bmi CAD's Model Rocket Fin Alignment Jigs and parts

bmiBay

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.  For the 6", 12" & 18" jigs, radial angular alignment is extremely accurate and axial alignment is highly controlled, but is still somewhat dependant on care of assembly.  On the mini jig (Ulf's Jig), axial alignment is extremely accurate, but radial angular alignment is completely up to you!

The Mini Jig ("Ulf's Jig"):

The 6" Fin Jig:

The 12" Fin Jig:

The 18" Fin Jig:

Slightly larger body tubes can be used, but the uprights begin to hang off of the base.

The center studs are the same for all size jigs.

Tips for the 6", 12" and 18" jigs:

 1)  For the 6", 12" and 18" jigs, it is still a good idea to draw a line on the body tube using a door jam or other angled object.  These jigs 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.  The mini jig will give you vertical alignment that can't be beat, but the angular alignment is completely arbitrary.

 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.

Tips for the Mini Jig:

1) The mini jig will give you vertical alignment that can't be beat, but the angular alignment is completely arbitrary, so it is a good idea to draw lines on the tube at the correct spacing.

Tips that apply to all 4 jig styles:

1) Apply a light wax to the areas where adhesive may stick to the jig.

2) 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.

This is a unique 'Must Have' for your rocket projects!

Thank you for considering our product and feel free to email with any questions!

  More Rocket stuff here 

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.

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Description Pricing $USD
3" Single Fin Jig Kit
Includes 3" Base with attached upright,  13mm Center Stud & 1 clamp
$39.99
3" Single Fin Jig Deluxe Kit
Includes 3" Base with attached upright,  13/18 &24mm Center Studs & 1 clamp
$59.99
6" Fin Jig Kit
Includes 6" Base, 4 Narrow Fin Uprights,  13mm Center Stud & 4 clamps
$79.99
zvg-deluxe 6" Fin Jig Deluxe Kit
Includes 6" Base, 4 Narrow Fin Uprights,  13/18/24/29mm Center Studs & 4 clamps
$99.99
12" Fin Jig Kit
Includes 12" Base, 4 Fin Uprights,  13mm Center Stud & 4 clamps
$109.99

12" Fin Jig Deluxe Kit

Includes 12" Base, 4 Fin Uprights,
13/18/24/29mm Centers Studs & 4 clamps
$149.99
18" Large Fin Jig Kit
Includes 18" Base, 5 Fin Uprights, 13mm Center Stud & 5 Clamps
$199.99
18" Large Deluxe Fin Jig Kit
Includes 18" Base, 5 Fin Uprights, 13/18/24/29/38MM Center Studs & 5 Clamps
$249.99

 

Shim Kit

Fin Jig Shim Kit
Includes 6" dial calipers, .008", .016" & .032" shims
$15.99

 

S&H via UPS upgrade $12.99

 

 

International Shipping
via UPS Expedited*

*Please contact us  - some items will incur additional shipping charges
$30.99

13mm Center Post
Precision Turned Aluminum
$7.99

18mm Center Post

Precision Turned Aluminum

$9.99

24mm Center Post


Precision Turned Aluminum

$12.99

29mm Center Post


Precision Turned Aluminum

$15.99

38mm Center Post


Precision Turned Aluminum

$19.99

54mm Center Post


Precision Turned Aluminum

$25.99

75mm Center Post


Precision Turned Aluminum

$37.99

98mm Center Post


Precision Turned Aluminum

$49.99

Fin Clip
Standard
$0.99