Parting off tools for 102 lathe

[Karl ManssonParticipant @karlmansson91253]

Hello!

It's been a while since I last posted. My Habegger DLZTE with 102mm center height is up and running.

I'm trying to come up with a good system for parting and I managed to come by some parting inserts rather cheaply a little while back. They are Sandvik N151.2-300 inserts, 3mm wide that is. I also, from a different source, found a parting blade that turned out to be one size too small for these inserts.

I'm torn between selling the blade or selling the inserts. The blade is for 2mm wide tips. What would you recommend for a machine of my size? I am planning on working on some 45-50mm diameter steel stock in the future, which will fit a chuck in my machine but not the collets.

I am also thinking I would make a rear parting toolpost. Mostly due to the solutions with separate holders looking like they have a great deal of flex and overhang. I was thinking I would copy the mechanics of one of the Sandvik holders for their blades and mill it with a dove tail cutter directly into the toolpost. It would make for a rigid and compact solution. I've read quite a bit about the pros and cons of front and rear mounted parting tools and I've come to the conclusion that both work about equally well. I'm using a Tripan 111 quick change system and apart from the holders being pretty pricey they don't take the Sandvik blades direclty but would need an intermediary block.

I also thought about making my own parting blade. I have a piece of what I think is silver steel that would fit the bill quite nicely. But then again, seeing as the parting blades sold are about 120 pounds each, I'm thinking there is something to them not directly abvious to the naked eye?

Looking forwards to your input on this!

Best regards
Karl

[Karl ManssonParticipant @karlmansson91253]

[old martParticipant @oldmart]

I would sell both lots and start with something less proprietary. Sandvik is very good, but expensive, and there are much cheaper alternatives. I use blades in 26 and 32mm with Kennametal and Kyocera, but if starting out, I would get GTN3 inserts and a SPB263 blade. Most are Chinese, but Korloy also makes the inserts. These are 3mm wide, but SPB262 and GTN2 are 2mm wide.

The cheap ones will be just as strong/weak as the expensive ones, I destroyed one end of a Kennametal 1.6mm blade, and still have 9 inserts unused, the work moved in a three jaw chuck, so I prefer to have the extra security of a 4 jaw independent if parting is required. Making a dedicated rear toolpost for inverted blades is a great idea if you have a mill. I also added a rear lock for the saddle to stiffen things up further when using it. If I remember, I will take some pictures of it tomorrow.

I would advise against making an integral blade/post, sooner or later it will get smashed, the blades have two ends and can be replaced easily.

Edited By old mart on 19/11/2019 19:20:37

Edited By old mart on 19/11/2019 19:23:54

[Neil WyattModerator @neilwyatt]

Probably 3mm for a lathe that size, but in an ideal world having both is nice.

Neil

[old martParticipant @oldmart]

3mm is the commonest size and is certainly my first choice out of 1.6mm, 2mm, 3mm and 5mm that I have. The 5mm are too big for parting on anything other than a very large lathe, but they were so cheap, I couldn't resist them, they may be used for grooving some day.

[David George 1Participant @davidgeorge1]

I made an upside part off tool holder for an Iscar part off blade it is the best thing I have made for ages. It's solid and you just unclamp the blade and slide it in and out for different does of cut.

David

[VicParticipant @vic]

A quick google of your machine and I’d say you could use 2 or 3mm tips on it. They used 2mm tips where I used to work on M300’s, I never thought to ask why. I personally gave up using inserts for parting and went to T shape HSS blades and wouldn’t go back unless I had to part something particularly hard. These are the blades, I use the 1/2” ones:

**LINK**

These would obviously also work well in a rear tool post.

[Howard LewisParticipant @howardlewis46836]

+ 1 for David's suggestion of having the parting blade inverted in a rear toolpost.

In my book, it is essential for cutting tools to be mounted so that the cutting edge is on the centreline. NEVER above it.

In feed should be constant, but not heavy. For steel lubrication, soluble or neat cut oil ,should ,be applied. A steady drip feed should suffice. For Aluminium, the lubricant should be paraffin, (kerosene ), or WD40 or one of its clones.

Keep the cut free of swarf. Hopefully, you will be free of dig ins.

Although I have inserted tip parting tools, I very rarely use them, and rely on my aged, at least secondhand, 3/32" wide HSS parting blade. This has been used in my shop for some twenty years, and still has a lot of life left!

HTH

Howard

[old martParticipant @oldmart]

Here is my version of a rear parting off toolpost for inverted blades. It has a top half which can be turned round for using either 26 or 32mm blades.The edges just have to be aligned parallel to the cross slide by eye or feel when tightening the SHCS for the blade to be at right angles to the axis. I added a rear saddle lock at the same time, using two helps the rigidity.

[old martParticipant @oldmart]

As for tool height, if you use industrial type blades, I read the manuals of both Kennametal and Kyocera and both companies recommended 0.004" high if parting off solid stock. This would have been arrived at after the extensive testing that they do with their products.

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