[time-nuts] Machining some aluminum help!

Tim Shoppa tshoppa at gmail.com
Thu May 18 14:16:13 EDT 2017

I'm very dubious that you need a tapped 4-40 hole to be threaded any deeper
than 0.25". If you work with the machinist I'm sure you can come up with
some reasonable spec that does not require a bottoming tap and will save
you a lot of money.

I bet you went to 0.25" wall square tubing only because you want to tap the
walls for 4-40. Alternative designs can let you use much thinner material
and a very different flange on the ends, but the costs will likely move
towards welding/brazing rather than machining.

Tim N3QE

On Thu, May 18, 2017 at 12:54 PM, <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.
> 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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