[TheForge] Re: Shrink fitting steel to wood

Sun Aug 10 22:48:00 2003

Just looked it up, my book ( METALS AND HOW TO WELD THEM) by  the James F.
Lincoln Arc Welding Foundation says its 6.5 x 10^-6 so a bar 100 ft. long
heated 100 degrees  will gain .065 feet.
Any one else know who's right.
I think it was Roy Underehill I seen put tennons in hot sand to dry them
prior to assembling chairs, this might work to dry your hub.
Randy Mundt
----- Original Message -----
From: "Mike Spencer" <[email protected]>
To: <[email protected]>
Sent: Sunday, August 10, 2003 11:21 AM
Subject: [TheForge] Re: Shrink fitting steel to wood


>
> > Ideally,  wooden hub should be made of elm.
>
> You may say that.  I was once given a bunch of elm bolts for firewood,
> and took the trouble to haul it all home.  Back before I knew better.
> I believe I was able to split a couple of pieces off just to prove who
> was master but it took a while and I'm pretty handy with axe, maul and
> wedges.
>
>
> The splitting tendency of elm relates to that of maple of oak about the
way
> the crumbling tendency of, say, fibreglass grinding wheels relates to that
> of crystal wine glasses. :-)
>
> The coefficient of thermalexpansion of steel is around 13 x 10^6. By
> my quick calculation, a 4" ring would gain about 1/32" in
> circumference (or ca. ten thou in diameter) if heated to 400 deg. F.
>
> I vaguely recall that some old timer told me once that if you heat a
> metal band to where it just barely chars or browns the wood it's going
> on, then force it on a cool it quickly, that the slight charring makes
> for a perfect fit that the heat shrink is enough to make a
> difference.  Can't remember my source.  Might have been the guy who
> hewed the replacement rafters for Old North Church in Boston 70 or so
> years ago.
>
> - Mike
>
> --
> Michael Spencer                  Nova Scotia, Canada       .~.
>                                     /V\
> [email protected]              /( )\
> http://home.tallships.ca/mspencer/   ^^-^^
>
> --
>
>
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