Straightening a bent axle.

I bought a used wheel but now discovered that the axle is bent. Can bent axles be straightened satisfactorily?

I can sometimes straighten bolts just by banging them with a sledge hammer.

How does one go about bending their axle in the 1st place?

The alternative is replacing the axle. Consequently, it looks to me like you have nothing to lose by trying to straighten the axle without boogering the threads. I've not been successful in doing that to my satisfaction but maybe I just haven't tried hard enough.

What kind of rear hub? In the days of freewheels, bent and broken rear axles were semi-common because the right side bearing was located so far toward the middle of the hub. Cassette hubs are much better in that regard.

I'm working on a '70s era Schwinn 10-speed. The wheels have cassettes attached. Last night my wheel saw it's last ride and I bought a used wheel with a bent axle, so I used my axle on the new wheel. It's not a great match and I would love to use the correct axle and cones.

Maybe if I remove the nuts and cones and support the threads with wood, then maybe a smack with the sledge at just the right spot would do the trick.

before I swapped the axles last night I tested the roll of this defective wheel and it didn't look too bad ...

I think even if you got it straightened to the point where it looks fine to the naked eye, the bearing balls would be rolling on an uneven surface and wear much quicker as a result. I would go dig through the local vintage-friendly bike shop's junk bin for a new one. I know, such a thing is rare nowadays but I have faith in Boston...

The best way to straighten it would be in a large bench vise with 3 small blocks of wood. Roll it on a flat surface to check it after, or spin it in a drill press or lathe.

How do you position the 3 blocks of wood?

Try using multiple nuts on the axle to protect the threads. Use a large wrench or pipe to slowly bend the axle back, checking often. Take your time.

Well, I would position the axle between the jaws so the bend is visible when looking down on it and place one block at the "peak" of the bend and the other two on the opposite side near the ends of the axle. You would need at least 3 hands, a helper, or be creative. Of course, if you screw nuts on the ends all the way to the inner ends of the threads, you can use just one block on the opposite side and need only 2 hands.

OK, thanks I got it.

You will never solve it. Eventually you will have to replace the hub. Take it to the shop, follow their recommendation. Way less headache in the end. Actually, you should ask them first.

kellyjdrummer - Thanks. You are right of course. Last night I swapped in another axle but it wasn't the same brand, and when i got to work after my 17 mile commute it was loose. Went to the local shop where I work and they are looking at it now. They think they can supply a used or new axle. We'll see. They said the old bent axle that I carried with me was too far gone and some of the nuts were also trashed. This is a wheel I bought used last night because my regular wheel was toast. I should just buy new wheels or a new bike ...

I started building bikes before "Sting Rays" were around. I've tried everything at least once.

I used OLDYELLR's technique to successfully straighten my bent rear axle. Sure, it's not perfect, but it's straighter than it was. After locking down my cone nuts, it spins smoothly and the axle doesn't wobble as it did before.

Brass hammer its softer than steel ... saves the threads/.. heavy steel table top.

99% of the damaged parts I've come across never make it back onto any bike. It just isn't worth the aggravation, and once replaced the old part is never needed again. A bent axle just isn't worth it. It'll never ride right even if it appears to have been straightened. It would be the LAST part I'd try to use that way, and 2nd to last would be a bent BB. Getting a hub just right is a fairly precise adjustment with a straight axle, how could you ever achieve that precision when you don't know how straight yours is.

In my case, I didn't even know my axle was bent until I went to repack my bearings. So, my bent axle was somehow not causing me any noticeable problems. After straightening it somewhat, it still seems fine. With my quick release clamped down, there's no play in the hub and it spins freely enough for me. If I remove my chain from my freewheel, and use my hand to spin my wheel, it will spin on its own for 75 seconds.

I'm not sure I've actually improved anything functionally, but the axle looks much straighter than it did.

Also, I don't care very much about the hub. It was used and cheap and it has had a long life. If riding with a slightly bent axle is going to shorten its life, that's fine with me.