Henry motor

[conny]

We used to have air driven circular grinding discs for undercutting large armatures. They came in different thicknesses, (only about 20mm diameter), but most blokes hated them. One slip and the comm would need to be re-skimmed or, worst case scenario, actually replaced which could be a very, very expensive slip. Us old hands preferred the steady, patient method of using the hand saws. For bigger comms we used a longer blade.

 

[SUNRAY]

For what it's worth our blades had the teeth facing the other way so worked on the back stroke.
Something a bit like this with approximate sizes:

Remembered from 1980 when I used them last. I always assumed to give reach into cage to avoid too much disassembly. The blade then fitted into a slot in the holder, very similar cranked shape of yours.

Edit: I only got to deal with smaller motors in those days, in more recent times it's been controlling them rather than maintaining.

 

[conny]

Some of the lads I worked with used to back cut but I was taught to do it forwards and couldn't get out the habit. Last worked on AC motors about 5-6 years ago. Medium sized DC about 10-12 years ago. Last large DC in 2012 when I had been seconded to our Chesterfield branch to help them out. Ostensibly for 2 weeks but ended up there for 3 months working on these beasts. Second pic is complete re-bar of the squirrel cage rotor, (can't remember the kW size but probably near the 1,000 mark). I was operating the cranes. That armature certainly doesn't belong with that AC stator. LOL