Offset machining work

Bouledogue · 2026-03-17T08:33:26+0000

Agroshield said:
The centre is needed both ends. Making sure the two offset centres are in an identical clock position needs thinking about.

The design of the offset sleeve would need some thought - what is the minimum amount of material on the 'thin' side and thus minimum diameter? How does it fix to the bar? It would need to be close to seamless where the steady fingers run so might have to be made in two halves clamped together and machined as one (slitting afterwards would leave a kerf to bump the steady fingers).

I agree. The sleeve would be a fun (or miserable, depending on one's outlook) project all of its own.

Or get the centres on the mill, as @Jacktegla suggests. If the mill isn't large enough to do them in one set-up, it'd need to be fixtured so that the bar can't rotate when being flipped. Or machine flats to allow you to re-index it.

Bouledogue · 2026-03-17T08:34:00+0000

Just overlapped with @Pete. re flats.

Jacktegla · 2026-03-17T10:15:01+0000

Bouledogue said:
Why not make a 1/4 scale version on your Colchester Mastiff (and suitable small mill) after work as a learning exercise. Then perhaps approach the machinist again to discuss it. Or, you might decide that he was right all along and the job is a complete nuisance?

Either way, don't embarrass him.

Ahh I wouldn't embarras him, they're big boys and worked in this industry a long time its more the fact I think theyre dragging they're feet on it, definitely a nuance im sure

Oh ive got more than enough to be playing with than practicing ill hopefully end up doing a real thing at osmepoint.

Jacktegla · 2026-03-17T10:17:55+0000

Pete. said:
Aligning the centres is a piece of cake. Stick it in the mill and mill a flat on top. Spot your two centres one end with the head turned 90 degrees then flip the bar around, clamp it down amd put a sensitive level on the flat you milled earlier. Spot your two centres the other end (and make sure you go the correct direction).

Turning 100kg offset 40mm you're gonna want a huge lathe or turn it very slowly.

I think both haha, my i had slight disagreement with my boss over it all and thr best way to understand why, comes from the statement he said to me " I value the machinist 30 years experience more, you wouldn't know how we do it .... we don't have a machine capable of spinning it at the 2000rpm" i may have laughed when he said last bit