Tuning pin drilling? followup

[Ron Nossaman]

> .>I should qualify this. My 1/4" first pass is with a short 
>> flute bit about 10" long, which is plenty flexible. 
> 
> 
> Aha!!  You never mentioned this bit (no pun intended) before!!  Now I see why I couldn't duplicate your results. 
> No bit I would have considered using would be that ...I guess...compliant would
> be the word.  
> 
> So... you find your transfer punch dimple by letting your bit do the walking, which being that
> long, it's happy to do. Carefully lining up the press and its axix to the dimple becomes not very
> important...right?

Not exactly. I try to line it up carefully, but the flex of 
the bit most likely does help. This is partly what I've been 
talking about as I keep stressing that absolute precision and 
rigidity of the setup isn't strictly necessary to drill 
precision holes. Incidentally, I wasn't entirely happy with 
the way the bit centered in the punch dimple, so I started 
center drilling the dimple some years back, making it 
downright unlikely that the bit wouldn't center.


> Your  "go with flow" procedure and material has alot going for it.

Making the existing characteristics work for you is easier 
than fighting them.


> Finding the transfer punch mark is the achilles heal, of my rigid set-up...very time consuming.

I expect so, as is all the repeated clamping. These are what I 
consider to be the benefits (as I see them) in my system. The 
plate is in for the final time when the block is drilled, so 
there's no chance of misalignment anywhere. The holes are 
located with a transfer punch (turned off center so the hole 
is a bit toward the keyboard) in uniformly reamed webbing 
holes, and center drilled. Both of these are pretty quickly 
done. The 1/4" pass, with a standard short flute long low 
helix bit, removes the bulk of the material quickly. If I push 
too hard and lift the front of the drill rig, I don't care. If 
the chips don't clear from the flutes and I have to make two 
plunges per hole to clear the chips, I don't care. If the bit 
sticks and spins the pulley on the worn belt, necessitating 
shutting the machine off and backing the bit out with a quick 
reverse twist by hand, I don't care. If my feed speeds aren't 
uniform from one hole to the next, I don't care. If the bit 
heats up, short of turning blue, I don't care, except that the 
damp steaming chips that come out of there are hot to touch as 
I brush them away. I'm not remotely concerned with what the 
precise diameter and uniformity of these holes may be, I'm 
just removing material in preparation for drilling the real hole.

The second pass has no alignment problems, no chip clearance 
problems, no feed rate problems, no heat buildup problems, no 
chip accumulation problems, and is considerably faster than 
the first drilling pass. I've used both the 6.8mm jobber 
length bit brazed into a 1/2" extension (because I could 
*find* 6.8mm in jobber length), and long 17/64" bits. The long 
bit is obviously more flexible, but the results seem to be 
close enough to the same (except the smaller 17/64" bit makes 
a tighter fit) that it's a non-issue.

It's not entirely idiot proof, but it's close enough that I 
can do it repeatably with what passes for my attention span 
and skills.


> How picky is the timing of the final plunge with your system?  Mine is very picky, which is good and 
> bad...good in that I can accomodate different mic'd pin dimensions by varying the timing of the plunge,
> bad in that if I'm not consistent with the timing, results can vary.  Interestingly I can vary the torque
> by a good 60inch/lbs by timing alone...requires a metronome.

Not picky at all, because I'M NOT REMOVING A SIGNIFICANT 
AMOUNT OF MATERIAL. Sorry about the shouting, but that is THE 
fundamental reason that this system works at all. I feed by 
feel. Not punching, and not skating. I feed as it cuts, and I 
can put it on autopilot and mostly go somewhere else mentally 
until it's done. Usually mentally going over some other 
process looking for something I've screwed up, or might.

Also, I haven't mic'd pins (Denro blue) for a long time, and I 
find even less reason to do so with my composite block, which 
is considerably more forgiving then the Delignit I used before.


> If I can get over the thought of 10 inches of wobbling steel, I will seriously consider flexing(again no pun intended)
> on this proceedure.
> 
> Live and learn..maybe...
> 
> Jim I

Just remember that the first pass isn't a real hole. It's 
creating an absence of material, a void, that lets you drill a 
real hole on the second pass. Before you can sweep, you have 
to shovel the big chunks up off of the floor to get them out 
of your way, and this is the same thing.

When you consider that the single most numerous and expensive 
to install items in pianos are the holes (count the number of 
holes, and holes in holes, that it's necessary to install to 
build a piano), it's not hard to understand that the 
installation processes can be challenging.
Ron N