Parting off – again, sorry

[Philip PowellParticipant @philippowell34749]

That's just asking for trouble sticking the bar that far out of the chuck then parting off.

Phil

Edit typo.

Edited By Philip Powell on 14/10/2018 12:48:09

[not done it yetParticipant @notdoneityet]

Posted by fishy-steve on 14/10/2018 12:24:36:

I personally wouldn't part off with that much overhang without tailstock support.

Steve.

Neither would I, especially as the perspective, and given distance, makes the item look very much slimmer than the 38mm quoted earlier in the thread! More so, knowing that parting has not worked out well, previously.

[JonParticipant @jon]

Presume its about 1 1/4" dia, 2" sticking out will or should be ok, done it relentlessly where parts need to be done as one rather than removing and put back in the chuck wrongly.

If you look carefully you will see the tool post moving, coud be all manner of things. Other than that spindles way to slow, deep cuts if ever did get that far will break the cutter and or tip.

That type of tip not the tool you should be able to part 6" dia off in 6082 the worst of all evil. Just be quick when hear tonal change and draw out.

What will help is a 2mm parting tool and tip such as DGN Do Grip my favourite go to tool used for turning, grooving and parting. Saying that broke it after 6 years and cant find another at a respectable price.

[petro1headParticipant @petro1head]

 

It’s 1.5” dia.

6082?

I can’t see the toolpost moving

It’s the speed and feed bit that I am very unsure about. When I run it after it does not sound right, to me and am scared of fing another tool.

So would this formula work for the speed:

RPM=SFMx(12/3.142)/work dia inches

RPM=150×3.82/1.5 = 382rpm

Edited By petro1head on 14/10/2018 22:25:41

[petro1headParticipant @petro1head]

I have just found Neil’s post with the cutting chart.

That suggest the SFM for Ali is 200. So that would be 509rpm

 

It’s getting confusing

Edited By petro1head on 14/10/2018 22:07:26

[Niels AbildgaardParticipant @nielsabildgaard33719]

I am owner of 2018 WM250 and 2011 WM280 lathes and both have a rather stupid compound slide system.

It looks like something copied from austrian EMCOs.The made in millions 918 lathes has them as well and the first advice on all 918 pages is to scrap it.

If You want better parting try making a better/stiffer/more direct force path from tool tip to lathe bed.

Avoid the flex of compound slide and quick change toolholder for parting.

The video indicates chattering.

I made a holder of this kind and parted 100mm mild steel routinely on a Boxford and a single 125 disk of seawater resistant aluminium.

 

My new 250 lathe with old floppy tool slide system.Lovely lathe apart frpm compound slide system

Edited By Niels Abildgaard on 15/10/2018 06:44:06

[JasonBModerator @jasonb]

Posted by petro1head on 14/10/2018 22:06:45:

I have just found Neil’s post with the cutting chart.

That suggest the SFM for Ali is 200. So that would be 509rpm

That table is a bit useless without the text that went with it where you will see that David said" for Carbide I would double the shown speeds and industry would be 4-5 times faster".

Kind of brings us back to what I said on the first page of this thread 900-1000

[JasonBModerator @jasonb]

I did think the cut from your video looks a bit rough and inconsistant so quickly popped out to the shed for a quick video.

Speed is not such an issue and sometimes a bit slower can make things more relaxed and easier to keep up with the lube so did a bit a 600rpm and then some at 950rpm. Also using a slow power cross feed so tool is constantly loaded, the only time you hear a hint of chatter is when I stop the feed to move the camera and that is because tool is not being kept under a decent load.

Warco 280VF, Glanze 2mm holder, APT general purpose insert 6082 38mm dia ali, paraffin, 600 & 950rpm. Saddle and topslide locked, topslide well back.

Sorry about the noise, my belt creaks when cold, its not the head honest!

[not done it yetParticipant @notdoneityet]

We have two threads, running concurrently, on really the same subject – the inability of the OP to part off successfully.

I really think it is time for the OP to step back and consider every aspect of his working practice and improve each and every one to its maximum.

Among others, we have, so far:

Possible excessive overhang from the chuck with no additional support.

Possible excessive overhang of the tool from the holder.

Possible excessive overhang of the tool from the carriage.

Non locked-down axes while cutting on another.

Possible drawbacks with the machine design.

Cutting speeds in relation to diameter of work, material and cutter type.

Apparent differences between tool holders and some examples not being secured properly.

A possibly compromised parting-off tool.

Possibly poorly secured, or loose, tool post on the top slide

Likely others, too, not listed above from this or the other thread but that little lot should provide at least some considerable practical improvement in this task.

We don’t actually know which (or combination) of these factors led to the original cry for help. So time, now, for all the possibilities to be examined by the OP? Then, and only then, the OP might try parting off again, because changing one thing (in this case) seems very unlikely to solve the problem in one go!

[Neil WyattModerator @neilwyatt]

You've left off strange noises/chatter causing the lathe operator to either slow down the lathe or reduce the feed rate.

Neil

[petro1headParticipant @petro1head]

On phone at the mo but will study posts and report back.

I did find a post re double the speed for carbide

[petro1headParticipant @petro1head]

Excellent video. This is what I have to aspire to

I have moved the tool post so is better located

I have added a lock on the saddle that I can access

I use the calculation to get the RPM

I make sure the work does not stick out too far from the chuck and also ensure the tool does not overhand too much.

Use paraffin as cutting compound

Make sure everything is locked down

Make sure the tool tip is centred and not above ctr and that it perpendicula to the work

Edited By petro1head on 15/10/2018 10:44:42

[JasonBModerator @jasonb]

Don't forget to put your lucky pants on

[petro1headParticipant @petro1head]

Posted by JasonB on 15/10/2018 11:25:57:

Don't forget to put your lucky pants on

I did and am happy to say, yeh! sucess

This video has highlighted another problem, I know i'll get me coat

 

Edited By petro1head on 15/10/2018 12:13:53

[JasonBModerator @jasonb]

That's more like it and not a rear toolpost in sight

[petro1headParticipant @petro1head]

Posted by JasonB on 15/10/2018 12:06:36:

That's more like it and not a rear toolpost in sight

Did you notice the noise at 1:08, sound like a bearing. I know, i'll get me coat

[JasonBModerator @jasonb]

has it always done that, could it be noisy electronic braking?

[Brian BParticipant @brianb]

May I suggest you change the tip for a new unused one and try again! If this doesn't

work then the cutting edge is not at right angles to the job or is not being advanced at right angles to the job.

[petro1headParticipant @petro1head]

Posted by Brian B on 15/10/2018 12:22:28:

May I suggest you change the tip for a new unused one and try again! If this doesn't

work then the cutting edge is not at right angles to the job or is not being advanced at right angles to the job.

Not sure why, did you watch the last video?

[petro1headParticipant @petro1head]

Posted by JasonB on 15/10/2018 12:19:22:

has it always done that, could it be noisy electronic braking?

Probably the last 6 months. Does it when its on, not just when stopping

[Michael GilliganParticipant @michaelgilligan61133]

Posted by petro1head on 15/10/2018 11:57:51:

Posted by JasonB on 15/10/2018 11:25:57:

Don't forget to put your lucky pants on

I did and am happy to say, yeh! sucess

.

Nicely fixed, Sir

MichaelG.

[JasonBModerator @jasonb]

Probably better to start another thread about the noise.

[petro1headParticipant @petro1head]

Good idea

Thanks again, everyone, for the superb help

[thaiguzziParticipant @thaiguzzi]

Posted by Philip Powell on 14/10/2018 12:47:02:

That's just asking for trouble sticking the bar that far out of the chuck then parting off.

Phil

Edit typo.

Edited By Philip Powell on 14/10/2018 12:48:09

Concur. Insane.

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