Fit Prep Question

[mmranch]

I am basically a welding newbie and currently configured for stick welding only. I have a question about fit before I repair something.

The backhoe on my tractor has a lock pin to keep the boom from swinging when not in use. It's made out of what looks like grade8 metal (goldish in color). It's basically a 3/4" to 1 " diameter rod, about 4" long which is welded to a smaller, long rod which is the handle of the lock pin.

I wasn't paying attention and I hadn't removed the lock pin and I swung the boom and it sheared the lock pin in two.

The break is very clean and if you put the two pieces together, the break almost disappears. When I weld this back together, I will need to grind off the outer surface of the weld to try to keep the diameter the same as the pin so it will go back in the hole.

My questions are:

1. Is it safe to weld this grade8 looking metal back together? (Hopefully no deadly gas generated?).

2. On the fit. Since I've got to grind off the protruding part of the weld afterwards... I want the weld to penetrate deep into the pin so it retains it's strength. If I were to fit the pieces together and weld it... how much penetration will I get into the pin? Would it be better to space the pieces apart about an 1/8" and weld it? Or should I grind the edges of the break then put the pieces back together, creating a small V shape gap at the outer break?

Thanks for any ideas!

 

[yomax4]

It will be tough to keep/make the pin straight after beveling heavily and welding. I'd buy a new one. Good Luck.

 

[Roadworthy]

The bevel will be the way to go. If the pin is really grade 8 you'll not likely get that strength back with your weld. I agree with yomax4 - buy a replacement.

 

[Industrial Toys]

That is a lot of sideways force your hoe has. Or the pin was of some really weak material. I almost can't believe that. The pin will be even weaker if welded barring any extra hardness acquired by welding.

 

[mmranch]

Thanks for the ideas! I'm going to try to weld it as I always need the practice anyway. I'm also going to look at the hardware store for what kind of large pins they might have as opposed to getting the replacement from the dealer. It really only functions to help secure the boom during transport.

Thanks again.

 

[ptsg]

It's just a lock pin anyways. Mostly used for transporting. Doesn't really see any forces unless someone forgets to take it off before using the backhoe, which a common mishap.

Get you a piece of angle iron, so you can just clamp both pieces on the V of the angle iron. That way it helps you getting things aligned and actually works very well.

 

[Big Barn]

You have nothing to lose by welding it but I agree with others. Just buy another piece the right diameter. It might not even be Grade 8 if it’s only for locking the boom.

 

[dstig1]

It's probably just a mild steel pin. The color you are seeing is possibly cadmium plating, but that has gone away due to toxicity issues, so it is probably just yellow zinc plating. Purely to give it some corrosion resistance. I suppose there is a chance it is hardened or maybe just case hardened to improve durability but I would still suspect just plain old steel. Will a file make a mark or just skid off it?

 

[WranglerX]

Cost effective, buy new pin.....

IF you have to weld it, bevel both sides, clamp firmly in piece of angle iron to maintain alignment, weld for deep penetration and grind for clearance fit.... Get big hammer and anvil to adjust for any misalignment....

The color of the handle or loop end on any pin designates what grade material it is....

https://www.extension.purdue.edu/extmedia/ppp/ppp-94.pdf

Think this is as follows..

Black is grade 2
Red is grade 5
Blue is grade 8

Hitch Pins & Clevises


Just like bolts but uses colors instead of marks on bolt heads...

Dale

 

[mmranch]

Thanks for all the ideas! I got it repaired and we'll see how long it lasts (I'm sure it won't be long before it sees some force applied!).

I beveled the edges, welded it and ground off the excess. It's plenty straight but I'll see how it holds up.

Thanks again.