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Facing off backwards

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Former Member17/02/2020 08:45:04
1329 forum posts

[This posting has been removed]

David Standing 117/02/2020 08:52:49
1297 forum posts
50 photos

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

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

It's a time saver too!

Mick B117/02/2020 09:01:11
2444 forum posts
139 photos

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...

blush

JA17/02/2020 09:07:09
avatar
1605 forum posts
83 photos

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 yet17/02/2020 09:11:01
7517 forum posts
20 photos

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 Member17/02/2020 10:00:15
1329 forum posts

[This posting has been removed]

Mike Poole17/02/2020 10:08:03
avatar
3676 forum posts
82 photos

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 Colwill17/02/2020 10:59:32
782 forum posts
40 photos

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 Farr17/02/2020 12:11:09
avatar
3988 forum posts
1799 photos

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.

Baz17/02/2020 12:44:31
1033 forum posts
2 photos

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 Member17/02/2020 12:55:26
1329 forum posts

[This posting has been removed]

SillyOldDuffer17/02/2020 13:20:57
10668 forum posts
2415 photos

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 117/02/2020 16:26:40
avatar
800 forum posts
16 photos

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

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