Stump jumper welding

[jake98]

I thought welds were supposed to be stronger than the parent metal. (as to welding a blade bar being insane..)

 

[LD1]

I thought welds were supposed to be stronger than the parent metal. (as to welding a blade bar being insane..)

Key word is supposed

You have to be a skilled welder, using the right kind of weld method/material, AND you have to understand what kind of stresses the weld/heat does to the base metal.

In other Words... The weld itself may be stronger than the parent metal, but what does the heat of welding do to the parent metal RIGHT where the weld material meets it?

I have seen welded things break, and the weld bead itself was intact and looked good. But it weakened the parent metal right at the joint.

And cracks are a whole differnt story. A lot different than just butting two peices together and welding them.

 

[BeezFun]

One thing I'm going to do is check my stump jumper next time I sharpen the blades. I usually just raise the deck high enough to crawl under there with a hand grinder and do the blades, never ocurred to me to check for cracks on the disk. Mine's over 50 years old, it's built like a tank, even if both blades flew off I'm not sure they could penetrate the sheet metal. I should send this thing to Afghanistan, they could cut it up and use it for armor on their humvees.

 

[Degolyerent]

The stump jumper is trying to be difficult to get off but I still have a couple of tricks left before applying heat to it as I did not want to have to change the seal, but we will see as the day goes on.
I agree that welding the stump jumper is no huge deal, like LD 1 said it is not what is retaining the blades on the unit anyway, and the cost for that jumper is $600 I don't know where you buy that particular jumper for &100 or so, if that was the case I would buy 2 and have a spare.
I touch up my blades on a regular basis and I am going to keep a good watch on it.
The 7018 rods that I used came in a sealed plastic container which I opened less than five minutes before using , I know that the Fl humidity is bad but they where fresh rods, I used to work for a commercial refrigeration outfit that did large ammonia systems and I labored under a few different welders cleaning welds and preparing stuff to be welded so I am not completely ignorant in that respect it has been back in the 70's though since I worked with them but I weld from time to time on my own stuff
I didn't really expect to get rave reviews from welders anyway because most of them don't like each other so thanks for the input it has made for some good reading, my only original need was advice on which rod was best for the job!
And by the way it did crack right next to original welds and stitching the weld on the repair was good advice I believe and so is drilling a hole at end of crack. Thanks for the advice and I will keep y'all posted on the progress

 

[Short Game]

We've probably all seen where a crack next to a weld was welded and so was the crack that formed next to that weld. Vibration seems to find where to make the next crack. Would general heating and then burying the work in dry sand to cool slowly help stop future cracking?

 

[Shield Arc]

Would general heating and then burying the work in dry sand to cool slowly help stop future cracking?

Yes!
Preheat, and a very slow cool down is the correct method for items that are or will be under a lot of stress.:thumbsup:

 

[Degolyerent]

Well I got the stump jumper off by using a top portion of a jackstand to drive the jumper straight down off the shaft, I used the blade nut access hole and placed the solid metal piece of the jackstand top part down so the wide flange rested on the blade retainer and took a sledgehammer and knocked it loose, on the second hit it fell right off, I'm sure all the PB Blaster and white lithium grease spray over the last couple of days had to help also.
So now I'll take some pics before I prep it to be welded, I will take advice and drill holes at end of cracks and use some new 6011 rods on it, and stitch the welds in, so far so good!

 

[weldermike]

Try a little pre heat, weld it, let it cool slightly, pour some 90wt gear oil over areas that were heated and welded, than take a folded up welding blanket and let sit on top so it cools very slowly. I use various methods of checking hardness on such jobs, but little late now. Even if you dont try what I sugested, just keep in mind for the future. Later bud ! check it occasionally tho, those things are super powerful, I hit a rock once that hit my truck about 200ft away. Truck was downhill tho, and also put another rock through my garage door, just be careful, had many times I bent over quick and covered my head cause thought it was ready to explode on me.

 

[Brad_Blazer]

The reason it cracked next to the original weld was not necessarily because of any weakness associated with the metal. It is simply an area of stress concentration where the thinner metal of the pan meets the thicker metal of the blade carrier.

You can get a replacement stump jumper at Agri Supply for less than $100 but not with the offset like this one. I figured right away that $OEM$ was the only replacement option. What brand is your mower?

 

[Degolyerent]

Yes Brad that makes sense for sure, i understand the thinner and thicker relationship comparison. The cutter is a Landpride RCR 2672, which is a good cutter it has been used and abused, it has 130 HP gearbox