[time-nuts] Machining some aluminum help!

jimlux jimlux at earthlink.net
Thu May 18 13:04:35 EDT 2017

On 5/18/17 9:54 AM, cdelect at juno.com wrote:
> Hi,
> I have a square aluminum tube 5" X 5" with a .25" wall it's 8 1/2" long.
> I need 20 holes in each end tapped for 4/40 and 1/2" deep.

So you're putting 5 holes in each side? in the ends? (i.e. the long axis 
of the screw is within the wall?

That's a fairly tricky operation, especially if the tube is standard 
extruded tube, because the sides might not be perfectly flat or at right 
angles. You're drilling a 0.112 hole in a 0.25" wall, so you've got some 
clearance, but I assume you've got a matching cover plate you want to 

How critical is the spacing of the holes?

A good drill press (or vertical mill), and a really good clamping setup, 
and "match drill" the cover plate and the tube at the same time.

> This is for a Rubidium project.
> The local machine shop want's $360.00!!!!
> Anyone have a machining setup that could do the work a bit cheaper?
> If not I'll give it a try myself.
> Please contact me off list.
> Thanks!
> Corby Dawson
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