> On May 18, 2017, at 8:13 PM, jimlux <[email protected]> wrote: > > On 5/18/17 2:36 PM, Chris Albertson wrote: >> It would be easy to re-design the job for cheaper machining.. Do you >> really need to tap the holes? You might use self taping screws. Id the >> would work then you can do the work yourself with just a hand drill. >> >> OK it you must use machine threads and they must be #4 size try "rivets" >> these work like pop rivets but leave a hollow thread insert in the hole >> that will take screws. Takes all of 5 seconds to install a thread hole. >> >> Think again about threading aluminum. It is not very strong, it would be >> easy for an end user to strip the #4 threads. Better to use the rivet or >> other steel thread insert. Even native nuts installed with flush rivets >> is better > > Interestingly enough, for 4-40 hardware, the screws fail before the aluminum > does. The area of the thread engagement is quite a bit larger than the cross > section of the fastener that is not thread.
There are a lot of variables involved. Run the screws in and out of the aluminum a number of times and the holes will fail first ….There are other gotchas as well. Bob > > For large fasteners, where the thread depth is a smaller fraction of the > fastener diameter, this may not be the case (as anyone who has stripped the > threads on an aluminum cylinder head with a steel sparkplug will know, in a > deep and visceral way). > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
