Small face mill using tangential cutter

FYI, the spreadsheet I attached to message #3 in this thread calculates the offset needed to get the geometry right for a specified amount of cutter stick-out. More or less stick-out will result in a less-than-perfect cutting situation, but I'm not sure how that will affect actual use. I'd expect tools with a larger machining radius to be less sensitive to this variation.
 
Homebrewed & brino
I have been struggling with the angles, and then I went and took the Diamond Tool Holder off the Lathe and began to play with it so I could more appreciate the Tool bit and the required cutting angles.
Here is another person who has been working with a similar concept.
I found someone who has had a similar idea.
Tangential Flycutter - https://www.hobby-machinist.com/threads/tangential-flycutter.32367/
To obtain the most from the Tangential Cutting tool the cutting force must be against the entire tool and not any of the edges.
This changes the entire view of how the tool interacts with the tool holder, in my idea, the flywheel.
The 12 degree tool angle, at the beginning of this thread is not how I now think I want to pursue.
The 12 degree tool angle is up from the work surface face similar to angle approach in the attached Tangential Flycutter thread.
This changes hot the tool bit clamping method.
 
@courierdog,

Thanks to the link to that thread by @Jim2.
I don't know how I missed it.
I just read the whole thing, what a great build!

The other good news is that he is still active on this forum; so perhaps he would field any of your questions.

-brino
 
courierdog said:
Homebrewed & brino
I have been struggling with the angles, and then I went and took the Diamond Tool Holder off the Lathe and began to play with it so I could more appreciate the Tool bit and the required cutting angles.
Here is another person who has been working with a similar concept.
I found someone who has had a similar idea.
Tangential Flycutter - https://www.hobby-machinist.com/threads/tangential-flycutter.32367/
To obtain the most from the Tangential Cutting tool the cutting force must be against the entire tool and not any of the edges.
This changes the entire view of how the tool interacts with the tool holder, in my idea, the flywheel.
The 12 degree tool angle, at the beginning of this thread is not how I now think I want to pursue.
The 12 degree tool angle is up from the work surface face similar to angle approach in the attached Tangential Flycutter thread.
This changes hot the tool bit clamping method.
Click to expand...
That design stays closer to the geometry associated with a standard tangential (or diamond) cutter. It's a bit puzzling why he didn't get an excellent finish, particularly since his DOC was only .003". It doesn't look like chatter so perhaps his feed rate was a bit too high, but that's a pure guess on my part. I'd ask @Jim F about that, and for follow-on observations on its performance.

Due to the shallow angle you will get a much larger variation in the cutter-to-work geometry if you extend the cutter to get a larger DOC. Tradeoffs....always tradeoffs :)
 
The comments really help me to better understand the Tangential cutting concept better and refocus the effort. The Diamond Tool holder (a Tangential Lathe Cutting Tool Holder) is my starting point for the cutting, sharpening and tool holding process. The originator of the design Des Burke himself went back to basics several times before achieving the current working design. I was directed to this tooling by a video by Rudy Kouhoupt. What has really stuck with me about using this type of tooling is the ease of the initial shaping and routine sharpening of the tool bit material. Turning metal on the lathe using this tool has been reduced to simple steps and I derive a great deal of satisfaction using a simple tool to achieve my desired results.
So after my long winded explanation back to basics, after reading your original article which was well put together and pushed me into actively wanting to have an Mill Equivalent Tool for simple surfacing and edge cutting. The Lathe Tangential Tool has all the forces pushing on the tool bit through its length. The Clamp therefore is only holding the tool against a vertical force pushing down upon the vertical tool Bit (Post) this can be seen in the engineering field of Power Tower design where the individual tower is holding up or supporting the weight of the power line which is horizontal but the weight is directed down vertically on the tower.
The Tangential tool similarly is supported in such a manner as to disperse if you will the force of the work removing the metal pushing directly through the length of the tool bit. This means the tool bit has to be orientated so that the single facet ground onto its leading edge is being supported by it entire length not by any of its sides.
This allows the Tool bit to protrude beyond the clamp (with in reason) without the same risk of collapse as a bit which has unsupported side thrust placed upon the bit. The entire Tool bit length must be positioned behind the ground facet.
I hope this better explains without getting into the mathematics of the thrust forces involved.
Please be patient with and old man and his rambling thoughts
 
Homebrewed and Brino:
I really appreciate your comments as it helps me to better understand the mechanical concepts. While I did have to study some mechanical engineering my focus was on Electrical and even then more on the RF broadcasting and later Antennas in particular. The entire amateur machining is new and very exciting to learn new (old to most here) things to me. Learning is a life process and you both are very helpful to an old man groping his way along.
 
Always willing to help when I can! And I am always are ready to say: "I don't know", rather than to make wild-ass guesses.

I'm learning too, and this is a great place to do that. One thing I've been impressed by is the sheer range of knowledge you can find here. And so freely given. Astonishing. There are those who hoard their knowledge as something to be doled out to the privileged few. My lifelong philosophy has been: there are no secrets that divide us. Only differences in the individual's ability.

Mark
 
Mark:
A man after my own heart. What I have seen so far is the experienced people take time to assist people coming into the hobby so they are able to develop their skills and use their mini machines to achieve more than what was originally envisioned by the Machine builders. Forums like the Hobby Machinist are a pleasure to read and join as I have not seen any form of actual or implied intimidation.
I have been attempting to work through the design and figurative build of a Fly Cutter as an inexpensive and achievable tool build using HSS tool steel as the cutter. My prime interest is devising a tool using the simple Tangential Tool. My reason again is simplicity of the shaping and sharpening of the tool bit. There is more design involved in the tool holder however this is offset by the simplicity of actual day to day use in the hobby shop.
The secondary article I also found on the Hobby Machinist forum illustrates the Tangential Tool holder I am used to in the Diamond Tool Holder. Jim in his Tangential Fly Cutter places the Tool cutter in the same manner as the Diamond Tool Holder.
I received the call to go to bed so I will sign off for now and come back in the morning to continue my thought.
Again thank you for your patience and helpful comments
 
Rambling thoughts on how to make a 90 degree V slot in 1/2 of a 1" diameter rod.
Required: square collet block & collet
Make the parts longer than needed and bring to length as a final operation.
With enough rod sticking out of the collet block, mount in the mill vice.
Touch off on the top of the rod. Machine away 1/2 of the rod diameter.
Rotate the block 90 degrees and mill the V. Saw the first piece off.
Repeat the process for the 2nd piece but do not cut it free from the rest of the rod.
The loose piece can now be stacked on the still connected piece and put back in the collet. Leave the bottom part sticking out from the other part enough to be able to indicate it square to the mill. The extra length of rod sticking out the back of the collet will allow you to twist the slightly snugged parts square to the mill. You can now drill, tap & counterbore for one of the screws that hold the two halves together. Put that screw in.
The screw(s?) to clamp the tool bit in place can now be drilled and tapped to hit the corner of the tool bit.
Cut the parts free and rotate to put the other clamping screws in. You can use the tool clamping hole as a reference back to square.
Finish the ends. Optional? Using the hex collet block put wrench flats on the top of the sleeve that sticks above the main disc body to allow the tip of the tool to be rotated for best finish. (I'm assuming this sleeve is being clamped into the main body so it can be adjusted.)

The sleeve for the round tool bit can just be drilled, reamed, drilled for clamping screws & slit.
Having some sort of indexing marks on the sleeves relative to the body would make life easier.
Any possibility that this would work?
 
LarryS
Excellent approach, I have had more time to digest the various comments and suggestions. the interior Round Clamp should have the minimal material to for the clamp on a piece of HSS Tool Stock, worst case is the 1/2 in stock and the interior square clamp is cut depending on the end users cutting tool requirement. We have to keep in mind the interior clamp need only be large enough to hold the tool stock as the clamp which really the large Flywheel and can comprise of one or two screws squeezing down upon the inner circular clamp.
The Tangential tool alignment I have been reminded is 12 degrees tilt up from the Horizontal not as I had first thought of as 12 degree down tilt from the centre line of the vertical mill Spindle.
So this puts most of the actual tool inside the Flywheel where it cannot be seen from the exterior.
My approach is to drill this 12 degree through the exterior of the flywheel.
This approach is for two reasons.
1. the Tangential tool angle
2. hide the entire cutter and interior clamp within the flywheel.
3. the flywheel will be cut along the drilled hole for the cutter clamp
Keep in mind this is all in the wetwear of the mind at the moment and as anything in there is subject to erasure at the slightest disturbance in the blood flow. ha ha I have to blame the unreliable memory and poor thought process on something. ha ha
Once I begin cutting in metal many of the great ideas vanish at first contact.
The idea of the nominal 6 inch cutter came originally from the LMS Specifications of 2 inch maximum, having come from the old school of single cylinder motorcycles where the flywheel was as physically large as possible and twice as heavy as required.
When you geared down these beasts you were virtually dragged to a halt. The reverse is also true any instantaneous speed change was resisted with equal force. This is why the old steam powered engines had massive flywheels. The purpose was to have a constant speed. Take this idea and think now of the Brushless motor. which is great at high RPM but has very low torque at Low RPM. Hence use a large massive flywheel which is keep at speed by a powerful but low torque motor. So once the Flywheel is running at speed any attempt to slow it down, the interrupted cut of the flycutter will be resisted by the inertia of the flywheel, and those that worry about the spindle bearings and the interrupted cut pounding on the bearing, this effect as well is minimized by the inertia of the flywheel. While this approach is contrary to todays high speed and carbide insert mentality the physics is sound and if one has the applied math to calculate out all the forces at work you will find good old flywheel mass wins out over momentary attempts to slow it down. For other example of the Flywheel approach is to analyze the industrial age factory where one small steam powered engine supplied power to one central massive flywheel which intern drove many shafts with additional flywheels and take offs to provide an entire factory with a centralized spinning source of power and each take off required different speed and amounts of power which was constantly changing yet the main powered Flywheel was held constant by one single small motor.
This is jut my attempt to turn back the clock so to speak to achieve with our tiny Mini-Mills a smooth cutting cutter capable of producing with minimal tooling and cost what the higher speed and expensive insert tooling can do.
Yes this approach can be taken to far but remember this is a hobby and not a commercial venture.
Plus any who think time is not valuable to a retired person had better realize we have far less time to spend than younger people so yes ever second does count. some spend their resources as money we spend a finite unit of time.
Thanks for Listening to an old man
 
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