Fly Cutter Milling Speed?

[Jon GibbsParticipant @jongibbs59756]

Dear All,

This may be a bit of a dumb question but do I follow the conventional rules about milling cutter speeds for a single tooth HSS fly-cutter? – or can I push it a bit faster?

I've just made a 2" diameter flycutter with a 1/4" round HSS toolbit. For milling mild steel at say 60 feet per minute I reckon it's about 120 RPM. Does that sound right?

I suppose if I'm too fast my toolbit will just dull more quickly, which is no great shakes, but I'd prefer to get it right.

Any guidance gratefully received – Many thanks.

Jon

[Jon GibbsParticipant @jongibbs59756]

[Mick DobsonParticipant @mickdobson]

Hello Jon, yes seems about right as a first go. I would normally base mild steel at 80 feet/ min, giving a cutter speed of about 150 rev/min at 2" diameter.

Not sure if your mill is a "model engineering machine" size, in which case err on the lower speed and work up until it seems right. Depth of cut and feed rate will play a part also. The more rigid the machine and set up, the more you can push the depth of cut and speed.

Regards,

Mick

[Jon GibbsParticipant @jongibbs59756]

Hi Mick,

Thanks very much for the guidance.

I am using my lathe (Myford ML7) with a vertical slide so it's perhaps not as beefy as a dedicated milling machine?

Thanks again

Jon

[NJHParticipant @njh]

Hi Jon

Yes certainly nowhere near as beefy as a dedicated milling machine! ( In fact to many here it may be deemed a very flimsy set up indeed.) No matter the previous generation of model engineers had no other way of milling – the lathe had to do it all. So in case you are worried just look at some of the "stuff" those old guys turned out. Just ensure that everything is held tightly, take small cuts and go very gently. Listen closely too – this will often give a good clue to how things are progressing.

Good luck!

Norman

Edited By NJH on 24/04/2014 14:16:50

[Jon GibbsParticipant @jongibbs59756]

Hi Norman,

Thank you for the words of warning. OK, I'll take it steady and tighten everything down well.

Thanks again

Jon

[Tim StevensParticipant @timstevens64731]

If the shavings come off even slightly blue you're going too quick, I reckon.

cheers, Tim

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