sparks were more
"fireworky" than a piece of steel pipe. I assume this means it is an
alloy steel of some type. A file cuts into it easily, so it is not
hardened.

More sparks generally mean more carbon. Alloys, in general, make fatter,
less-sharp sparks.

Although some folks here will disagree, my guess, based on some materials
experience, is that the original is a piece of cold-rolled, medium carbon
steel. The most likely grade is 1040. That's a very common steel for
mass-produced parts that have to withstand a medium load. It's probably the
most common steel used for machinery parts, and it's even used for things
that we think are very demanding, like the shafts on McPherson struts.

As a rule I go upscale from what I think the original is, if I'm machining a
replacement part for something. 1020 may do the job but I'm not going to
machine a part twice to find out, when I could have used stronger steel and
done the job once.


Luckilly there was not a lot of drama when the shaft broke. The blade
fell off the machine while cutting, and when I tried to re-mount it,
the upper wheel broke free.

I will take some photos and post my replacement shaft.

Thanks and happy new year!

Andy

Happy New Year to you, too, Andy. And good luck making the part!

--
Ed Huntress