I have a disk of aluminium alloy, thickness 8 mm, OD approx 70 mm, with a 25 mm hole in the centre. I need to turn this down to OD 50mm.
Can anyone suggest a good way to do this in a mini lathe (a Sieg C2A), please?
(In searching I found this which may not be the way to do it but looked interesting anyway)
I don't know the C2A, but on my C3 the inmost section of the three-jaw will fit into a 25mm hole... surely it can't be that easy?
-- Peter Fairbrother
You could do it that way but you've got a lot of metal to remove.
I would mount a piece of say 2" bar in the lathe chuck, turn it down to give a short spigot 25mm diameter to a good fit in your centre hole and say 6mm long, then drill and tap for a bolt. Without removing it from the chuck, mount the work and hold it in place with a bolt and a big washer then turn away - guaranteed concentricity of rim and hole and a good solid grip.
Will the inside jaws go in the 25mm hole?
Or turn up a mandrel from say 30mm or larger stock with a 25mm dia section
7.5mm long, drill and tap the centre, bolt and washer to hold the disk on and go for it.25mm bolt and a nut.
Depends what you have lying around and how accurate you need it to be.
Andy
Yes, it is! They will go down to around 18mm. Thanks for prompting me to check!
Sorry: I meant 23mm. About 1mm clearance all round in the case of my disk.
In article , Norman Billingham writes
A much posher version of Norman's suggestion, for more than a one-off- task, might be:
John
I would remove the chuck jaws completely and use a piece of rubber sheet between the chuck body and the work to provide the friction and plenty of support.
John
Have something to add? Share your thoughts — no account required.
Ask the community — no account required