[Bell Historians] Worn out garments show new patches

[Bickerton, Roderic K (SELEX) (UK)]

Very common, and not an arrangement I like. The same "design feature" is
being proposed at Bushey.
The problem is that wood is not dimensionally stable as it absorbs
moisture during wet winter months and no matter how nice and tight it is
sandwiched between metal frame and metal foundation beams, come the
summer when it bakes dry and shrinks the clamping tension will be lost.
If the beams are oak there is never quite an end to twisting and warping
to add to the problem. 
There are hundreds of installations built this way and it works well
enough, but can never be as stable as all steel.
Maintenance wise you have the corrosion prevention for the steel added
to the need to tighten regularly of wood, the worst of both worlds.

Roger, I will pass on any other comment is generated by this group.
 
	

I hoped this learned group might be able to help in a not totally
historical matter.
 
I am considering a proposal to build a new metal frame with one set of
new girders going into the wall.  At right angles to the girders are
four substantail wooden beams on which it is proposed to mount the new
frame and clamp it to them.
 
Are there many other examples out there of a mixture of wood and metal
foundation beams and how successful/unsuccessful is this situation.  I
can only call to mind one such installation.
 
Andrew

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