Making a vulcanizer

Hello to all you ‘do it yourselfers’

A while back I posted that I would report my results on trying
to build a vulcanizer from an adjustable temp. waffle iron.
Someone else (sorry, I don’t know who) had posted the idea and I
tried it. I took the 2 halfes of the iron apart and extended the
wiring with stove wires and ceramic nuts. I bolted the halfes to
plywood with a sheet of steel and 2 layers of automotive heat
gasket insulation on each side. The top half moved (notice I’m
using the past tense, You’ll see why when you read of the fate
of my attempts) up and down on steel rods supported to the base.
Compression was supplied by a humongeous ‘C’ clamp bolted to top
and bottom. I brazed together a large aluminum mold frame,
prepped the piece to be molded with castaldo gold label rubber
and fired the monstrous contraption up. The first thing I noticed
was that the temperature settings were not accurate. Having set
the dial to just over 300 degrees farenheit I heard little
popping, hissing and bubbeling noises (I guess the rubber was
boiling!). I turned the temp down some, trusting my questionable
instincts, and continued to tighten the clamp every few minutes.
Next thing I noticed was the aluminum grill plates bending. The
housing was not sturdy enough to support the plates. Then a
couple of loud pops- My mold frame popped open. Hoping against
hope that I might be able to salvage the mold, I did not abort
the process until… The whole mechanical sandwich began to
smoke. The wood, despite the insulation was starting to smolder.
I quickly escorted the monstrosity ouside and to my garden hose
and doused it, waffle iron, mold and all, with water (unplugged
it first of course- I’m not that stupid). When I inspected the
mold the ouside was sticky and overcooked while the inside did
not fill in completely. I’m going to put the wicked thing out of
its misery! I would like to know if anyone has had success with
this or related ideas (not that I’m gonna try it again!) As I see
it: Waffle Irons are for making waffles- Then again, I bet you
could make great waffles in your vulcanizer!

Tom Tietze- The Artisan Workshop, Fresno, California

Hello Tom, I made molds for many years this way: Take two sheets
of aluminum 4 x 6 inches square and at least 1/4" thick, 3/8" is
better. Drill 9/16" holes in the corners. Put a packed mold
frame in the middle, put huge bolts in the corners. Tighten the
bolts down and put the whole thing in the family oven at 275deg.
After 20 minutes, take it out and retighten the bolts. Bake it
according to the instructions on the rubber. You might put
aluminum foil between the mold and the frame, it will come apart
easier. Have fun. Tom Arnold

I would like to know if anyone has had success with this or
related ideas (not that I'm gonna try it again!) As I see it:
Waffle Irons are for making waffles- Then again, I bet you
could make great waffles in your vulcanizer! 

You’d have trouble getting the pattern from the flat plates of
the vulcanizer. Crepes, maybe…

For your molds, though, try the kitchen oven, with a seperate
accurate thermometer used first to be sure of the calibration of
the thermostate on your oven.

Use heavy steel plates, at least 1/4 and probably 1/2 inch thick
for larger molds. Inner sheets of aluminum inside the steel ones
to more evenly transmit the heat. The mold frame should be
either commercially made, or milled out of heavy aluminum solid
stock with walls at least 3/4 inch thick, I’d guess. Like the
commericlally made ones. too thin and you’ll burst em,
especially if it’s welded shut or something like that. the whole
sandwich, mold frame with rubber and model, then aluminum sheet,
then steel plates, held by sufficient steel C clamps to provide
pressure, can simply be set into the oven at the right temp, and
left there long enough to cure. Allow enough time, more than
with a vulcanizer, to get the heat through the steel. A cookie
sheet underneath will catch any excess droppings of rubber from
hitting the oven element. Remember that you need to put it in
the oven to start vulcanizing, then remove it after a couple
minutes to retighten the clamps. You’ll need heavy gloves for

Or, of course, you could always just use RTV rubber. If you’re
doing little enough casting that you balk at buying a vulcanizer,
then you probably don’t need the high production life of the
vulcanized molds, and the easier wax removal from a silicon RTV
mold might be an advantage.

Peter Rowe

Tom: what a story. You had a hell of a time with that waffel
iron vulcanizer. I’m the one who first posted the idea, but I’m
in Ohio & you’re in california so it’ll be difficult for you to
beat the hell out of me. I did build one and I use it frequently
with great success to vulcanize rubber and I’m sure it will make
great waffels as well like you suggested. You said that you would
not try to build one again- but if you or anyone else does try,
you might want to consider the trial and error process I went
thru before I was successful:

  1. Like you, I took the 2 halves of the iron apart and extended
    the wiring with stove wires and ceramic nuts.

  2. unlike you I bolted the top half of the iron to the BOTTOM
    half of a carpenters vise, then bolted the top half of the
    carpenters vise to a steel channel which I had shapped into a
    square (picture frame). The bottom half of the waffel iron I
    bolted to the top of the bottom of the steel channel frame. The
    channel I used for this frame was about 1 1/2" wide x 1/2" deep
    (thick) x about 36" long. I used a hack saw to weaken the channel
    where the bends were to be made. The whole thing, steel channel
    frame with the waffel iron halves and carpenters vise was then
    bolted to a piece of scrap 1/4" steel plate- no wood anywhere.

  3. The carpenters vise has 2 steel round guide pins to keep the
    2 halves in line when moving up and down and the vise screw and
    crank is used to crank the top half of the waffel iron up and

  4. my waffel iron adjustable temp gauge was calibrated by trial
    and error using a plating pyrometer placed against each plate of
    the iron and adjusting the the waffel iron temp gauge to as close
    as possible match the pyrometer reading-once set I never moved
    the waffel iron temp dial.

  5. I use the castaldo mold frames and pre cut castaldo rubber
    (gold).The top part of these frames fit down into the bottom half
    of the mold frame. I place the castaldo top piece into the bottom
    part of the mold frame then crank the carpenter vise down till it
    meets then crank it down fairly tight and leave it there - no
    need to crank down after this with the castaldo frames and
    castaldo rubber.

  6. I attached a timer and a light to my unit and I set the timer
    for which time the unit shuts itself off. (high tech toy).
    Finally, my waffel iron plates, like yours, did bend
    some-especially if I tightened too hard, but I now have the
    pressure down pat and even if they bow a little, it doesn’t hurt
    a thing. I could have saved a lot of hassel by buying a new
    vulcanizer - but I love to build things and test my creativity.

You sound like the same kind of guy so go ahead and build another
one. If you do and you think I can help, e-mail me anytime.
@plastics (Robert Wayne)