[TheForge] Re: Another pulley question (brazing cracks)

[Ralph Sproul]

Mike, a 4 of 6 spoke would be fairly easy as the others are holding the
outer rim true.

Sounds good on the newly found one.

I had that lock n stitch done on a large diesel engine block years ago when
she threw a rod off #2 journal and thru the side of the block......it held
until we scrapped the truck 12 years later.  It was great for a plug and
seal - but I'm not sure how it's do on a spoke - cuz it ain't that wide.  My
understanding is the epoxy sometimes used is the real meat of the
repair......besides the threaded stubs.

I'm not sure why they don't want to use propane......maybe it's the water
content - but after a certain heat it won't matter as it will disapate.  The
900 degrees I do understand as that is the maximum expansion point of steel.
Most of the expansion occurs to 450, but you can still induce stress up to
900 degrees.......this is why they want you to take it to 900 as it's as big
as it's gonna get - then do the repair and let it all cool at once is the
theory there.

I would be interested in hearing more on why they don't want to use propane
for preheats................

Ralph

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net]On Behalf Of Mike Spencer
Sent: Friday, November 25, 2005 10:44 PM
To: theforge at mailman.qth.net
Subject: [TheForge] Re: Another pulley question (brazing cracks)



> The part your kind of leaving out on this note is information being
> 2 cracked spokes out of 3? 0r, 2 out of 4?

Either 4 or 6.  I forget.  (I left the thing in the car when it went
to the shop and I won't get it back before Saturday.)

Thanks for the discussion, Ralph.  I may end-run this because the
machinist who's fixing up the 2" shaft for me has a 16" for cheap
that's in good shape and he will try to fit it to the shaft.

> What the heck, it's junk till you try...

Exactly, so if the one from the machine shop works, I'll try to repair
the cracked one anyway, just for the experience.

An interesting aside: in private email someone suggested (mechanical)
stitching. I don't think this is a candidate for that tech but on the
suggested web site:

     http://www.locknstitch.com/

there's also a discussion of the relative merits of brazing, welding
etc.  They suggest a preheat of 900F and say to use natural gas or
diesel but *not propane*?

Huh?  Why not?


Ob blacksmithing: I used a 250# LG briefly about 1980 to make a hardy.
Heard later that the shop had burned down around the hammer.  Saw it
later still in another smith's yard in sad shape.  It sat there for 17
years.  The machinist I went to to get this shaft turned said he had
just recently overhauled a 250# hammer.  What do you know?  A smith
not too many miles from me has lugged it home, had the shaft replaced
(with a *lot* of difficulty), re-babbitted, brandy-new spring from Sid
etc. etc. and has it sitting in his shop next to a 10HP motor.  I took
him what I hope is the last bit he needs -- a flat belt pulley for the
motor -- to get it going.  Real nice to see the old lady rejuvenated
and ready to debut.


- Mike

--
Michael Spencer                  Nova Scotia, Canada       .~.
                                                           /V\
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^

--


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