An alternative to parting-off

[Andy PughParticipant @andypugh44463]

It isn't easy to part-off material on the lathe much over 2" dia in my experience.

I think I have thought of an alternative having noticed that Aldi are selling a handheld bandsaw for £150 (identical model available on eBay for £220…)

The bandsaw comes with a vice and table as an accessory, and my lathe has a T-slot at the back for a taper-turning attachment.

A bit of cutting, welding and machining later:

[Andy PughParticipant @andypugh44463]

[Chris Evans 6Participant @chrisevans6]

That looks interesting. Now all the bracketry is made does it take long to set up ? I am happy parting off up to 2" with a rear mounted tool post after that or if the material is a bit difficult I use my cut off "Donkey" saw. Your method would eliminate the problem of holding short ends and differing diameters.

[Mark RandParticipant @markrand96270]

I would look into what is wrong with the lathe to be causing problems with parting off. Something's severely out of kilter if you are having problems with that lathe.

[not done it yetParticipant @notdoneityet]

Yep, it is usually the last bit of parting off large diameter parts, when the parting tool is well extended from the holder.

Cutting the last bit with a hacksaw is not a problem for the odd occasion it might arise.

I suppose that if you need a saw for other duties, using it like that might be justified…

[thaiguzziParticipant @thaiguzzi]

He's joshin'. Havin' a laugh……..

[JasonBModerator @jasonb]

Is it not easier to just take the work out the chuck and use the saw on its stand on the bench?

[Ady1Participant @ady1]

Another choppy uppy thread

[Neil WyattModerator @neilwyatt]

[Mark RandParticipant @markrand96270]

Posted by thaiguzzi on 03/11/2018 04:12:53:

He's joshin'. Havin' a laugh……..

Yeah, sorry Andy! Must have had the sense of humor switched off.

[larry phelan 1Participant @larryphelan1]

Like many others I have had "problems" when parting off,still have,but I dont think I would go for that approach !

Sometimes it works for me ,first time. Next time,no way ! The Gods are fickle [as we all know ]

If I think it,s going to be" one of those days ",I just take it out and cut it off in the band saw. I doubt if I will live long enough to to really master the art,but I keep trying !

One thing I like about this Forum,is that you never know what you,re going to see,or learn .

Keep them coming.

[vintage engineerParticipant @vintageengineer]

Never understood why people have problems with parting off. Now we have insert parting tools it's a doddle, as they are made for power feed parting off. I usually set the lathe speed to about 500rpm to 800rpm and a medium speed feed and let it go.

I have happily parted off 10" round bar with no problems.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by vintage engineer on 04/11/2018 09:41:17:

Never understood why people have problems with parting off. Now we have insert parting tools it's a doddle, as they are made for power feed parting off. I usually set the lathe speed to about 500rpm to 800rpm and a medium speed feed and let it go.

I have happily parted off 10" round bar with no problems.

No doubt on a Super Adept lathe

Russell

[egaParticipant @ega]

Posted by vintage engineer on 04/11/2018 09:41:17:

Never understood why people have problems with parting off. Now we have insert parting tools it's a doddle, as they are made for power feed parting off. I usually set the lathe speed to about 500rpm to 800rpm and a medium speed feed and let it go.

I have happily parted off 10" round bar with no problems.

Where does one obtain a parting off tool with a 5" projection? And what lathe runs it?

Not everybody has power cross feed. CNC apart, how does conventional parting off account for the progressive reduction in surface speed of the cut?

[Tony Pratt 1Participant @tonypratt1]

Posted by vintage engineer on 04/11/2018 09:41:17:

Never understood why people have problems with parting off. Now we have insert parting tools it's a doddle, as they are made for power feed parting off. I usually set the lathe speed to about 500rpm to 800rpm and a medium speed feed and let it go.

I have happily parted off 10" round bar with no problems.

Please supply all details for us amateurs to learn from. Parting 10" diameter of any material is a serious business & all at one speed.

Tony

[Kevin FParticipant @kevinf]

 

I never use feed too part off , I always feed in by hand , this way I can ‘ feel ‘ what’s going on during the parting process and if need be I can clear the swarf by winding out the tool a little .

I think the op needs to Take out the backlash before parting off and check how much play he has in the bed and cross slide , also the tool clearance and center height and spindle speed .

Edited By Kevin F on 04/11/2018 11:53:01

[not done it yetParticipant @notdoneityet]

VE could mean that although left on power feed, he has varied the motor speed (like I could on my Raglan). But I would not wish to try parting off 250mm on that! Increasing the speed as it progressed would also increase the feed rate! Also, it might well swing 250mm but certainly not over the cross slide!

Or maybe that ‘10” round bar’ was plastic? Maybe he works at a scale of 1” to the foot and is building traction engines? It would be good to read the particular details of the exercise. I would expect Abom79 could do it quite easily if he wanted to.

[OldironParticipant @oldiron]

Here is an interesting webpage for those interested.

**LINK**

[larry phelan 1Participant @larryphelan1]

To those who dont understand why others have trouble parting off,it,s very simple,we just dont know how !!

Perhaps we are using the wrong material to begin with. The next time I visit my supplier,I ,ll ask him if he has a few bits of 10" round kicking around that I could practice on.

Just thought of something—-my chuck is only 6" ! Problems,problems,problems !!

The fact of the matter is that many,if not most people find parting off a difficult operation,and not all of them amateurs.

I suppose when you get used to it,you can have a cup of tea while you,re at it..

For the rest of us Dream on.

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by Tony Pratt 1 on 04/11/2018 11:48:49:

Posted by vintage engineer on 04/11/2018 09:41:17:

Never understood why people have problems with parting off. Now we have insert parting tools it's a doddle, as they are made for power feed parting off. I usually set the lathe speed to about 500rpm to 800rpm and a medium speed feed and let it go.

I have happily parted off 10" round bar with no problems.

Please supply all details for us amateurs to learn from. Parting 10" diameter of any material is a serious business & all at one speed.

Tony

I did 125mm on a Boxford many years ago.

[MuzzerParticipant @muzzer]

I see it's one of the Iscar TGFH parting tools. Different inserts to the "GTN" used in many (most?) other insert tools. I was provoked into getting one recently after similar reviews here, on offer from Zoro (Cromwell).

I found it worked nicely on steel and loominum. Not quite 125mm but it looked as if it would cope if the time came.

Murray

[Neil WyattModerator @neilwyatt]

Posted by Russell Eberhardt on 04/11/2018 11:19:45:

Posted by vintage engineer on 04/11/2018 09:41:17:

Never understood why people have problems with parting off. Now we have insert parting tools it's a doddle, as they are made for power feed parting off. I usually set the lathe speed to about 500rpm to 800rpm and a medium speed feed and let it go.

I have happily parted off 10" round bar with no problems.

No doubt on a Super Adept lathe

Russell

What do you think it is at bottom left of that cartoon?

Maybe some braggadocio there, but to be honest, the larger the diameter the easier it is, assuming the lathe is big enough to cope. Bigger, heavier bar is less likely to chatter or stall, and presumably to tackle a big bar you have a hefty, rigid tool and a hefty, rigid lathe.

The tricky bit is parting things in the ~2" size range where folks use light parting tools on small lathes and don't use power feed. My experience is that power feed and carbide tooling makes all the difference.

Verb sap: Sandvik suggest using an inserted tool set 0.001 to 0.002" high for parting, 0.001" if you want to cut all the way to the centre.

Neil

[larry phelan 1Participant @larryphelan1]

Would love to be able to part off 125mm just like that,as the late Tommy Cooper used to say [God rest him ]

For now,I,d be happy with 50mm. Anybody with me ?

[MikelkieParticipant @mikelkie]

10 inch ? How big your rig?

Edited By Mikelkie on 04/11/2018 18:48:57

[clogsParticipant @clogs]

always had trouble with parting off…….gen I go up to the next speed for the chuck……

some times good then not so….snapped a few TCT tool holders……..

now gonna try a rear tool post with a Co HSS tool….will let u know……

most of the time on the 50mm dia bar I remove the bar and use the bandsaw…..which is a pain in the bottom….

it just makes me nervy……

I use a Myford S7 and a Colch/Student sq top larhes……!!!!!!!!!!!!!

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