Homebrew Fin Alignment jigs...

I was building a High Flyer XL recently and one of the fins got canted off some 10 degrees. Some of you probably saw that thread "Doh!"

In that thread a member mentioned a really cool web site where you could generate templates for fin alignment templates.

That got my creative juices flowing and thought "I can do that but better!"

Being somewhat competent with Autocad I drew up a template for a BT60 with 3" span fins 3 x 120

I printed it out on 11 x 17" (tabloid sized) paper. Then affixed it to foam board, cut it out and made my own Jigs

20190723_153925 by Tom Whit, on Flickr

This is the plot of my Mark 1 UM jig (prototype).

20190723_173132 by Tom Whit, on Flickr

Here is the plot glued to some foam board and cut out.

20190723_223910 by Tom Whit, on Flickr

Fitted together side view.

20190723_221842 by Tom Whit, on Flickr

Parts all glued together and fitted on an already built High Flyer XL.


Now... if anyone wants plots or prints for a specific model, all I need to know is the OD of the body tube, the fin span and thickness, and number of fins. I will be quite happy to mail you a set of paper templates. You will have to do the gluing to the medium of your choice (cardboard, foamboard, cororplast, plywood) and cut it out. Free! No really! It took me like 10 minutes to draft this and plot it. I would love to give back to the community if I can. Unless the demand becomes overwhelming that is

ps; I can do up to 20" spans! Limited by 24 x 36 inch paper!

Nice! As you already know, the hard part with foamboard is getting square/parallel cuts. Even with a sharp scalpel it likes to grab and twist the blade, ending in some funky cuts.

Yep it can be tricky. Need a sharp blade and a metal strait edge for sure. And lots of practice

Nice work!

I like to make the ones for 3 fins with a hexagon outer shape so that you can use them to position the airframe for fillets as well.

Those are very sweet!!... One suggestion. Print the OD of the body tube, and the thickness of the fin slots on them in a region close to the body tube hole. BT-55 and BT-56 are close in size, and 3/32" and 1/8" can look close, and this would help extend the life of the jigs by preventing damage from being used on the wrong size tube/fins.

Print the OD of the body tube, and the thickness of the fin slots on them

Good idea! Since I only have two of them so far a bt20 and a bt60 it's pretty easy to keep them sorted out But they are still kind of prototypes. Here is one I made for a BT20 three fin 3/16" fins.

20190726_151324 by Tom Whit, on Flickr

Note the difference in the 'glue slots'. I think this gives me a little more working room but still maintains more of the center circle.

I got to thinking that maybe a heavy cardstock might be a better medium. I got to looking at some on Amazon but I am confused as to their thickness. They state a weight like 120lb and I have no idea what that number means.

I was thinking of some about as heavy as what Estes uses for their centering rings or such or slightly heavier. If anyone has some insight to this it would be much appreciated