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Repairing a Broken Cast Iron Gear

sbosecker

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An eBay purchase arrived in today's mail. The box was in decent condition but the collection of Gears that were within had managed to move during shipment.




2018 11 24 - Broken Gear 01.jpg 2018 11 24 - Broken Gear 02.jpg

One of the gears was damaged. Is this repairable?


Scott
 
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lilredex

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I had a SB eighty tooth gear broken similarly to that. I "veed" the outer two sections (leaving the center section intact) and welded it up with nickle rod. You don't even have to grind it down.

Piece of cake.
 

bad_idea

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I have welded a cast axle center section to the tubes. Heated housing to 400 degrees, welded with 7018 stick rod, wrapped in fiberglass insulation to slow cooling. Has held up fine under abuse.

Considering the gear is small enough, I would stick it in the oven until it reached 400. Weld it up with 7018 DC. Shove it back in the oven. Shut the oven off after a half hour or so and let it cool in the oven.
 

matt_i

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I wouldn't even put any heat on it. Turn a round disk (thin plate) and bolt (drill and tap the thin disk) the two parts to it with some screws, after the parts are fitted tightly back together. It might be useful to use something like superglue or epoxy to hold the parts in that arrangement before applying the final metal repair part.
 
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PugetDude

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An eBay purchase arrived in today's mail. The box was in decent condition but the collection of Gears that were within had managed to move during shipment.




2018 11 24 - Broken Gear 01.jpg 2018 11 24 - Broken Gear 02.jpg

One of the gears was damaged. Is this repairable?


Scott

Have you contacted the shipper? If it wasn't properly packed and broke in transit, you might have some recourse.

Assuming you can't get a replacement, I'd find a really good TIG welder and have them weld it with stainless rod. They'll know to go slow, move around/side to side and keep it cool to prevent warping.
 

gte718p

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I'm in the braze crowd. Make a little fixture to hold everything in place. Braze it and to a little work with a file to fix the two effected teeth. Probably an hour or two to fixture, five minutes to braze, and fifteen to finish. Easy day.
 

NitroShark

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I could TIG weld that with nickel rod in 5 minutes.

Final results would still make for a Noisy gear while running but would get you by till you found a replacement. Done if more than once before.
 

The Cobbler

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by making the cast molten it screws it up and hardens the **** out of it.
I'm in the camp braze with torch
Search Keith Fenner on you tube , he has several videos on brazing cast.
he may even consider doing the repair for you.
and contact the sender for poor packaging, they should come good for it
 

vpd66

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Well you have a lathe.... A lathe can reproduce any of its own parts. Seriously, look into making a new gear. Its really not that hard and a little imagination should be able to produce a good useable new gear. Braze the old gear back together and you have a guide for indexing the new gear and grinding the cutter.
 
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sbosecker

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I wouldn't even put any heat on it. Turn a round disk (thin plate) and bolt (drill and tap the thin disk) the two parts to it with some screws, after the parts are fitted tightly back together. It might be useful to use something like superglue or epoxy to hold the parts in that arrangement before applying the final metal repair part.

matt_i,

This is an interesting idea... In addition to the welding/brazing procedures, I'll check and see if there is clearance in the gear assembly to achieve this solution.

Best regards,

Scott
 
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sbosecker

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Have you contacted the shipper? If it wasn't properly packed and broke in transit, you might have some recourse...

...and contact the sender for poor packaging, they should come good for it


The seller was contacted as soon as I opened the package and found the broken gear. He immediately responded with an offer of "me return - he refund".

The reason for the "repair investigation" is that this kit is "rare". I know that word gets used all the time but that is truly the case here. I would be delighted if someone proved me wrong and pointed me to a bushel basket of these Gear Kits. Ha!

I'm trying to see what (if any) repair could be made and how much it would cost. With that information in hand, I might see if the seller and I can come to a new agreement on me keeping the gear kit at a different price than the original eBay purchase.

Best regards,

Scott
 

sqznby

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Turn a round disk (thin plate) and bolt (drill and tap the thin disk) the two parts to it with some screws, after the parts are fitted tightly back together. It might be useful to use something like superglue or epoxy to hold the parts in that arrangement before applying the final metal repair part.

This is what I would do before welding/brazing it. But, I would use a thicker plate, maybe aluminum to help hold and draw the heat out.
Fixture it so you have access to both sides. Clean the crack if need be.
Tig braze and let sit until cold to the touch and unbolt it.
Heat treat if necessary.


I'm glad the seller got back to you.
Maybe he'll refund a portion of the sale price and you'll both be happy.
 

TheEquineFencer

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FWIW, a big hose clamp to hold it in place during rework might help. I'd do that, then get it Tig welded with a Nickel rod starting with the inside edges of the holes that go through the gear.
 
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sbosecker

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Thanks to all for their thoughts on this problem.

On Monday I contacted a friend of mine. A retired Delta Airlines mechanic, I had met him because he had an Allis-Chalmers Model G like I have. Mostly we had laughed & scratched at an annual local Farm Heritage Days event so I knew of his welding skills mostly by reputation. I had used him one time to do some aluminum welding on my trailer and I was impressed by his work on that project.

On the phone I told him I had a broken gear that I believed was cast iron. I asked if would look at it and give me his opinion on if it was a repairable situation. He said to bring it to his shop and he would look at it.

I drove about half an hour to his place and he examined the gear. He stated he thought it was repairable. I asked him if he knew someone that could do the repair. He replied, "Yes".

I asked, "Is he close?" He smiled a big smile and said, "Yes".

He gave me a quote on the repair and I left with the gear. I still needed to negotiate with the eBay seller on a reduction in the price to offset the cost of the repair and other incidentals.

By Tuesday morning the seller and I had come to an agreement that allowed me to keep the gear set with some compensation for the damage during shipping. I called my friend and asked when I could drop the gear off for repair.

He told me to bring it right over and - because he was busy with other projects - to leave it in a designated location. I did this at about 11:00 am yesterday. I had already told him there was no hurry in getting this gear back to me.

This morning I got up and, as I was drinking my coffee, I was thinking about calling him to see if he had found the gear. As I was considering when would be an appropriate time to do that, my phone rang. It was my friend: "Your gear's ready.", he said.




20181128-04.jpg 20181128-05.jpg

20181128-06.jpg 20181128-07.jpg

He indicated he had welded it with silicon bronze. I'm very pleased with the repair.


Scott
 
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James-W

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I am glad it turned out well for you.

As a side note to this, many years ago a good friend of mine owned and operated a blacksmith shop. One day I stopped by to see him and he was working on repairing a large gear. The gear was broken roughly in half. My friend put both pieces of the gear in his forge and got them both red hot, then he welded them back together. When he was done he let the gear cool down and then used a small grinder and smoothed out the welded areas. When it was cold he put on a little black spray paint and you could hardly tell the gear was ever broken. I was quite impressed.
 

MoonRise

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He indicated he had welded it with silicon bronze. I'm very pleased with the repair.

FWIW, that repair is "brazed". It is not welded.

Brazing is when the filler metal is melted, but not the 'parent' material. Welding is when all the materials are melted together.

Looks like he did a nice job.

(hopefully the gear teeth are still 'within spec' and all. To me, it's not so much the what looks like a nice brazing job, but whether those gear teeth are still within spec down to the thou or less.)

:beer:
 
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sbosecker

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FWIW, that repair is "brazed". It is not welded.

Brazing is when the filler metal is melted, but not the 'parent' material. Welding is when all the materials are melted together.

Looks like he did a nice job.

(hopefully the gear teeth are still 'within spec' and all. To me, it's not so much the what looks like a nice brazing job, but whether those gear teeth are still within spec down to the thou or less.)

:beer:


MoonRise,

I am aware of the difference between brazing & welding but that's about it. I'm pretty sure he said he "welded" it. He was probably talking to me like one would talk to a slow child - trying to use words he thought I would understand.

Ha!

I may ask for clarification at some point.

Best regards,

Scott
 
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sqznby

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MoonRise,

I am aware of the difference between brazing & welding but that's about it. I'm pretty sure he said he "welded" it. He was probably talking to me like one would talk to a slow child - trying to use words he thought I would understand.

Ha!

I may ask for clarification at some point.

Best regards,

Scott

Glad it worked out for you.

He said he welded it because he used his welder to do the job.
Technically he tig brazed it.
He did a nice job:thumbup:
 
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