Hardening mild steel...

[Hypocacculus]

No can do, the surface behind the bearing is the commutator: too fragile.

I'm going to give it a try, but I will cut down the C-washer diameter in 3 places so the jaws of the puller are as close as possible to the commutator, this should reduce the bending moment.

If that fails, and you have the wherewithal to cut the steel, then you could try finding a piece of Gauge Plate. This can be bought in relatively small pieces. It is a really tough carbon steel and relatively easy to get hold of from model engineering suppliers. It might even be strong enough to do the job unhardened. You can harden it using the heat to red and quench in oil method. Then you must clean at least part of the surface so that it is shiny and free of grease. Heat it again slowly (I do my bits sat on a piece of brass on the gas stove) until you see the surface begin to change colour; it will go yellow first, then brown, then purple, then blue. Stop at blue. If you overshoot, then you have to do the hardening process again.

If you use a domestic gas stove, make sure it's clean first - otherwise bits of food and grease get very hot and cremated to the surface and really difficult to clean off which isn't great for domestic harmony. Guess how I know this...

 

[PuffTheMagicDragon]

Do you intend to re-use the same bearing? If you are going to replace it with a new one why not just split it with an angle grinder?

 

[nigelmercier]

It worked!

The brass thing is a puller guide I made on my new lathe, one end with a countersunk hole, the other fits the shaft.

 

[30boat]

Does the shaft have a thread on the end? If you are replacing the bearing, find a bit of tube with 30mm OD, tack weld it onto the bearing, washer over the end, few confangled nuts and washers and you can wind off the bearing. Its how we got inner bearings off Lambretta cranks.

Or, find a bit of steel plate, bore a 30mm hole in it, cut it into halves, clamp these around the bearing to get hold of it, then either tap tap tap the shaft or confound some threaded bar and nuts/wahsers to wind it off.

I was going to suggest tacking two small tangs on the bearing casing and using a two legged puller.

 

[30boat]

It worked!

The brass thing is a puller guide I made on my new lathe, one end with a countersunk hole, the other fits the shaft.

Great,good on you.

 

[Hypocacculus]

It worked!.

Brilliant! I hate threads withoug a resolution.

 

[NUTMEG]

With all due respect while I believe the events occured just as you state, you are unlikely to have been using mild steel; you will have been given carbon steel in an annealed, or soft state when it is indistinguishable from mild steel. Uneven heating and overheating is the most likely source of the cracking and it's not unusual to crack steel like this. Quenching in oil is not the same as case hardening.

It was nearly 40 years ago so you could very well be right!

 

[srp]

Cheers guys. This forum can be such a useful source of info!

True, but in this case many of the posts on heat treating steel are incorrect, so be careful which ones you take note of.