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rmcphearson
03-19-2009, 08:51 PM
I had a spindle nut come off of one of my large mowers today. The hub/wheel fell off and mangled the spindle threads in the process. I found another nut and made a die so I could clean the threads up, put another nut back on to get the machine back to the shop. We heated the nut red, then dipped in water, then cut a slot in it to expand it over the mangled threads. We also cut a couple grooves across the threads of the die. It worked good enough, but was there a better way I could have done this? This had to be done in 2 hours, so "get the proper die" responses will not be welcome. Usually I would pick the machine up with a tractor, but they were tied up doing other things today.

Roland

knedvecki
03-19-2009, 09:54 PM
It is hard to tell what you ended up with. The proper method would have been: 1.) Measure the thread diameter(Major) to see if it was within limits for a Class 3 fit per Machinerys Handbook or other reputable source. 2.) If salvageable, Use a thread file of the proper pitch or a triangle file to dress up the threads with a thread gage or a substitute of a bolt of the same thread to compare and a new, good nut as a go gage to verify fit. It is highly unlikely that all of the threads got boogered up, usually just the first few threads or a flat on one side. It really would not take any longer to do it this way than your improvised method. If there is not enough thread material left to meet the thread specifations, then it will probably fail and possibly hurt someone when it comes of again. My $.02

Keith

Carld
03-19-2009, 09:55 PM
Sounds like you did it right. I have used nuts to make into a die and hardened them with Kasnite. It's a one time die but I saved some of them.

bollie7
03-19-2009, 09:56 PM
It worked good enough,

Roland

Roland, desperate men do desperate things, I reckon you have answered your own question. I would have done (in fact, have done)almost exactly as you have described to get a bit of machinery back in service in a hurry.

regards
bollie7

bob ward
03-19-2009, 10:05 PM
A 'proper' die may not do the trick anyway, not if you have to start on badly mangled threads and have it mate cleanly with the good threads.

What you have done is a good fix, and once the threads are tidied up then maybe use a 'proper' die when time permits.

You used to be able to buy, I don't know if you still can, split dies about 2" square, with the appropriate holder. You could clamp them on the good threads and wind them back out over the damaged threads.

rmcphearson
03-19-2009, 10:21 PM
I have used nuts to make into a die and hardened them with Kasnite. It's a one time die but I saved some of them.

That's what I was getting at. How to harden a nut. I'll look into the Kasnite. Keith makes a good point about safety. Only the threads on the end were mangled. Even a proper die may not have started correctly. The threads further back were the nut gets tight were ok. I will get the correct die and clean them up better.

thanks,
Roland

J Tiers
03-19-2009, 11:51 PM
You DO know there are actual re-threading dies, right?

Basically they are similar to your manufactured die, only purpose made. Like the bottom one in this picture.

it's a problem if the end threads are too gnarled to get any sort of die onto.... Then there is a clamp-on type of re-threader.

Both types, AND thread files, are really good to have whenever you have machinery maintenance to do. else-wise lots of wasted time happens.

You do what you gotta.

http://img.photobucket.com/albums/0803/jstanley/dies.jpg
http://img.photobucket.com/albums/0803/jstanley/re-thread.jpg

bob ward
03-20-2009, 01:54 AM
This is the type of split die that I referred to earlier. The set is a little neglected, it came from a farm auction a while ago.

Its for Whitworth threads 3/4 x 10, 5/8 x 11, 1/2 x 12, and 7/16 x 14 and made in Germany, labeled 'Arren's Goodline'

http://i237.photobucket.com/albums/ff28/sirrobertthegood/Splitdies.jpg

Your Old Dog
03-20-2009, 06:12 AM
I know hindsight don't count but just let me pose this.

Could a guy take a good nut, cut it in half and turn it in to a die, slip it on the bolt and then slip a socket over it to hold it together and then back it off? Would that have worked and maybe been faster and easier?

Thanks JTiers for the pic. I do a lot of flea markets and such and if I can find one of those I can use it to strong arm the local farmers for quart of maple syrup now and then!

Circlip
03-20-2009, 06:48 AM
Although an internal thread, I once rescued the threaded hub of a M/Cycle wheel with the use of a "Dremel" type tool with a 20 thou "Slitting" disc. By carefully angling the cutter horizontally you can get the cutter to touch both sides of the thread and the bottom. It does require a deft touch, but certainly saved trying to locate a tap of approx 50mm dia x 1mm pitch ???? on a Sunday morning to reclaim the bearing clamping ring.

Regards Ian.

wierdscience
03-20-2009, 08:43 AM
There is also such a thing as a thread file for straightening out threads before attempting to run a die nut on.

Be careful with those mower spindles though.I saw the result of a mower blade coming at speed once.Went through one wall of a house and stopped in another.

Carld
03-20-2009, 09:54 AM
When the thread on the very end of a shaft is buggered it's a waste of time to try to use a die on it to start and clean the thread. It will most often be cross theaded when it reaches the good threads. Splitting the nut and putting it on the good threads and working it off the end of the shaft is the way to go if you don't have the factory type thread chasers. Not everyone can afford them just laying around waiting for a chance to use them.

I have cleaned a lot of threads by splitting a nut, sawing cuts in the thread and then hardening it and clamping it on the shaft and working it back and forth to dress the damaged area. Then you can get a thread chaser to start on the end of the shaft without buggering it up worse.

You gotta use what you got. Or, as racers say, "run what ya brung".

camdigger
03-20-2009, 12:07 PM
For external threads, a thread file is my weapon of choice. They're available in multiple groove types about the size of 1/2" keystock with 8 different pitches on them. I've seen both SAE and ISO metric. I've also got a 60* single pitch file that looks like a straight flat file with the teeth along one edge.

I've seen thread restorers that have two guide teeth to engage what's left of the original threads and guide a cutting tool down the damaged thread. I'm not sure how well it works for the last thread on the end though (haven't tried mine yet)

Your Old Dog
03-20-2009, 01:13 PM
There may be a simpler way now that I think on it. Don't think of the shaft with the messed up threads as glass but think of it as hard putty. Now with that mind thought, make a conventional cold chisel with a 60 degree face on it. Drop the V in the first good thread past the damated thread and lightly pean it all away around. In a few minutes you should have "bent" or "displaced" all the major thread back from whence it came ! I do something similar to repair screw heads on gun screws. I light pean the buggerd up areas back down to a clean head and then refile the slot and it works perfect everytime.

rmcphearson
03-20-2009, 02:07 PM
Could a guy take a good nut, cut it in half and turn it in to a die, slip it on the bolt and then slip a socket over it to hold it together and then back it off? Would that have worked and maybe been faster and easier?

That's basically what I did. Only one slot was needed to expand the die. I have thread files and a multihole fine pitch chaser (nutcracker) like the pic, but the pitch was not the same. It actually worked fine, but I was curious if I did any good at all heating the nut and quenching it in water. I was just guessing that that would harden it.:confused:

Roland

bob ward
03-20-2009, 08:52 PM
... but I was curious if I did any good at all heating the nut and quenching it in water. I was just guessing that that would harden it.:confused:

Roland

That's a bit of a lottery and depends on the composition of the steel of the nut, most probably the nut you used didn't harden much if at all.

One thought is that if it had, cutting spreading and clamping the nut onto the axle would have been a lot tougher to do.

But then the fall back position would be to cut a nut in 2 per YOD's post and then harden.