Resin Rotator and Keychains

I am a teacher and I make key chains for my graduating students as gifts to recognize their achievement (and acceptance) into their next school. After many iterations and failed experiments to make keychains that look professional and unique I finally came up with this solution which combines my affinity for both laser cutters and two-part clear resin. Resin, while a bit messy and smelly, can provide an impressive finish with just one coat. The laser cutter provides the detail and customization abilities.

The challenge for me was how make a two sided key chain with "sealed" edges. The solution is a rotator for drying the resin evenly. A rotator is a pretty common solution for drying resin on cups and tumblers (link) but I did not find any examples for other objects such as key chains. So I built one.

Materials for Rotator

- 1/8" plywood

- 3D Printer and filament

- 3M Super 77 Spray Adhesive

- screws

Materials for Keychains

- 1/16" plywood or hardwood (I like maple from Ocooch Hardwoods)

- Painters tape

- 1/4" brass grommets and brass keychains from Amazon

- Crystal Clear Table Top 2 part resin

- digital scale

- Lighter / torch

- 3M Super 77 Spray Adhesive

- Dremel Versa polisher

- Meguiars Mirror Glaze

- Crayola Brown Broad Line Marker

Find an electric grill rotisserie (here's one from Amazon). Cut the base and rotary holder on a laser cutter (laser cutter files included). Also 3D print the connector with 5/16" mount (stl file included).

Engrave your key chains if you have a laser cutter. Definitely use painters tape on the back of your wood before engraving/cutting. This will make it much easier to glue your pieces together later by being able to remove resin that sneaks around to the back of the piece.

My school logos* are found using google and then vectorizing using Inkscape / Trace Bitmap or on www.vectorizor.io. This web site does an amazing job and has many options but has recently gone to a "freemium" model so you can only vectorize a few images per hour *I only gift my finished products so I don't believe there are copyright issues. However if you are looking to sell logo products then you should definitely research copyright issues further.

Set up your key chains on a flat piece of cardboard. Also put small wood discs under each keychain to elevate them off the surface of the cardboard (this will help to prevent them from sticking to the cardboard).

Add grommets to the eyelet holes to provide added reinforcement and adornment. Make your epoxy resin compound. I use this two-part resin as it is a good value and makes a clear hard surface. Attached are instructions for mixing the resin using weight rather than volume. I find this method to be very helpful when mixing small batches as precision is critical. Using the tongue depressor from mixing I put one largish glob of resin directly into the center of each keychain side to make a "flood coat". It settles on its own and a brush is not used. Do not over pour - only enough to fill 50% to start and then let it slowly spread to the edges. In about five minutes the resin will bleed to each edge. I use a paperclip or a pushpin to create paths for the resin to creep to the edges. Add small amounts of resin by dripping as needed. Use a lighter or heat gun to remove air bubbles - I like the long torch lighters like this one. Make sure your cardboard is on a level surface so that the resin will spread evenly. Wait 12 hours, usually overnight.

Remove the backing tape. Sand the backs of each piece to make sure they are uniform. Glue the two sides together with spray adhesive (wood glue should be avoided as it can warp the wood) and let it dry (30 minutes). Make sure the seal is very precise and tight - I tape the pieces together and place under a block of granite to ensure the seal. Sand the edges to create "one piece". Then use a Sharpie or markers (I like these) to create uniform edge coloring. Attach to the rotary machine using a small flat piece of wood snugly through the hole with a binder clip. Make sure to align so that it is perfectly vertical and turn on the rotator to verify.

Apply a thin bead of resin to the center of the edge as it rotates. Do not "paint" just allow it to naturally spread out. This will take about ten minutes as you add just a little bit with each rotation. Do your best not to let it get on the front or back surfaces - if it does wipe it off with a q-tip or paper towel.

Use your lighter/torch to ensure there are no air bubbles. Set on a level surface while rotating and wait another 12 hours.

I use a Dremel Versa with 2500 grit paper to clean up the edge to surface joints and then polish with Mequiars Mirror Glaze, again with the Versa. Also a bit of polish rubbing with a chamois cloth.