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Someone else posted this idea on the Rocketry Forum recently and I thought it was brilliant. I apologize for not linking to it or naming the author, but I can't find it again. I took their idea and printed mandrels that fit inside BT-5, BT-20, BT-50 and 29mm tubing. Each mandrel is printed with a 3.3mm diameter through-hole, which I tapped with a M4 tap to take an M4 buttonhead screw and metric washer. I found that moistening the tap with my spray bottle of alcohol provided better lubrication without having to resort to Tap-Magic or other oily lubricant. I used the 3.3mm tap size (0.130") because I had a bunch of M4 screws lying around. But you could use the same hole and try a #8-32 tap (needs a 0.136" hole) or ream out the current hole with a #29 drill. If you decide to use #8-32 fasteners, the hole in the end cap will also need to be drilled out with an 11/64 bit.
I have metric and imperial punches that go up to 30mm and 1 3/16". So I used a 4mm central punch concentric with the larger punch to make discs of sandpaper. I use 3M blue Stik-It sandpaper but non-adhesive paper should work just as well. For the 29mm sander I stuck the 37mm end cap to the sandpaper and used a snap knife to cut around it, then chased the edges with a file to clean them up.
I have a home made body tube cutting jig that makes really clean and accurate cuts so I don't need to do a lot of sanding. But for a really clean and dead square edge I wipe the inside of the tube edge with a touch of BSI Insta-Cure CA then slide the sander in and give it 4-5 twists. Voilá, a sharp and square edge in a matter of seconds. Much more precise than a sanding block or belt sander, which is what I used before.
If anyone has the link to the original post for this idea, please let me know so I can give proper acknowledgement.
Thanks.
I have metric and imperial punches that go up to 30mm and 1 3/16". So I used a 4mm central punch concentric with the larger punch to make discs of sandpaper. I use 3M blue Stik-It sandpaper but non-adhesive paper should work just as well. For the 29mm sander I stuck the 37mm end cap to the sandpaper and used a snap knife to cut around it, then chased the edges with a file to clean them up.
I have a home made body tube cutting jig that makes really clean and accurate cuts so I don't need to do a lot of sanding. But for a really clean and dead square edge I wipe the inside of the tube edge with a touch of BSI Insta-Cure CA then slide the sander in and give it 4-5 twists. Voilá, a sharp and square edge in a matter of seconds. Much more precise than a sanding block or belt sander, which is what I used before.
If anyone has the link to the original post for this idea, please let me know so I can give proper acknowledgement.
Thanks.
