The Home Machinist!

I've read a bunch on this type of tool and holder through searches. It seems like a reasonable way to go, given the simplicity of sharpening. Before I order one of these things, my thick skull needs some penetrating with a couple answers.

They use square tool bits, they are sharpened on quite an angle, 30 degrees I think. So the question is, with that angle of grind, and the tool mounted with the 12 degree rake, will the cutting surface of the tool actually be less than the square tool? Meaning, will it have clearance/relief on both sides if cutting to a shoulder?

And along the same lines, could a bit be "simply" ground so it could be used in regular 60 degree threading?

Thanks.

If you take a square tool bit, stand it up vertically, and cut it on an angle from corner to corner, you end up with a 80° diamond shape if looking down on it, if the angle is then aligned with a horizontal plane.

Is the cutting surface of the one on the left still square when the square tool bit is cut on an angle and tipped so that the top surface is horizontal?



One must have less than 90° in order to use the same tool for both functions unless different corners of the tool are the cutting edges. In this case, the cutting tool is assumed to be a 90° square HSS blank.

If you then properly oriented it in a holder, it WILL turn and face using a square tool bit.

I made one one afternoon out of curiosity just to play with after following a discussion on them.

Might have taken an hour to make from 4140 Pre-Hard Bar. 5/8 shank.







I was not real impressed with the chip control, or lack of, but it was OK on aluminum for light cuts.

Never really used it again.

I will add that I use a six horsepower lathe and mainly indexable tooling, with the exception of HSS form tools, so removing metal has never been a real problem. Using a smaller bench lathe may be where the advantage is with this type of tooling.

Just my $.02

I did a threading one back a few years ago it works BUT you can't get close to a shoulder with
it.
link to a bunch of pix :

http://home.earthlink.net/~lhartswick/Diamond threading tool/

HUMMMM! for some reason the last part of that is not included in the link.
I'll try to fix it.
Even on second try it wont put the - threading tool - in the link Anyone know why it doesn't?
I cut and pasted the link.

http://home.earthlink.net/~lhartswick/Diamond threading tool
I typed this in now to check it
Still won't complete the entire link.
just go to the first part and look for the rest.
...lew...

lew,

It looks like it doesn't like the spaces in the URL.

http://home.earthlink.net/~lhartswick/D ... ng%20tool/

Ed

EdK wrote:lew,

It looks like it doesn't like the spaces in the URL.

http://home.earthlink.net/~lhartswick/D ... ng%20tool/

Ed

Thanks I wonder why the other ones work with a space. I must have typed that entry
somehow different from the others.
Anyway it works the way you posted it.
...lew...

Glenn,

Nice large scale example with the wood.

Here is my version of the tangential tool holder:





The pictures are not that great, and as you will see in the second picture, I got the dovetail on the holder a little over-sized -- but nonetheless, the tool works extremely well. This is the one tool I use 90% of the time.

OK, thanks for the replies. It seems like some people really like the tool held this way and it's performance and some are not crazy about it. I guess that goes for most anything.

The idea of threading with one, and threading to a shoulder seems to be in the position of the tool. Since only the leading edge of the tool cuts while threading, it seems like the tool would have to be reduced in size and the back half ground away. I only need to get as close as about .075' to a shoulder.

I'm still thinking hard about getting one.

Wayne Shaw wrote:I'm still thinking hard about getting one.

If this helps--------I worked in the machining trade for 26 years, non-stop. In all those years, I never once saw a tool like that used. They're not new----they're just not practical. Further, there's nothing particular about them aside from the angle in which the tool is presented to the work. You can duplicate the geometry with a conventional tool easily, plus you have far greater latitude in tailoring the tool to a specific application.

Said another way----take note that Glenn abandoned the use of the one he made. If nothing else, they're too restrictive in their application, and as a bonus, if you can't easily fashion a chip breaker on a cutting tool, it likely is best not used. Once you've received a dozen (or more) stitches because of long stringy chips, that may make more sense.

Harold

Harold, I hesitate to disagree, but ... I respectfully disagree.

There are many things suitable for home shop use that you will rarely or never find in a commercial shop ... starting with HSS tooling!

Yes, you could grind the shape into a conventional tool, but I guarantee that I can grind a new bit for this tool holder a whole lot faster -- and when it comes time to regrind to touch it up, I'll definitely be way faster! And yes, I do grind other tool bits -- many of them, for various specialized needs.

Though the picture above shows a long continuous string, I almost never actually get that kind of chip off this tool. Most of the time I get nice 6's and 9's, or else a tight spiral that breaks off as soon as it gets 1/4 inch long or so.

I certainly respect Glenn's personal experience, but mine differs -- as I said, I use mine 90% of the time. Most of the other 10% is threading -- I don't use this tool for threading, nor do I have any desire to do so. The extra effort to grind it just so would eliminate the whole point of this tool for me.

awake wrote:Harold, I hesitate to disagree, but ... I respectfully disagree.

There are many things suitable for home shop use that you will rarely or never find in a commercial shop ... starting with HSS tooling!

Considering your comments, I agree (although prior to CNC operations, HSS was very much a part of commercial operations, and still is where multi-toothed cutters are concerned (side cutters, for example). I am jaded in that while I operated a humble shop, it still was expected to perform in keeping with industry standards. I tend to avoid tools that can not be applied as one might be expected to. Truth is, every tool has a place, including carbon steel tools.

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.

Harold