Cutting BMS Bar

[Smudger]

Hello all. Advice please. New to this hobby I have limited tools and machinery for making my model engine, I have a 50 mm diameter piece of steel 150 mm long and need to reduce its length to about 25 mm to make a flywheel. I have inherited a Chester conquest lathe, it has a 80 mm chuck but only internal Jaws. What would be the easiest way to cut to length and then mount it on the lathe so I can turn it down.
I’m not sure if manual hacksawing will work

[Pete49]

I would cut it with a hacksaw slightly longer than needed then face it square in the lathe.

[Jasonb]

Yep, hacksaw would be safest

Parting part way through near the chuck with tailstock support will probably be more than the lathe can handle so not worth trying.

[sco]

Will the 80mm chuck safely hold 50mm bar though?

I'd invest in a new chuck with both sets of jaws as will increase the versatility of the lathe for future jobs.

Simon.

[Vixen]

I think you will need a set of external jaws to safely hold a 50mm bar in a 80mm chuck, plus tailstock support.

Mike

[Ian S C]

I'd go with the hacksaw, cut a couple of mm over length, then face of in the lathe. I did a 6" one a couple of years back when the bandsaw was out of action, I did it in a number of sessions, over a few days with a new 18 tooth blade.  The lump of steel was a bit too long to fit the lathe.
Ian S C

[Pete49]

Forgot to add ... to safely hold it in the lathe to face it I would drill a centre hole smaller than the shaft size, cut the head off a bolt and fasten the steel between two nuts done up tight. For a facing cut it works well.