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"):
3"
square base, 3/8" thick
Many fin configurations
Upto
30mm diameter body tubes
Fins
can be upto 1/8" thick
Upright is fixed to the base
The 6" Fin Jig:
6"
square base, 1/2" thick
3
& 4 fin configurations
Upto
2" diameter body tubes
Fins
can be upto 1/4" thick
Uprights are 2" wide and slide in the base slots
The 12" Fin Jig:
12"
square base, 1/2" thick
3
& 4 fin configurations
Upto
4" diameter body tubes or fin cans
Fins
can be upto 1/4" thick
Uprights are 4" wide and slide in the base slots
The
18" Fin Jig:
18"
square base, 5/8" thick
3,4 & 5 fin configurations
Upto 10" diameter body tubes or fin cans
Fins can be upto 11/16" thick
Uprights are 4" wide and slide in the base slots
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!
