Molded Silicone Parts Follow Up
Background
In my last post, I wrote about my experience attempting to recreate out-of-production rubber parts for my vintage motorcycle. The post left off with promising prototype parts. This follow-up covers the process of refining those prototypes into a full set of installed parts for my bike.
From Prototype to Final Parts
To make the parts look correct, I wanted them to be black like the originals. While specialty silicone pigments exist, I ended up using black mica powder obtained from Amazon.com. The mica powder seemed to work well for my purposes.
I also 3D printed two additional copies of my mold. Each mold can cast two bushings, and each casting was taking around 12-24 hours to cure. Since I needed six bushings in total, having three molds allowed me to cast them all in one shot, with the added benefit of wasting less silicone material.
Casting the Parts
The process of mixing the silicone and pouring the parts was identical to the one described in my last post, except for the addition of the mica powder. I simply eyeballed a small amount of the powder and added it while mixing the two-part silicone. After pouring the parts, I left them on my 3D printer’s heated bed overnight at 40°C to cure.
De-molding the parts and removing the flashing went smoothly, leaving me with six black bushings ready for installation on my motorcycle.
Installing the Bushings
A few days later, I found time to work on my bike in the shop. The first step was removing the existing bushings, which were in a deplorable state, as the picture below illustrates.
Installing my silicone bushings, I was pleasantly surprised by how well they fit. The internal cone/washer piece that ran through the middle fit snugly without requiring excessive force.
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| Installed Cone Washer from the Front | Installed Cone Washer from the Back |
The bushings themselves were easy to install into the sheet metal holes in the air box, requiring just a bit of squeezing to get the wider part through the opening.
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| Front view of the bushing installed | Side profile view of the bushing. Although the side profile shot is slightly out of focus, you can make out the bushing on both sides of the sheet metal it slots into, and the nut welded to the motorcycle’s frame that everything bolts down to. |
Wrap Up
Casting and installing the parts went smoothly. While I can’t comment on their long-term durability yet, I’m optimistic as they seem quite robust. The color, fit, and finish of the parts exceeded my expectations for this DIY project.
I already have another rubber piece on the motorcycle that I’m looking to recreate next. That part has a much more intricate geometry and will offer additional challenges, but my spectacular results here have given me the confidence to tackle it.