Tangential tooling/holder

[Conrad_R_Hoffman]

Never used one so I may be talking out the wrong orifice, but the design seems more confusing than just grinding the necessary angles on a conventional tool. It's then perfectly clear what the clearances are and they're easy to adjust as needed. I'm not so sure diagnosing why the tangential does or doesn't cut as desired is as easy, and the cure may be harder to come up with as well. Still, if one has the right application that needs to be done over and over, sharpening the tool becomes a no-brainer.

[Harold_V]

Never used one so I may be talking out the wrong orifice, but the design seems more confusing than just grinding the necessary angles on a conventional tool. It's then perfectly clear what the clearances are and they're easy to adjust as needed. I'm not so sure diagnosing why the tangential does or doesn't cut as desired is as easy, and the cure may be harder to come up with as well. Still, if one has the right application that needs to be done over and over, sharpening the tool becomes a no-brainer.

The one real advantage to the tangential is the lack of skill required to accomplish a grinding edge. That's not to imply that those that use them lack the skill, so please don't go there, readers.

The point is, the top of the tool is all that requires grinding. so it would be faster, of that there's no doubt. All relief angles are a function of the tool holder and are not adjustable. That can be a good and bad thing. Rake can be accomplished by varying the top grind, both back and side. Beyond that, I struggle greatly with seeing any particular advantage. and in spite of claims made to forming 9's and C's, I am not keen on any tool that lacks a chip breaker. When I grind a tool for a job, I can guarantee a breaker that works, assuming the chip load is somewhat constant (light finish passes excepted). Not sure you can do that with a tangential tool. After all, regardless of how the shank is held, other features can be duplicated---so the cut has no idea how the tool is held.

Harold

[GlennW]

One thing to be factored in is the cost. At the time I made mine, Tangential Tools were being sold via the Internet for about $150.00, which is for sure a deal breaker. If I'm going to hand over $150.00, it will be for an indexable holder and inserts that would accept CCMT/CCGT inserts and do a fine job and leave a fine finish on ferrous or non ferrous as well as hard or abrasive materials.

I see no reason to spend that much for what is basically a single purpose tool that still requires the use of HSS and a bench grinder!

If I still need to use a bench grinder, it would be to just grind up a conventional square tool bit that suited the job at hand for a small fraction of the cost. Seems like the whole advantage to HSS is it's being inexpensive, and universal as far as it being fairly simple to grind a simple square tool bit to just about any configuration needed to fit the job. Adding a $150.00 tool holder to that sort of defeats that!

Just another view of the situation from a cost standpoint.

As I stated earlier, it did OK on light cuts and left a finish as expected with HSS.

If you plan on making a holder as "awake" did, (nice one!) rather than purchasing one, and don't have the HP or rigidity to take large roughing cuts, the Tangantial Tool may be just what you are looking for as far as simplicity of use.

Hey, if it works for you, why not!

As for a threading tool, I wouldn't consider a Tangential style, as it would be far too restrictive as most of my threading is right up to a shoulder. Once again, if I have to grind HSS anyway, I'll just grind up a conventional HSS threading tool to fit the application.


Conrad,

Will your lathe accept 5/8 toling?

[Conrad_R_Hoffman]

Hi Glenn,

Heck, my lathe barely accepts 5/8" stock! Seriously though, I think the 5/8" tools will fit the QC holders, but I'd have to cut the bottom down to get them on center.

CH

[awake]

The one place where I expect a tangential tool would not compete well is in taking heavy (roughing) cuts. Unless some provision was made for the exceedingly high pressure pushing downwards, I expect you might experience movement of the tool (not an acceptable thing to experience). If you can take .250" off per side with a .015" feed, I might view that idea differently. Can you? That would really sort it in my mind. In spite of not working for gain now, when I operate my lathe, if there's material to be removed, it's done as quickly as it can be done on my machine----never would I consider being hampered by tool design.

A good question. My lathe is an old Cincinnati TrayTop. Theoretically it should be capable of heavy roughing cuts ... but in practice, not so much. (And yes, I'm talking about using conventional HSS tooling, with and without chipbreakers.) This lathe had a hard life before it came to me, and while I've been able to work out or work around most of its faults, it is not as rigid and tight as it should be. One of the worst issues in the lathe has to do with the crossfeed -- when I change the angle on the compound, the friction on the crossfeed changes quite markedly. Sometime in its life, the crossfeed was converted from a tapered gib to a straight gib with set screws. I don't know if that is contributing to the problem or not ... meanwhile, the crossfeed ways are significantly worn. Put it all together, and it is challenging to set the gibs snug enough for rigidity while still allowing movement at the extremes and/or at other compound settings.

All that said, I can work to .001 easily, and to tenths if I need to. I just can't push it too hard.

[jkilroy]

You can take darn hardy cuts with a tangential tool holder. I have taken very heavy cuts with mine, on my Rivett 1020, but I don't know if I can get a full .250 because I am not sure if the tool bit presents a flat edge that long. But I have engaged the entire cutting length with no problem.

[mechanicalmagic]

I started off using rocker tool posts, with the tool angled in the holder. It set the back rake angle for me. I had to grind the front and side clearance angles.
I've used square tool blocks and Aloris type that set the back rake at zero. I had to grind the clearance angles and the back/side rake.
The Tangential sets the front and side clearance angles, again I have to grind the back and side rake. (With a guide block, usually provided).

I ask a simple question, and propose an answer.
If a tool (mounted in a holder, used for steel) has;
the suggested 10 degrees back and side rake,
the suggested 8 degrees front and side clearance,
rigidity.

Question: What difference does the holder make?

My answer: The holder makes it easier for the user to grind and sharpen the tool.

Dave J.

[Harold_V]

A good question. My lathe is an old Cincinnati TrayTop. Theoretically it should be capable of heavy roughing cuts ... but in practice, not so much. (snip good stuff)

Understood! Early on in my learning years, I was assigned to a tray top Cincinnati. I was then moved to the EE I operated for over a year. Only one that has experienced something similar can come to understand the difference. The tray top I operated was nearly new, just as the EE was, but to compare one to the other isn't fair. I am quite fond of many of Cincinnati's machines, in particular their tool and cutter grinders, and their centerless grinders, but the tray top, in my opinion, was not a very good machine. I struggled with tolerance, yet moving to the EE made the same work easy.

jkilroy's comments about depth of cut were interesting. I can assume that he has employed a generous feed with the depth mentioned. Makes a huge difference. My only concern, then, would be chip control, which, to me, is just as important as the ability to generate a chip. I still question how easily one can create chip breakers in such a tool, although even that appears to be not beyond one's capabilities. If I had time to waste, I'd be inclined to make a tool similar to that which was made by Glenn, and do some experimenting. Considering I don't have, I likely won't. I'm not keen on fixing things that aren't broken, and I'm very comfortable with conventional tooling, be it HSS or carbide (of my generation).

Harold

[GlennW]

If you can take .250" off per side with a .015" feed, I might view that idea differently. Can you?

What speed?

[awake]

Understood! Early on in my learning years, I was assigned to a tray top Cincinnati. I was then moved to the EE I operated for over a year. Only one that has experienced something similar can come to understand the difference. The tray top I operated was nearly new, just as the EE was, but to compare one to the other isn't fair. I am quite fond of many of Cincinnati's machines, in particular their tool and cutter grinders, and their centerless grinders, but the tray top, in my opinion, was not a very good machine. I struggled with tolerance, yet moving to the EE made the same work easy.

Harold, this is very interesting. I have been assuming that the wear was the problem, but your experience suggests the lathe itself is contributing to the problem. Maybe I need to start looking for another lathe ... would you mind telling my spouse for me?

[CarlD]

The only advantage I can see to the tangential tool is not having to change tooling when turning the OD and then facing the shoulder. I have a tool holder of a similar design but not tangential that I use on occasion but I consider it a light duty finish cut tool.

When using a QC tool post the holder I have allows me to turn the OD and face the shoulder without angling the tool post. Many times when using a 60 deg cutter to finish turn the OD and face the shoulder I run into clearance problems with the tool post and/or the tool holder. That is the one time the holder I have is best for the job.

I just don't see the point in using a tangential holder for all jobs. To me it's a finish cut tool just as I use the shear cutter for finish work.

[Bill_Cook]

Tangental tools were handy before carbide inserts for production work. The old screw machines didn't have graduated dials and had to be adjusted with screw stops on the slides and pivots.

HSS and before that older tool steels can require a lot of sharpening. Having a tool that could be moved up to the same position after sharpening doesn't require much resetting to get back up and producing.

It can be adjusted and held from drifting down with an adjusting screw under it.

Getting it set right to do one feature by adjusting it up or down would likely get it right on other features of a part.

Form tools were made to work under the same principal either straight or round. The (older) Machinery's Handbooks had formulas to get the right profile since the tool couldn't be held vertically and have clearance. With round tools the cutting edge had to be below it's center to get clearance.