Another Metal Selection Question

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rake60

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A couple weeks ago the maintenance guys at work brought me a worn out traveling key
and a length of 1/2" square 360 brass. They asked me to make a replacement key from
that material. A week later they brought the worn out brass key back to me and asked for
4 more of them.

OK, let's take a look at this application.
The traveling key slides up and down in the keyway of a shaft to keep it from rotating.
It needs to be softer than the shaft's keyway, so it will not cause any damage to it, but
strong enough to not wear out in a week. Is is a sacrificial part that is expected to wear.

After considering several materials, I decided to try 12L14 steel.

Keys.jpg


It's soft enough to wear without damaging the shaft but I have no idea how long it may last.

Any input would be appreciated!

Rick
 
Hi Rick

What's the shaft made of should be the first question I guess

Regards Mark
 
The shaft is hard chromed.

The original key was standard spring steel key stock, but it was scoring the
sides of the keyway.

Rick
 
This is going way out on a limb, and bear in mind that the instance to which I am referring was a very low torque situation, but I once used a piece of UHMW nylon as a sliding key. The keyway needed some work to remove burrs, etc., but once the key slot was cleaned up, the UHMW worked quite well. It did not bind or gall, and it lasted a long, long time. We tried it on a whim and it far exceeded our expectations in that case. Judging from the rapid wear showing on your brass key, UHMW wouldn't stand a chance in your case.
 
Would a half inch ball race at ninety degrees on the end of the key work ?
 
I hadn't considered non-metallic options.

Years ago I used to machine a phenolic material that was reinforced with a canvas fiber regularly at work.

It was designed to be a dielectric material with high wear resistance.
It may be the perfect solution.

Thanks for all of your input! :bow:

Rick
 
Looking at the way the key is worn, the appears to be quite some load on that key. plastic would not last if brass wore out in a week. While you Don,t want to wear the shaft, consider this a 1/2" brass against what length travel on the shaft, 12", 2' I Don,t know what that dimension is, but I would go with a hardened and ground finish steel key. the wear issue is proven by the steel key that was designed into the machine. That shaft is likely hardened, to have little wear after wearing out both steel and brass keys.
 

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