Using parting tool on the face

[Dan Rowe]

If the important part is to save most of the center disk then a combination approach could be used. I am not sure how wide your trepan tool is but you could trepan say 7mm from both sides leaving 6mm in the center. Then use a drill the same width as the trepan tool to chain drill. It will be a simple operation to chisel the webs between the holes if they were spaced as close as possible.

Dan

[steamer]

If your going to do it anyway....put some NEGATIVE top rake on the tool so it is less likely to grab when it goes through

LOCK EVERYTHING exept 1 axis that is feeding the tool.

Make sure your spindle bearings and gibs are properly adjusted

Wear you safety glasses....and keep everyone else away from it

Go slow.   

Minimum tool overhang.

Treppaning on a home shop lathe...of unknown condition can be very dangerous.   Please consider every other way to do it before you settle on it.......and even then ....maybe think about it some more.

Dave

[Dan Rowe]

Dave,
Yes all good points and as John said it is WHITE KNUCKLE machining.
I have a real nice set of Starrett hole saws, and it would be cheaper to buy a good hole saw than repair any damage to the machine or operator.

Dan

[mklotz]

I'm with the others who have advised you against trepanning.

Do you (or perhaps a nearby fellow machinist) have a mill with a rotary table?  That's a very safe alternative for what you want - saves the slug and leaves a nicely finished hole that will require little or no finish machining.

[sco]

Yep I'm ditching the treppaning idea and don't have a rotary table so hole will just be bored out.  I'm going to cut some radial slits to make the swarf less troublesome.

Cheers for all advice,

Simon.

[steamer]

I'm with the others who have advised you against trepanning.

Do you (or perhaps a nearby fellow machinist) have a mill with a rotary table?  That's a very safe alternative for what you want - saves the slug and leaves a nicely finished hole that will require little or no finish machining.

Plus 1 for Marv's suggestion....worth the investigation.....
Dave

PS....I'm glad your staying away from the treppaning ...I've had stuff grab and when it comes out.....oh it's ugly!

Dave