[pianotech] pinblock drilling clamp

[tnrwim at aol.com]

Wim,
The problem you have solved is not the problem I was having.  During the 
econd pass, when the .257 drill enters the .219 hole, it can grab and 
ift the pinblock at any point during the feed, not just at the end when 
t penetrates the bottom of the block.  By clamping the block securely 
uring the entire stroke, not only is this grab-and-lift prevented, but 
ny random shifting of the pinblock that might make the hole slightly 
arger is also prevented.
Mike



I never did a two pass drilling. I don't understand why two passes are necessary in the first place. 

The only time I did a two part drilling is when I drilled for the plate screws. I was taught that for plate screws, because the throat is wider than the threaded part, you need to drill the wider part first, and then the narrower part going all the way through the block. The small drill will find the bottom of the hole, and it's centered. If you do it the other way around, the drill will grab in the hole, and it will get stuck, or it will lift the block, which is what you're experiencing. 

Using my dowel, you only need to make one pass. Try it. 

Wim






-----Original Message-----
From: Mike Spalding <mike.spalding1 at verizon.net>
To: pianotech <pianotech at ptg.org>
Sent: Thu, Aug 12, 2010 9:00 am
Subject: Re: [pianotech] pinblock drilling clamp


Wim,
The problem you have solved is not the problem I was having.  During the 
econd pass, when the .257 drill enters the .219 hole, it can grab and 
ift the pinblock at any point during the feed, not just at the end when 
t penetrates the bottom of the block.  By clamping the block securely 
uring the entire stroke, not only is this grab-and-lift prevented, but 
ny random shifting of the pinblock that might make the hole slightly 
arger is also prevented.
Mike
tnrwim at aol.com wrote:

     Some folks complain about pictures placed in forum posts. My
     complaint is a lack of pictures. My limited cranial capacity will
     not form a workable picture of what is described below. If the
     dowel is bolted to the depth guide, won't the dowel advance
     downward at the same rate as the drill bit? How does that "release
     the bit"? Sorry, just can't picture what this dowel is doing.

     Terry Farrell

 Terry
  
 I don't completely understand why it happens, but when the dowel, 
 which does come down at the same rate as the drill bit, contacts the 
 pin block, it "releases" the drill bit, and allows it to come back out 
 of the block.
  
 The dowel is about 6" long. To make sure it does it's job, before I 
 start drilling, I lower the drill to the side of the block, and look 
 to see that the bit is about 1/8" past the bottom of the block. That's 
 the point the dowel should touch the top of the block. When each hole 
 is drilled, when the bit goes through the bottom of the block, that's 
 the point at which to dowel hits the top of the block. The drill is 
 brought back up, and the block stays where it is, without having to 
 hold on to it, or clamp it down.  
  
 Wim



 -----Original Message-----
 From: Terry Farrell <mfarrel2 at tampabay.rr.com>
 To: pianotech <pianotech at ptg.org>
 Sent: Wed, Aug 11, 2010 11:53 pm
 Subject: Re: [pianotech] pinblock drilling clamp

 Some folks complain about pictures placed in forum posts. My complaint 
 is a lack of pictures. My limited cranial capacity will not form a 
 workable picture of what is described below. If the dowel is bolted to 
 the depth guide, won't the dowel advance downward at the same rate as 
 the drill bit? How does that "release the bit"? Sorry, just can't 
 picture what this dowel is doing.

 Terry Farrell

 On Aug 12, 2010, at 3:55 AM, tnrwim at aol.com <mailto:tnrwim at aol.com> wrote:
> I had the same problem you describe, the pin block riding up on the 
> bit. I used to hold the block down with my forearm, but that 
> seriously bruised it. What I wound up doing is attaching a dowel to 
> the guide, which on your press is to the left of the chuck. I drilled 
> a 5/8" hole in one end of a 3/4" dowel, and attached a 5/8" diameter 
> T-Nut. On the guide, I put a 5'8" bolt, and screwed the dowel to the 
> bolt. The dowel is long enough so that when the drill is all the way 
> through the block, the bottom of the dowel would hit the pin block. 
> That would release the bit, and you're ready to drill the next hole.  
> No clamp to tighten and release, and no bruised forearm.  
> Wim


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