Tangential threading tool?

Re the tool mounting angle required, as shown in post #6, I'm thinking the reason no one has done it before is that the relief angle under the tip would be so much that it would be too fragile.

There's the criticism I've been looking for.
tool holder threading assembly v4.png
It's quite a bit, yes.

Another option is to grind an entire blank into more of a diamond. The tool would then be held more vertically; it wouldn't have to be leaned over as much to achieve the 60 degree inclusion angle.
This would be a bit more up-front work, but regular grinding will be just like any other tangential tool.
 
Stronger you say? Please explain. The cutting forces could push the bit right out of the holder. Or, did you mean the tool bit is at a stronger position?
For a full explanation look up eccentric engineering Diamond tool holder, they explain with pictures.
 
I was putting together a design for a tangential turning and facing tool holder and was curious if the tangential design could be leveraged for threading. I understand that a regular tangential tool holder can be leveraged for threading by cutting additional angles to the tool. That's not what I'm after. I did some sketching in Fusion 360 and found that if you angle the tool from corner to corner about 35 degrees then the included angle of the sides is just under 60 degrees.
I haven't seen this done this way, but I haven't looked too deeply. Am I missing something? Am I looking at this correctly?

I understand what you are trying to do. Not sure if it will work, I suspect that the angle of the tool bit to vertical will be such that the tool bit will suffer from lack of support under the cutting edge, can you show in fusion the tool bit at this angle from different sides. But good luck.
 
I have been making metal chips longer than I want to acknowledge. I have been using an Aloris tool holder for many decades. I use Super MO Max tool bits most of the time. And contrary to standard grinding practices, I do not grind the face/top of the tool bit. Why you ask? Because it makes it much easier to re-grind/re-sharpen. Yes, it does not help in a better cutting action and requires more HP. But I’m very happy with status quo. I have found that the simpler is the better! All this typing is hinting;)…Dave
 
I have found that the simpler is the better!

An effective tool requires certain angles. Certain of these angles can be built into the tool holder. A certain amount of flexibility in angles is advantages. There's a balance between ultimate flexibility and having all the angles built in.
 
My vote is with the threading tools that Aloris makes; they are simply sharpened on top and are adjustable for helix angle AND, they last for a LONG time with normal use; they also make cutters for acme threads.
 
A threading tool requires that the Cutting Edges form the thread profile, if indeed the relief angles are insufficient the non cutting part of the tool will rub on the flank of the thread. in the case of a high helix angle thread with a small TPI such as 16 TPI with a lead of .250" you will either have to rotate the tool to somewhere near the helix angle or use large relief angles.

Large angles result in very sharp tooling, very sharp tooling does not last long in many materials as noted above. If you do not want to do the math yourself the helix angles by diameter for thread leads are available in table form in MH.
 
I was putting together a design for a tangential turning and facing tool holder...
t if you angle the tool from corner to corner about 35 degrees then the included angle of the sides is just under 60 degrees.

That's part of what you want in a threading tool; you'd also want a chip breaker behind the cutting edge (usually the left
edge cuts, the right edge just slides deeper). As sharpening tasks go, making a threading 60 degree
tip on HSS is pretty easy, though. And a conventional 60 degree sharpening puts about 7 degrees
clearance underneath (not 35), so it's a well-supported working edge.

The blank has to be accurately square, for this to work well; how good ARE they?
 
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