Broken weld on backhoe frame

[Longbeard]

Hi guys,

My frame on my Case backhoe is broken. Just above the rear axle on the shuttle shifter side. Im thinking Ill grind a v in it and weld it up with some 7018 then maybe put a diamond plate on it. Any other suggestions. Anyone have a break here on theirs?

 

[MIKE R]

I would get a professional to weld it as there is a lot of stress on it. There is more to welding than what the average person sees. I do thing adding the plate on is a good idea.

 

[chriswheeler]

Grinding the crack is a good start. Also make sure to drill the ends of the crack to prevent it from spreading. Having everything clean in the area to be welded helps as well. ( no paint ) Frame member should weld fine with 7018 and DC, but to be sure I'd use 10018 ( DC ) and if I only had a AC machine, it would be 11118. Either of these rods have a 100,000 yeald per inch and are good for high alloy steels where 7018 has a 70,000 lb per inch yeald and is best for mild steel. Grind the weld flat, cover with your patch, and weld all around with the same rod. Don't forget to disconnect the battery before any welding, don't want to fry your voltage regulator. ( don't ask how I had to learn this one )
Chris
Chris

 

[Reyer Farms]

Could I bother you for a picture?
I have a hard time pricing things over the phone.

 

[Shield Arc]

I never did like grinding out cracks, the grinding dust will cover the crack, and make it hard to see it's limits. I always liked using a carbon arc, or now days a plasma, either one will open up a crack so you can see it. But I realize most people do not have those tools. Drilling a hole at each end of the crack is always a very good idea, but do this before grinding! Just encase the frame is still under stress.
I would never recommend using 11018 unless I knew exactly what the base material was. I seen a guy splice some mild steel beams once with 11018, the welds cracked right down the toes before completing the splice. Personally the highest I'd go is 8018. You could call case and ask them for a welding procedure.
If you do use a doubler plate, try not to use any sharp corners. Round or oval is best, but if you do use sharp corners make sure you tail out your welds like this picture! This will confuse any stress lines.

 

[Longbeard]

Yep, no access to air arc or plasma cutter. In fact I'm going to have to get my Lincoln weld n power running before I do anything. I bought a Hobart 135 wire welder a few years ago and dont use the stick much anymore so its been sitting. Vert up, mutlipass with the little wire welder holds anything I need welded. The backhoe is a different story. I wasnt sure what kind of steel the frame was made out of, I was hoping somebody here would. Im just going to go with the 7018. I'll have to remove the wheel to get to it. That will be another tricky operation I imagine. Ive never removed a tractor wheel. Shouldnt be hard with the out riggers, but manhandling it will be. No fork truck here either. Thanks for the tips guys. BTW I didnt mention that this is the factory weld thats cracking.

 

[Shield Arc]

To be safe, I'd use a little preheat, and wrap the area up in some old house insulation when done. And let it cool to the touch.

 

[cowski]

you could gouge it with a torch.i would use 7018.

 

[Reyer Farms]

I never did like grinding out cracks, the grinding dust will cover the crack, and make it hard to see it's limits. I always liked using a carbon arc, or now days a plasma, either one will open up a crack so you can see it. But I realize most people do not have those tools. Drilling a hole at each end of the crack is always a very good idea, but do this before grinding! Just encase the frame is still under stress.
I would never recommend using 11018 unless I knew exactly what the base material was. I seen a guy splice some mild steel beams once with 11018, the welds cracked right down the toes before completing the splice. Personally the highest I'd go is 8018. You could call case and ask them for a welding procedure.
If you do use a doubler plate, try not to use any sharp corners. Round or oval is best, but if you do use sharp corners make sure you tail out your welds like this picture! This will confuse any stress lines.

Slick fix- very nice.
I use my torch to find cracks a lot of the time. Heat one side of crack evenly and the crack shows up because it will not let heat pass on other side. Bonus is you are preheated! I realize that there are people who might frown upon this and I am open to their view. I have used mag-flux once and it was pretty neat. I am just a welder and easily amused.

 

[sdd1986]

Yes grinding sucks but you need to do it. Drill holes grind the crack if you have a tourch heat it at least until all the moistureis gone then weld it with 7018 do not use mig/solid wire. Dc welders are the best way to go. If you put a patch over it you absolutely have to round the corners, a pop can or coffee mug would be a great templet to mark the rounded corners out with. Also grind the crack weld flat so the patch sits flat on base metal. The patch doesn't need to be any thicker then what you are patching.

 

[Longbeard]

Still fighting my welder. I got it running but its not running well. It's not giving me much of an arc, probably because its not running right. Anyone know how to flash the DC field? Its a Lincoln 225/210 Weldanpoer.

 

[Shield Arc]

This is how you do a SA-200, but it may work with your welder, I've done the same thing with AC generators.

Flashing the exciter field consists of passing current through the fields using an external source of 6 to 125 volts of DC power from a storage battery or DC generator. If using a DC generator, keep the generator turned off except when actually applying the flashing current. To flash the fields:

Turn the welder off. Raise one exciter brush off the commutator.
On Lincoln welders, attach the positive lead from the external DC source to the right hand brush holder.
Carefully holding an insulated section of the negative lead from the DC source, touch its lug or clamp to the left hand brush holder for five seconds. Pull it away quickly to minimize arcing.
Remove the lead from the right hand brush holder, replace the brush on the commutator, start the welder and the generator voltage should build up.

There are two schools of thought on how to do this, here is the second way.

At the bullet nose of the machine, under the cap you have 2 exciter brushes, one on each side of the exciter armature.
Each brush has a screw stud that the pigtail of the brush connects to.
The right hand brush (black wire) is positive
The left hand brush (red wire) is negative

With a automotive or lawnmower battery AND THE MACHINE ****NOT**** RUNNING, connect the positive cable from the battery to the positive (right hand) brush screw stud. Attach the negative cable from the battery to the negative screw stud of the brush (left hand)

 

[Longbeard]

If I put a patch on both sides of the weld repair should both patch plates be as thick as the material being patched? I'm picking up a carburetor kit for my welder tomorrow so I'll be able to flash it once I have the carb straightened out.

 

[Johnp33]

Welding anything is a choice, if you reinforce it to much it will not flex and absorb shocks as it was designed. Then it breaks something else, because the shock load is still there it is just transfered. I have welded quite a few frames on class eight trucks, and never fish plated them, never had one break either. The most common fault people do is they want the weld to look good so the end up grinding the frame away, You are welding the crack, gouge it out, fit it, do not overheat it, that means chip it clean and spray with a water bottle, I use to use an air chisel with a shortened flat blade to chip and stress relieve the weld, clean with a wire brush, then weld again, clamp scrap steel to the other side to keep in place, and act as a heat sink. Then grind the back side clean, and weld that up. You have to set your heat and speed so you do not undercut. I was never into grinding the weld off, unless it was an area that had anouther piece bolted to it, then only where it overlaps.
Just a thought!

 

[Shield Arc]

spray with a water bottle,

Unless you know for a fact the carbon content of the base material is low, I'd be real careful doing this.

Carbon content, steel classifications, and alloy steels - Metals/Materials Tech Cell - TheFabricator.com