Anyone ever gas weld without flame arrestors?

[Sebculb]

Thanks rScotty, I'm looking forward to understanding more about bare vs Flux coated vs bronze vs all the other metals available for brazing.

Now that I've pretty much got the question of the flame arrestors answered, gonna start another thread to document my steps learning oxy torch processes.

Been playing with the thing, it's going well!

Thanks again

 

[etpm]

The most common brazing rod is a brass alloy and it has a lot of zinc in it. It melts at about 1600° F. Silicon bronze rod melts about 300 degrees hotter. Silicon bronze is about 3% silicon and 97% copper. Just adding 3% silicon significantly increases the strength over pure copper. It is stronger than zinc containing brazing rod.
When it comes time to braze the part make sure the part is fixtured well so that it cannot move during the repair process. You can make your heat containing setup with fire brick, red brick, or ceramic wool. You can even use dry sand piled around your part. Messy but maybe that's all you can get. After the part is well fixtured and surrounded with the heat retaining material make sure you have your rod and some powdered flux ready. Start heating the part and when it is good and hot throughout start heating the area to be brazed with the oxy-acetylene torch. Shake some flux onto the work and when the area starts to get hot enough the powder will stick and then start to melt. Heat the end of your rod and dip it into the flux. The flux will stick. When you think the work is hot enough rub the brazing rod on the work. It should start to mark the part or even melt the rod. This is what you want. Melt the rod with the work, not the torch. The torch is for heating the work, the part to be brazed, and not for melting the brazing rod. Don't try melting the rod with the flame and then try to get the molten brazing rod to stick. It won't. Once the work starts to melt the rod work quickly to completely wet the surfaces to be brazed. Rub the brazing rod into the work. You will get the hang of it fast and it will be fun. You will need to keep dipping the brazing rod in the flux as the rod gets used up.
It is important, once you start using the flux, to bring the work up to brazing temp quickly and then to work quickly. This is because the flux does two things: it cleans oxides from the metal and it prevents more oxides from forming. It does this by absorbing oxygen. The flux can only absorb so much oxygen which is why you need to work fast. Using too little heat is bad because it takes too long for the work to get hot enough and the hot flux will absorb all the oxygen it can and quit working.
Once the flux quits working the only option is to stop brazing and clean the flux off and then start over. Adding more flux to used up flux is useless. Used up flux often turns very dark brown or black and is called burnt flux for obvious reasons. Anyway, burnt flux must be removed before adding new flux. Trying to fix burnt flux by adding more flux is pointless. It's like trying to get dry underwear after peeing your pants by putting on dry underwear over your wet underwear. It just won't work. I'm really stressing this because using too little heat and burning the flux are two of the most common mistakes when brazing. I have done it more than once.
Other folks here are giving you good advice and I hope my advice is as good and helpful. Also, there are lots of good YouTube videos about brazing and you should find and watch a few of them. Then your chance of success on this job will greatly improve and you can show us all some pictures of the great job you did.
Eric

 

[jones6780]

Don't think I ever saw cast iron on a backhoe, cast steel, yes.

 

[etpm]

Don't think I ever saw cast iron on a backhoe, cast steel, yes.

Yeah, I don't think its cast iron either. I think it's probably a forging. Fortunate!y the brazing advice is the same. And cast steel would be easier to braze. As would a forging. In any case the OP says it is cast iron so I will continue to go along with that.
Eric

 

[deereman75]

There is a ton of castings on backhoes. Many of them are cast nodular iron. It falls about halfway between cast steel and grey cast iron in terms of weldability. Axle parts, depending on the brand of machine the outrigger feet, outriggers themselves, some of the linkages around the bucket, ect are cast as well. The bucket linkages more likely cast steel. The outriggers are typically cast nodular iron.

 

[Sebculb]

So that's the piece in question, it's part of the front hub. Not certain it's cast or iron, but the way it's broken looks like cast something. There are lots of cast pieces on these machines.

 

[Sebculb]

The most common brazing rod is a brass alloy and it has a lot of zinc in it. It melts at about 1600° F. Silicon bronze rod melts about 300 degrees hotter. Silicon bronze is about 3% silicon and 97% copper. Just adding 3% silicon significantly increases the strength over pure copper. It is stronger than zinc containing brazing rod.
When it comes time to braze the part make sure the part is fixtured well so that it cannot move during the repair process. You can make your heat containing setup with fire brick, red brick, or ceramic wool. You can even use dry sand piled around your part. Messy but maybe that's all you can get. After the part is well fixtured and surrounded with the heat retaining material make sure you have your rod and some powdered flux ready. Start heating the part and when it is good and hot throughout start heating the area to be brazed with the oxy-acetylene torch. Shake some flux onto the work and when the area starts to get hot enough the powder will stick and then start to melt. Heat the end of your rod and dip it into the flux. The flux will stick. When you think the work is hot enough rub the brazing rod on the work. It should start to mark the part or even melt the rod. This is what you want. Melt the rod with the work, not the torch. The torch is for heating the work, the part to be brazed, and not for melting the brazing rod. Don't try melting the rod with the flame and then try to get the molten brazing rod to stick. It won't. Once the work starts to melt the rod work quickly to completely wet the surfaces to be brazed. Rub the brazing rod into the work. You will get the hang of it fast and it will be fun. You will need to keep dipping the brazing rod in the flux as the rod gets used up.
It is important, once you start using the flux, to bring the work up to brazing temp quickly and then to work quickly. This is because the flux does two things: it cleans oxides from the metal and it prevents more oxides from forming. It does this by absorbing oxygen. The flux can only absorb so much oxygen which is why you need to work fast. Using too little heat is bad because it takes too long for the work to get hot enough and the hot flux will absorb all the oxygen it can and quit working.
Once the flux quits working the only option is to stop brazing and clean the flux off and then start over. Adding more flux to used up flux is useless. Used up flux often turns very dark brown or black and is called burnt flux for obvious reasons. Anyway, burnt flux must be removed before adding new flux. Trying to fix burnt flux by adding more flux is pointless. It's like trying to get dry underwear after peeing your pants by putting on dry underwear over your wet underwear. It just won't work. I'm really stressing this because using too little heat and burning the flux are two of the most common mistakes when brazing. I have done it more than once.
Other folks here are giving you good advice and I hope my advice is as good and helpful. Also, there are lots of good YouTube videos about brazing and you should find and watch a few of them. Then your chance of success on this job will greatly improve and you can show us all some pictures of the great job you did.
Eric

Etpm, thanks for the detailed instructions, as well as the information on different brazed and fluxes. I'll be incorporating all that into my plan as I develop it.

I joke like I'm just a jackass that bought a torch kit and is ready to set some stuff on fire, but the truth is I'm studying this pretty seriously and have a few small projects to do to get used to the equipment and build some skills. In these situations I really appreciate all the information I can get to roll it all into a plan that works in the situation with the resources available.

Could probably take this to a shop and have it done cheaper and faster, but all this is something I've been wanting to get into for several years now. This way we've got the tools for next time and who knows, eventually it'll probably earn some money also. We've got two old backhoes that work a lot in season so having these capabilities in-house is very useful.

Thanks again!

 

[etpm]

Etpm, thanks for the detailed instructions, as well as the information on different brazed and fluxes. I'll be incorporating all that into my plan as I develop it.

I joke like I'm just a jackass that bought a torch kit and is ready to set some stuff on fire, but the truth is I'm studying this pretty seriously and have a few small projects to do to get used to the equipment and build some skills. In these situations I really appreciate all the information I can get to roll it all into a plan that works in the situation with the resources available.

Could probably take this to a shop and have it done cheaper and faster, but all this is something I've been wanting to get into for several years now. This way we've got the tools for next time and who knows, eventually it'll probably earn some money also. We've got two old backhoes that work a lot in season so having these capabilities in-house is very useful.

Thanks again!

Yeah, that piece does indeed look like it's cast. It should be easy to repair.
Eric

 

[etpm]

So that's the piece in question, it's part of the front hub. Not certain it's cast or iron, but the way it's broken looks like cast something. There are lots of cast pieces on these machines.

Looking at your part I see a good opportunity to make the part come out right. Since there is a large machined surface it is obviously important. It is also perfect for keeping the two pieces in the same plane. If I was doing this repair I would clean all dirt, dust, paint, and oil from the two pieces. Then I would clamp them well to a piece of thick, FLAT steel. Clamping well meaning in this case not just securely clamped to the flat steel but also clamped together, using the broken faces to accurately locate the pieces. Then I would vee out the break about 3/4 of the way through, leaving the last 1/4 to maintain location. when brazing I would make the bead proud of the surface the same amount as the thickness of the 1/4 left as well as double the width of the vee. This is of course only if you have the room. If the brazed assembly is then left to cool so slowly that it takes several hours it will be unlikely for the part to have warped, cracked, or pulled. I think you will do a job you can be proud of and will be confident that the part can be returned to service.
Eric

 

[deereman75]

Best bet for a part like that is to remachine it after welding it brazing. But if you're careful enough it may be good enough without

 

[etpm]

Best bet for a part like that is to remachine it after welding it brazing. But if you're careful enough it may be good enough w

Best bet for a part like that is to remachine it after welding it brazing. But if you're careful enough it may be good enough without

Fortunately most of the part is intact. It looks like there are 2 holes for locating dowels which are also intact. It is hard to tell from the picture but it looks like there is an outside diameter made to fit into a bore that would then keep the bearing race inside the part concentric to whatever the part bolts to. If the broken smaller piece is brazed in carefully, and while clamped or bolted to a thick, flat, steel plate or something similar, then I think the chances are good for a successful repair. But yeah, if I was repairing it I would follow all my own advice about how to braze the part and then I would still put it in the lathe, indicate the bearing bore, and machine the part as suggested. But since I own a machine shop this is easy for me.
Eric

 

[rScotty]

OK. After looking at the photo and seeing that it is a piece of the front hub I don't believe that I would attempt a fix. Yes, I'm experienced with gas welding and brazing.... and my shop is also equipped with lathe and mill for restoring bearing surfaces. But for this job I would look for a good used or new hub. And here is why:

The FEL on your JD310D can lift nearly 8000 lbs. You might still be OK with that load on a brazed hub....until you tried to turn and/or the front wheels sink in the mud and the rears keep pushing which side-loads the front hub. I'm guessing that may be how it broke in the first place.

You've gotten a lot of really good advice from everyone here about brazing. I guarantee it will come in useful. Torch welding and brazing sure did for me the year I spent doing mechanical work in Central America.
But there is a time and place for everything.

I haven't bought a hub for our 310SG, but I'd expect front hub parts for a 310D to be reasonably priced and available the world over. The 310D is probably the most widely produced backhoe ever made.

I'm seeing too much of the wrong kind of load on that hub. I'd replace it. Save your brazing for another day. But if you do braze it, I'd for sure use a hi-nickel rod, and expect to do some clean up machining when you are done.
Be careful clamping to a plate. Make sure it is a really heavy plate that won't warp, and consider letting one part float for differential heat expansion & cooling.
Consider that when you get done, a lot of the side load is going to be carried by the steel wheel. So pay attention to keeping the wheel mounting surface flat and also to the wheel studs.
Good Luck,
rScotty

 

[Sebculb]

Looking at your part I see a good opportunity to make the part come out right. Since there is a large machined surface it is obviously important. It is also perfect for keeping the two pieces in the same plane. If I was doing this repair I would clean all dirt, dust, paint, and oil from the two pieces. Then I would clamp them well to a piece of thick, FLAT steel. Clamping well meaning in this case not just securely clamped to the flat steel but also clamped together, using the broken faces to accurately locate the pieces. Then I would vee out the break about 3/4 of the way through, leaving the last 1/4 to maintain location. when brazing I would make the bead proud of the surface the same amount as the thickness of the 1/4 left as well as double the width of the vee. This is of course only if you have the room. If the brazed assembly is then left to cool so slowly that it takes several hours it will be unlikely for the part to have warped, cracked, or pulled. I think you will do a job you can be proud of and will be confident that the part can be returned to service.
Eric

Hola Eric, there is another outer "cover" to the hub that houses the planetary gears or whatever they're called. It's got another plate with the same bolt pattern. Planning on bolting the whole thing to that to keep it all stable. Preheat, or at least begin it, by throwing the whole thing in the kitchen oven for a while. My wife loves it when I do stuff like that with 40lb backhoe pieces.

My idea has been to bevel it out almost all the way from the top side and a little bit from the bottom side. Then I'll just lay one bead of nickel welding stick in the bottom side (preheated obviously), I'm not worried about just that amount of heat warping the piece. That'll keep everything in place and not allow any braze to leak through to the outer hub cover that I'll be using a guide. Then flip it over and fill with braze.

Welding the patch in like that with one bead will also allow me to work on the holes for the lug nuts before brazing. That's gonna be a pain in the ass, those are big holes. Probably use a combination of drill bits, the cutting torch, and maybe even a dremel to get it just right. Gonna have to practice with the cutting torch a little more first...

Thanks!

 

[Sebculb]

Best bet for a part like that is to remachine it after welding it brazing. But if you're careful enough it may be good enough without

Hola! That's what the dude at the machine shop who sold me the piece of metal to make the patch with said. Maybe I can pull it off with just a grinder and a sanding disk but the shop is a kilometer from my house so no biggie if they need to do it. Thanks

 

[RichNJKubota]

I'm not exactly clear on just where this is used and therefor the forces that could be on it. But I would opt for a new or used part. If this is from an old machine where parts are not available I would consider making a new one. Once again I don't know if this would be appropriate. But making one on a milling machine from plain steel could be fine.

 

[Sebculb]

RScotty and RichN,

Those are valid viewpoints, but we're just gonna bonehead on forward cuz, well, y'know... Just weld that schit up and keep moving, right?

Availability issues for new or used parts are a big problem here and, while totally possible, machining a new one would cost real money. So I'm just going to burn it and see how long it keeps working.

Thanks!

 

[etpm]

Hola Eric, there is another outer "cover" to the hub that houses the planetary gears or whatever they're called. It's got another plate with the same bolt pattern. Planning on bolting the whole thing to that to keep it all stable. Preheat, or at least begin it, by throwing the whole thing in the kitchen oven for a while. My wife loves it when I do stuff like that with 40lb backhoe pieces.

My idea has been to bevel it out almost all the way from the top side and a little bit from the bottom side. Then I'll just lay one bead of nickel welding stick in the bottom side (preheated obviously), I'm not worried about just that amount of heat warping the piece. That'll keep everything in place and not allow any braze to leak through to the outer hub cover that I'll be using a guide. Then flip it over and fill with braze.

Welding the patch in like that with one bead will also allow me to work on the holes for the lug nuts before brazing. That's gonna be a pain in the ass, those are big holes. Probably use a combination of drill bits, the cutting torch, and maybe even a dremel to get it just right. Gonna have to practice with the cutting torch a little more first...

Thanks!

I didn't realize until this post that you are gonna weld in a patch. I assume the patch is made from steel. And you are gonna use nickel rod. Some nickel rods are not machinable, which means the weld deposit is really hard. Which also means less ductility. This means the weld bead should be peened as it cools. If this was my part, for my machine, and I was using an oxy-acetylene torch, I would be using regular brass brazing rod. Whether I was brazing together two broken pieces of cast iron or brazing in a steel or cast patch. I would build some sort of "oven" out of fire brick or at least red brick. I would make sure that after brazing I could close the top of the oven with more brick. If no brick available I would use dry sand. I would pre-heat the **** out of it. Get it to 700 or 800 degrees. At least. Hotter wouldn't hurt. This would not only make brazing easier but would also help greatly with stress relieving as the part cooled. Once done with the brazing I would cover well enough to make sure it would take at least 6 hours to cool. I can't stress enough how important slow cooling is for a successful repair. Did I say slow cooling is important? Oh yeah, I would also take that bearing race out.
Eric

 

[Sebculb]

Thanks Eric, I'd been wondering about the bearing race

 

[etpm]

Thanks Eric, I'd been wondering about the bearing race

I know you are in a tough situation because it is not easy to get replacement parts. All the more reason to carefully remove that race.
You do not want to warp the bore when you braze in a new piece. Because the bore for the race had to be accurate the part must have been stress relieved before machining. Since this basically involved heating the part at a controlled rate and then cooling it the same it is unlikely that you heating the part will change it. But brazing in a steel piece may. So you want to make sure that the brazing material will give before the cast iron and help retain the original part shape. You don't want the patch to pull the part out of shape.
Cast iron has a yield strength that ranges from about 10,000 PSI to 60,000 PSI. Brass, which is what typical brazing rod is, has a yield strength from about 18,000 PSI, to about 45,000 PSI. Good cast iron is usually going to be near the high end, say 45,000 PSI yield. I'm thinking your part was probably made with pretty high quality cast iron. Brass brazing rod is probably closer to the middle as far as yield strength but may be closer to the top, but still probably has a lower yield strength than you cast iron part. This is good. Allowed to cool slowly a brass brazed joint will probably move and stretch instead of the cast iron.
Since you are putting in a patch I would not worry about brazing at all from the machined flat side. I would make one side of the patch as flat as possible. This side of course gets clamped to whatever you clamp the part to be repaired to. Then grind it to fit you part. Vee the patch and part almost to the flat sides, getting as close as maybe 1/16 inch. Don't go all the way. The part does not need to be brazed 100% of the way through. Just make sure your braze bead is proud of the surface that fits the air the same amount. At least.
I would also suggest looking on YouTube for similar repairs, I'm sure there are a few videos done by folks who know what they are doing that will give you some good hints.
Please show us some pictures of your repair.
Eric

 

[Sebculb]

I gotta get a little more practice with the torch before I start messing with the hub, but I feel like it's all coming along nicely. Thanks for all the advice, I'll definitely be putting pictures up soon.