The Swelling Pin hole Conundrum

[Delwin D Fandrich]

A440A@aol.com wrote:

> John mentions:
>
> >Not necessarily the branch water itself, but what is mixed with;
> >which causes the swelling and clogging of the pores.
>
>      I debush keys with a homemade steam contraption.
>       ( a small hot-water-heater element that is mounted in a 3 lb. size fire
> extinguisher, held side-ways in a small wooden frame so that the row of
> homemade nozzles (drilled out zerk fittings)are pointing up and are just the
> right height to steam the bushings of keys that are supported by the frame,
> it will hold 6 at a time, ),   but I digress........
>       Using steam to remove the bushings of vintage, hide-glue bushed keys
> only takes about five seconds per key, and leaves no stains.  Even on this
> exposure to moisture, the balance rail holes swell, and if carefully eased,
> stay quiet for years after the job.
>      I have rebuilt numerous engines that use a heat fit, (BMW motorcycles).
> The aluminum cases and the I.D's of holes enlarge with heat, but wood?  I
> still see tighter fits after moisture than before.
> So,   before I go fill up the bathtub to see which way the water  really
> spins,  I still want to know who has  wooden holes growing with moisture .
>
> Regards,
> Ed Foote

  -----------------------------

Ed, you're comparing apples with oranges again. Applying the artificial stimulus of steam to heat & wet the inside of the
hole has the same effect as glue-sizing.

Try this: Take a piece of wood -- any wood -- about 8" square and, perhaps, 1/4" thick. Put it in your oven and bake it for
about one hour at 250° F. Quickly and carefully bore a 1.0" hole in the center. Use a Forstner bit so you have nice clean
edges. Now, using a dial or digital caliper, measure the diameter of the hole both with the grain and across the grain and
write the numbers on the board. Next, take the board into your bathroom and take a really long shower. In fact, you might
leave it in there while the whole family takes their showers. Sequentially, not all at the same time. Actually, if you have
any teenagers around, one of theirs might suffice. Finally, re-measure the inside diameter of the hole. You will find that it
is now larger than it was when you bored it. Most of the dimensional change will have taken place across grain, but it will
have grown slightly with the grain as well.

If you want to go one step further, you can take the board out to your workshop for a few days and let it reach equilibrium.
Once again measure the inside diameter in both planes with your caliper. Now take your glue-size mixture and coat the inside
of the hole. After it has dried, again measure the inside diameter. You will find that the inside diameter has decreased.

Now to understand what has just happened, read Chapter 4 (Water and Wood) and Chapter 5 (Coping with Wood Movement) in
"Understanding Wood" by R. Bruce Hoadley.

-- ddf