My Take on a Tangential Tool Holder

rleete · Dec 8, 2024

I've been wanting to make one of these for quite a few years. Thanksgiving week finally gave me the opportunity to make one. First, I cut a block out of some steel I got as scrap. Had to buy a new bandsaw blade, as the old one just wasn't cutting it (pun intended).

Next, I made a P.V.C. angle block using my engineer's protractor. Then I set the part in the mill and cut the top and bottom faces parallel. Then I drilled a hole for the HSS tool bit. Plan was to simply file it out square. Unfortunately, my square file leaves far too large a radius in the corners, so I resorted to a combination of broaching using the tool bit and filing with needle files. It was a lot more effort than anticipated, and I have new appreciation for those old time apprentices that had to make stuff by hand.

Next step was to drill and ream a cross hole for the clamp. Then I set it up (as shown in another thread) for cutting the chamfers on the nose. Finally, I stuck it in the soft jaws and filed the whole thing smooth and even, adding the radii where I thought it needed more clearance. A quick wipe on the deburring wheel resulted in this:

Now I needed a way to clamp the tool in place. I decided on split cotters, as they are quick and easy to make, and have a surprising amount of clamping force. This was the result of that endeavor:

And all assembled:

timo_gross · Dec 9, 2024

Did you already try the tool? How does it work?

trlvn · Dec 9, 2024

Beautiful! To get an idea of scale, what size of tool bit is it designed for?

Craig
(PS Great photography. Are you using a light box?)

PeterDRG · Dec 9, 2024

Bravo ! One of my memories of Cherry is being presented of one by her husband, Ivan. He liked making tools.

rleete · Dec 9, 2024

timo_gross said:
Did you already try the tool? How does it work?

Yes, I tried it. Using mild steel, I was able to take a .010" deep cut with no chatter. Very nice surface finish. This is using the standard 7x minilathe.

rleete · Dec 9, 2024

trlvn said:
Beautiful! To get an idea of scale, what size of tool bit is it designed for?

Craig
(PS Great photography. Are you using a light box?)

I use 5/16" tooling almost exclusively.

As to pictures, I use a table saw covered in a sheet of white paper from a poster frame, with an LED light right above it.

kiwi2 · Dec 11, 2024

Hi,
I've had a pair of tangential tool holders from Eccentric Engineering for years and am a big fan. I'm useless at grinding the top relief needed on tool steel cutters for turning steel and used to avoid doing so whenever I could. Grinding the cutters for a tangential tool is dead easy using the Eccentric Engineering grinding jig and now I prefer cutting steel rather than brass.
You (rlete) went to a lot of trouble cutting the square hole to hold the square tool steel cutters. It may have been easier to drill a round hole to accept round tool steel. A round cutter gives a really good surface finish (better than square cutters) but can be a problem if you are turning up to a shoulder. If that is the case, it's fairly easy to cut two faces at right angles on the side of the cutter on the ground end.
I have found that round cutters in a tangential holder are excellent for turning wood. Even cutting across the end grain gives a smooth finish with no tearing out of the fibres. I made a tangential tool (round) holder for my ball turning attachment for making wooden balls which require no further finishing before varnishing.
Regards,
Alan C.

Steamchick · Dec 12, 2024

Maybe I'll make a round tool holder? But as I usually work with around 0.020" ~0.040" radius for corner radii where a square corner is not needed, that would be 1 - to 2 mm diameter tool -- Hmmm, not so good!
But I like your idea for wood. What diameter bit do you use? I have a piece of 1/4" for a tool bit.
K2

kiwi2 · Dec 12, 2024

Hi K2,
I use 1/4" dia. round tool steel to cut wood. The clean cuts you get using a tangential cutter are also useful when cutting threads. I used to have to clean up single point turned threads with a die nut but now they are good to go straight off the lathe.
Regards,
Alan C.

Steamchick · Dec 13, 2024

Thanks Alan, Interesting advice.
Personally, I finish threads with a chaser, as I have a couple of metric (60degree) thread tools, but other threads are not 60 degrees, and my "hand ground tools" are not perfect, compared to the proprietary chasers. (But I rarely need to turn a thread, as I have many dies).
A question. A tangential tool would normally use a square or round tool bit, but for thread turning you must be grinding the tool to the thread angle. Can you post a photo so we can see your tool please, with the thread profile? It will help explain to all I think.
Thanks,
K2

ChazzC · Dec 13, 2024

Steamchick said:
Thanks Alan, Interesting advice.
Personally, I finish threads with a chaser, as I have a couple of metric (60degree) thread tools, but other threads are not 60 degrees, and my "hand ground tools" are not perfect, compared to the proprietary chasers. (But I rarely need to turn a thread, as I have many dies).
A question. A tangential tool would normally use a square or round tool bit, but for thread turning you must be grinding the tool to the thread angle. Can you post a photo so we can see your tool please, with the thread profile? It will help explain to all I think.
Thanks,
K2

Some info from Eccentric Engineering:

https://www.eccentricengineering.com.au/products/diamond-tool-holder/the-diamond-tool-holder

https://www.eccentricengineering.com.au/products/diamond-tool-holder/features-and-tips

Henry K · Dec 13, 2024

The Eccentric Tool holder is great for turning and threading. It clearly put much less strain on the lathe and makes it very good for non professionals. I supervise machine shop labs for a University with a BSME program (among others) and bought 2 out of my own pocket because it makes machining so much easier for the total newbees I have in my labs. (We train degreed Engineers, not machinists)
Threading angle is perfect with included sharpening fixture which has a different setup for perfect grinding of turning tools weather square or round.

Steamchick · Dec 14, 2024

Thanks Henry,
As I made my own (from scrap - cost = zilch!) from simply copying the pictures and making suitable drawings, it works fine. Just like the video. Easy to get the correct cutting top relief using the grinding fixture. Also easy to accurately set centre height. - A novice can learn to do it in seconds? - well maybe a few minutes.
BUT to have a 55degree thread cutting tool would mean grinding the Square to "Something other than 60 degrees" - (Not done the geometry to work it out).
So I was wondering what the "official" way of doing this was... Looks like a different angle tool bit at 1 min.15secs. on the video. The geometry of the tool makes the 90degree square bit into about an 80 degree angle on the job, (7min37secs on Video) so there is side relief from the point. I guess the similar on a 60degree tool would give a 50degree thread?? .... OOOPS! at 8min 24secs he shows how to grind the tool shape to the thread gauge... - Thereby no advantage to grinding and sharpening the tool compared to conventional tool grinding. And the use of the pointed tool bit (from square) is abandoned as the thread tool needs a radius on the point...

BUT I can see an advantage - especially to the "simple" Newby who wants a "tool for all jobs" - until he develops his expertise at making all the specials we end up owning...
https://commons.wikimedia.org/w/index.php?curid=65184789
But if it is adequate for you... Enjoy! After the first year, mine is no longer fixed in the tool post, as I have more specialised tools held there, (Cutting angles for various materials, directions, etc.).
I can do thread cutting with conventional tools, so the tangential tool will not become a Thread cutter in my workshop. And carbide tips are cheap enough and SO accurate! if I want to go that route?).

Thanks for the advice all!
K2

Niels Abildgaard · Dec 14, 2024

There is another way to make tangential holders illustrated from 17 feb 2013 in thread
Tangential holder squeese

or another thread

TanTool

KellisRJ · Dec 14, 2024

FWIW. I use the |Good|Quick|Cheap| you can have any two model. Which two are selected can and does change depending on what I need when and if I have the skills to do what I want. They have changed more now that I'm retired.

I still destroy more material than usable, and for the reasons given above use the tangental tool holders the most, for me far cheaper than carbide inserts and I believe easier on a ~70 year old lathe. For the mill I have, slowy, learned to grind HHS to use in fly cutters.

kiwi2 · Dec 15, 2024

Hi K2,
Here is the Eccentric Engineering instructions for grinding a tangential threadcutting tool.

It uses the sharpening jig

kiwi2 · Dec 15, 2024

Hi again,
Sorry I messed up the last post. As I was saying, it uses the sharpening jig which comes with the holders. I've attached a few pictures of threadcutting tools and a round tool inserted in my ball turner.

Regards,
Alan C.

Steamchick · Dec 15, 2024

Thanks Kiwi,
But I'll stick with the conventional tools and thread chasers I have for thread cutting, as they all work fine.
This is one of those arguments, like guys discussing the merits of automatic and manual transmissions. Both parties are right, for their wants, needs, budget, etc. - Simply a matter of "taste" at the end of the day.
Although I can say "Tangential tool holders are fine!" - for thread cutting and special forms you still have to develop more grinding skills - or buy proprietary shaped tools - to get the special forms.
The big advantage, when you want to buy your FIRST tool, is that it cuts along and across the workpiece with almost no understanding of cutting angles - Thus you don't need "2-tools". And setting the tool to centre height is easy, without buying a set of interchangeable tool holders, etc. - So it becomes the "versatile Universal tool we all desire". - until the day we want something more and buy or develop grinding skills to suit.
As I have boxes of inherited tools, and although I made a tangential tool that does what it does, I find I still use a lot of "regular" tools in a 4-way tool post as that changes quickly, for example when changing from steel to brass workpieces, etc. or a sharp point to radiused tip of tool. What suits one will never suit us all, will it? - So the tangential tool sits idly-by awaiting the day when it suits to re-install it in the tool-post.
Anyone into hand-graving? I.E. just using a hand-held tool, instead of machine mounted and manipulated! A great skill for fine cuts, or special shapes... Pre-dates saddle mounted cross-slides for holding the tools.
https://www.bbc.co.uk/ahistoryoftheworld/objects/Ofj89jJHQbytbQAc2TfDTQ

K2

Richard Hed · Thursday at 12:17 AM

Steamchick said:
Thanks Kiwi,
But I'll stick with the conventional tools and thread chasers I have for thread cutting, as they all work fine.
This is one of those arguments, like guys discussing the merits of automatic and manual transmissions. Both parties are right, for their wants, needs, budget, etc. - Simply a matter of "taste" at the end of the day.
Although I can say "Tangential tool holders are fine!" - for thread cutting and special forms you still have to develop more grinding skills - or buy proprietary shaped tools - to get the special forms.
The big advantage, when you want to buy your FIRST tool, is that it cuts along and across the workpiece with almost no understanding of cutting angles - Thus you don't need "2-tools". And setting the tool to centre height is easy, without buying a set of interchangeable tool holders, etc. - So it becomes the "versatile Universal tool we all desire". - until the day we want something more and buy or develop grinding skills to suit.
As I have boxes of inherited tools, and although I made a tangential tool that does what it does, I find I still use a lot of "regular" tools in a 4-way tool post as that changes quickly, for example when changing from steel to brass workpieces, etc. or a sharp point to radiused tip of tool. What suits one will never suit us all, will it? - So the tangential tool sits idly-by awaiting the day when it suits to re-install it in the tool-post.
Anyone into hand-graving? I.E. just using a hand-held tool, instead of machine mounted and manipulated! A great skill for fine cuts, or special shapes... Pre-dates saddle mounted cross-slides for holding the tools.
https://www.bbc.co.uk/ahistoryoftheworld/objects/Ofj89jJHQbytbQAc2TfDTQ

K2

How much does one of those cost?

Steamchick · Thursday at 3:04 AM

https://www.eccentricengineering.com.au/index.php?option=com_content&view=article&id=32&Itemid=297

The Diamond Tool Holder
The Acute Tool Sharpening System
The Turnado Freehand Metal Turning System
FoR Inverted Parting Tools
The Flexi-Chuck Workholding System
Acute Tool Sharpening System Drawings - Digital download 28 AUD
Metric set of 4x Square Broached inserts. 85 AUD
100mm (4") 7075 Grade Adapter 114 AUD
Myford 7 backplate for Flexi-Chuck. 101 AUD
#4 Morse Taper Back plate 142 AUD
125mm (5") Milling Baseplate 155 AUD
Flexi-Chuck - Starter Kit 405 AUD
FoR12 Inverted Parting Tool Holder with square type shank. 105 AUD
FoR8 Inverted Parting Tool Holder with square type shank. 99 AUD

Convert Australian Dollars into real money, then ad P & P. ... became over £100 for me so I made my own...

BUT I have the inverted parting tool holder, as it is the only one I know that has a Vee-grooved blade. Why?

A single square-ended blade cuts easy materials OK, but is prone to chatter on harder/tougher materials due to the "blunt shape". But has NO side-thrust. So parting is straight. Consider a line set parallel to the machining axis at exactly tool centre height. Full shearing forces across the whole cutting edge.
Carbide inserts can be too brutal on small parts for models too, unless honed to "proper sharpness"... IMHO.
The slight angle of the cutting edge to the centre-line of workpiece causes a tangential cut at the mid-point of contact = "Tangential cutting" which seems easier (to me) when parting-off. But in doing so, a single chamfered tool will develop side-thrust when cutting. I have one, not so good as my Square ended tools. The blade bends under the side thrust so the parting line is not square and this can ruin a workpiece if no allowance for finishing square is made. I prefer a straight "final cut" parting, to just "crude cutting off that requires finishing.
The VEE-shaped tool sold here, has benefits of the angle ground side chamfered tool in that it performs tangential cutting, if the half-way point between end and middle of the VEE is set at lathe-centre-height, but as a vee shape has a left-hand angle countered by a right hand angle, thus neutralising the side thrust. - Positively the best parting tool I have. Worth every penny! It sits permanently on the back tool post and does all the parting work. All other parting tools have become redundant.

K2.

My Take on a Tangential Tool Holder

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