Pem nuts- love the things. I use the broaching nuts, and have never use a tool other than a screw, washer, and screw drivers To insert them.
Pay close attention to the recommended drill size.
Make sure you get the type for soft metals and plastics. They are also used for circuit boards. Buy the matching drill bit at the same time.
I use an Allen wrench a short cap head screw and a stack of washers to pull them into the tube wall.
Dave,
I use the tin plated KF2 type:
https://catalog.pemnet.com/viewitems/nuts-broaching-types-kf2-kfs2/broaching-nuts-types-kf2-kfs2-unified
I drill the hole with the recommended drill size. Don't try to use whatever you have in your drawer. I use my fingertip or a dowel with double sided tape to hold it against the inside of the hole. Thread a short cap head screw with a couple thick washers into the nut. Then carefully turn the screw until the nut is started in the hole. Then use an Allen wrench to crank the screw until the nut bottoms out in the tubing or against the washers. Once they are in they won't come back out.
For Loc tubing, I just shape a piece of oak about 3/4" wide and 1" long and 1/4" thick so it fits flush to the ID of the tube. I then shape the ends so there are no sharp edges for recover items to catch on. Glue that to the inside and use 3/8" to 1/2" long SST #6 sheet metal screws. Drill your hole, put a little soap on the screw and screw it in to set the threads. Once the threads are set, you can grind the tip of the screw down so it stays flush with the top of the wood if it's in the BT with recovery gear. Shouldn't be needed if it's in the av-bay.
The screw heads do protrude into the air stream, but I've used this method on a 4" rocket I built in 2009 and has 36 flights on it. It's held up great so far, even Mach speeds, drogue only landings, and various other minor mishaps. YMMV
For any tubing other than fiberglass, I just cut a small square out of G10. Press the PEM nut into the G10 and epoxy that to the inside of the coupler.
Check out the big brain on Graduator. I'm stealing that idea.[/]
Ditto! Solved my problem without me having to try to glass an inner radius (probably still a good skill to have though).
Glass interior radius. Have glass cut and epoxy ready. Wet glass with epoxy and insert rolling it flat. Insert long balloon into tube, inflate, and tie off. When epoxy sets pop balloon.
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