Stump jumper welding

[Degolyerent]

I Lack knowledge in knowing what grade rod is best to weld crack in my stump jumper.I realize that it is a very hard, high grade steel because of the abuse it takes
I have old ac welder ( Lincoln 225) stick welder, can someone reccomend what rod I need for this application?

 

[vic4news]

I'm just a hobby welder, but I usually use 6011 and sometimes 7018AC for things like this.

Vic

 

[Shield Arc]

Knowing what rod is important enough, but knowing the procedure is just as important.

Are you talking the frame of a truck? Don't know what a stump jumper is!

 

[BeezFun]

Are you talking the frame of a truck? Don't know what a stump jumper is!

A stump jumper is the frisbee shaped disk under a bush hog that the blades attach to. It allows the bush hog to jump over stumps without ruining the blades or tearing itself apart. It spins pretty fast, takes a lot of abuse, so a good weld is important. Also balancing it would be an issue. They don't have to be perfect but if you booger up the weld with a lot of extra material, it could make the thing vibrate pretty bad and put wear on the bearing.

 

[Mark @ Everlast]

I would not weld the stump jumper UNLESS you are a qualified welder. Those things can detonate and fly apart sending pieces clean through the top of the bush hog and into your hear or any body part and incredibly fast speeds. Likely a crack in the jumper is an indication of metal fatigue. Either replace it or get someone qualified to look at it.

 

[Shield Arc]

I would not weld the stump jumper UNLESS you are a qualified welder.

I'm most likely not qualified, but I'd probably tackle it.
Maybe I should see it before making a statement like that tho!

 

[Degolyerent]

I added a pic, you can see small cracks on either side of yoke on both sides of unit, they do not extend all the way across, I have 'v' cot along the cracks since this pic, I plan on welding the ' v' full and grinding it back flat so blades can swivel like designed. Then I will remove jumper and weld on other side. What I was trying to find out is which grade rod to use for this application

 

[Brad_Blazer]

It only spins at around 800RPM.

I would use 7018, welding in short sections to reduce the heat affected zone and mitigate weld shrinkage. Your plan sounds okay. Take some pics so we can see how it turns out.

 

[LD1]

I'd weld it also. But I am comfortable with my skills as well. I wouldn't be afraid for using the MIG on both sides if it were mine. But thats just me.

And 7018 is a difficult rod to run for a rookie and/or small homeowner buzz-box. So without knowing your skill and welding setup, I am going to err on the side of caution and tell you to take it off and take it to a weld/fab shop.

They probabally wouldnt charge much, especially if it is a small local outfit.

And out of curiousity, have you even priced a new one?

 

[Shield Arc]

Good plan of attack with any crack, is first drill a hole on each end of the crack.

 

[Degolyerent]

This is some pics of repair, one shows it prepped with it 'v' cut, the next is stitching the weld, then grinding flat and then painting also is a pic of the rods I used at 105 setting on machine
Tomorrow I will pull it off and weld the other side

 

[Brad_Blazer]

Looks good. You will probably find that the cracks were on the edge of the original weld holding the disk to the blade carrier.

 

[crash325]

Another :2cents:

I see cracks extending past where you have been welding.

#1 Drill a hole at the end of each crack.

Forget 7018 unless your are a real welder, can keep it hot and dry. A good weld with 6011, 6013, or 7914 is better than a poor weld with 7918.

Best of all get a new one. Second best take it to welding shop. 3rd Best you are already doing.

 

[RoMad]

It looks like a pretty good repair to me. Hard to tell but did you always weld to the middle and not leave your craters at the edges? I would just look at it regularly and make sure you don't see any new cracks.

 

[yomax4]

I would surely drill holes at each end of the crack and weld it up with a 312 Stainless Stick Rod like Stoody Versalloy, MG 600 or Welco Super Missel Weld. 120,000# tensile with fair ductillity. 7018 or 8018 next. I fix'd a chunk that was tore away but not removed on mine. I used Versalloy for the cost and it has held well for 4 years. Just saying what worked for me. I don't think that at 800 rpm it is a huge deal. Mine runs on a 540 pto but the gear box makes it run faster..Maybe 800 Rpm's or so.. Unsure. I'm an expierienced maintenence and repair person so I don't want to put you up to something you are unsure about. . Proceed with caution.

 

[Mark @ Everlast]

First, I'd chunk the rods. No name.
They're wet anyhow...you'd just have an issue with hydrogen cracking, and an AC box isn't capable of making the kind of weld you want with that rod IF they were dry. Being in an unsealed container virtually negates any strength properties they would have added.

ONLY ?800 rpm???...now lets see....that disk is about 3 in diameter. One revo means that lets see....remembering some math here. The distance around the edge is the circumferance. C=2pi(r).or pi(D). 3 x 3.14 equals about 9.4...Now we multiply 9.4 feet by 800...thats a travel speed of 7520 ft per minute. 7520 ft per minute is about 85 mph.... Now if a blade is attached to that the tip speed may be in excess of several hundred miles per hour.

Any engineer want to calculate the force of what a 10 lb(average educated guess) flying at a tangent at 85 mph can generate?

Stump jumpers aren't that expensive around a 100.00 or so for most brands...Better safe than sorry. http://www.agrisupply.com/stump-jumper-f-hp-k-k-/p/39031/cn/1900059/

 

[jake98]

I can't figure why it would have cracked to begin with, not that that helps much.

 

[LD1]

I agree that a good weld with 7014 or 6013 is better than a bad weld with 7018. And 7018 requires some specific care.

But to those of you nay-sayers, Mark @ everlast especially:

Take a good look at how that thing is put together. That stump jumper is NOT what is holding the blades on. That thick ~4" x 1.5" bar is what is holding the blades on.

The "stump-jumper" is just a disk attached to that to prevent that bat from catching a stump. But in no way is holding the blades. And with the blades bolted on through the jumper AND the bar, even it it totally cracked out, there is no way it would come off there. It just may rattle around a bit. You could actually cut that stump jumper completely off there and be just fine. As long as you were just mowing fields with no stumps ofcourse.

 

[RickB]

The "stump-jumper" is just a disk attached to that to prevent that bat from catching a stump. But in no way is holding the blades. And with the blades bolted on through the jumper AND the bar, even it it totally cracked out, there is no way it would come off there. It just may rattle around a bit.

That is the important message here. Welding a blade bar is borderline insanity, but welding a stumpjumper isn't a big deal if done correctly.
And for what it is worth, most stumpjumpers are welded assemblies including the blade bar which come at a cost of several times the suggested "$100 or so" when purchased as OEM quality parts.

 

[High Compression]

Good plan of attack with any crack, is first drill a hole on each end of the crack.

Definitely. Keeps the crack from going further after you weld it.:thumbsup: