Re: [ATM] Another machining question, please

[Jarvis Krumbein <jkoptic@juno.com>]

Thomas, a little more info would be helpful.  Do you need these holes to
be blind (not all the way through the aluminum)?  How thick is the
aluminum?  Will your drill press chuck handle a 1/2" drill shank?

There are several ways to do what you propose, some quite simple.  For
example, if you can live with a very narrow shoulder, the easiest
solution is to use a step drill (readily available from most well
equipped hardware suppliers such as Home Depot or Lowes).  One of these
requires a 1/2" hole to start.  The step drill has steps in 1/16"
increments with a maximum diameter of 7/8" and drills a very clean hole
in 6061 aluminum.  Just remember to feed slowly and use plenty of
lubricant.  If a wider shoulder is needed, can you live with sloping
shoulder?  If the answer is yes then drill with a 1/2" drill to deeper
than the desired shoulder depth and re drill to the required shoulder
depth with a 3/4" or 7/8" Silver & Demming drill.  These have 1/2" shanks
and are available from almost any tool supply house.

Jarvis Krumbein

On Thu, 15 Feb 2007 09:01:07 -0700 Thomas A Simmons
<tasimmons@raytheon.com> writes:
>   I want to have 3 flat bottom holes ~ 3/4 to 7/8 inch in 6061 
> Aluminum. I
> don't have access to a lathe
> 
> 
> or mill, but do have a benchtop drill press.Could I drill the holes 
> to
> depth with common metal drill bits
> 
> 
> and then run a Forstner bit down after it? All I really need flat is 
> a 3/16
> inch lip for a nut to rest on. I would
> 
> 
> assume this would ruin the Forstner bit...
> 
> 
> 
> 
> 
>   Since I'm effectively "homebound now" due to medical issues, 
> taking it
> locally to a machine shop or
> 
> 
> shipping it anywhere isn't going to work.
> 
> 
> 
> 
> 
> Tom
> 
> 
> Too stubborn to quit being an ATMer
> 
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> 
> 
 
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