8A Herman Drive
POB
522
Simsbury, CT 06070-0522
bmibay@bmicad.com
These custom made Heavy
Duty Model and High Power Rocketry Fin Alignment Jigs are Precision CNC Machined from
6061-T6 Aluminum in an aerospace machine shop. These
jigs can even help with thru-the wall (TTW) designs, like
Aerotech and others, by assuring that the fins
protrude from the slot perpendicularly, thus controlling the rotation of the Motor Mount
assembly relative to the slots in the body tube. Radial angular
alignment is extremely accurate. Axial alignment is highly controlled, but
is still somewhat dependant on care of assembly.
The Regular kits:
The Large kits:
Slightly larger body tubes can be used, but the uprights begin to hang off of the base. The uprights and center studs are the same for both the 12" and 18" base designs.
Tips:
1) It is still a good idea to draw a line on the body tube using a door jam or other angled object. This jig will get you angular alignment that can't be beat, but even the tightest upright can still have a small amount of vertical alignment play in it, especially with a long fin.
2) If your uprights are too tight, try placing the unit on the stove and the uprights in the freezer. The slots are .2500 inches wide and we have found that an upright that is .2499 thick has play and one that is .2500 can get stuck. We strive for snug fit uprights, but +.0000/-.0001 tolerances are just too tight to be commercially affordable! If they get too loose from wear, try spraying them with a lacquer and sanding them to fit.
3) There are as many assembly techniques as there are rocketeers, but one thing we have found is to use a bit of CA to adhere the fins on and once everything looks good, then use a dab of epoxy at the tip and base of the fin. Let it cure than remove the rocket from the jig and put the full fillets on.
History: I had one of the little Estes grey plastic fin jigs for some time and the concept worked well. That unit was a bit flimsy and warped, but adequate for LPR. Eventually I had problems with the fin uprights breaking, so I went onto eBay to look for a second jig. I bid $50 for the first one I found and lost the auction. I waited another couple of weeks before another one got listed and I bid $70 for that one and was out-bid again! About a month later, another one was listed and I reluctantly bid $91 for it and just barely won it at $89! A few days later I was the proud owner of my 2nd Estes Fin Jig. Then, in less than a month we managed to glue an upright in and in the attempt to remove it snapped it off at the base. I was crushed! So, at this point I was in a BAR fever and began contemplating another solution. Since I own a machine shop, I began thinking that for the kind of money these things were fetching on eBay, I could probably CNC something up with out too much effort. Not soon after, my shop got a little CNC time freed up & I fabricated the first jig. One of my rocket pals saw it & had to have it, so I sold it to him & made another. The amount of machine time and material costs were a bit more than I had at first anticipated, but I was in for the long haul and the rest is history. We have sold many fin jigs of both this size and it's larger brethren.
This is a unique must for your MPR or HPR rocket hobby projects!
Thank you for considering our product and feel free to email with any questions!
Attention International Customers! You must add the international shipping option to your cart or your jig will not ship!
Shipping questions? - just email us
your ZIP.
