Two Hands on the Wheel

Our current build is for an ad campaign. I can't mention the the details, but the build is proving to be fun!

We basically have to make 2 hands gripping the steering wheel of a car. The hands have to meld into the wheel like they are becoming one piece. Cool!
We only have to fabricate the hands and the leather wrapped portions of the steering wheel. The rest of the wheel will be comped in to the existing interior I think.

In the beginning, I was going to model and machine the 2 sections of the steering wheel, but we were able to get the proper steering wheel that's going to be used. It's always best when we can get the actual part someone needs!

I imagine that this wheel is fairly expensive, so we certainly don't want to damage it! I started off by masking the grip portions that we're interested in. The great part is that there is a natural seam line right at the part we need, so this makes things even better!

We carefully masked off the rest of the wheel. We will be using plaster bandages for this, and I didn't want to get any plaster on the wheel.

We started out by using some sulpher-free soft clay to create a mold flange on the inside of the wheel.
Although in a last minute decision, we scrapped this idea and decided to just coat the whole piece, an cut the rubber off after we were done.

Then it was off to the really messy task of brushing on the silicone rubber. We actually used 2 different rubbers for this. The first thin coat was done with a rubber that has a 10 minute kick time, then we backed it up with 2 coats of a 90 second rubber. The 90 second stuff was quite a bit more viscous and thus went on really thick, building up the rubber thickness pretty fast!
We let it set up for around 30 minutes.

The next step was to create the mold jacket. The whole point of the jacket is to add some rigidity to the very flexible rubber portion.

We kept adding quite a few layers of the plaster cloth, while creating a flange right around the center of the wheel. Once the tops of both sides where done, we flipped the wheel over, greased the flange with release cream, and plastered up the back side. This will allow us to separate the mold jacket from the wheel, then clam-shell the rubber portion back inside at casting time.

We decided to wait until Sunday morning before we popped the plaster off, letting it dry out as much as possible. Once we popped it apart, we carefully split the rubber off the wheel with an X-acto knife.
The inside of the mold looked great! And with brushing the rubber on, we had no air bubbles.

With the mold all re-assembled and clamped, we dammed up the two ends with clay, then slush cast the inside of the mold. The slush cast process really just means that we rolled the resin around inside the mold. This coats all the walls of the mold in resin. That way, if there is any trapped air when we do the fill pour, it won't affect the casting. I doubt the mold jacket will take much abuse, so I plan on doing this once!

The final cast came out great! There is a seam up the middle, but my hand will be covering most of it, so there will be very little cleanup in the end.

The mold captured all the stitching detail perfectly Any where the seam was seems like it will be covered anyway!

The next part is going to be fun! I think..................
8)
JO