How To Mold Antique Car Steering Wheel

Posted by Alumilite on Sep 3rd 2021

How To Mold Antique Car Steering Wheel

Molding an antique car steering wheel.

In this how to you'll learn to mold a antique car steering wheel using Alumilite products.

Products Used


Step 1 Press part to be molded into modeling clay and build clay up to parting line

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.

Step 2 Mix silicone rubber and degas to remove air bubbles

Once you have the part clayed up and the mold box sealed, mix your silicone rubber and begin to pour.
We are using Alumilite's Plat 55 mold making rubber for this part because it has excellent dimensional stability, a firm hardness, good tear strength, and a great mold life for casting lots of parts. After mixing, it is highly recommended to degas the Plat 55 to remove the air you introduced when mixing. If you do not have vacuum, 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 and allows the air bubbles to float to the top of the mold away from the part.

Step 3 Pour rubber into center of mold

Once the critically 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.

Step 4 Allow to cure overnight

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.

Step 5 Once cured, flip and remove clay. DO NOT remove wheel

Once the Plat 55 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. A putty knife and/or Alumilite Spatula tools are helpful in removing clay around and near steering wheel.

Step 6 Cut locators in the silicone to align the two halves of the mold and mix and pour the second half of two piece mold

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 3-4 coats of Rubber to Rubber mold 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.

Step 7 Remove mold from mold base

Once the second half of the mold rubber has cured, remove mold from the mold base, box, and inner box cavities.

Step 8 Using seam lines, begin separating halves

Find the seam line with your fingers and begin separating the two halves of the mold.

Step 9 Follow seam lines to separate halves

Slowly work the mold apart following the seam line between the two halves.

Step 10 Now you have your two piece mold

The mold will separate cleanly and you will now have a beautiful two piece mold with locators that will line up the two halves beautifully.

Step 11 Prepare mold for casting

Now you are ready to prepare the mold for casting.

Step 12 Create pour hole for resin

Using a Key Knife or Excel blade, 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 wheel.

Step 13 Set piece aside to be inserted back in later

This piece will be inserted back into the mold immediately after the resin has been poured into the mold before it cures.

Step 14 Create plywood splint to hold mold while filling

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.

Finished Project

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 at all.