[Milsurplus] [Boatanchors] Probably OT: Drill press runout question

[hwhall at compuserve.com]

 >
I have several Albrecht chucks that I use in my 1/2" chuck on the milling machine, including one that will hold a .008" drill, and have no problem with concatenating any of them.
>

That's good to hear. It's not normal then, and I need to upgrade my hardware. In the meantime, I was able to complete the first prototype board drilling using the excellent idea of heat shrink tubing. The bit slowly slipped at first but I remade it with some GOOP glue on the bit's shank under the heat shrink tubing and that seemed not to slip anymore.

Thanks!

Wayne
WB4OGM


-----Original Message-----
From: Mike Hanz <aaf-radio-1 at aafradio.org>
To: hwhall <hwhall at compuserve.com>; milsurplus <milsurplus at mailman.qth.net>; boatanchors <boatanchors at mailman.qth.net>
Sent: Tue, Apr 29, 2014 9:01 am
Subject: Re: [Boatanchors] [Milsurplus] Probably OT: Drill press runout question


On 4/28/2014 10:46 PM, hwhall at compuserve.com wrote:
> I need to drill some very small circuit board holes for a project, #64 drill 
size (.036 inch). My drill press chuck wouldn't grab a bit that small, so I got 
a mini chuck to fit into the press. The mini chuck shank is 1/4 inch. When I 
installed the mini chuck, the drill bit wandered in a circle, like a case of 
runout. Not like a bent bit, the whole length of the bit was moving around. But 
when I put a 1/16 inch bit into the drill press, there isn't any runout anymore.
>
> Thinking the mini chuck to be faulty, I looked around the workbench some more 
and found a hand drill that would grab the #64, and it ran true when I turned 
it, so I removed it and inserted it into the drill press. It had a 5/16 inch 
shank. This combination also showed wobble. But the drill press still will turn 
a small diameter drill bit without noticeable wobble.
>
> It's as if the wobble turns up only when the drill press chuck is made to hold 
a larger diameter, and goes away with the smallest diameters. Does that make any 
sense or suggest something that I should inspect or adjust?

It makes sense, and is simply a reflection of a very worn or very 
inexpensive drill chuck.  You should be able to chuck the smaller chuck 
into the larger one and still maintain less than .001"TIR.  I have 
several Albrecht chucks that I use in my 1/2" chuck on the milling 
machine, including one that will hold a .008" drill, and have no problem 
with concatenating any of them.  You are probably getting the runout 
with larger drill bits in your drill press chuck but never noticed it.  
What that does is to cause the drill bits to wear more rapidly on one of 
the two cutting edges.  You can certainly try the tape and sleeve 
approach if you're in a hurry, but to fix it right, I'd get a decent 
Jacobs chuck for your machine from Enco 
(http://www.use-enco.com/CGI/INPDFF?PMPAGE=480 ) or other machine tool 
dealer.  You get what you pay for in this area.

73,
Mike  KC4TOS

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