Was "individual hitch pins" - Now: New Screws in New Pinblock/RichardStrang's Question

[Farrell]

This sounds like a great idea Joe. I have long wondered why you can't find a tap (or is it the die?) to thread a hole for a wood screw. If you just run one of our big wood screws into a maple block - if the hole is too small, you end up rounding over the screw threads (if not snapping the screw off) - but if you make it big enough to screw in, you are not taking full advantage of the gripping power of the threads. Solution: thread the hole first with a tap. It sounds like this is what you have made. But how do you "cut a slot, slightly off center of the axis of the screw" with a round file?

This was one of the major factors I juggled when deciding whether to replace the entire pinblock on my M&H upright or to just rout out the tuning pin field and epoxy in a chunk of new pinblock, thereby preserving the original plate screw holes (none of which were stripped).

Terry Farrell
  
----- Original Message ----- 
From: "Joseph Garrett" <joegarrett@earthlink.net>
To: <pianotech@ptg.org>
Sent: Friday, June 20, 2003 1:43 AM
Subject: Was "individual hitch pins" - Now: New Screws in New Pinblock/RichardStrang's Question


> Richard,
> I'm not too sure what other techs do, but I prefer to use a fail-safe
> method, that I developed after a few broken screws in pinblocks. I have a
> chart on the wall, that is essentially from "CABINETMAKING And Millwork", by
> John L. Feirer. (This is considered to be the Bible of woodworking, by
> many.) This chart gives the appropriate drill sizes for screws, in Soft
> Woods and Hard Woods. There are two diameters to be considered: The diameter
> of the Shank of the screw and the diameter needed for the threaded part of
> the screw. The first hole to be drilled is the Shank hole. This hole should
> be just slightly less than the length of "unthreaded" part of the screw.
> Then the "thread" hole is drilled to the depth of the length of the screw. I
> prefer to go just about 1/16" less, as the tip of the screw needs to "cut"
> into the wood. Of course there are  combination drills to accomplish this,
> as well as do a countersink. However, there are none of these "combination"
> types, that I know of, for the large screws we use in the plate, etc. There
> is a third kind of bit/combination that is tapered. I have a set of these,
> but don't like them.
> Anyway, once the holes have been drilled, I have some "screw cutters", (my
> term), that I have made out of the appropriate sized screws. (The ones I
> have are for #16, #18, #20 & #24.) Essentially, what I did to make these
> "Screw Cutters", was to use a round file, (Chain saw type), to cut a slot,
> slightly off center of the axis of the screw. This slot is all the way up to
> the "Shank". This, off-axis groove exposes the sides of the threads, which
> become cutters.<G>
> I then, slather the "screw cutter" with Bee's Wax and start the "screw
> cutter in the predrilled holes. I run it in, in the same fashion as one
> would do when cutting threads on a round drill rod, etc.(i.e., turn one full
> turn, back off one half turn, turn one full turn back off, clear the
> chips......., until you've "threaded" the holes, so that they will accept
> the proper screw without a binding situation. Oh, I use vise-grips on the
> top part of the shank to give me the leverage to do the Threading.
> If this description is unclear.....it's been a long day.<G>
> Best Regards,
> Joe Garrett, RPT, (Oregon)
> 
> Been There, Didn't Like It, So I'm Here To Stay! [G}
> 
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