How To Mold Antique Car Steering Wheel
As with any normal two piece mold, begin by starting with
a bed of Alumilite’s Synthetic Modeling Clay and pressing
your part (the steering wheel) into the bed of clay. Then
build the clay up to your determined parting line. It
is important to have a very clean and straight parting line
to reduce flash and post clean up of your cast resin piece. So
spend the time necessary to make sure the line where the clay
touches the steering wheel is straight and clean. Then
build your mold box around the part and inside the part to
take up the extra space between the rungs of wheel.
Once you have the part clayed up and the mold box sealed,
mix your silicone rubber and begin to pour. We are using
Dow Corning’s Silastic M-2 mold making rubber for this
part because the undercuts are minimal but we still want great
dimensional stability as well as tear strength. Start
by drizzling the rubber over the steering wheel. This
will wet out the surface of the part and allow the air bubbles
to more freely rise up and away from the surface of the part. If
your part has a lot of undercuts, you may not wish to do this
step. But due to the size of the part and the openness
of the mold box, this process helps to make sure the air releases
from the surface of your part.
Once the critical detailed surface is covered, begin pouring
the bulk of the rubber in the center of the mold box allowing
the silicone to flow naturally over the part until it completely
covers the wheel.
Make sure the liquid rubber covers the part by at
least ¼”-3/8” and make sure your mold box
and inside cavities are not leaking. Allow the rubber
to cure overnight.
Once the rubber has cured, flip the mold over, remove the
mold base, and begin digging all of the clay off of wheel. DO
NOT remove the wheel from the poured silicone rubber mold. The
seal between the mold and wheel is critical in producing a
smooth/clean seam line.
Continue cleaning all of the clay off of the part until absolutely
no clay can be seen. Once all of the clay is cleaned
off, cut locators in the surrounding flange areas of the silicone
rubber that will align the two halves of the mold. Mold
release the entire mold and part with Alumilite’s UMR
release to ensure the two halves of the rubber do not stick
to one another. It is not necessary to mold release the
part but with this piece it would be next to impossible to
cover every bit of the cured silicone without getting some
on the part. Then mix and pour the second half of your
two piece mold.
Once the second half of the mold rubber has cured, remove
mold from the mold base, box, and inner box cavities.
Find the seam line with your fingers and begin separating
the two halves of the mold.
Slowly work the mold apart following the seam line between
the two halves.
The mold will separate cleanly and you will now have a beautiful
two piece mold with locators that will line up the two halves
Now you are ready to prepare the mold for casting.
Using Alumilite’s Key Knife, cut a wedge in the mold
to produce a pour hole for the resin. For cosmetic reasons
cut the half of the mold that will be the back of the steering
This piece will be inserted back into the mold immediately
after the resin has been poured into the mold before it cures.
Using plywood, create a splint that will maintain the dimensional
integrity of the mold and will make for easier handling of
the mold while pouring. Two pieces of wood with holes
drilled so bolts can hold it together work great.
The bolt holes will line up with the holes in the mold
left to take up space and will not interfere or touch the silicone
lease call us toll free if you have any questions
regarding your mold making or casting project. 800 447-9344