New member trying to machine silver steel

[nmw01223Participant @nmw01223]

Just to describe myself, as requested:

I’m a retired design engineer, but over the years have done a fair amount of hobbyist metal working – starting with a six month workshop training course over 50 years ago now. Got a very old small 8″ swing Myford lathe, arc welder, pedestal drill, small CNC router, 3D printer etc.

Introductory question: need to machine circlip grooves in some 1.5mm silver steel bar. The grooves need to be 0.5mm wide, and 1.2mm bottom diameter. First attempt, despite feeding very slowly, with an HSS tool (which from what I read should be OK) bent the bar and snapped the (very fragile) tool. Think I ground too much top rake on to the tool and it dug in. What should the top rake be for something like that?

[Andrew CrowParticipant @andrewcrow91475]

<p style=”text-align: center;”>Hello and welcome to the forum, I’m sure there will be a few more replies within lots of advice.However, my suggestion is that there probably isn’t anything wrong with the tool more likely with holding such a small diameter in a chuck on an old machine.
The chuck is probably a bit bell mouthed with lots  of use and is unable to grip such a small diameter right at the business end so that the bar has probably bent as you started to cut.
My suggestion would be to get an ER collet chuck that mounts on the  Myford spindle plus a suitable collet then you can cut the groove as close to  chuck as possible. Also don’t run the spindle too slow silver steel should be cut at about 15 metres per minute.</p>
I think that works out at about 30000 revs for 1.5mm diameter, I don’t think the Myford will run quite that fast but give it the best you can.

Andy.

[bernard towersParticipant @bernardtowers37738]

Any particular reason its got to be silver steel?. I find it very overrated for a lot of jobs, its difficult to tuirn with a good finish and yes parting off/grooving not for the faint hearted. collets do make it better and the small dia stuff i turn is travelling very fast when I have to use it.

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