Backhoe steel

[John25mm]

Does anyone know what kind of steel Kubota uses for the steel in the main boom on a BH92 backhoe? I am wanting to weld a receiver hitch to the right side 9from the BH seat) of the boom at the very bottom of the boom to be able to pull smaller trailers around. I have a couple of family members who are expert weldors and are wondering if it's a special steel so they can use the right rods/wire for the steel involved. There is enough room even at full swing to the right for it to fit without hitting anything. The other reason for this location is it's as low and close to the main pivot/hinge of the BH so it will put low amounts of strain on the BH itself. I've seen others who have made adapters that either clamp on to or are welded to the bucket and to me this would put a lot of strain on the BH with weird angles of pull especially when you go into a turn. another reason I'm looking at welding this on instead of bolting it is there are a lot of hoses in this area and I think the bolt heads or nuts might chew them up way to fast.

Don't hesitate to either throw another idea at me or why it would be a major safety issue and to not do it. In spite of this being a web forum I won't yell and scream that you hurt my feelings.

 

[Lil Foot]

Can't answer the steel question, but....

Check this thread for alternative ideas:

Trailer hitch on backhoe (revisited)

This has been discussed before, and someone posted this pic, a pretty slick solution:

www.orangetractortalks.com

 

[John25mm]

Thanks for the link. There is a picture of basically what I'm interested in with the welded on one. It could be me but the others that are attached to the bucket/stick are just putting the weight and strain too far out from the main part of the machine. I just see me doing something with a bit of weight even though I know I shouldn't and trying to turn and having the weigh out way there bend stuff. I know me I get impatient and can do foolish stuff.
Again thanks.

 

[Kennyd4110]

I can't see it being anything special, just regular A36 mild steel.

 

[Donystoy]

Have you considered using your loader instead of the bh. I frequently move a tandem trailer with just a ball on a small steel plate which in turn is bolted to the center hole on the loader cutting edge. Been doing this for years without issues. Very easy hook up and travel easily in either direction.

 

[Russell King]

I can't see it being anything special, just regular A36 mild steel.

Question for someone that does production welding or manages the production…

As a mechanical engineer I used to specify A283 steel and then that became problematic to procure so they started making things from A36 which is pretty loose in definition (last time I looked) as basically any steel that has at least 36ksi yield point strength. There was no limit in the specification on the carbon content. After some time one of the suppliers suggested specifying a steel that limits the carbon content to “low carbon steel” values because the A36 was mostly recycled steel and was getting to be higher carbon content and more difficult to weld. We simply told them they could use any steel they wanted to use for welding that had a yield of 36ksi whenever we specified the A36. (We had too much work to change the drawings again and again)

What carbon content are you seeing in the A36 plate you buy? Do you have any difficulties welding it or do you just adapt to higher carbon content steel?

I am not sure what you are using to weld high strength hooks to plate steel so you may not really deal with A36…

 

[John25mm]

I can't see it being anything special, just regular A36 mild steel.

Thanks for the info. The reason I'm particular is the BIL weldors I was talking about and them being a bit anal in making sure they use the right stuff for the job. One restores old steam traction engines and has to make sure things are safe because if they aren't very bad things can happen if they blow up. The other is a weldor for a chemical plant and leaks in their pipes aren't very good for the neighborhood. They are particular to say the least. However, their welds are great and the cost to me would be the rods they use and some beer. Not a bad deal.

 

[John25mm]

Have you considered using your loader instead of the bh. I frequently move a tandem trailer with just a ball on a small steel plate which in turn is bolted to the center hole on the loader cutting edge. Been doing this for years without issues. Very easy hook up and travel easily in either direction.

I haven't really explored this route, but it isn't totally off the table. Thanks for your input.

 

[mcmxi]

What carbon content are you seeing in the A36 plate you buy? Do you have any difficulties welding it or do you just adapt to higher carbon content steel?

I am not sure what you are using to weld high strength hooks to plate steel so you may not really deal with A36…

A36 is easy to weld. If you're building something important you can bet that certification from the steel supplier will be required which will include carbon content among other things. If the carbon content exceeds 0.29 wt. % it won't qualify as A36 steel since it'll no longer be a low carbon steel.

I don't know what grade of steel is used for backhoe booms, but it could be something like A572-50. A572 is also a low carbon steel that is easy to weld but it's superior to A36 in terms of wear, fatigue and yield strength. It's used in crane booms and such.

 

[PoTreeBoy]

A36 is easy to weld. If you're building something important you can bet that certification from the steel supplier will be required which will include carbon content among other things. If the carbon content exceeds 0.29 wt. % it won't qualify as A36 steel since it'll no longer be a low carbon steel.

I don't know what grade of steel is used for backhoe booms, but it could be something like A572-50. A572 is also a low carbon steel that is easy to weld but it's superior to A36 in terms of wear, fatigue and yield strength. It's used in crane booms and such.

When I bought my bridge beams, 50 ksi was standard on them. That boom probably has lots of factory welding, and I don't think they'd do preheat or PWHT. An experienced pipe welder with 7018 should be at least as good as factory.

 

[Vlach7]

I welded a chain hook on my BH near the base, over heated/caused smoke from the sheath or hose, be careful.

 

[Kennyd4110]

What carbon content are you seeing in the A36 plate you buy? Do you have any difficulties welding it or do you just adapt to higher carbon content steel?

1) Not really sure
2) No, no issue welding

I am not sure what you are using to weld high strength hooks to plate steel so you may not really deal with A36…

They are done on a robot now, MIG process. We do not do this in-house however, just doesn't make since to invest in a robot. The plates are A36, laser cut. The hooks are forged from 4130 stock.

 

[mikester]

I can't see it being anything special, just regular A36 mild steel.

Wrong answer

Any manufacturer worth its salt will use a structural high strength alloy steel grade that's formable and tough allowing them to make the parts as light and strong as possible.

Cheap Chinesium and garage built crap will use mild steel to fabricate a BH.

Expert welders should know enough NOT to weld a trailer hitch to your BH boom.

 

[GreensvilleJay]

FYI I made a 'trailerhitch' for my BX23S. It hangs from the 'thumb' holes( 1/2" water pipe for the 'pin', has 'retainers' to latch inside the bucket, standard 2" receiver so I can use whatever sleeve I need for the job.
I use it to move my empty 7K dump trailer, zero problems.
It was a simple, cheap, easy solution with NO mods to the BX23S.

 

[Yooper]

My guess is it is grade 50 steel. Just a step up from A36. In fact if you look on the charts the upper end of A36 crosses into grade 50 territory. ER70S for wire feed or 7018 for stick. No preheat necessary unless you live in the arctic and you are welding outside in subzero. Good luck!

 

[jaxs]

We could wag at this til Christmas and not be any closer than at the start. The most important thing you should know is why your bils are being cautious. They don't want to risk losing your trust and friendship over the boom cracking from effects of heat. Here's what I recommend. Tell them you will take 100% responsibility for anything unfavorable happening then write it down along with what procedure you want them to use. That way noone forgets what was said if something gos wrong. On the least critical spot on boom hit it with tig torch or 6011 stick so that metal melts. Scratch the spot and a place 6 inches or farther from there plus any factory weld with a file. If the spot isn't resistant to being cut with file, weld as you like without fear of cracking. If spot is discernably harder to scratch, the material is high carbon and needs a couple extra steps while welding. Preheat area to receive weld to 450-500F, weld it with nickel rod/wire then encapsulate with Kwool, welder's blanket or other fire resistant insulation until it cools back to 400f.

 

[John25mm]

We could wag at this til Christmas and not be any closer than at the start. The most important thing you should know is why your bils are being cautious. They don't want to risk losing your trust and friendship over the boom cracking from effects of heat. Here's what I recommend. Tell them you will take 100% responsibility for anything unfavorable happening then write it down along with what procedure you want them to use. That way noone forgets what was said if something gos wrong. On the least critical spot on boom hit it with tig torch or 6011 stick so that metal melts. Scratch the spot and a place 6 inches or farther from there plus any factory weld with a file. If the spot isn't resistant to being cut with file, weld as you like without fear of cracking. If spot is discernably harder to scratch, the material is high carbon and needs a couple extra steps while welding. Preheat area to receive weld to 450-500F, weld it with nickel rod/wire then encapsulate with Kwool, welder's blanket or other fire resistant insulation until it cools back to 400f.

I agree and wouldn't hold it against them at all if they said it was a bad idea because the steel is not one they would be comfortable welding due to the type of steel, any extra work involved like preheating it, or they just don't feel good about it. They are the Subject Matter Experts (SMEs) in this endeavor. There is an old Italian saying, "If you are going to hire someone to fight your fights for you don't joggle their sword arm while they are doing so." I know enough to know that I don't know, and they do. I'm probably not going to have it done if even the only issue is preheating it because right now everything on it works well and there would be way too much stuff to pull out of the area to heat it without messing up if nothing else the hoses routed on the inside right there. If it can't get an answer from someone at Kubota corporate or even the local dealers (they have an excellent service dept that people travel some distance to deal with because they do excellent work and don't BS people) service people to see if they have every welded on one and if so, have they had any issues. Again, I agree with your comments and thanks for providing them.
If I do have it done, I will take pictures of before, during and after and post them along with updates as to the effects of the part.

 

[PoTreeBoy]

If they're that cautious they shouldn't listen to SGOTI, but here's a (poor) picture of where a previous owner of my L35 welded 3/8" grab hooks on my bh boom for chains to replace the latch pins.

My nephew also welded the thumb bracket onto the stick.