Robin Allen wrote:
PRODD LAMINATING PRESSWhat you will need to make this prodd laminating press.
- Four pieces of ranger board 20”x 12”x ½”
- One piece of 1/8” ranger board 20”x 8” x 1/8” or plywood
- One strip of Formica 20”x 2”
- One metal pressure strip 20”x 2”
- One length of 2”x 24” fire hose
- Two end plugs to fit inside fire hose
- Four strips of flat mild steel bar 1”x10”x3/16”
- Six 3 1/2”x1/2” bolts with nut and washer
- Four 2” auto hose clips (hose clamps)
This prodd press is for making one limb only. You
will need two limbs for a set. The reason we make two limbs and not a
one-piece limb, it is very difficult to shape a one-piece prodd mold and
get it to be exact on both sides of the mold.
Making this prodd press is fairly easy if you follow the basic rule
that all sides of the prodd mold must be square, for this reason I use
medium density fiber board (trade names Medite or Ranger board) for all
my prodd presses. This is a man made product from sawdust and glue that
is compressed under very high pressure, this board is dead flat on both
faces, so all you have to make
square, are the edges.
First
we glue up the four (4) pieces of 20”x12”x1/2’ Ranger board, you can use
any good wood glue, scuff one side of the board with 120 grit paper, do
the same with all the boards, two boards only one side, two boards both
sides, this will give the gluemore surface to lock into, wipe all the
boards to get rid of the sanding dust, or use a soft brush, you must get
rid of the dust to get a good glue bond, apply glue to one surface of
your board, scrub the glue into the board, (what this means is whatever
you are using to apply the glue, I use a 2” piece of Bo tuff scrap,
really work the glue into the surface of the board this again will give
you a good glue bond) lay on a flat surface, then apply glue onto both
sides of your next board, lay it down on the first board, repeat with
the next board, on the last board only one side needs to be glued line
up the parts as close as you can , you can screw the boards as well to
give your press more strength, but make sure that there are no screws
where you need to cut out your
limb shape, check that all the pieces
are lined up, load up the block with heavy weights, let this block cure
for about 24 hours.
You should now have a block 20”x12”x2”.
You now need to square up the edges, do this on a tablesaw, or take it to someone with a tablesaw.
Yes
you could use plywood, I don’t use plywood because in Canada there is
no ½” plywood, we have only metric, and as the Bo-Tuff that we are going
to use is 2” wide the metric size plywood will not work out to
thickness, anyway Medite seems to give me much smoother curves in the
reflex part of the prodd and you end up with a much better prodd press,
and some plywood will have parts of the lamination missing which you
will have to fill in, the reason youdo not use lumber is after it has
been planed to get it square it will not be 2” thick, your prodd press
must be 2” thick, also a piece of 12”x 2” lumber that will be heated up
to about 1208 to 1808 F would be
prone to warping and twisting, and
that, we do not want to happen, so use Medite or if in the U.S. you
could use a good grade ½” plywood.
Now we have the Medite block
square, next thing we need to do is the shape of the prodd limb, for
your first limb, stick to a simple recurve shape.
This type of prodd limb has been proven over years of shooting.
Find
the center lines of the 1/8” Medite(plywood) that is the length line
and the width line, this will make it easier to mark out the limb shape,
transfer the limb shape onto the piece of 1/8” Medite, keep everything
square, now cut out the shape of the limb, cut just shy of the line,
then you can carefully file to the exact shape, now we go back to the 2”
thick block, mark out the center lines as you did on the thin Medite,
the prodd shape should lay along the center line, make sure that the
edges line up, nail the profile prodd shape onto the 2” Medite block,
just use ¾” brads for this, draw a pencil line about ¼” from the edge of
the profile shape, cut on this line using a band-saw, cut out the prodd
shape, an easy way to draw this line, use a small washer, lay it up
against the profile shape put the pencil or what-ever you are using to
mark out inside the washer and draw around the shape this will give you a
nice even line around the shape. Now carefully saw around the shape
just on the line, you now have two parts of your mold. Do not remove the
1/8” Medite shape this is now used to sand the shape of your prodd on
the sanding drum, (see how to make a sanding drum shaper) you must keep
the Medite flat on the bed of the sander, check to make sure that the
drum is square to the bed of your sander table or it will sand out of
square to your prodd mold. (Photo). Check to see if it is square to the
sides of the mold.
Now that the mold has been sanded to shape,
you can take off the 1/8” shape now, you will not need this any more,
make sure that you have all the nails out, that is the hard part done, I
now glue on a strip of Arborite to the part that we sanded this is to
ensure that it is flat and it is easy now to apply wax when glueing up
the prodd, you can glue this with epoxy or contact glue, file the edges
square to the sides of the mold, now fit a plate at the riser end of the
mold so that you can butt up all the parts of the prodd
flush with the end.
Now
we have to fit both parts together, this is how I do this, the four 1”x
3/16 flat bar is for clamping, drill 2 ½” holes in all four pieces in
one end, I clamp two of the strips together and drill both at once so
now you will have a drilled pair, this is to bolt to the prodd mold,
make sure that the bolt holes line up with each other, in the other end
of the clamping bar drill a single ½” hole.
What you need to do
now is have your prodd parts on hand, that is two pieces of 18” Bo-tuff,
18” prodd laminations and your riser, lay down one Bo-tuff strip one or
two
laminations the riser lams Bo-tuff remember we are NOT glueing,
lay on the metal pressure strip, this strip helps to give an even clamp
along the length of the prodd, use parcel tape to hold all the parts in
place, lay on the fire-hose do not inflate yet, now put on the top part
of the mold, that is the part that you had left over when you cut out
the profile of your prodd from the 2” block of Medite, line every thing
up, clamp with a bar clamp each end of the prodd mold, not to tight,
inflate the fire-hose with about 40lbs of air, now shine a light on the
back side of the mold, and look to see if you can see light thought the
prodd riser and lams, if you can increase the air pressure a little say
5lbs check for light, if you can still see light, another 5lbs, but
don’t go over 50lbs as you may have glue starvation, if you still have
light showing, it will be the fade out on the riser, so make sure it is
feathered out.
So now we have no light showing thought the prodd
parts, take the clamping strips that you drilled, and lay on the prodd
mold, one each end, mark where the holes are, mark carefully, now let
the air out of the fire-hose, take all of the parts off the prodd mold,
drill ½” holes where you marked on the lower prodd mold, bolt the two
clamping strips on to the mold, now drill top part of the mold, I do
another dry run to make sure that every thing is in order, put the prodd
parts back on the prodd mold with the metal pressure strip tape all the
parts together put on the fire-hose, put on the top part of the mold
and bolt up, check to make sure that every thing is o.k. This is the
moment of truth, inflate to 45lbs of air, with the light at the back of
the mold check for light, great no light showing, this means that you
have a nice tight glue line, if you have light showing you WILL have a
clue gap, this in turn will break the prodd.
Now we can glue up
the prodd limb, now apply masking tape to the smooth side of the
Bo-tuff, this helps to keep the Bo-tuff clear of glue, and you can mark
the centre of the limb a lot easier on the tape, I find the centre of
each piece of Bo-tuff and draw a line down the length, when you are
ready to cut the profile of the prodd you now have a centre line to work
from, where you lay up the prodd on your bench must be free of dust and
dirt, some prodd makers have a room just for gluing up so they can keep
it dust free, I am not so lucky so we have to make do, lay down news
paper on the bench, now put on rubber gloves or the very thin plastic
ones, this is to keep the
parts free of your skin oil, any oil will
prevent a good glue bond, I now brush all the parts with a clean brush
(I keep this brush just for this, stored in a plastic bag to try and
keep it clean), this is to get rid of the sanding dust etc, now you
should wipe all the parts with clean Acetone this will get rid of any
oil and dirt.
Lay all the parts out in the order that you are
going to lay up your prodd, i.e. 65tho Bo-tuff, 45tho, lam 50tho lam,
riser, 35tho lam, 65tho Bo-tuff, write this down so that you can be sure
you have the right order when you glue up the other prodd limb.
I
use smooth on epoxy from Bingham as my prodd glue, this epoxy has a
long open window, so there is no need to rush the gluing up this will
give you ample time to get it right,
IMPORTANT mix the two parts well for at least 5 minutes, use a
clean plastic cup and stick I use coffee stir sticks, IMPORTANT when
gluing up the prodd remember wet on wet, take your first Bo-tuff strip
check that it is clean, start applying the epoxy on the rough side only,
it is best to scrub the epoxy in to the part this will give you a
better bond, lay this aside make sure you have covered all of this side
with epoxy, hold up to a light and see if you can see any dark spots, if
can go over it again, the dark spot has no glue, now do the same for
the wood lams, now the wood lams have to have glue on both sides, This
is how I do this I glue one side first, then I lay the glued side down
on the Bo-tuff glued side (wet on wet) the I can apply the glue to the
dry side of the lam, do the same for the other lam ( wet on wet ) now we
can glue up the riser, Take care at the fade out it breaks very easy so
apply the glue away from the feather edge, apply the glue to the other
lam and bo-tuff, remember glue only one side of the Bo-tuff, wrap all
the parts in kitchen cling wrap, place all the parts on the prodd mold,
push all the parts hard up against the end plate so that all the parts
are even at the riser end of the prodd, lay on the metal strip and the
fire-hose put on the top part of the mold and bolt up, inflate to 45lbs
check that you have no air leaks, with that all done put your prodd mold
in to the oven to cure I cure my prodds for about four hours at 180 f ,
I then let it cool down over night, do the same for the other limb now
you should have a set of prodd limbs, but they have no shape in the
profile this then is the next part, remember the line that you drew down
the length of the B0-tuff, this is the line you work from, most prodd’s
at the riser end would measure 1 ¾” wide, tapering down to 1” at the
nock end, so at the nock end , measure ½” ether side of the center line,
at the riser end measure 7/8” ether side of the center line , use a
flexible tape for the next part, clamp the tape on your 7/8” mark at the
riser end do the same at the nock end, the tape will follow the
contours of the recurve prodd limb in a straight line, you can now draw a
line down the limb, do the same for the other side of the limb, you
should now have two lines on the limb.
Draw the lines on the other limb.
CUTTING OUT THE PRODD LIMBWe Now have both prodd limbs marked out,
cut on the waist side of the line do not try to get to close to the
line leave yourself lots of room, as you will be grinding the rest off
later, now you can cut the prodd with a hacksaw with a fine blade, use a
new blade so that you can control the cut, saw slowly and carefully.
To finish up the shaping of the prodd we
go back to the sander, if you have a flat bed sander this will do a
real good job of finishing the prodd limb to size, if you have to use
the drum sander grind the limb carefully to the line, now we glue on the
nock reinforcement, on the back of the prodd you need to glue two
pieces of Bo-tuff about 1 ½” long at the nock end clamp and
allow to cure overnight (use epoxy for this)
MAKING THE FIRE-HOSE CLAMPYou will need a length of 2”x 24” fire
hose (Bingham or your local fire hall) two end plugs you can get these
from Bingham or make your own, this is how you do it you need two
plumbing on one of the parts solder a plate that’s all you have
to do for this plug (see photo) on the other one solder a plate, but
drill a hole for a tire valve now solder this valve into this hole, put
the four hose clamp on the fire hose loose, apply epoxy glue in side the
hose push in the end plugs make sure they are in as far as they will go
now screw on the hose clamps tight, two on each end , let the glue set
over night check to see you have no air leaks inflate to about 50lbs (
fire hose will inflate to over 200lbs) I half fill the bath tub and
check, if you have no leaks, that part is done.
MAKING THE RISER OR WEDGETo make a good riser we need to grind it
to a feather edge, this is so that we get a good glue line and every
thing blends in smoothly at the riser fade out, (feather edge) (most
prodds fail at the riser feather edge) to do this we have to make a
simple fixture for grinding on the drill press sander that you have made
for the prodd mold.
The parts that you will need for this jig
- A piece of Lexan or Pexi-glass
- A piece of Medite
- A block of wood
- Screws
- ½” ready rod with nuts and washers
- Two lock down plates and butterfly nuts.
This wedge (riser) has a very simple
shape, the secret of a riser is to get the fade-out feathered very thin,
so that you can see light thought it this jig will do this for you.
THINGS TO REMEMBER WHEN MAKING A PRODDTo
make the riser you need a piece of high grade hard wood, Walnut, or
Rosewood, must have no flaws or knots about 8”x2”x1” square this piece
on all four edges, draw a line diagonal across the 1” face saw across
this line you should have two riser shaped pieces.
When cutting your Bo-tuff to the 18” length, cut it square across the piece.
Use a hacksaw with a fine blade.
Put masking tape on the Bo-tuff this makes marking out a lot easer, and helps to prevent tearing of the fibers.
Wear gloves when handling Bo-Tuff.
When mixing the Epoxy, mix for at lease 5 min, this is to ensure that you have ALL of the parts mixed.
Scrub the epoxy into the parts, and make sure that all parts to be glued are covered.
Clean all the parts with clean Acetone.
When using any of the Rosewoods make
sure that you have washed all the oil from the surface of the wood with
Acetone, THIS IS VERY IMPORTANT!!! Oil in the Rosewood will prevent a
good glue bond.
When making the riser, make sure that the fade out is paper thin,
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