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

 

[cowski]

flip it over and weld the backside . i would use 1/8 6011 for all or at least first pass then 7018 .no need to drill if its welded right.

 

[Degolyerent]

I welded the other side after cleaning up real well and I cut another 'v' drilled holes at end of cracks and welded with new box of 6011, I tried to download some pics but I am doing it from my phone and it is not working at the moment it keeps cutting off part way thru the loading process.
Anyway I stitched it in and let it cool slowly, and I put it back together with out the blades on it and ran it at 540 rpm and it ran smooth as silk. I was glad to have no balance issues, then I bolted on new blades with new bolts and nuts spun it again and it was still smooth.
I will keep a eye on it as I touch up the blades on a regular basis being I mow several hours a week and it is a lot of Bahia which is very tough grass.
Thanks for the info and the imput
John

 

[eastexan]

I had a brush cutter one time that had the blades bolted directly to the stump jumper. I don't remember the brand name, as I've had several different makes over the years.
It was a very heavy plate and I never had cracking problems with it, but NO WAY would I have welded it myself (except in my naive & stupid younger days).
And I would really have to have faith in a professional welding shop to do it either. That's one of those things where it's sometimes better to just bite the bullet and buy new or scrap the mower. :mur:

 

[Degolyerent]

Well I have been using the cutter again for about three weeks in some pretty tough conditions and so far the welds are holding up real well, I check it after each job and so far so good

 

[LD1]

Sounds great. Nothing beats the personal satisfaction of being able to do something like that yourself:thumbsup: Good Job

 

[Gary Fowler]

From description of your repair I would not expect you to have any problems with the repair. It should function normally for quiet some time. Fatigue cracks like you had will creep back in over time and misuse but that would be the case with new also. I cant believe the guys here saying dont repair-buy new from someone who knows what they are doing. I briefly worked in a shop when I was in my teens that built equipment and let me tell you, most of the welding done in those shops is not by "certified" welders. I have did inspection surveillance in shops World wide and the same thing applies to almost all of them. They is no welding procedure or welder testing required for structural welding. Anyone that can make a weld in flat position that wont fall off the steel when they are finished is allowed to weld. The workers are usually lower paid than certified craftsman in the trade and after welding in those little farm equipment shops for a few years will usually get certified and work at a higher paying job.
The phrase "fit for service" is better description of the work you get from those shops. That is why the welding on most farm equipment looks like crap compared to a really professional job.
I am not afraid to tackle just about any welding job but then again, I did it professionally for many years as a certified pressure welder and then many many years as welding inspector and quality manager so I know a little bit about the subject.

 

[Degolyerent]

I just wanted to do an update, the stump jumper finally gave up the ghost. It has been 2 years and 3 months since I welded it and I have gave it **** with some of the stuff I cut. I found a jumper on line complete w/ blades and bolts w/ nuts sold as a whole assembly sent directly from Landpride thru a company in Indiana for $318.00 plus $28 for shipping! I was amazed at the good deal because buying it locally was $420 plus tax and shipping which would put it close to $500 with no blades or bolts.
Thank god for the Internet and some research!! I put a pic of the stump jumper and some of the stuff I have cut with it. I am sure when cutting large stuff,3" or so that when the material gets hung up between the top of the stump jumper and the bottom of the mowing deck, that is what tears up the jumper. I have made a lot of money with that Landpride cutter and will be happy to put on another stump jumper especially at such a good price. I look toward to getting another few years service from it.

 

[Willie B]

In a day I only owned AC welder 1987 I bought a worn out Bush Hog 105, the stump jumper was cracked open and opened up a good 5/16" gap at each end of the blade holder. 26 years later after a life of alarming abuse, and perhaps 10 grind it out, gap it and weld it with 7018 I finally decided it was getting to be sufficiently dangerous, and enough stumps have been removed. I used acetylene torch to remove the stump jumper entirely. It works as well as ever. These things are scary, blades are heavy enough to take your head off, and they sometimes fly off at full speed. I once lost one, along with any portions of the bolt that held it. 20 years later, I've never found any of it. It is either underground, or hundreds of feet away.
Knowing now that I am a mere mortal, I would opt to replace it with new, less chance of being decapitated. They are cheaper than human life, and even cheaper than most tractor tires.