Facing off backwards

[Former MemberParticipant @formermember19781]

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[Former MemberParticipant @formermember19781]

[David Standing 1Participant @davidstanding1]

If it works and is safe it isn't bad practice

If you have the right tool tip for the circumstances there isn't a problem.

It's a time saver too!

[Mick B1Participant @mickb1]

Whichever way the tool cuts is fine. On screw threads particularly, I somtimes face the end, run the tool over to the far side, engage low speed reverse, move the tool a millimetre or two chuckwards, then draw the angled cutting edge backward to form a chamfer of approximate flank angle.

Of course, occasionally I forget to switch the lathe back to forward rotation, and wonder why the tool won't cut on the next op – but I don't wanna talk about that…

[JAParticipant @ja]

I occasionally do this with mild steel using a HSS left hand knife tool. As you say the cut is easy and, I find, gives a good finish.

JA

[not done it yetParticipant @notdoneityet]

Lathes turn both ways, ‘left’ or ‘right’ handed cutters can be employed, cutters can be used usual way up or upside down. No difference while facing, as I see it

[Former MemberParticipant @formermember19781]

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[Mike PooleParticipant @mikepoole82104]

I use both directions if the tool is suitable, a centre hole is best to start from the middle though as the plunge to start off can be a bit messy.

Mike

[David ColwillParticipant @davidcolwill19261]

It may be because the bulk of material is being removed by a different part of the tool which may not be subject to wear and so is reducing cutting pressure.

Regards.

David.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Bill, if it is bad practice or wrong, I've been a naughty boy very many times. As has been said, if it is safe it's OK.

Regards Nick.

[BazParticipant @baz89810]

Bad practice, absolute rubbish. Nothing at all wrong facing out from the centre, used to do it hundreds of times a day on a CNC lathe, rough face into centre and then after roughing o/d back into centre, face outwards and finish profile, nothing wrong either with back turning, rough along towards chuck as usual but then apply a thou or so deep cut and feed back to tailstock, you are now using an unused edge of tip and will get a good finish.

[Former MemberParticipant @formermember19781]

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[SillyOldDufferModerator @sillyoldduffer]

What doesn't work is facing off with the lathe in reverse. Don't ask how I know…

Bill said 'I have been experimenting this morning since the earlier comments and find that I can take deeper cuts and get a better finish which is interesting. Using Glanze carbide tip tool.' Just another wild suggestion, but that might be the smart way to face off with carbide. When the tool starts at the centre and moves out to face off, the cutting speed at the tip accelerates, which is what carbide likes. In the other direction, carbide is decelerating, ie constantly moving away from it's preferred mode.

Experiment needed, all same material and lathe, at the same settings. About 20 examples of facing inwards to compare with 20 examples faced outwards. Is there a detectable difference?

Dave

[mark costello 1Participant @markcostello1]

FIL used to run a W+S #2, facing out keeps the hot chips from finding You.

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