Tangential Tool Holder

[DiogenesIIParticipant @diogenesii]

Good morning,

I had some success measuring and milling yesterday, and some failure with surface finish.. ..unfortunately, the tedious responsibility of "work" intrudes today, I will post some photo's and a fuller text this evening.

[DiogenesIIParticipant @diogenesii]

..parting a slot – now that is scary! ..I'll stick with a slitting saw..

[old martParticipant @oldmart]

There is a YouTube video of either Sandvik, or Kennametal demonstrating parting off a section of railway line in a lathe. Personally, I wouldn't have the nerve to try it.

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by DiogenesII on 08/06/2020 08:30:30:

..parting a slot – now that is scary! ..I'll stick with a slitting saw..

 

You aint seen nothing yet

It has tasted a 12.9 screw and chatters at lower work rate than my 2times 2 square versions.

The distance from front bearing to work area is far to long.

Bigger spindle and shorter overhang before making final verdict.

Edited By Niels Abildgaard on 08/06/2020 18:47:19

[old martParticipant @oldmart]

Makes me glad to have the use of two mills, although not while the lockdown stops the museum from opening.

[DiogenesIIParticipant @diogenesii]

Bah – 9 humid hours of clipping Buxus Sempervirens, followed by the infuriating agony of "Microsoft Photos" mysteriously re-materialising on my PC and sending two years worth of pictures that MS didn't know I had back to Silicon Valley, presumably to be inspected for any identifiable brand logos and the faces of people who might be on my contact list.. Wish you joy with that..

So where were we? ..I used Niels' method of turning a cylinder of known radius and a feeler gauge to establish that the surface of the Hobbymat slide is 10.07mm (THAT much wear, eh?..) below centre-height – milling the toolholder to this height, so that the point of the toolbit can now be set by turning the holder upside-down on a flat surface..

I think I will accept Niels' challenge and make a dedicated holder to fit the Myford – I'm sure that I will not win a straight race, but maybe I can cheat, or think of an even more outlandish set-up.

I really need to get some new toolbits ordered – the small HSS drill-shanks are coming to an end, and because most have been used/chewed, I notice that although the overall surface finish is okay, using magnification shows that "Edison Phonograph Cylinder" effect.. Stoning, testing & stoning "old" 2mm rounds is one of those things that life may be too short to be doing much of.. I'll have to sell my television or something, and buy a 2 x 100mm stick of carbide. And a quality pin vice, maybe..

How and what do you sharpen your toolbits on, Niels?..

What a day..

 

Edited By DiogenesII on 08/06/2020 22:58:57

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by DiogenesII on 08/06/2020 22:56:08:

How and what do you sharpen your toolbits on, Niels?..

Edited By DiogenesII on 08/06/2020 22:58:57

There is a picture of sharpening here and stone is a carborundum or silizium carbide and not expensive,but diamond in some form is better.

Tangentials

[Jouke van der VeenParticipant @joukevanderveen72935]

Posted by Niels Abildgaard on 07/06/2020 10:40:18:

Concerning round tangential toolbits.

It was tried with 3,4 and 6mm round carbide and flat top on mild steel.

It worked very well until depth of cut was equal to radius of toolbit ,that is 1.5 and 2 and 3mm.

The cutting edge was much more robust than any of my homebrewed square things.

Interupted cuts,cast iron skin etc

For our small lathes there is no reason to opt for bigger toolbits as 1 to 2mm depth of cut is power limit anyway

Niels,

Could you explain why the depth of the cut can not be deeper than appr. the radius of the toolbit? I expect that you mean that cutting a depth of, lets say 2mm, will be done in more steps.

I intended to use some kind of tangential tool holder to cut a radius in a home made milling cutter for clock wheels. For this I have to go deeper than the toolbit radius.

When you start with a toolbit with known diameter and you place it in a holder under a known angle to the vertical then the small radius of the horizontal elliptical cross section of the toolbit is exactly defined. Of course, this radius is not constant moving along the circumference of the ellips but it varies only a bit for a substantial angle.
This could be a way to machine a well known radius in a work piece (e.g. milling cutter). For me it worked in brass but not so good in silver steel (to be hardened later on). Perhaps a tungsten carbide toolbit is a better option.

Regards,

Jouke

[Jouke van der VeenParticipant @joukevanderveen72935]

was double

 

 

Edited By Jouke van der Veen on 09/06/2020 10:39:29

Edited By Jouke van der Veen on 09/06/2020 10:40:04

Edited By Jouke van der Veen on 09/06/2020 10:40:30

[Jouke van der VeenParticipant @joukevanderveen72935]

This was the “trial” tangential cutter I used. A toolbit of silver steel in a brass tool holder. Angle of toolbit and diameter were chosen to get the desired cutting radius. I used it in an Emco Compact 5.

Edited By Jouke van der Veen on 09/06/2020 11:14:03

[Niels AbildgaardParticipant @nielsabildgaard33719]

Niels,

Could you explain why the depth of the cut can not be deeper than appr. the radius of the toolbit? I expect that you mean that cutting a depth of, lets say 2mm, will be done in more steps.

There is an old thread that have pictures etc.

I tried 6mm carbide and allwent well untill 2.5mm depth of cut.Then lathe was not really up for more.It was therefore reasonable that a 3mm tool should be able to do 2.5mm wide also from a lathe power viewpoint.

That might have been the case put cutting was not possible.Noise was unpleasant,swarf curled wrong and it had to stop.

Doing 1.5mm and down it was pure music

Round tangential tool limits

[Leo F Byrne 1Participant @leofbyrne1]

I have a tangential tool holder from Eccentric. Wouldn’t be without it.

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by Leo F Byrne 1 on 09/06/2020 13:29:28:

I have a tangential tool holder from Eccentric. Wouldn’t be without it.

What lathe do You have?

It could be fun if someone will try and compare with my homemade.

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by Jouke van der Veen on 09/06/2020 11:13:11:

This was the “trial” tangential cutter I used. A toolbit of silver steel in a brass tool holder. Angle of toolbit and diameter were chosen to get the desired cutting radius. I used it in an Emco Compact 5.

Edited By Jouke van der Veen on 09/06/2020 11:14:03

Jouke

Interesting,but why so much tilt on toolbit if You can make it to any diameter,as I asume You can from the photo?

Your Emco spindle has what I ,after much consideration and not much expirience, consider the best way.

Three or four screws through chuks to front of spindle.

Very short ,strong,safe and fast to change.Whats not to like?

[Jouke van der VeenParticipant @joukevanderveen72935]

The toolbit + holder shown in the picture have the following dimensions (I just measured):

Diameter at top: 4.5mm

Angle from vertical: 26 degrees

These values together define a defined minimum radius of the horizontal ellips at the tip of the toolbit. I have to calculate it again to achieve the required radius I wanted some years ago.

So, by choosing a combination of diameter and angle you make a required tip radius in the horizontal plane. You set the top of the toolbit at center height to cut the required radius

I tried to use this tool to cut a radius in the corners of a disc blank. The first step in making a milling cutter. The problem was that it did not cut so well and I stopt wit it.

A different approach would be to braze a carbide ball with a diameter more than 2x larger than the required radius on the tip of steel toolbit and then grind the ball down to below center to the height with the required radius.

[DiogenesIIParticipant @diogenesii]

Posted by Niels Abildgaard on 09/06/2020 06:49:35:

Posted by DiogenesII on 08/06/2020 22:56:08:

How and what do you sharpen your toolbits on, Niels?..

There is a picture of sharpening here and stone is a carborundum or silizium carbide and not expensive,but diamond in some form is better.

Tangentials

Thanks for that, it is much as I thought, except that on Sunday I hadn't thought of, er, the high-level advanced technique of using a strip of abrasive paper.. you clearly have more of a head start than either of us ever imagined..

And still I can't find a day to make chips. Work is the curse of the Model Engineering classes..

[Jouke van der VeenParticipant @joukevanderveen72935]

Posted by Niels Abildgaard on 09/06/2020 11:59:45:

There is an old thread that have pictures etc.

I tried 6mm carbide and allwent well untill 2.5mm depth of cut.Then lathe was not really up for more.It was therefore reasonable that a 3mm tool should be able to do 2.5mm wide also from a lathe power viewpoint.

That might have been the case put cutting was not possible.Noise was unpleasant,swarf curled wrong and it had to stop.

Doing 1.5mm and down it was pure music

Round tangential tool limits

Niels,

I have to read this thread all through. It contains a lot of information.

Probably, you are right that the angle I had chosen (26 degrees) was to large. Making it smaller (more vertical) gives an ellips closer to a circle and the tip angle constant for a larger angle along the circumference of the tip.

[JGParticipant @jg22384]

Jouke's intention of making horological cutters is appealing.. might be the temptation I need to finally make one (once some other projects are finished).

In terms of the maximum cutting loads / depth, I'll just see how the thread progresses (that's likely to be sooner than I can make one).

[DiogenesIIParticipant @diogenesii]

Hi Jouke, and JG – thanks for your interest.

I think in brief, that cutters will only have longevity in harder materials if the edge is kept within quite a narrow range of angles maybe only a couple of degrees either side of about 12 from vertical – less and the tool may start to rub, more and the edge becomes too thin and will lose strength.

I'm unable to contribute much to the thread during this week in any case, so if anyone wishes to experiment and post their own findings, it will be both interesting and helpful in keeping the thread progressing..

regards D

[Niels AbildgaardParticipant @nielsabildgaard33719]

I hadn't thought of, er, the high-level advanced technique of using a strip of abrasive paper..

 

 

Diogeness reminded me of something I had forgotten.

In 2012 I fooled around with a square cutting material called Tantung(Stellite) and rounded the active edge to be, with abrassive paper with Corund/aluoxide.

Worked very well but it was important that the rounded edge was polished afterwards along the edge for better resistance to chipping.

Very precise rounding of edge

I am all Tungstencarbide now and wonder where I can buy abrassive band with Carborundum/SiliziumCarbide that can repeat that stunt .

Carborundum or silizium Carbide is much harder than aluminium oxide or corund that do not touch Tungsten Carbide .

Ebay also mention bands with Zirkonia as abrassive.

Is that hard enough to grind TungstenCarbide?

Edited By Niels Abildgaard on 10/06/2020 08:29:26

Edited By Niels Abildgaard on 10/06/2020 08:32:33

[AdrianRParticipant @adrianr18614]

What about diamond paper? **LINK**

Adrian

[SillyOldDufferModerator @sillyoldduffer]

Posted by AdrianR on 10/06/2020 08:43:50:

What about diamond paper? **LINK**

Adrian

+1 That's the stuff

Zirconia won't do – it's only as hard as a steel file, and softer than Carborundum. Tungsten Carbide is a step harder above Carborundum. I think only Diamond and CBN (Cubic Boron Nitride) will touch TC.

Dave

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by AdrianR on 10/06/2020 08:43:50:

What about diamond paper? **LINK**

Adrian

Thank You.

Never seen it before

Will try

[Jouke van der VeenParticipant @joukevanderveen72935]

Round tangential tool limits

Niels,

I have to read this thread all through. It contains a lot of information.

Probably, you are right that the angle I had chosen (26 degrees) was to large. Making it smaller (more vertical) gives an ellips closer to a circle and the tip angle constant for a larger angle along the circumference of the tip.

Niels,

I went through the thread above and I think I understand now what you mean by a depth of cut not more than half the diameter of the toolbit. But I have a question which I hesitate to ask.

When I look at your pictures It looks to me that you make, as an example, a depth of cut of 1.5mm, measuring in the axial direction of the lathe And you feed in the radial direction by movement of the cross slide. So, I would mention it a radial feed and not an axial feed. But I may be completely wrong. Please, could you clarify this?

Jouke

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by Jouke van der Veen on 10/06/2020 20:05:53:

Round tangential tool limits

Niels,

I have to read this thread all through. It contains a lot of information.

Probably, you are right that the angle I had chosen (26 degrees) was to large. Making it smaller (more vertical) gives an ellips closer to a circle and the tip angle constant for a larger angle along the circumference of the tip.

Niels,

When I look at your pictures It looks to me that you make, as an example, a depth of cut of 1.5mm, measuring in the axial direction of the lathe And you feed in the radial direction by movement of the cross slide. So, I would mention it a radial feed and not an axial feed. But I may be completely wrong. Please, could you clarify this?

Jouke

What is Your difficulty with depth of cut being either radial or axial ?

Some videos here show both axial and radial .

My feeling is that a 2mm square can cut 1.9mm deep and a 3mm round only 1.5 or somewhat less.

Enjoy some cutting phornography.

Carbide phornography.

[Author]

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