Repairing Stripped Screw Threads in Wood
By S. Lee Walker
There is an epidemic about striped wood threads relative to old player
pianos. Several reasons are the type of wood and the age. Poplar and
maple wood seems to be the favorite. It's because it has a homogenous
grain and is easy to fabricate with wood machines.
The old wood screws 1917 to 1930 are fine thread; an example is 18
threads per inch and 0.135" diameter.
When you use a wood tap on small threads there is a tendency for the
wood fibers in the soft wood to break loose due to the small distance
between threads, thus a poor thread. This happens on only small
diameter screws. One way to correct this is to use a dry-wall screw.
One close to the same size is 5 threads per inch and 0.147" diameter.
There is more mass between the threads.
I use all new style wood screws that have a Philips head. I don't use
the slotted head screw because the screw driver slips and damages the
finishes. By the way, screw drivers are like drills -- they also get
dull and distort the slot. They need sharpening, too.
A problem with dry wall screws is they are limited in size and
lengths. Here is a way to solve this problem. Take a longer length
screw and cut its length to size you want using a radial blade for hard
steel. Next make a wood fixture with a hole just a little larger than
the screw diameter. Use a grinder and put the fixture on the grinder
support and turn the screw and grind to a point. You now have shorter
length. Ref: MMD 2016.04.13.02
S. Lee Walker
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(Message sent Thu 22 Dec 2016, 17:02:58 GMT, from time zone GMT-0800.) |
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