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Flux Capacitor Solenoids

The Round Base

Three of the major components inside the flux capacitor are the round metal disk shaped elements. It turns out that they are electrical vacuum solenoids used to switch heavy currents in industrial equipment. They have a glass tube running through the middle and exiting at a right angle.

By angling the three glass tubes towards the middle of the box, they form the "Y" of the flux capacitor. They come up on ebay every once in a while but unless you want to drop a few hundred dollars each, you'll need to come up with a substitute. I found the dimensions for the actual solenoids on the web in a BTTF forum. There are also plenty of pictures of these solenoids from all angles, so crafting a replica should be doable.


It so happens that I have a large stash of electrical components and I found a few dc motors with metal gear boxes that have the same dimensions as the metal base of the vacuum solenoids. My plan is to transform one of these into a replica of the actual base. Then make a silicone mold of it and crank out several copies.

I have plans on using clear acrylic rod for the glass tube. I used the acrylic rod for a few parts inside my Lost in Space Robot, so I know how versatile it is.


I took apart the motor and placed the metal ring on a scrap piece of plastic. I then put clay around the base to seal it and I filled the center with plastic resin from Smooth-On. This will allow me to fashion it into a replica of the solenoid.


My replica base is starting to come together. Next I drilled a 9/16 inch hole completely through the middle. I then painted it with primer. After applying the primer, I noticed a few pinholes in the resin. A little automotive Bondo putty filled the holes and I then wet sanded it with 400 grit sandpaper.


Here, I've drilled two holes for the soldering posts and a small slot where the electrical wires exit from the solenoid case.; The base is about ready to be used as my mold master. That is when the fun begins.


I've set in place the soldering posts and added two wires. The wires have one end stripped and wrapped around the top of the posts while the other ends go into the body of the solenoid through the small slot I made. In it's final configuration, the bare wires will be soldered to the posts.


Having finished the replica base I could now make a mold of it. I prepared the base by mounting it to a clean flat piece of PVC. I used my tried-and-true Lego method for building a box around the base and mixed up some silicone rubber. I've documents my molding methods in my Silicone Mold Making Guide. After degassing the silicone, I poured it over the base and vibrated any remaining bubbles to the surface where they could pop. I have to wait patiently overnight for it to cure


I was tempted to crack it open in the morning to peek but didn't as letting it sit another 9 hours would probably be good for it and I could wait until I got home from work. To see how I molded the duplicate solenoid bases, check out my Plastic Resin Casting Guide here..