Help with boring an interior cone

[Chris TickTockParticipant @christicktock]

[Chris TickTockParticipant @christicktock]

hi guys, I have been asking around for ways to make an internal 60 degree cone on 6mm mild steel. Various options are spot drill, chamfer end mill and boring bar. The first 2 options i get but not the third.

As I have done little boring can anyone advise as to bit required and setup on my Sherline lathe.

Regards

Chris

[Dave SParticipant @daves59043]

For a 1 off at that size I would make a 60 degree point on a piece of silver steel, then file away the “top” to make a d bit. Add a little clearance on the none cutting bits. Harden and temper to straw.
To use you could hold in the tailstock and drill, or use like a boring bar in the toolpost.

for a larger cone then setting the cross slide over at 30 degrees (half angle) and feed in with that to bore – which is probably what is meant. The problem with that is the bottom of the bore – if required to be a point will need a boring tool which is very pointy.

Dave

[David George 1Participant @davidgeorge1]

Small boring bar.

The small boring bar on the right hand side will bore down a 2mm hole. You just have to set dead o center line and set top slide at angle you need but it won't bore any smaller than 2mm so you would have to drill a hole first.

David

[Chris TickTockParticipant @christicktock]

Thanks guys really interesting. I ended up making a D drill bit and it worked well…to my surprise.

Chris

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