key rebushing irregularities

[Phillip Ford]

>Greetings,
>
>I've been using Spurlock's cauls for rebushing keys with great success. I
>use the mortising cauls when removing the old felt, which leaves the slots
>smooth and uniform. Then I use the two step- intermediate and final- cauls
>for gluing (hot hide glue, of course) in the new cloth. I've done several
>sets this way and always had very little easing to do when installing the
>keys. They've been near perfect- until this last set.
>
>This last set, a Schafer and Sons (read Samick) upright, about 20 yrs old,
>the front rail pins are all a little snug, not too bad, but they all needed
>a little easing. But the balance rail was all too loose, really unacceptably
>loose. We used the same mortising cauls, the same intermediate and final
>cauls, the same bushing cloth. The only difference was my son-in-law took
>out the balance rail bushings and I took at the front rail bushings. Our
>method is to turn up the heat on the glue pot so the water is bubbling
>boiling and hold the key over the steam for a few seconds. The old cloth
>practically falls out. He may get it a little moister than me, or vice
>versa.
>
>On this particular set, he removed the old balance rail cloth about 2 weeks
>before the new was glued in. I removed the front rail cloth about a week
>before the new was glued in. My son-in-law put the new cloth in both balance
>rail and front rail, so there would be no difference in method there.
>
>Anybody have any thoughts on what happened?
>...
>Dean

What is the material of the key buttons?  I haven't done this in a long 
time (I now pay someone else to do it), but as I recall hardwood and 
softwood respond differently to this treatment.  The glue will cause the 
wood to swell somewhat (softwood more than hardwood) and will also tend to 
'size' (bind or stiffen) the wood (once again softwood more than 
hardwood).  As I recall, if you're putting a bushing into hardwood then you 
need to have a much snugger fit with the bushing in order to get it to come 
out right, because the hardwood won't swell very much or 'size' very 
much.  In softwood (and the softer it is the more it seems to respond this 
way) you can have a really loose fit on the caul and after it sets up it 
will still be about right because the wood swells a lot and sizes readily.

BTW, how long are you leaving the cauls in there?  I used to leave them
at least overnight.  You need to leave them in there until the wood stabilizes.

Phil Ford