Parting off stainless hex bar

[Keith MathesonParticipant @keithmatheson47708]

Hi. I have been parting some 19mm across flats stainless and a bit unsure as to feeds and speeds when starting to cut. After the flats have been removed by the tool I found about 480 rpm with ‘sensible’ hand feeding worked well ie cuts well, sounds happy nice crisp sound. However, when I start to part the hex parts sound dreadful as the tool smacks itself into the tool at high speed.

I have a Toolco lathe which looks identical to the warco 290. I’m using a rear tool post with a (carbide?) indexible type tool bit (glanze I think). I dribble cutting oil on it with a brush. Basically when it starts it sounds like I’m hammering seven shades of **** out of the tool bit and need to know if I should a. Slow it down initially b keep it as it is or c speed up for the first cutting part.

many thanks Keith mm

[Keith MathesonParticipant @keithmatheson47708]

[egaParticipant @ega]

It's normal for the initial interrupted cut to be noisy. You could consider taking off the flats with a front-mounted HSS tool at slower speed and then move to the RTP at your favoured speed and feed.

[vintage engineerParticipant @vintageengineer]

Start slow until the bar is round then treat the same as round bar.

[Author]

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