Fixing Cracks in a Backhoe - Big ! with pics

[john_bud]

Hi,

Thought I would post a new thread on a project to fix up my old backhoe.

"Thingy" spur'ed this with his comments, so if it's a waste of bandwidth - blame him too!

Actually, if there are things done wrong - feel free to pipe in and share the correct methods. That's how I learn - screwing up then fixing it up!

Well,if you just spent the day fixing cracks with a short circuiting mig,,I shouldn't have to tell you the dos and don'ts,,,

{But you do! }

[if you fixed them],


{Don't know if I did!}

sounds like you might know as much or more than me about it.

{No where close}

Why don't you tell us some dos and don't when it comes to mig welding? Cause,there certainly are some dos and don'ts,,,and most of your backyard type wire burners,don't have a clue about them,or care,,,,,your turn,,,,thingy

Thingy,

I don't have much more than a clue. Didn't stay at Holiday Inn last night, but took a class at the Tech School.

How about I tell you what I was doing, you can tell me how I did.

Fixing cracks on a backhoe. After taking it all apart, it "feels" like the hoe was in a conflict with an overpass at one point. Could be just 43 years of wear and tear, but...

When repairing cracks, I try to have the work in a normal flat position. Makes it easier to pour the heat in. Grind a new spot for the ground clamp. PRessure wash the grease and oil off. Wire brush off the rust and what ever paint there may be. Grind the crack. 4 1/2" grinder or carbide cutter in an air grinder. Cracks I am fixing are ones that are all the way thru. Many have been welded before. Some by trained monkeys with a stick welder. (And I offer appologies for the comparison to monkey's everywhere.) I dry out the cracks with compressed air and spray them down with brake cleaner. If it is more than 10 ga, I will give it some heat O/A rosebud. Also give heat if there is a lot of grease and oil.



Here's the machine in use.

Here's the hoe as bought.

Here's some of the "issues"
Cylinder to swing post.

Top pivot point of swing post

Here's some pictures of the dipper stick.

Some grinding of the cracks. Still need to remove the barnicle. Look close and see there is still slag in the weld from not chipping between passes.

Under the barnicle.

If there is interest, I can post more. There are a lot more cracks.

jb

 

[Bill Barrett]

Nice, now if you have the room fabricate gussets and weld them over the top.

 

[john_bud]

Here's some more repair work.

Hoe in the shop -- sort of takes over the place.

Taking the boom off - Love the engine hoist~!

This may be a problem....Top right point for 4pt attach.

Top left side. Note the "junk" tacked on hapazzardly.

View of the bottom of the hoe body. Anybody see any signs of earlier damage and "stellar" repair? (I do HOPE the person that did that was stagarringly puking drunk!!)

43 year old slag that the factory failed to chip off.

Bottom of the hoe body - stabilizer mount

Extra strap added for the bottom 4pt mount and crack filled

Little different view. The crack took 3 slow passes to fill.

Tools used to degrease, wire brush and grind.

jb

 

[IH3444]

Oh gawd that is some mean work, I've done some of that to my backhoe, and dozer. That's man stuff fighting with those heavy parts.......like eddie walker does also, but oh-la-la, when you are using it, and the tasks you can do.

 

[thingy]

Man,you wern't kidding when you said that. That darned thing is busted all to ****,,,but wait,,we can fix it....right??,,,right,,,,,,welds look good,sounds like you are doing the prep good,but,think about that p.t. stuff,,,it lets you see more,,,it lets you finally see all of crack,,,,,,thats why you end up with some of this garbage,,,,they just weld up what they see,,,,that red **** [p.t.]lets you see the whole crack,,,,if you don't get the crack out in a part like this,,,it just speads,,and real quick,,,invest in some p.t. cans,,,,get that crack out,,,,you'd be amazed sometimes,where it goes to,,you see the crack here but it ends up over there,,,,,you are doing a good job,,just need some p.t.,,,,or mag,,,but thats another story,,,thingy

 

[IH3444]

Exactly Thingy, when done right it usually doesn't bust again. Most also do some heavy up on repairs. Got all the cracks ground out of the dozer lifting frame for the blade.....That was a toughie....I was eating stone dust that day.

 

[Doc_Bob]

Nic work!
Bob

 

[joes_427_vette]

Like they say.... anything can be fixed. From repairs I had seen the cracks reappear a short time later adjacent to the welds. Heating the area with a rose bud tip might be the answer. I'm glad I don't have to participate in this situation. My hoe is 4 years old, no cracks, and my major task is figuring out the mount to the tractor.
My friends have reserected some vehicles that required quarters, doors, frames, cowls, ect. They turned out great after hundreds of hours labor. I just don't have complete confidence driving it the speed limit.
Did you ever attend a heavy equipment auction and view the welds, bondo covering the mess, and four coats of paint ? Yes there are some artists in the repair shops.

 

[SPYDERLK]

Like they say.... anything can be fixed. From repairs I had seen the cracks reappear a short time later adjacent to the welds. Heating the area with a rose bud tip might be the answer. I'm glad I don't have to participate in this situation. My hoe is 4 years old, no cracks, and my major task is figuring out the mount to the tractor.
My friends have reserected some vehicles that required quarters, doors, frames, cowls, ect. They turned out great after hundreds of hours labor. I just don't have complete confidence driving it the speed limit.
Did you ever attend a heavy equipment auction and view the welds, bondo covering the mess, and four coats of paint ? Yes there are some artists in the repair shops.

The reasons things crack next to a weld are; 1) residual stress left as a result ofthe shrinking hot metal as it solidifies and cools, and 2) a stress riser situation caused by the abrupt change in cross section from the parent metal to the weld bead which sits proud to the surface. The strongest weld is one that you cant see. It is done from both sides by grinding a v then filling - then v'ing from the other side, all the way down to the 1st weld, and filling. Strain relief of each pass while cooling using a needle scaler is helpful as well. Afterward, the welds should be ground flush and re-peened with the scaler. When you cant get to both sides the v should go almost thru, and be filled -- with the scaler used between passes. Afterward, the weld should be blended gracefully to the surface using a flap disk - but leaving it humped about 10% proud - then peened again. This is the best you can do. It will ultimately crack from the root of the original v. If you can add reinforcement, do. Slightly thinner than original metal is good - you dont want to super stiffen one area or it will crack next to it. Blend the welds. Peen the edges. Changes should be gradual rather than abrupt.
Larry

 

[thingy]

You gotter in a heated space,[looks like],,keep it there,if you want to fix it,,,all cracks can be fixed,,,in your case you got your work ahead of you,,,,get you some of that dye check stuff before you weld another inch,,,if its worth your trouble welding than its worth your trouble figureing out where to weld,,,heat it up,,take your time,,,,,you can make this a brand new hoe,,,you can weld,,,just weld in the right spots,,,[ok,,thats all the pep I got],,it could be better than new,,if you do it right,,,,,,,,thingy