Help bending Bucket pin straight

   / Help bending Bucket pin straight #1  

Sodo

Elite Member
Joined
Apr 21, 2012
Messages
3,198
Location
Cascade Mtns of WA state
Tractor
Kubota B-series & Mini Excavator
Looking for ideas here.

I recently purchased a Kubota KX41 mini Excavator. It has an aftermarket hydraulic thumb by PECK. The thumb pivot pin is bent.

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I see 2 options:

1) put a Sawzall blade in the gap and cut it at the bend, replace it with a new pin. (seems to be 1 3/16" diam.)
2) Think of a way to use the bucket and thumb hydraulics to bend it back straight without removing it.

#1 is pretty straightforward. Cut it out, & excavator is disabled until all the elements fall into place. Bend the thumb arm back straight too and re-assemble. "Bend back straight" is easier said than done.

The reason I'm considering #2 is that it might be possible to complete #2 in a half hour, which is a fraction of the time to even locate suppliers of replacement parts. Has anyone had luck using tractor hydraulics to fix itself?

It seems worth a try so whats the risk? If it bends back halfway, it the gap may close then I can't get a Sawzall blade in there (to cut it at the bend). I know about bending pins they sometimes squirm & rotate themselves to avoid bending.
 

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   / Help bending Bucket pin straight #2  
It's hardened steel. Bending is really tricky and is best done red hot and in a press, then correctly heat treated.

Id just replace it.
 
   / Help bending Bucket pin straight #4  
Just replace it, least down time to do that than work half day trying to straighten it. Might be worthwhile to figure out how it got bent so that it can be avoided in the future.
 
   / Help bending Bucket pin straight #5  
Looks like the collar bracket is bent, too. That may prevent you from pulling it out. A new pin isn't just going to slide in. Heat that bracket part orange+, too, in order to straighten it. You can buy short pieces of steel rod in sizes like that on eBay. All you then need to do is drill a hole for the retaining bolt. I'd pull it if I could, heat it up orange and peen it on an anvil. Put it in a charcoal barbecue for 10 minutes using a leaf blower or air line to get it uniformly hot.
 
   / Help bending Bucket pin straight #6  
If thumb still works ok I would leave it alone
 
   / Help bending Bucket pin straight
  • Thread Starter
#7  
It's hardened steel. Bending is really tricky and is best done red hot and in a press, then correctly heat treated.
Id just replace it.

^what he said^

who said, me or him?:D

#1 is pretty straightforward. Cut it out, & excavator is disabled until all the elements fall into place. Bend the thumb arm back straight too and re-assemble. "Bend back straight" is easier said than done.

The reason I'm considering #2 is that it might be possible to complete #2 in a half hour, which is a fraction of the time to even locate a supplier of replacement parts. Has anyone had luck using tractor hydraulics to fix itself?

If it was hardened I doubt it would have bent. It's just a little excavator. But the hardness was worth checking so I put a drill to it and it drills like butter.

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To "just replace it" I first have to get the bent pin out which may be the biggest part of the problem. I have to either bend it straight first then pound it out. Or cut it at the bend and get the two halves out, then dial 1-800-custom-pin and order a new one and spend half a day or more on that. :D

Or 2) bend it straight and call it good. Or straight-er. OR
If thumb still works ok I would leave it alone
That may happen if I can't figure out a way to bend it back with the tractor hydraulics!

Anyway I'm still interested in ideas to bend it without disassembly. No idea how it got bent, maybe it got hit with a larger excavator. Its possible it bent because a collar was lost, I'd expect it to have a collar to prevent the thumb clevis fro spreading not just that carriage bolt.

Good idea about the BBQ. I can blow with the shop vac. It would be ideal if I can get it straight enough to pound the pin out, then I can straighten everything even the thumb clevis.
 

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   / Help bending Bucket pin straight #8  
It also should have shims between the collars along the pin. That would also help keep it from bending. Just installed a mechanical thumb on mine this weekend.

****, my dealer bent a caster on my MMM on delivery. I figured no big deal. Took me an hour to find out I wasn't going to be able to bend it back and I just have to cut it off and realign it and re-weld.

Good luck. I think it's going to be tough because you have the pin and brackets to deal with separately.
 
   / Help bending Bucket pin straight
  • Thread Starter
#9  
Agreed on the shims.

Really hoping I can get it mostly bent back by tractor hydraulics or other shadetree methods. I won't know pin diameter until its all apart and all disabled. Just bending it back fits my schedule better, because if it's bent back then at least it will come apart so I can plan the repair.

Agreed what bent this pin is the guy lost the collar (and bolt and shims) then replaced it with just a bolt, which "lengthened" the pin allowing the thumb 'clevis' to spread (what chvfrk98 said). Thus bending the pin further along with the clevis. I can't live with that. Ideally, I get it bent back, then squeeze the thumb clevis back and add proper shims and collar. I'm not thinking this will be easy, but after an hour or so fooling with the hydraulics I'm bound to know "something".

I don't see that clevis bending back on its own.:( If I can get that thumb off the those collar bores somehow must be re-aligned, maybe to an eqpt. repair shop with a big press.

I don't think it has shims in the 'middle', there is no rotation there because the pin has an anti-rotation tab. A shim or shims under the end cross-bolt collar is likely.

Heres the pic again.
364553d1394384325-help-bending-bucket-pin-straight-kx41_bent-thumb_pin33.jpg


Doing a little research on replacing the parts with new. I found O1 Drill Rod in 1.1875 size at Victor Machinery in NY for $61.25. I dont know the size of the dipperstick hole but the pin end (where I test-drilled) is 1.18".

Is O1 drill rod drillable? How much stronger is drill rod than CRS (for example)? Is there a functional difference that I should know about (between O1 and W1) drill rod when used for a "pivot pin"?

I will need a collar for the bolt, to maintain the clevis width and clearances agains the shims. It's like a shaft collar but rather than clamping is has a cross-bolt. And it needs to have inner diameter 1.1875"+. What's a search term for this item, I can't find them on the interweb. Does anybody know of a pic already how this joint SHOULD look (so I don't have to draw one)?

Got about a 1/4day invested in replacement already and I bet I'm about 10% there. Finding replacement parts for custom-built machinery ALWAYS SEEMS to takes --->me<--- more time than fixing what I have. I guess time flies when you're having fun. Lucky you guys who know where to find stuff quickly (and without paying thru the nose too)!
 
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