It Worked Stunningly Well - Gear Teeth Repair With A Candle! 

From 8:00 on, you should show us how to use the repaired gear to make a mold and then casting a complete replica gear from epoxy/cement. The repaired gear will have a non-uniform density, while a cast replica would be more uniform in strength and appearance. Plus, having a mold for the gear available allows multiple copies to be made, in the unlikely event of failure.

The end where you show off the finished repair would have been SIGNIFICANTLY more impressive if you had shown us the gear being put back into operation again with the other gears it was previously working with.

Interesting! I took a similar approach on my 4WD actuator. 2 sprockets sheared off and instead of buying even a used actuator for $300 i just started off as you did, but put 2 wire anchors in each sprocket before using CA Glue to fill the entire gap, then used a file to reshape the section by hand. It’s been working for the last 5 years without problems

For those that aren't watching the whole video, the repair is NOT made of wax, he uses was to cast the negative, then uses that to cast the repair in epoxy. Several comments mention that a wax repair won't hold, they didn't pay attention to the whole video. 4:49

Looks good, we saw enough angles. Great repair, didn't find out if it was strong enough!

Nice process. A friend did something similar as few years ago to be able to make sacrificial "high/low speed" double gears for his mini milling machine. He rebuilt a gear pretty much as you did, made a mold of that gear, then used the mold to cast the centre part of that to make a 3 piece mold in aluminium. Whenever he kills a sacrificial gear now, he packs the mold with glass fibre filler, clamps it all together hard in his vice so that the filler get's pushed right to the tips of all the teeth, then next day he has a new gear that just needs the centre hole drilling/reaming through, and 3 faces skimming on his lathe. Considering the OEM replacement gears cost over £30 each (About 35 USD at todays exchange rate), it's since worked out significantly cheaper than buying genuine gears every time he crashes his mill and spreads teeth all over the inside of it's head. :D

Very good demonstration & video overall. Especially if the broken part is irreplaceable/difficult to find or too costly to replace etc. I would really like to see the repaired part function after the work was completed.

That was a very clever repair. I wouldn’t have ever thought of that. Pretty cool to see it done👍🙂

You should have added more material in back of the gear teeth as the patch will be pulling on what little material was remaining. Thus the theeth patch can tear off easily as the previous damage shows a lot of force is applied while in use.

Congratulations! You made a broken gear whole again. Now let's see if it works without disintegrating when you reinstall that gear to whatever machine it came from.

Your process and the result is excellent. If I could offer a suggestion, it would be that you should have added much more material on the inside to provide more of an anchor for the new teeth. The thin section at the root of the new teeth is likely not going to last depending on how much torque is being transmitted through the gear.

WOOOOO!!! That was smooth. Brilliant idea and it worked perfectly. Thank you for sharing. 👍👍👍

Wow!! I thought you would use 3d printing...but this makes more sense and is a great repair work...kudos👏

I would suggest adding some kind of fibre strands in the mix will make it stronger.

Excellent ! The vid gives a great example for other repairs in plastic I can utilise.Thank you for uploading.

Forget the negative comments, I'm a dental technician, in my opinion you did the best ,you're a genius, thanks for the info.

Very nice repair and I am sure equally as strong too. If there is a will, there is always a way... Thumbs Up!

It would be good to see the repaired part working on the item it is from. A durability test would be good. Nice work.

Well done and good to see this working with a candle. I agree about the full mould to make new full replica gears, but life gets complicated, depending on the tolerence required for the gears. A full cast can be difficult to release and softer moulding materials are not good at very accurate shapes, which indicates a multi-part mould with locator pins. Then the mould can be a filled resin with fibres as well as other additives as required to make a much stronger gear, but again more complexity and multi-coating / casting if adding different layer properties. I hope that this gear works OK, but the bonding to the original gear may be the problem due to the plastics surface energy. The flaming will have helped a lot, but I had a thought that some pins (or screws) through the back could also help. Luckily, in some ways, it is quite a long repair and therefore a longer shear area for the load transfer through the bond. I first hit these problems with higher capacity paper shredders, that include plastic gears which shear, but are custom parts that are not available as spares, but appear to provide a limit in the drivetrain, although it would be better to sense the motor and fita cutout! But that would be more expensive in both gears and circuitry,

Looks surprisingly balanced. Nice work!

Really brilliant work, dude! Nicely done!!! 😃 Stay safe there with your family! 🖖😊

Não sei se a resistência no local ficou a mesma do restante da peça, mas a ideia é genial. Parabéns!!

Epoxy resin once cured is way harder than regular plastic ( I assume that is). Excellent reconstruction technique. Thank you.

Great approach, but how well will it handle the applied force and load? As the original break implies a seemingly strong torque/load application. All aside, nice video and editing job.

One of the best things about youtube, is that if you think an idea is funny or worth trying out, there'll always be someone out there somewhere that you can share it with & that'll get what you're trying to do

Reminds me of a story my Dad told me once from the 1940's when he improvised a clutch repair on his motorcycle using bottle corks from a chemist shop while on holiday in Wales. My Mum rode pillion and were stuck far from home when the bike broke down.

I'm going to have to remember this for emergency repairs on my boat, thanks for sharing this.

Nicely done! Great repair 👍🏼🤩❤️

I would be totally convinced seeing it in actual operation on the equipment it was initially used for. If this original part suffered this type of damage I doubt if this patch would hold up.

Браво Мастеру! Вполне жизненно-техническая ситуация,а решение ---остроумное и довольно быстрое...Спасибо и за хорошую и привлекательную съёмку !

Thank you for documenting this process so well

Good work. Now make a mould of the whole thing before it breaks again. It is happens once, it will happen again. A full resin gear.

One of the best videos you made to date! Awesome solution. I hope I remember this when I need it!

This is by far the most basic and most clever repair video i have ever seen. Liked and subscribed!

Absolutely AMAZING ! Intelligence, Imagination, materials... !

EDIT: Please read the replies, I know it's not wax, there are other concerns on why the repair would not be effective (assuming that damage was real and not staged for the video) --- The repair would fall apart as soon as load is applied, but it could be used to make a mold to cast a new full gear

Can you explain a bit about what "white cement" is? White portland cement?

PARABENS , MARAVILHOSO , MUITA CRIATIVIDADE E COMPETENCIA .

I have to be honest, once I started watching this video, I couldn’t stop. Wow great job. Bet it works too, cause some of that epoxy they make ain’t no joke.👍

Nice work. The repaired gear would make an excellent pattern for a 3D copy with carbon fibre, or a brass moulding.

I enjoyed watching it. For many who cannot afford a 3D printer ( me included) it’s a great display of creativity, knowledge, and skills. Good job. I’m subscribing. And using the Roman Gladiator hand sign for life. 😊

Great job. Should have added some black to the resin mix for an invisible repair. Interested to see how it would hold up to load.

This was fun to watch.. the only suggestion would be to use contrasting colors for the wax or the epoxy to be able to see what to clean off later more easily.

Does white cement helps to make epoxy glue much more hardener ? Or its need only changing the color ?

But how strong is it? Will you trust it with high torque?

Thanks! I will use this candle wax technique for my friend’s 2000 hp drag car!

Thanks for that mate I think it’s cool how you repaired it sometimes parts just aren’t available off the counter anymore and it’s a case of do what you have to do 👍😃

Very Informative, helpful and Educational video! Thx for the tutorial man!

Heck yeah, as long as that epoxy is strong enough and bonded well enough that should work!

Did it work well on the equipment when you reinstalled it?

Excelente vídeo. Obrigado por compartilhar seus conhecimentos.

Now it would be nice to now how durable the repaired one is compared to a new one, also how high is the friction of the repaired one? Does it damage the other wheel cause it has higher friction? Does the repair break at max forces it had to endure previous?

Nice technique and skills. No epoxy resin I've came across would adhere to thermoplastic

Ive been repairing equipment a long time. I have rebuilt plastic and metal parts. There are great epoxy resins out there....some even get hot while curing which helps them bond to their substrate. As many stated, we don't know what this gears purpose is. The damaged area appears to have been caused by another round gear, (watch the first time he shows the damage) when this gear locked up, the gear it meshes with continued rotating causing the half round depression. This gear that was repaired was locked up, if it were the drive gear, more teeth would have been torn off and there would not be a half round depression. Rather than being jagged all over, the depression is more smooth and half round indicating a low ,"shore hardness". The scrapes in the depression are from pieces that were torn off and rubbed against itself, showing again it's low shore hardness. The tengential force applied to the teeth is the greatest force in this application or the gear would be more solid. Perhaps being light duty is how it protects the machine from jams. The shear resistance of the epoxy against tangential loads would be even greater than it's resistance to radial forces. So based on what we do know, this repair will work just fine, and if it fails it will be because once again the machine gets jammed. If anything the epoxy may be harder than the rest of the gear and if it jams it will just break off at each end of the epoxy, much like a good metal weld repair will break on the sides of the weld. Something to consider, My Dad warned me against making the repair too strong as it may cause something else to fail. GREAT VIDEO!!

Brilliant! I wish I had a gear like this to repair 😁

Hands down the best “build” video I seen in a long while.

Great video! My only concern is about temperature changes during epoxy hardening, I think it can melt that paraffin mold

Excelente proyecto muy bien desarrollado y mejor ejecutado, esa rueda dentada quedó cómo nueva, gracias por compartir tanta información y conocimientos, un saludo cordial y por supuesto un gran like desde Narón (Galicia) 🔝

Well done!!!. Really like the thought and creativity involved.

Brilliant idea! I can see other types of applications that are similar. Strength could be greatly improved by the addition of either fiberglass or carbon fiber strands.

Balance of the gear might be off if weight of added material for the new teeth is lighter or heavier. Usually gears need to be equal weight all around to avoid a wobble.

Great craftsmanship! Love the use of very basic tools and materials👏 bravo!

I like your idea of using wax as a mold, I have to make a new differential lever for my my vintage industrial sewing machine and I've been pondering on mediums that could work. I think using j-b weld in a wax mold could do it.

That's brilliant. Nice to know it could be a DIY if needed.

This is really cool, I’m just wondering if this would be strong enough to still function as a gear? Either way though making a mold out of wax is always fun.

With a world so quick to buy something new, it's awesome there are still a few that actually repair

Nice work! If the gear isnt under intense load or high speed should work fine. Ive used my 3D printer with ABS plastic and have printed many different gears they all work well unless introduced to significant load or speed or both. The friction heats it up and causes self destruction! 😅 great video!

One of the few tip things from RU-vid that I'll keep in my memory. 👍

Amazing fix. Thanks for calm music at a sane level.

Great video that encourages us non mechanics to be able to make any type of “repair.” While a replacement could be bought quickly, it’s the challenge that is more rewarding.

Amazing way to repair broken stuff 😍 thanks for sharing

Probable one of the most useful videos on RU-vid 😎👍.

well that worked out nice. Did it work well when installed? Only thing I'd worry about is adhesion between the plastic and the epoxy, but it looks like there was quite a bit of surface area so should be fine.

Great idea. I did something similar when the drive gear on my garage door opener stripped gears. It broke again in a few runs. I ordered a new gear and it broke right away. They sent me a replacement, it broke. In the end I replaced the opener. Most likely something else is going on.

Trabalho de Mestre! Parabéns!

Great concept that can be applied to lots of things. Thanks for sharing

You didn't just show us "how to repair a gear"... You showed us how to repair a gear "with style"! :O)

Nice idea but you must make a video of it operating as a fully loaded cantilevered teeth in a gear mesh

Alot of folks hate ing on this. But I think its a great idea. Even if you just follow the process untill you can re mold a brand new cog. Very good. Thanks.

Thank you for this demonstration, can be useful in future. 👍

Very clever repair. However, it's longevity will depend upon what stresses it is under, and from which direction. As another mentioned, there is not much but a few peg holes holding it on the hub itself. Reinforcing the back, where the peg holes are, will make it more durable. Great job !

It might be a good idea to add a pigment to the epoxy, so that it's easier to tell the mold (wax) from the repair (epoxy). In this video they're both white. (it could be that it's actually easy to tell if you're actually doing it, I don't know. But having a sparkly blue gear would be cool.)

Other than the following question,.I am speechless. Has anyone called you brilliant today?

Funny how all you geniuses have a superior way of doing it without knowing any of the details of the gear or it’s uses. Pretty amazing if you ask me.

Our garage door opener has a sacrificial nylon gear about that size. It is the weakest and cheapest part of the mechanism. The gear is easy to replace. If a track gets twisted or something else makes the door too hard to move, the gear fails rather than something hard to replace. If the nylon gear fails, make sure you fix the real problem before repairing or replacing the gear. It is a safety feature, like a fuse. A spring loaded clutch like on a cordless drill is a much better solution for the customer. If the door gets jammed, the clutch will make a noise while preventing further damage. Then the customer can straighten out the track and lubricate the system.

This video would be more aptly named "Gear teeth repair with a candle, a dremel, some screws, play doh, a little copper tuna can holder, an empty tuna can, epoxy, a belt sander, ect ect ect....."

really cool video. I would never bother to do all that to fix a gear. I definitely wouldn't have thought of all that

I did this to a vintage RC car. Gone through 10 tanks and it still works.

Inginuitive, yes. I have to question using about $20 of materials for what looks like a part of equal cost. The repair most likely will not be nearly as strong as the original part. Nice idea if you have no alternative though.

Lo aplique, muy practico, ahora esperando que endurezca. Gracias

Colombia . excelente demostración . gracias

Looks great, but how does the patch perform compared to the original material?

Wow, this is the easiest method to fix a broken gear. 🎉🎉🎉🎉

Well done! If you add graphite powder in mixture it will be even better. Graphite good vs friction and for colour in your case.

Miraculous work. You're master expert.

Excellent repair. Especially if this gear cannot be ordered for replacement.

Reading some of these comments, it's glaringly obvious they've never fixed anything in their lives or come across not being able to find a part, it doesn't have to be gears. This is a nice solution.

Great work! Thank you for sharing

thank you

Great video, thanks for sharing. Baking soda and super glue works well to and cures much faster.