Thanks for the suggestions guys. Gives me plenty look at and I'm getting a clearer picture of what I'll be needing to do the parts I want.

The suggestion to DIY from scratch isn't feasible for me. Even converting an old lathe would be a big commitment in time and I wouldn't want to stretch any further than that. I'm definitely more interested in making parts than what makes the parts.

Seems that 70mm bore is indeed quite ambitious so I'll likely have to scale back the size of the parts to 50mm which seems more doable.

I'm not in a position to buy yet so I'm window shopping at the moment trying to get as much info as I can so I don't end up buying shite that doesn't do what I want.

Would these be able to handle what I have in mind?

Harrison 140 Gap Bed Centre Lathe , Very good condition | eBay

HARRISON M300 CENTRE LATHE WITH DRO £2250+ VAT | eBay

Problem is the 3 phase electrics, I could buy an inverter but you need a beefy 230v supply to start with and I'm not sure a 16amp socket will handle it.

I might be happier with an easy life and go straight with a 230v model which would likely mean waiting around for something on ebay or maybe buying new.

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Buy Axminster CQ6230A-2/910 Metal Turning Lathe from Axminster, fast delivery for the UK