Why cant you use a between centres boring bar and just swap it around after boring the first one….? You may need 'handed' cutters to do it? Obviously the boring bar needs to fit through the existing holes in the casting but needs to be rigid enough not to distort..( or is that bend? )

I think I know how I would do it, but difficult to describe in words….

Edited By John Rudd on 01/05/2017 15:43:33

Edited By John Rudd on 01/05/2017 15:45:28

Yes, as John says – between centres seems the way to go with this.

As a suggestion, I might make a special b/c boring bar – the actual 'bar' obviously being slightly smaller than the smallest diameter hole it has to fit through but then I'd add a 'tool holder' (just a piece of round mild steel bored to fit the bar) and Locited to it. This would then hold the actual cutting tool. Maybe overkill but it would mean that I didn't have to drill the actual bar, the tool itself would not be over-extended and I could clamp/adjust it a bit more securely & simply. The tool will need to be slanted to reach beyond the holder and a round HSS tool bit driven out by a (smaller diameter) screw makes for easier adjustment…clearly the work not being moved until both ends are machined​.

I'm afraid that I do tend to over complicate things (most of my work is one-off – so it's a learning thing) and that might well be the case here but sometimes extra care can be worth the effort. Anyway – just a thought and good luck.

Regards,

IanT

Stick it on the saddle and use a between centres boring bar, they used to do con rods that way, Drummonds even had a special attachment to help you get the rods straight

Going to be fun setting things up though….. you only really get one good shot at it

Edit: I would probbly rebuild the headstock with the spindle and then set it up between centres on the saddle

Then dismantle and bore

GL

Edited By Ady1 on 02/05/2017 00:25:37

You've got to rub it in

Neil