Grading Help? Broken mower blade bolt

[jesseb3@att.net]

While trying to remove the bolt that holds the middle blade, my buddy and broke the bolt. This is the one that threads into the main gearbox shaft, so a simple replacement would prove costly.

Has anyone else done this? Were easy-outs successul? Our opinion is that the bolt is mostly likely grade 8, and that drilling will be difficult, and if it broke as it was, then most likely we'll break the easy out as well. Heat will probably cook the bearings, so we're concerned about that route/

Any ideas guys?

Thanks
Jesse

 

[irwin]

Left hand or right hand threads? A picture would help us give suggestions. Most broken off bolts can be removed ..The HOW depends on factors..like how much room you have to work and the direction of threads, and whether it's hardened steel.

If it's a left hand thread, you'll want to be very careful.(left hand thread chasers aren't sold everywhere. specialty tool. )..If you have time, soak it with penetrating oil and let it sit a few days. If time is an issue maybe you should bring it to a machine shop..having the right tools, makes a world of difference..and if you end up going to a machine shop..don't buck it up too badly first..it'll be easier for them if its not all chewed up.

 

[Outlander]

Carbide drill bit, moderate heat and pray you don't break the EZ out. You need to ask yourself if you tend to be heavy handed? If so, take it to a machine shop. Sometimes those gear boxes are only available as units. $$$$$

 

[leonz]

Carbide drill bit, moderate heat and pray you don't break the EZ out. You need to ask yourself if you tend to be heavy handed? If so, take it to a machine shop. Sometimes those gear boxes are only available as units. $$$$$

===========================================================

Do as Irwin and Outlander have suggested as more than likely you will require the use of a drill with an electromagnet to secure the drill and magnetize it to
the underside of the mower deck to drill it out.

Then buy three Allen head caps screws and Allen head cap screw spring washers replacing the old ones from the machine shop and have them install them using blue loctite and a torque wrench.

No they will not tear up the lawn or the driveway and if they do the mower is too low!!!!!!!!!

It is easier to remove an Allen head cap screw bolt as it has more area to grip against-been there done that lots of dinged fingers and hands.

leonz

 

[savageactor7]

I gonna keep an eye on this cause I have a woods 72" 3ph mower whose middle spindle also disappears into a gear box.

Jesse do you have a woods mower?...if so I'll see if I can't find some manuals on it to give you a heads up.

For the rest of you next time you sharpen blades put some never-seize on those threads and you can avoid that problem. btw those are reverse threaded nuts that hold the blades on a woods mower.

More I think of it there's no easy way, flip the deck over, hose down broken bolt with PB blaster, go have dinner, come back with the right sized easy out and work at it. before leaving it hose with some more PB blaster.

 

[George2615]

Jesse,
I once broke off a mower blade bolt also. It broke off flush and at the time I did not have a good drill bit set or easy outs. I got it out by placing a nut on the broken bolt and welding the inside of the nut to the broken off bolt. Then after it cooled a little I used an impact gun on the nut and the broken off bolt unscrewed from the bearing assy. (a wrench on the nut hit with a hammer would also have worked). I think the heat from welding the nut on helped loosen it. By the way my bolt was standard right hand thread. Left (counter clockwise) to remove.

 

[B2400]

Check your hardware store for left hand twist drill bits. Another thing to try would be drill a shallow hole into broken bolt and try the Craftsmen stripped screw head remover bits. I've had luck with them lately on some bolts I thought would never come out!

 

[Volfandt]

I have an older BX23 w/60" MMM. I have had the blades off many times. They are not reverse threaded. Unless Kubota has changed the spindles they should be Righty tighty, lefty loosey.

The gearbox is rebuildable and you can order a new spindle should all else fail. I recall a post from long ago about someone else having a similar problem and he ended up buying the entire gearbox, seems it came out cheaper for him.
Good luck

 

[cdcole]

I broke one off once. I removed the entire spindle from the mower deck then locked it down in a vice beneath a drill press. I drilled a hole straight down the center but it slid to one side taking about 20% of the threads with it. This was almost a blessing in disguise as I then could use a small cold chisel to collapse the remnants of the bolt to the center then piece by piece I got it out with the last part spinning out while clenched to a vice grip. I tried the same trick for my neighbor but his bolt was too hard and I busted bits and they slid off the bolt to the softer shaft material. Good luck.

 

[jesseb3@att.net]

Thanks for all the suggestions guys. We've run the gamut of ideas, including welding a nut on it. I told my buddy that I had heard of someone, somewhere, doing that. Obviously it was here, and probably straight from George2615. We're both a bit embarassed that neither one of us owns a welder... we seem to have everything else!

For what it's worth, they're not left-handed threads on this deck, so we could use a standard Easy out. However, we've chickened out - it's being dropped of at a machinist's shop this evening. The guy is good, and he's a friend of my buddy, so for the price, it's just not worth risking further damage by the two of us.

In the background, I've got a line on a place that sells all the deck parts, and I'm inquiring as to what they get for a new box.

 

[proconnor]

we drilled it out and used an easy out and it would not budge with a 1/2 impact driver. we are going to bore it out with a milling machine and take it from there

 

[leonz]

we drilled it out and used an easy out and it would not budge with a 1/2 impact driver. we are going to bore it out with a milling machine and take it from there

=========================================================



If you have not done it already try assaulting it with a carbon dixide extinguisher-outside in the open air of course to shrink the broken stud first and then try to extract it.




leonz

 

[jesseb3@att.net]

Leonz,

It's in the hands of the machinist now, but that's a "cool" idea. Sorry, couldn't help myself.

We use freeze spray at work to troubleshoot electronics. Wish I would've thought of that, just to try it! With the nozzle, you could direct the spray right into the hole that was drilled into it. Much safer, and cheaper than a fire extinguisher too. And wow does it get cold!

Jesse

 

[jesseb3@att.net]

Well, this has been resolved. My buddy "proconnor", who also posted to this thread, got a machinist involved. After the easy out failed to extract the bolt, the machinist milled out the bolt as close to the threads as possible.

I guess he crumpled in some of the remaining bolt, and then used a tap to to remove the rest of the thread that was left. From what I understand, it's good as new - no damage to the original shaft threads.

The machinist, who builds custom hydraulic cylinders for equipment, says that he recommends pure silicon caulk for bolts. I'm going to remove my blade bolts, and make sure that I coat them so that I don't run into issues.

I found that the shaft would have cost $110 alone, not including the effort to rebuild the gearbox.

The machinist was a friend of proconnor's, so he got away with a cheap repair.

Jesse

 

[savageactor7]

Well that's good to hear for you that everything is fixed.

 

[dodge man]

Yeah, my experience with easy outs isn't good. If a bolt is broken off due to some kind of impact breaking it off, they work great. Most of the time bolt is broken off because it's rusted in place. In this case, the easy out usually ends up broken in the hole.

 

[have_blue]

we drilled it out and used an easy out and it would not budge with a 1/2 impact driver. we are going to bore it out with a milling machine and take it from there

I've had good luck simply drilling out the bolt with a left hand drill. When most of the core is drilled out, it relieves some of the pressure, and the heat and vibration from the drill usually causes the bolt to back out on its own. A little liquid wrench-type stuff also helps a little. If the bolt is grade 8, sometimes you can spot drill a dimple on the side of the bolt and tap it CCW with a hammer and center punch.