Another Reason to buy or make a diamond tool holder

[cfellows]

For those of you who have been riding the fence on how useful a diamond (tangential) tool holder is, maybe this will win you over. I saw on another website, can't remember which one, where a fellow had ground a round 1/4" HSS toolbit at a 30 degree angle and mounted it in his tangential tool holder. The result was the ability to make cuts similar to the small, round carbide inserts.

I thought it was a great idea, but my homemade tangential tool holder won't hold a round tool bit, so, I chucked up a 1/4" square high speed steel bit and turned the end of it round with a carbide cutter. A toolpost grinder would have worked as well. The result is about as slick as can be. Here are pictures of the cutter mounted in the tangential tool holder and several of the cuts I made in brass.

Chuck

 

[Blogwitch]

Very nice Chuck, and very rarely do I fault your work.

Because the cutting face is on an angle, and not flat, your cutting profile is in fact an elipse, not a true circle. It might be OK for getting nice surface finishes, but could give some weird results if you tried to use it for profiling, where a true arc usually looks and blends in perfectly.


John

 

[Nickle]

Looks Great Chuck. I was thinking of trying this style of tangential cutter myself. I was intending to drill holes on the appropriate angle in a block for a toolholder and start using up my stash of old drill bits. Like John says, it wont cut a perfect circle but it should give you a great finish.

Cheers,

Nickle

 

[New_Guy]

its an oldy but a goody i got a Herburt or a Ward tooling catalog from the 40s awhile ago, they had tangent holder and they were far more technical than what you can get these days incorporating a screw to adjust center height and came in square, round or triangular carbide blanks

by the way i love the simplicity of using carbide to turn HSS "i cant do this because i have no long series tap" no problem turn the clearance yourself on a gun tap Thm: so simple i love it!

 

[Lew Hartswick]

I did some playing around with those a few years ago. If you'd like to see them check:
home.earthlink.net/~lhartswick look at the two Diamond --- There are a couple files
that got put in the wrong folder but ignore them. Someday I'll fix that.
...lew...

 

[cfellows]

Very nice Chuck, and very rarely do I fault your work.

Because the cutting face is on an angle, and not flat, your cutting profile is in fact an elipse, not a true circle. It might be OK for getting nice surface finishes, but could give some weird results if you tried to use it for profiling, where a true arc usually looks and blends in perfectly.


John

Hey John, didn't really think of this as criticism so much as an observation. I did realize that the cutting edge reflects an elipse rather than a circle. Although there are occasions where a circular profile is required, in many cases, for me at least, an eliptical profile will work as well. And, as you stated, it still gives a very smooth finish.

Chuck

 

[Omnimill]

I made my first tangential tool holder and it works great but I also ended up buying one and this takes round HSS as well as the square stuff. It does, as you say make very nice finishing cuts Chuck.

Vic.

 

[FIXIT]

Looking with interest at this type of tool holder i think i will also make one as i think that it would be a little more rigid than the standard one on the Taig,

I don't have a QCTP as it's just as easy to change the whole thing , as its basically only a one inch square bar and i have made about eight of them allready with various tools setup in them with one having a 'boat' so it;s easily adjusted.

Anyway back to the thread , it looks to me that the cutting force would be directed at a down angle rather than the conventional 90 deg angle through the tool and post reducing the 'spring in the little machine.

So! thanks for the pictures Chuck and please comment on anything you think i also should look out for and advise me of the angle the the tool is in the post.


Vic where did you perchase your one.


Any comments from anybody else would be more than welcome.


Steve

 

[cfellows]

Here's a link to a build article for the tangential holder. Or you can just do a search for "tangential tool holder"...

http://www.gadgetbuilder.com/ToolHolders.html#Tangent

I used the angles suggested by the build article - 12 degees to the side and 12 degrees front to back. You can do it one of two ways and I've done it both ways. You could first mill the whole side of the blank to a 12 degree slope, then cut a slot 12 degrees back from the front into the sloped side. Or you could first mill the entire front to a 12 degree slope, then cut the slot 12 degrees to the side. The clamping screw will need to be on whichever side you mill the slope on.

Chuck

 

[owenh]

hmmmmmmmmmmmm I wonder how small a piece of round the commercial tangential holder will grip? must find out. A bit of drill rod of the right size hardened up to cut whatever sized radius. I wonder if a negative rake would cut brass? then the arc would be a true circle. You never know where an idea is lurking, just what I like about these sites.
Owen

 

[shred]

I suppose if you really needed a circle, you could turn a ball on the end of the cutting bit, then carefully grind that halfway down. If I remember my geometry, any planar section through the center of a sphere ought to be a circle. That seems like a lot of work, there's probably an easier way to generate it.

 

[Omnimill]

Here you go Steve:

http://www.eccentricengineering.com.au/index.php?option=com_content&view=article&id=2&Itemid=17

They have a UK agent now so no import duty etc to worry about.

The only problem I had was that I sharpen all my tools on a belt sander and the supplied sharpening jig is for a bench grinder, luckily Chuck also sharpens his tools on a belt and published details of his tangential grinding rest/jig on this forum - Thanks Chuck! Thm:

Vic.

 

[steamer]

Hi Chuck,

What kind of carbide are you using to cut HSS? edge geometry...ect. enquiring minds want to know....ie I would love to do that.

Dave

 

[Tin Falcon]

Lathes and lathe work
Paul Nooncree Hasluck
http://www.archive.org/details/lathework01haslgoog
talks about those tool holder IIRC on page 437
Tin

 

[Niels Abildgaard]

Another home-made tangential tool.
Cheap and much stiffer than anything comercial

 

[cfellows]

Hi Chuck,

What kind of carbide are you using to cut HSS? edge geometry...ect. enquiring minds want to know....ie I would love to do that.

Dave

Dave, the carbide inserts are TPG321 or TPG322. The 1 or 2 on the end signifies the radius of the cutting tip, 1 being the smaller radius. These are triangular, with positive rake and can only be used on one side. There is no center hole so they have to be held on with a clamp. I made my own holders and buy up the inserts on ebay whenever I can find a deal. They are usually pretty inexpensive. I've also bought a bunch of reground inserts which work well and were cheap.
Chuck

 

[cfellows]

Another home-made tangential tool.
Cheap and much stiffer than anything comercial

I like that. What is the angle, front to back that holds the insert?

Chuck

 

[Niels Abildgaard]

15 Degree

 

[f350ca]

Hi
New here, a great wealth of information and ideas.
Has anyone tried making a tangential tool holder to use in a shaper. Would seem to be a natural, with built in back rake.
Might need to use Niels clamping method to with stand the cutting forces.
Greg

 

[Dan Rowe]

Greg,
I just gave my commercial tangential holder a try in the shaper and it works great. It never occurred to me to try it.

Thanks and welcome to the forum.
Dan