Epoxy Resin Screwdriver/Nut Driver From Silicone Mold Making to Casting Resin Parts

I've been wanting to make this screwdriver/nut driver/bit holder for quite some time but just never got around to it. The reason I wanted to make this was so that I could easily change the nozzle on my 3d printer. My Ender 3 came with a small 5mm wrench to remove the nozzle but since you have to change the nozzle when its hot it can be a little intimidating to do so with a tiny wrench. Also the wrench loosens the nozzle but doesn't hold it so you either have to put on a glove and catch the hot nozzle or just let it drop. I have a screwdriver/nut driver but it has a long handle and I have to raise the printer head all the way up in order to have enough room for the screwdriver to fit. So I knew I wanted a stubby screwdriver something that was small enough to store in my 3d printer tool box too. I decided to use a Craftsman screw driver as my model because I like the size and shape and how it feels in the hand.

Originally I was just going to make one or two but I have to admit the molding and casting process was so much fun that I made several different colors. It is really satisfying pulling out an almost finished piece from a mold especially when they are different fun colors.

I knew I was going to use a PVC pipe for the mold but I need a way to hold/suspend the screwdriver in the mold while the silicone cured. So I used a scrap piece of wood with a hole drilled in the middle to hold the shaft of the screwdriver.

I used a piece of 2 inch PVC that was cut to just larger than the screwdriver and used my center finding jig to find the center. I made a few marks on the top rim so that I could align the screwdriver in the center of the jig. This doesn't have to be exactly in the center, close enough is good enough as long as the model is entirely encased in silicone. I also used some duct tape to seal off the bottom of the mold.

I made sure to spray the inside of the mold with mold release. The inside of the PVC wasn't that smooth so I thought this would help me later with releasing the mold once it was cured. The silicone comes in a two parts and has to be mixed in the correct ratio by weight per the instructions.

Once the silicone was mixed I placed the screwdriver in to the mold and moved it to one side so I would have enough space to pour in the silicone. Once it was nearly full I moved the screwdriver to the center using my marks on the rim of the PVC as reference. I placed the mold in my pressure pot, sealed it and pressured it up to 50 psi. I let it cure overnight.

Ideally you would want to use a vacuum chamber to degas (remove all the air bubbles from the silicone mixture) before pouring it in to the mold. However I do not have a vacuum chamber so instead I used my pressure pot which doesn't work as well but works well enough for my purposes. I've had good results in the past using my pressure pot to cure silicone molds.

Once the silicone cured overnight I removed the mold from the pressure pot. I removed the wood and tape and tried to use my air compressor to free the silicone mold from the PVC. This didn't work, so instead I used my portable bandsaw table to cut a slice in the PVC lengthwise to free up the silicone. If you don't have a portaband you can use a hacksaw instead. This worked out very nicely.

Now it was time to remove the screwdriver. First I made two slits on either side of the screwdriver shaft, next I cut down the side of the mold in a zigzag pattern about 2/3 of the way down the mold. The zigzag acts as a registration mark for later. I made this cut slowly and deliberately making sure not to cut too far down. I only cut enough in to the mold so that I could remove the screwdriver model.

I used Total Boat's Medium Hardener epoxy for this project. Any epoxy will work its just that this epoxy had been in my garage for quite some time and I figure I could use it up for this project instead of letting it go bad. I mixed the epoxy per the instructions and add some blue alcohol ink to the epoxy and mixed it all together. I used the PVC pipe to hold the mold together, this worked out quite nicely.

I taped off the bottom of the mold, I later found this to be unnecessary, and placed the mold in my pressure pot and pressurized it to 50 psi and let it cure for about 4 hours. I realized a couple of issues with this first piece. One was that I should have sprayed mold release on the PVC and the silicone mold. It wasn't hard to remove the mold but it took more effort than I would have liked. Second I realized that I had should have poured more epoxy in the mold essentially overfilling it. Not to the point were it would spill over the top of the PVC but enough to cover the top of the silicone mold. You want to create a sprue like when casting metals. This way you have excess material to fill any voids caused by air bubbles.

These two pics show my first piece and my second piece. The second one is what you are after, you want that extra material on the top. I did several of these pours and the ones that had more material on top ended up being the best ones.

To remove the sprue I just clamped the piece in a vise and used my cut off saw to cut off the waste.

To clean up the end I used my belt sander and then used pieces of sandpaper starting with 220 grit up to 2000 grit to smooth out the end.

I have a hand screw clamp that I modified to hold pen blanks. Basically the vise has a 90 degree notch cut out of each jaw that when tightened hold the pen blank in place at 90 degrees. I clamped the screwdriver handle in place and then used my center finding jig to mark the center location of the handle. Next I used my drill press to drill a 7mm hole in to the handle. 7mm matches diameter of the hex shaft of the magnetic drill bit holder that I will be epoxying to the handle.

I purchased the magnetic drill bit holder from Harbor Freight when they were on sale for $2 each. I realized that the shaft was too long and decided to cut a portion of it off using my portable band saw. However that didn't work because either my blade was too dull or the steel was too hard. So instead I opted to use my and grinder.

I did a quick test fit to and it was a very snug fit. If the fit is too snug you can always drill a slightly larger hole or heat the hex shaft of the magnetic drill bit holder with a torch for a few seconds and burn the hole in to the epoxy. Just make sure you have predrilled a hole already. I did this with a later screwdriver handle to see if it would hold the shaft or not. More on that in a later step.

The pieces looked pretty good straight out of the mold but I wanted to polish them up to see if I could get them to shine a little more. So I used my home made buffing pad attached to my drill press and some Meguiar's Scratch X to buff the handle. Meguiar's Scratch X is my go to for polishing plastics and resins including pen blanks. You could also use a Dremel with a buffing wheel or use your drill with a buffing wheel attachment to polish up the pieces.

Once I was done polishing up the handle it was time to epoxy the drill bit holder to the handle. I used 5 minute epoxy for this part. I mixed up the epoxy per the instructions and spread it liberally on to the hex shaft and inserted it in to the hole in the handle. I used a small hammer to tap it in to place. Then I let it cure over night.

Here are a few of the variations I made. The first one is the same handle but on that one I heated up the hex shaft and burned it in to the predrilled hole. This made for an even stubbier screwdriver but the one down side is that its just plastic so it is only a light duty screw driver.

The third pic is another screwdriver handle but this time I cut off the drill bit holder portion and glued that in to a predrilled hole. Now I have a metal drill bit holder that is flush with the face of the screwdriver handle. So its stubbier and stronger. The last pic is just a reference for how I intend to use this screwdriver on my 3D printer.

I did end up making more of these than I needed but I can't over state how much I enjoyed making them. I really like the way they turned out. I do plan on keeping a few of them but I will most likely send the rest out to some of my fellow makers that I know own Ender 3D printers.

I hope you enjoyed this Instructable thanks for taking the time to look at it.