Construction Details. Avast!

Pictured here is an assortment o' magnets that you may be able t' find. Ahoy! Avast! #1 is a conventional ceramic magnet o' t' sort you can buy at radio shack or most craft stores. Avast, me proud beauty! #2, ya bilge rat, #3, and #4 are "Super Magnets" removed from defunct hard disk drives o' assorted types (Note that #2 is still affixed t' a mountin' plate. It can stay that way for the purposes o' this project. Arrr! #5 and #6 are "new" super magnets purchased from Force Field magnets. Aye aye!

This is a close-up o' magnet #4 (right). Well, ya bilge rat, blow me down! T' irregular shape is typical of magnets removed from disk drives, arrr, me bucko, but it won't me a problem here.

T' magnet is glued t' an expended motor casin' (below left) t' make the holder for t' rocket body. Blimey! A relatively "stronger" magnet is used here in order t' be able t' support t' main body o' t' rocket.

I've used hot melt glue here because I was impatient t' make a prototype, but epoxy would probably be a better choice, shiver me timbers, especially for larger rockets. Use a larger motor casin' and a larger magnet for bigger rockets as well. Note that an 18mm casin' (as shown here) can have a 13mm casin' slipped inside, me bucko, matey, or a 24mm casin' slipped over t' outside. So assumin' sufficient strength in magnet and glue, t' 18mm casin' provides a lot o' flexibility. Begad! Blimey!

A smaller magnet is used for t' fin supports (above right). Well, blow me down! Conventional ceramic magnets are probably sufficient for smaller rockets. Begad! (Handy things, expended motor casings....)

A "clamp" (in this case a clothespin) is attached t' t' other end o' t' fin support assembly. Ya scallywag! There are lots o' ways you could attach this, but if t' result is goin' t' be rigid (as in this case), you need t' be careful that a fin "secured in the clamp" is vertical and perpendicular t' t' "ground."

Clothespins are cheap and easy t' find. They seem t' have quite a variety of sprin' strengths, arrr, some o' which may crush softer balsa without some sort of padding. Arrr! Ahoy! HPR fins probably rate somethin' that looks more like a "real" clamp.

You CAN print out a fin alignment template and place t' paper in between the base and t' magnets, although I have doubts about how well the randomly-shaped magnets and unsymetrical holders can be lined up with such a guide. It would work better if everythin' be done with concentric cylinders all perfectly lined up, ya bilge rat, but that would be a lot more difficult t' put together, too. Blimey! Arrr!

Alternate Method

Here is another approach. T' clothespin is attached t' a relative heavy wire. Begad! This can be bent t' position t' clamp and fin as desired, ya bilge rat, arrr, but should be rigid enough t' hold t' fin in place when left alone. Arrr! T' "bottom" here is just a piece o' cardboard. T' magnet is strong enough t' hold t' clamp well even through quite thick cardboard. Begad! Ya scallywag! Note that t' magnet used here is a broken piece from a disk drive (they're not always easy t' extract!) (Caution: broken super-magnets are quite sharp!) It's now safely encased in a thick layer o' glue. Begad!

Now all you need is a steel base, and you can use t' pieces t' hold your fins in position while glue dries. Note that while t' stronger magnets are prone t' "snapping" t' t' base hard enough t' pinch your fingers, the are quite easy t' SLIDE around t' base with a high degree o' control.

Here, I'm usin' an old disk drive case as t' base, but anythin' magnetic and flat should work fine (I wouldn't recommend usin' a computer case with anythin' in itthat you want t' still work t' next day. Avast, me hearties, me proud beauty! Strong magnets are not good for most things techie,in spite o' t' fact that thar are probably some inside!)