Thread: Motor shafts.

Are motor shafts, hydraulic rams etc any good for turning?

Some are.. A lot of modern ones are induction hardened... I got given a heap of CV axles and such from a mechanic... All seem to have been induction hardened... if you can anneal them, all good...

Ive machined a couple of motor shafts. Didnt seem to be anything more than maybe 1045 duraflex. I have an axle from an old coma im yet to make a pin out of. Yet to see about that.

Guess it depends on make and intended use.

Simon

How hot would you have to heat them to anneal them?

I have an old eclectic oven in shed.

Or could chuck in the BBQ, Wood barbie that is.

Just trying to build up a stock of steel, TC prices make you think you are buying gold.

I think you have to get them above currie point, though someone might be able to correct me. Thats usually quite a lot higher than your average BBQ will manage, up around 1000°C. If you can find a spec sheet on the likely sort of metal youre dealing with, then it usually contains that sort of information. I find the interlloy datasheets to be really handy.

Originally Posted by scottyd

I think you have to get them above currie point, though someone might be able to correct me. Thats usually quite a lot higher than your average BBQ will manage, up around 1000°C. If you can find a spec sheet on the likely sort of metal youre dealing with, then it usually contains that sort of information. I find the interlloy datasheets to be really handy.

Thanks, looking on Interlloy site
1020 carbon steel bar is used for shafts.
Heat to 870 oC - 910 oC hold until temperature is uniform throughout the section, and cool in furnace.

Originally Posted by scottyd

I think you have to get them above currie point,

That must be some hot indian curry to get to the temperatures required..

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The annealing temperature for 4140 is 850C, hold until uniform then slow cool...

To harden, heat to 850C then quickly cool to stop the steel transforming as the temperature lowers...

Originally Posted by wm460

Thanks, looking on Interlloy site
1020 carbon steel bar is used for shafts.
Heat to 870 oC - 910 oC hold until temperature is uniform throughout the section, and cool in furnace.

You cannot really harden 1020 through heating and quick cooling... Not enough carbon in it... You need carbon to harden steel... 1020 can be case hardened though...

Of course what it not mentioned is when you heat steels to those temperatures in the presence of oxygen, the outer surface will readily oxidise.. That is why when heat treating you either go for an inert atmosphere in the furnace, or you wrap up your part in something like stainless steel foil...

Originally Posted by .RC.

That must be some hot indian curry to get to the temperatures required..

The problem is that your...er...blowtorch has to be able to survive those temps after youve had the curry.

I was wrong by the by, its not the Curie temperature thats required for annealing, its called the recrystalisation temperature. RC is right though, youre gunna have to protect it to stop the outside from turning bad. Personally, I think youre on a hiding to nothing with the driveshafts, the costs of 4140 in that size arnt too bad given the more consistant properties youll get from new stock over recycling mystery metals. Im not sure how nitriding affects the annealing process either, some driveshafts could well have been hardened via that method.

Originally Posted by .RC.

That must be some hot indian curry to get to the temperatures required..

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The annealing temperature for 4140 is 850C, hold until uniform then slow cool...

To harden, heat to 850C then quickly cool to stop the steel transforming as the temperature lowers...

I like hot Indian curries but not that hot

I guess it will be easier to dump what I have collected up and give some more room under my bench.

Before you dump them, try turning a bit of it to see how they turn, they could turn OK or not. The chrome on the rams might take a bit to get through though. No point in dumping them if it's usable.

Just changing the subject slightly....I have a couple of cast iron flywheels out of Mini Minors and they look like
they could make good faceplates. I've been told they would need normalizing or some term like that which would
require heating.
How would I go about this?

In a basic way, the grains of metal will have been distorted from being used as a clutch, which can affect their hardness and how brittle they can be. Normalisation is aimed at getting a more uniform grain structure, both shape and size. It does usually result in some annealing, though not always, and in some instances it can change the grain composition if the particular alloy allows. The process is basically the same, heat up and allow to air cool usually. Annealing is usually done as slowly as possible to allow for maximum softness, whereas normalisation is more focused on grain structure.