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Tangential threading tool?

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burdickjp

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#1
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?
 

chips&more

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#2
I believe the tangential turning idea you are referring to is a great idea and believe it’s more for the folks that have a hard time sharpening their tool bits. So it’s basically just a grind on the top. For a threading tool, the sides would also need to be ground for the correct 60° angle…more grinding. Maybe just punt and grind a normal threading tool?...Dave
 

Downunder Bob

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#3
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?
The Diamond tool holder by Eccentric engineering claims to be able to be used for screwcutting, but I gather you do need to grind extra angles on the toolbit, but I think they provide am gauge for this.

can you post a pic of what your proposing, might help to see if it will work, can't visualise it. Pity they don't make triangular HSS tool bits, there's your 60 deg. right out of the box.
 

Dave Paine

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#4
The Diamond tool holder by Eccentric engineering claims to be able to be used for screwcutting, but I gather you do need to grind extra angles on the toolbit, but I think they provide am gauge for this.

can you post a pic of what your proposing, might help to see if it will work, can't visualise it. Pity they don't make triangular HSS tool bits, there's your 60 deg. right out of the box.
I also am not sure of the proposed design without a picture.

In the US A.R. Warner makes HSS triangular inserts for their tools. Some are for threading.

A.R. Warner inserts page
 

Downunder Bob

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I believe the tangential turning idea you are referring to is a great idea and believe it’s more for the folks that have a hard time sharpening their tool bits. So it’s basically just a grind on the top. For a threading tool, the sides would also need to be ground for the correct 60° angle…more grinding. Maybe just punt and grind a normal threading tool?...Dave
It's not really for "folks that have a hard time sharpening their tool bits". It's more about a better way to use and hold your toolbits, Sure the grinding process is much quicker and more simple, so it saves time even for those that do know how to grind them. holding a tool bit tangentially is a much stronger way to hold it.

The forces on the tool bit are longitudinal rather that transverse, in normal turning the force is trying to bend the tool bit and break it, In a properly made tangential holder the force if excessive will just push the tool down into the holder rather than break it.

Being stronger it allows you to change from say a 3/8 tool bit to 1/4 saving considerable cash and even more grinding time. you can even use odd pieces of round tool steel such as broken center drills, etc.
 

burdickjp

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#6
I am a fan of A R Warner's stuff, for sure.

Here's a view of the toolholder. I've set it up to be able to rotate to accomodate helix angles, but I'm starting to wonder if it's necessary, and recognizing that rotating to accomodate helix angles will inevitably change the inclusion angle, which defeats the whole purpose of doing it this way.
tool holder threading assembly v4.png

Here's a top view:
tool holder threading assembly top view.png
 

Downunder Bob

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#7
I am a fan of A R Warner's stuff, for sure.

Here's a view of the toolholder. I've set it up to be able to rotate to accomodate helix angles, but I'm starting to wonder if it's necessary, and recognizing that rotating to accomodate helix angles will inevitably change the inclusion angle, which defeats the whole purpose of doing it this way.
View attachment 270534

Here's a top view:
View attachment 270535
Looks to me you're over complicating the idea, and kinda defeating the purpose, have a look the Diamond tool holder from eccentric engineering to see how it's done. .eccentricengineering.com.au
 

burdickjp

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#8
I'm aware of the diamond tool holder from eccentric. It is a turning and facing holder and the angle the tool is held is optimized for turning and facing. I'm looking for a dedicated threading holder which means the lean angles of the tool can be made more for threading. The square can be leaned over until the adjacent faces are at a 60 degree inclusion. The tool can then be ground with whatever top rake is necessary.

I'm doing a little bit of modeling and I don't think the tool should have clearance for that without tipping.
 

chips&more

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#9
It's not really for "folks that have a hard time sharpening their tool bits". It's more about a better way to use and hold your toolbits, Sure the grinding process is much quicker and more simple, so it saves time even for those that do know how to grind them. holding a tool bit tangentially is a much stronger way to hold it.

The forces on the tool bit are longitudinal rather that transverse, in normal turning the force is trying to bend the tool bit and break it, In a properly made tangential holder the force if excessive will just push the tool down into the holder rather than break it.

Being stronger it allows you to change from say a 3/8 tool bit to 1/4 saving considerable cash and even more grinding time. you can even use odd pieces of round tool steel such as broken center drills, etc.
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?
 

higgite

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#10
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.

Tom
 

burdickjp

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#11
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.
 

Downunder Bob

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#12
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.
 

Downunder Bob

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#13
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.
 

chips&more

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#14
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
 

burdickjp

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#16
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.
 

benmychree

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#17
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.
 

P. Waller

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#18
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.
 

whitmore

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#19
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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