[pianotech] pinblock drilling clamp

[Mike Spalding]

Wim,

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