Hardening mild steel...

[nigelmercier]

I've decided to have a go at refurbishing the seized motors on two Jabsco Electric Conversion kits...

Sizes are approximate ...

I need to pull a 30mm OD bearing off an 8mm shaft. There is only 2mm clearance behind the bearing, so no room to get my puller jaws in. I've made a 2mm mild steel, 50mm diameter M10 washer with a 10mm slot to the edge, forming a C shape, the hole is 10mm to clear a circlip behind the bearing.

I can slot the C-washer behind the bearing, and put the puller jaws on the circumference. However, I'm pretty sure that as soon as I apply any pressure, the steel is going to bend.

As a metalwork numpty, what do I do to the steel to stop it bending?

 

[DinghyMan]

Buy a bearing puller that includes a proper plate? http://www.amazon.co.uk/Jago-LAAZ01...id=1403025448&sr=8-15&keywords=bearing+puller

2mm mild steel will bend very easily

 

[Border Terrier]

Try viagra?

 

[Hypocacculus]

Nothing. You can't harden mild steel.

 

[TQA]

Bolt a joiner across the open part of the C and just start pulling. The plate will bend but you should still get it to pull the bearing off.

If not rent or buy one of these http://www.bennetts.com/sykes-pullers-and-separators/sykes-pickavant-09500000-wheel-bearing-separator-10-55mm-2212942-417962-828504.php

 

[pvb]

Just as total thread drift, why do you want/need electric toilets?? Just something else to go wrong, as you've apparently discovered.

 

[penfold]

Bolt a joiner across the open part of the C and just start pulling. The plate will bend but you should still get it to pull the bearing off.

If not rent or buy one of these http://www.bennetts.com/sykes-pullers-and-separators/sykes-pickavant-09500000-wheel-bearing-separator-10-55mm-2212942-417962-828504.php

This is the sensible answer; if possible find a bearing puller kit with the right extractor plate, which will be made of at least high carbon steel, perhaps even unhardened tool steel.

 

[Caer Urfa]

Nothing. You can't harden mild steel.

Oh yes you can!

Heat it up to red then quench it in engine oil

Mike

 

[superheat6k]

Put the shaft assy in the freezer for several hours or overnight.

Then with a turbo torch or possibly a hot air paint stripper rapidly heat the bearing, with the end of the shaft downwards, held from above, but avoid the heat getting into the shaft. The idea is to heat the bearing to above 110C without the shaft getting too warm, when the bearing is hot tap it downward if necessary using a hefty screw driver as a pry bar and off it (might) come. 110C is the temp a bearing heater operates at to install a new bearing by the same principle.

 

[30boat]

Nothing. You can't harden mild steel.

You can.What you can't do is toughen it.

 

[30boat]

Oh yes you can!

Heat it up to red then quench it in engine oil

Mike

It'll do nothing for mild steel.

 

[prof pat pending]

Agreed, the only option with mild steel is case hardening

 

[Pagetslady]

you could case harden mild steel when I was a lad,

Nothing. You can't harden mild steel.

when I was a lad many years ago we used to case harden mild steel but that would not help in this case.

 

[Pagetslady]

Oh yes you can!

Heat it up to red then quench it in engine oil

Mike

I dont think so it needs some carbon in it first

 

[Heckler]

Nothing. You can't harden mild steel.

Sorry but you can! Basic schoolboy stuff, Casenite. http://bbs.homeshopmachinist.net/archive/index.php/t-34377.html
I was in my local grammar school, proper metalwork master, making a spanner out of mild steel, used casenite in a forge.
Stu

 

[Heckler]

I dont think so it needs some carbon in it first

Oil, a hydrocarbon, get it hot and it carbonises, carbon and mild steel basically lo carbon steel, equals hard!
Stu

 

[prof pat pending]

Oil, a hydrocarbon, get it hot and it carbonises, carbon and mild steel basically lo carbon steel, equals hard!
Stu

Sorry, it'll do nothing for it

 

[prof pat pending]

when I was a lad many years ago we used to case harden mild steel but that would not help in this case.

It's only 2mm thick.
Depth of the case will depend on how hot you get it, and how long you leave there

 

[Hypocacculus]

Oh yes you can!

Heat it up to red then quench it in engine oil

Mike

Er, no you can't. That's why it's called mild steel. If you want to harden steel, it has to have a certain percentage of carbon in it. This is called, (wait for it...) "carbon steel". There are many different sorts; arguably the most user friendly for amateur use is silver steel which can be hardened and tempered quite simply. If you heat such a steel to cherry red and quench it in oil, you will indeed harden it but it will be brittle. So you then have to temper it, by heating again to a certain temperature (depending on the amount of temper you want) and cooling slowly. This makes it slightly less hard but much tougher.

As for case hardening, it is a surface effect. Useful if you are trying to make an anvil; useless for stopping a small washer bending.

 

[PuffTheMagicDragon]

Sorry but you can! Basic schoolboy stuff, Casenite. http://bbs.homeshopmachinist.net/archive/index.php/t-34377.html
I was in my local grammar school, proper metalwork master, making a spanner out of mild steel, used casenite in a forge.
Stu

What you were doing was a simple form of casehardening, nothing more. It is/was useful where one wished a surface to be somewhat wear-resistant. Casenit was simply an ancient method in 'modern' clothing, making it a less disagreeable process than it used to be. It replaced the age-old method of placing the mild steel object inside an iron tube that was filled with such things as crushed bones, hooves and other similar carbon rich material. The tube was then sealed and then placed in a forge until the whole thing was glowing orange-red and then left to 'soak' at that temperature for several hours. Inside there was no oxygen and so the MS object could 'absorb' some of the carbon into its surface. Quenching would fix this carbon in the metal surface.