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, <cdel...@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 > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
