When creating a fin guide to center and align fins, how do you get the correct size diameter when you print the pattern. I think it defaults to 129%. At that size its still too small. Is there an accurate way to figure it out?
Also what is the largest diameter you can print? I'm assuming probably 7" and just extend the fin lines for the cuts.
Also do you prefer card board or foam board?
I have a 16 x 16 (make it exactly) piece of 1/2 birch ply.
I draw from corner to corner to make the pattern for the 4 fin rocket, the intersection is the center.
I take one line. using a 30-60 triangle ($4) at Michaels or Walmart, go 60 deg twice, draw that line to center.
Then from that original line, go 120 deg the other way, there you have a pattern for 3 and 4 fin rockets..
Use a simple pencil compass to draw any circles or tubes you may ever use.
I stand the tube centered for the tube size, make marks at he end of tube that align for type of fin arrangement.
I have several sets of 1/2" x 24" aluminum angle sticks for aligning dual sets of fins. Actually bigger ones for huge projects.
Aluminum angle pieces are rolled and pulled straight, never use iron ones, they have a slight curl in them.
Lay the angle upside down on top of the tube until it is laying completely flat on the tube, that is a dead center line down the tube.
I have done every tube this way from 3" up to 9", works every time.
For holding huge fins in place while drying, I take 1/4 paneling or masonite sheets and cut out the fin and tube silhouette, then slide over the tube and fins to hold till dry.
