In this video I'll show you how you could repair a broken gears teeth at home with a very simple technique.

How I did it - you can check by looking DIY video or you can follow up instructions below.

For this project you will need:

Materials:

Wax candle
Epoxy resin
Silicon
50mm PVC pipe piece
Candle in a metal cup

Tools:

Rotary tool with grinding and cutting disc Link to product!
Hacksaw or any saw to cut PVC pipe
Utility knife
Lighter and small metal can
Sanding paper or sander (80 grit)

Step 1: The Broken Gear & Small Clean Up

This is a broken gear from lawn mover. The device is still going strong, so I decide to fix this gear and get back the lawn mover to work. With a rotary tool I cleaned broken place and made it a bit more even. After that I grab a diamond cutting bit and made few hole for better and stronger bond with upcoming material.

Step 2: Preparing Form

I cut a short piece of 50mm PVC pipe. With sanding paper made it perfectly flat. Then with a utility knife made a cut out to get a bit flexing form, which perfectly sit in healthy gear teeth's.

Step 3: Securing and Sealing Up

With a pair of flathead woodscrews secured the gear to the surface. And to make it water tight - sealed with a plasticine.

Step 4: Melting Vax From a Candle

With a utility knife I chopped a regular candle and placed all pieces to small metal can. Lighted up the candle in the metal cup and with a help of managed wire holder placed the cup over the light. Keep it there until the wax was completely melted.

Step 5: Pouring Into a Mold

When the wax was liquid as water - I poured it into a prepared form and let it to cool down.

Step 6: Taking Out the New Template

When wax cooled down I removed the from and with utility knife scraped all excessive wax to make the part flat with gear. After that I carefully slide down from the teeth's. In my big surprised - I was able to managed that in the very first attempt. In a result I had a perfectly negative form of my gear teeth's.

Step 7: Placing Wax Form In

When I got the perfect wax negative template - I placed it over the missing teeth part. With a help of small plastic piece and few drips of silicon - I sealed the newly formed mold.

Step 8: Secret "souce"

I mixed a two components epoxy resin with small part of white cement. First I mixed one epoxy resin component with a white cement, and after that added an epoxy hardener and give a good mix again. When I was satisficed with the consistency I poured it in to the mold and let to cure overnight.

Step 9: Removing From Mold and Cleaning

Next day the epoxy resin was rock solid, so it was ready to take out of the mold. Scraped out all silicon parts and go to the belt sander to even the epoxy overfill evenly to the gear. With a help of rotary tool and small sanding attachment recreated the inner gear lines

Step 10: Removing Wax

Lastly I removed the wax. This time it wanted slide off as previously, but with small flat screwdriver and removed all bigger wax parts and rest of them was brushed out with a brush.

Step 11: Stuning Final Result!

And here it is - my broken gear has new, perfectly formed teeth. I'm more than happy with the result, and the gear is now running in my lawn mover without any issues. I hope this was helpful:)