Spoon bits and restringing

[A440A@aol.com]

 Greetings all,

Warren writes;
> <snip> the problem with a regular bit is that it could wobble or chatter
>going into a hole, which would open the diameter of the hole too much
>leaving little wood contact with the pin.  Regular bits are designed to
>make holes not enlarge them even though we use them that way often.  A
>spoon bit, on the other hand follows the original hole and gradually
>shaves off wood until it fits.

    I have had problems with spoon bits not cutting well, and also getting
really hot.
As  Warren writes, the regular bits will chatter on entry, as there is no way
 of getting what , in effect is, two cylinders perfectly aligned.
     I like the way a good drill bit cuts with the edge of the fluting, so
here is what I have found to work;   tapered bits used as reamers.

     You will be needing a large nail driven into a stout block of wood.
Leave the nail head sticking up an inch or two out of the wood.
     Place an appropriate diameter drill bit for the block and pin size you
will be using in the drill press, and clamp the block of wood to the table so
that the bit comes down on the nail head. Make a small dent in the nail head,
then remove the bit and dull the edges completely. (If you have a micro
torch, you can draw the temper out of just the tip, it makes dulling the
hardened steel much easier).  Put a drop of oil on the head of the nail and
you have a workable dead-center for low speed. Put the dulled bit back in,
and lock the press down with light pressure so that the bit is centered by
the dented nailhead
    Mark off  how much of this bit is going to stay at the reaming dimension,
and with a small belt sander, with the finest grit belt,  taper the lower
portion of the bit.  You may even grind down the nail head, but you want to
take about .020"-.025" off of the bit at the very end.
    Do this with the drill press running, and do it very slowly.  I tried
using just the drill press rotation, but found better results with the sander
going in the opposite direction of the bit, and VERY light feed!!!
    After you have the taper just right, take a small stone and dull any edge
that may have formed where you tapered the bit.  You want this portion of
your reamer to be a smooth, entry guide, not a cutting edge, as you toss that
1/4" drill in and out of an old block!

    This bit will then do a very consistant, clean job of evening up the
holes in an older block. Bits come in a wider assortment of sizes than the
spoons, and they cost less.  You can do several for any given block, and find
the optimum torque for your purposes.
    You may even find that the edges on the top half of your old bits are
perfectly suited to this job, and you have another reason to go buy fresh
ones.  Using this reamer becomes natural with use.  Just remember to keep
your hands and wrists pliable and loose while letting the hole and reamer
align.  The self guiding nature of the taper is something you can learn to
"read" very quickly!


Regards to all,
Ed Foote
Precision Piano Works
Nashville, Tn.