OT - How hot to expand enough...?

Kenneth wrote: ...

Are you sure you don't have any side torque?

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When it starts showing red, move the torch on around.

Do it as quickly as possible to get as little heat transfer to the shaft as possible. I usually fill it full of WD4O or another (relatively) non-volatile lubricant first. Seems to help some as it sizzles but won't start a big flame.

Have the pulling gear all set before start, of course, so doesn't just cool back down. Good would be if have an extra hand who can apply the tension or can arrange where you can do it together--then when it begins to move you don't need to keep on heating...

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Hi again,

Please see my comments inline...

I can't be positive, but I do not think so. I have moved it both ways several times and each time it hangs at (roughly) the same point. I doubt that I would have it twisted at the same point each time.

I am astounded that I would want it that hot, but am happy to give it a shot. Right now, the thing is one very heavy paperweight.

Thanks for the speedy response, and the great suggestions,

WD-40 is NOT a lubricant.

WD-40 is NOT anywheres near "non volatile" basically kerosene, it burns quite well.

It flashes w/ the torch and works quite nicely for the purpose...

I never said anything other than it works as a wetting agent and tends to (it appears from many trials) to help in getting dirt out of ag splines like the aforementioned PTO shaft subject thread. It's not for any long term lubrication for the application.

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On 2/20/2009 5:06 PM dpb spake thus:

IANAM*, but I'm pretty sure that red-hot is too hot. I think you'd basically be annealing a hardened steel part, which is probably not what a guy would want to do.

• I am not a metallurgist.

I told him when it starts red, move...

If he's got some tension on it, it'll move before then.

The casting won't be particularly hardened; it'll be all right as long as he doesn't go overboard.

I've done many, most on combine header shafts that "grow on".

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Why won't the last 1/2 inch come off? Is it getting tighter, or are you just out of removal leverage.

Metal can change when heated especially heat treated parts.

Do not make the yoke glow at all. Your best bet is to have your pulling device ready and heat the part as fast as you can so that the shaft stays cooler. No need to go above 600 degrees.

Hi again,

It appears that the last part of the shaft is rusted, and with that, yes, as I move the yoke off, it does appear to be getting "tighter." It is not a leverage issue.

You suggest not going higher than 600 degrees, but...

How might I know when I am somewhere near that temperature?

Thanks for any further thoughts,

Hi again,

It would be impossible to describe the problem verbally, but there is no way to use a puller. Earlier today, when I was away from the machine, I thought that it might work. I headed back to my shop, grabbed a puller, and took it to the blower. It was immediately clear that it could not work. I just can't get any pressure to the shaft because the yoke of the universal is in the way.

Thanks for any further thoughts,

When doing this one usually uses a rose-bud torch so that the part can be heated quickly. Just keep the part from getting hot enough to glow and you should be ok.

If it won't move use bees wax and let it flow into the tight spot through capillary action. Return the yoke to its original position and use more bees wax. Try again.

Hmmm, bees wax?

I've not heard of that use before...

I assume that you are suggesting that I apply it when the parts are hot, so that it can flow. Interesting.

Thanks,

I saw a History Channel show on locomotives. In the show, they demonstrated how they changed the tires on railroad cars (yes, they do have tires). They heated the sucker up until the tire expanded and it popped right off. Then they took a new (and hot) tire, pounded it on the wheel, and let the thing cool.

So, I suppose heating the object - whether a yoke or a railroad rim - is sufficient.

This is my favorite trick, heat it up with a torch not too hot then apply candle wax to the joint. Hot candle wax is a very good penetrating lubricant. Works for rusty nuts and bolts and problems like the OP has.

Jimmie

Hi again,

Any hints about what "not too hot" might mean?

Thanks,

Have you tried hammering the u-joint back on as far as it will go and sanding off the rust n the outer section that is binding? That and some 90 weight lube oil might let it slide off. Gear oils are exceptionally slippery which is why they are used in auto final drives and such. Use a brass drift on the u-joint to avoid damaging it. HTH

Joe

I anneal before no man.

I think you're right.

I have never done anything like this, but I think it might not take much. For one thing, I think the heat might weaken the crud in btween the two pieces. Can't you try it with moderate heat, and if that doesn't work, let it all cool and start again in an hour. It s cold out, right. Should cool quicker than that.

Hit the whole thing with a hammer, to try to break up that crud. Even rust should break up some, if that's what you think it is.

Hit it also while youre trying to separate it.

Not on the bearings of course. IIUC it's binding beween a shaft and a sleeve.

Wear safety googles in case the hammer shatters. I hear they do that.

Hi Joe,

That is another good idea, and I would take that approach.

But when I hammer the yoke back on (as I have done a few times) virtually none of the shaft sticks out in front, so there is nothing available to sand.

I had tried it for another reason:

I knew that nothing would be available to sand, but I thought that simply sliding the yoke back on would abrade the surface of the shaft helping the situation.

Each time I did that, things did get a little better in that I was able to move the yoke off further.

I guess that I will have to try that a few more times, but it has been very slow work.

Thanks,

Any way you can rig something onto the business end of a slide hammer to bop it off with?

You didn't describe the universal joint in detail, but if it's still all assembled I'd be leary about using heat because of possible damage to the bearings or other parts of the U-joint.

Jeff