Thread Cutting Tooling

[Big Al]

Yep that will be you moving the goal post again....

 

Now you accuse me of knowing nothing of the subject matter, fine, but tell me where you YouTube clip addresses suitability for manual machines? It doesn't? Seems ok for you to refer to a YouTube clip but not me ?

 

I was originally trying to adress the misconception that setting the compound over makes the tool tip cut on one side only - it doesn't. The tip still cuts on both sides as demonstrated by the clip I linked to, the one you choose to dismiss.

 

I don't deny the reference bullet point you use in your last post but your clip also high lights the use of incremental feed and radial feed so really all techniques have their merit and like I said in a much earlier post, you have to choose the tip and techniques suited to the work piece.

 

We are obviously not going to agree so crack on and use what works best for you and good luck.

 

 

Had you ever considered a career in politics, I think you would be well suited.

[MJR]

When people can no long support their argument or point of view with well balanced, reasoned logic they often resort to personal insults and innuendo.

 

Crack on canny lad, you've been rumbled....

[lee w 118]

Had you ever considered a career in politics, I think you would be well suited.

You can cut a thread for me any day Alan , Lee

[bradders]

[MJR]

Cousins Bradders?

[bradders]

No, the one on the left looks like a Benchrester while the other two look like they dabble in F class

[Breacher]

No, the one on the left looks like a Benchrester while the other two look like they dabble in F class

I thought at least one would have been a bipod user.......

[MJR]

Look more like mag resters to me but hey ho.

[Big Al]

When people can no long support their argument or point of view with well balanced, reasoned logic they often resort to personal insults and innuendo.

 

Crack on canny lad, you've been rumbled....

 

 

With respect MJR I can't continue to debate with you because you respond very much like most politicians, you duck the pertinent points and come back again with smokescreens. I honestly believe you know a little on this subject but not a lot and we all know how dangerous a little knowledge can be. I have given you facts and simple to understand drawings which are supported by major well respected names in industry yet you choose to ignore them and quote some random Youtube guy as your source of fact. Come on lad, even those who dont really understand the subject matter have contacted me today to ask what your on?

 

Im more than man enough to admit if Im wrong, quote me facts to support your thinking based on information from credible industry sources like I did and I will gladly listen. I will be grateful if you can find me anything I didn't already know but again with respect I dont think you will.

 

Go back and read my post 23. The one where I point out how you grabbed the wrong end of the stick with one point and then suggested we have all worked under a misconception all our lives on another. Show us all clear concise industry recognised evidence to support your claims, no more of this American Youtube nonsense, for me to take you seriously I need to feel you know what your talking about, at the minute I dont think that at all, I just see a guy back peddling and trying to blur as much of the discussion as you can so it goes away.

 

I can't really debate with you any further because your not bringing any new or different theory or evidence. As such when I try to leave the discussion with a quip you try to turn it back on me and suggest Ive been rumbled which is just silly.

[MJR]

Al you are driving yourself nuts going round in circles. Go back and re read what I said. Setting the compound over still allows the tool tip to cut on both sides by the depth of cut, it has to to remove the material.

 

So let me ask you a question. You set the compound over, touch off on your workpiece to zero, back out and then advance your compound to make the first cut. Engage the half nuts and take the first pass. Does the tool tip only cut on the side of the tool in which direction the carriage is moving or does the tip cut on both sides?

 

I say it cuts on both sides. Then you repeat the process and take a second cut and the process is repeated, the tip cuts on both sides by the depth of cut and the flank of tool behind that depth of cut runs parallel to the previous thread flank, assuming you've set the compound to 30 degree or less for a 60 degree thread form. But the tip itself still cuts on both sides.

 

I don't dispute it reduces friction on the flank of the tool face.

 

I don't know how to better explain it so you grasp the idea?

 

You have quoted reference from manufacturers that does not relate to what I'm saying and you yourself choose to ignore a demonstration using computer programs to illustrate the forces involved.

 

If you cant grasp it you are not as experienced or knowledgeable as you claim.

[Big Al]

Al you are driving yourself nuts going round in circles. Go back and re read what I said. Setting the compound over still allows the tool tip to cut on both sides by the depth of cut, it has to to remove the material.

 

So let me ask you a question. You set the compound over, touch off on your workpiece to zero, back out and then advance your compound to make the first cut. Engage the half nuts and take the first pass. Does the tool tip only cut on the side of the tool in which direction the carriage is moving or does the tip cut on both sides?

 

I say it cuts on both sides. Then you repeat the process and take a second cut and the process is repeated, the tip cuts on both sides by the depth of cut and the flank of tool behind that depth of cut runs parallel to the previous thread flank, assuming you've set the compound to 30 degree or less for a 60 degree thread form. But the tip itself still cuts on both sides.

 

I don't dispute it reduces friction on the flank of the tool face.

 

I don't know how to better explain it so you grasp the idea?

 

You have quoted reference from manufacturers that does not relate to what I'm saying and you yourself choose to ignore a demonstration using computer programs to illustrate the forces involved.

 

If you cant grasp it you are not as experienced or knowledgeable as you claim.

 

This is what you said that sparked this debate MJR

 

 

 

Also the theory that suggests setting over the compound to allow a HSS tool tip to only cut on one side is again incorrect. Sure setting the compound over to 29.5 degrees or less does reduce friction on the trailing edge of the tool but the tip is still cutting on both sides whichever way you look at it - draw it out and you will see what I mean

 

You were picked up on this by myself and Vermincinerator and then we discussed the differences between flank infeed and radial infeed. Clearly radial infeed cuts on both sides of the cutting tool with equal force (notice here I say cutting tool not tip, I dont want to confuse what the tip is doing with what the tool as a whole is doing) whereas flank indeed doesn't.

 

Just a quick reminder of the images

 

Radial Infeed

 

Flank Infeed

 

Its quite clear to anyone looking at these industry acknowledged pictures the difference between the two methods and what side of the tool is doing the cutting. Of course with flank infeed there will be some element of shear on the root radius but this will not be in the same way or to the same extent as your Mr All American Youtuber thinks, his computer modelling of what is happening is disingenuous to say the least and he has done that to prove his point. I have have watched his video in full just to prove to myself that his thinking and in turn yours is flawed.

 

Here is a very relevant screenshot from the video upon which your argument hangs.

 

 

Now, lets look at this and exactly what Mr America said in detail.

 

The flat at the root of this tool we were told was 0.006" which seems fair enough, so based on that flat being 6 thou how big exactly is the cut he is showing and how would that relate to real world thread cutting of barrel muzzle or tenon proportion? With a bit of quick scaling on this image it relates to a cut of approx 0.030" which is holy unrealistic in what we are doing. Cutting threads like we find on a barrel tenon never involves depths of cut anything like that, maybe 0.010" the first pass or two then we are decreasing the depth of cut as the flank contact increases. Cuts of even 0.006" which is the width of the root are big as we get down to depth. Towards the end of the thread we are even advancing the tool by literally 0.001" or less with a spring cut. How much of the right side of the tool will be shearing with a 0.001" cut - arguably none.

 

As such I would still be very confident to say that at best you have your root in flat or radius profile having a shearing effect to slit the chip away from the right hand side but as I said earlier its disingenuous to suggest the right hand side of the tool is cutting in any significant way.

 

Getting back to the point we have debated, I think based on the different pictures of flank and radial cuts and my explanation of how Mr American has scaled things to suit his thinking, there is nothing here that makes me think you or he is right. Personally I think you have been surfing Youtube and found something that you felt made sense, you have bought into it and decided to drop a turd onto Vermincinerators original valid comment for a bit of oneupmanship which I think has backfired on you. Sadly for me I happened to agree with him and so got myself embroiled in this.

 

Again, I go back to the tool companies information in their data sheets which Ive quoted along with the countless amounts of text that has been written and taught to people like me in technical colleges around the world over most probably 100yrs about thread cutting on a manual centre lathe.

 

Radial infeed cuts on both sides of the tool and flank infeed doesn't. Now I dont expect you to agree but thats as far as I can go with this, something to do with leading a horse to water springs to mind

[onehole]

Wow,,,love this,,,and then we go and tack on wobbly mods and rails and mounts etc and undo all the precision you guys have laid down in your care and precision,,,,, no matter how you all eventually arrive at the same job well done?,,,,Doh!!! I just take my hat off to you all "respected" Smithys ,,,,you aint all that far apart,,eh!!!!kiss and make up for FS,,,,,,,O

[MJR]

So you are now acknowledging the tip does cut on both sides? And yes of course it's minimal on a 0.001" cut but I've never suggested anything else?

[brown dog]

kiss and make up for FS,,,,,,,O

 

100%.

This is turbo-dull.

 

[Big Al]

So you are now acknowledging the tip does cut on both sides? And yes of course it's minimal on a 0.001" cut but I've never suggested anything else?

 

No Im not suggesting that at all, that I why I used the differential between tool and tip in my last post. The tip is a part of the tool which in threading we would call the nose or root, sometimes it flat other times its a radius. To call the threading insert a tip is common but it shouldn't be confused with the tip of the insert itself known better by other names as described.

 

What is cutting the thread is a tool not a tip, a form tool to be exact and that form tool can appear in a number of different designs, the most common being ground HSS or pressed cemented carbide. The shape of these tools for the sake of this discussion can be the simple V-profles like shown below.

 

HSS

 

Cemented carbide

 

Now going back to the video you use as evidence to support your theory (quite why you used some random guy on Youtube to believe over the engineering industry I'll never) the problem lies in the scale and how Mr America has inaccurately used his computer modelling to arrive at a conclusion that you have then bought into and which brings us to where we are now.

 

The scale of his modelling is wrong, he has introduced his tool into the work on the computer without considering the realities of trying to shove it in the same way into a live workpiece in the real world. His depth of cut in relation to his root form is all wrong and so it appears that the shear forces needed to cut are wrapping around the root and coming back onto the right flank of the tool significantly - note the use of tool again and not tip, its very relevant. He has arrived at an incorrect assumption based on poor/inaccurate computer modelling.

 

In the screw cutting work associated with building rifles a 10 thou cut on a manual centre lathe is a big one and a 30 thou cut as the modelling shows isn't realistic at all so you will never get the wrap around he suggests and you believe supports your ever diminishing argument.

 

Yes, cuts of 30 thou and more are not uncommon on screw cutting jobs in industry, its all relative to the size of the thread being cut but the important point here is as the job gets bigger so does the tool dimensions including the root flat or radius, because of this the correct scale stays the same and we are back to the beginning again. The flank cuts and the root radius does the shearing.

 

With respect MJR you launched into this thread with a putdown of Vermincinerator, a man with a lot of years experience as a turner, as soon as I validated his correct point Im told I have worked under a misconception my whole life and the man who trained me and the man who trained him all had.

 

I have laboured far too long over this thread for one simple reason, I have a lot of pride in the skills I possess and I have a lot of pride in the men who taught me them, guys who have bent over a manual lathe for 40yrs+ I also have pride in the system that has taught many millions of manual centre lathe operators the world over using pretty much the same methodology for the last 100yrs, all of them understand as I do.

 

Ive quoted you industry data to back up the years of teaching and experience in this method and all you have came back with is to grasp at a video on Youtube made by some random guy who has fudged his computer modelling and drawn an incorrect conclusion from it.

 

Im sorry you backed the wrong horse in this race as it would have saved me a lot of keyboard time but in reality yours wasn't even a horse, more of a three legged donkey but hey ho, I guess we all live and learn

[Big Al]

 

100%.

This is turbo-dull.

 

 

 

If its dull dont read it, how crazy is that comment from a forum owner? Threads that appeal to you often dont appeal to me, thats the way of forums.

 

Forums are for active discussion and learning which is what is happening here. People are reading this thread because it interests them and if it doesn't interest you then dont read it. Nobody is being abusive, there is no bad language and I can't see what forum rules its breaking so please leave it alone to run its course. I have invested a lot of time into this thread and I dont want to see it deleted because it doesnt interest you.

[bradders]

 

You're on a hiding to nothing Al, MJR is a member of the Gang of Four.

If he wasn't involved in this and wasn't a mod then this thread would've disappeared long ago.

 

Anyway, I'm sat on a plane at Heathrow about to embark on a round the world trip

Bon Voyage

[Charlts]

Great thread from my point of view, I've learned some more about machining and got a new meme from Mr Bradley. Best thread ever!

[MJR]

Yes Al, exactly, its a form cutting tool. I used the term tip to try to explain where it cuts. The illustration does use excessive cuts to simply enlarge and demonstrate the cutting action in detail its as simple as that. You are now attempting to introduce a differentiation between cutting and shearing? Why would one side of the tool cut and the other shear?

 

What's all this talk about backing the wrong horse etc etc. I've offered a different perspective and you cant provide a reasoned explanation and are going off at a tangent.

 

Bradders, have a good trip.

[Big Al]

You are now attempting to introduce a differentiation between cutting and shearing? Why would one side of the tool cut and the other shear?

 

 

 

Go back to year one apprenticeship for that one MJR and relearn the different ways in which a lathe tool can cut - maybe Google lathe shear tool and look at how it is presented to the workplace and learn about the different way it cuts and the forces it applies and chip formation during cutting.

 

With respect MJR your argument is getting weaker by the minute, at this rate by lunchtime you might have learned something

 

Its been an interesting debate with you MJR but Im afraid this will be the last I have to say on the matter, I dont want to end up in trouble with the management in my attempts to educate you. The more you debate the less I think you really know, that is going nowhere from my point of view.

 

Getting back to the original point of the thread, there are a number of ways we can introduce a screw cutting tool to the workpiece, all of them work in different ways and have different pros and cons, I think both myself and Vermincinerator have a good handle on this so will leave you with your own work methods and misconceptions.

 

No hard feelings on my part

[Artiglio]

Must be said , for me its been an interesting thread, not so much for the technical detail discussed ( though as a non machinist it'd not occurred to me that things were so complex) more that it shows the care and attention and to a degree artistry involved in building the rifles we shoot.

From whats been discussed there has been no argument that any of the techniques and tools used would not produce perfectly good results in the finished product.

If I recall correctly Bradders started his original thread with a statement along the lines of " this is the way I do it, there are other ways and techniques that will also work" .

I expect that we all want the best results from the components we buy , to either have a rifle built or rebarreled etc. Its good to know that there are those pretty much dedicated to achieving this.

[brown dog]

If its dull dont read it. How crazy is that comment from a forum owner? Thread that appeal to you often dont appeal to me, thats the way of forums.

 

Forums are for active discussion and learning which is what is happening here. People are reading this thread because it interests them and if it doesn't interest you then dont read it. Nobody is being abusive, there is no bad language and I can't see what forum rules its breaking so please leave it alone to run its course. I have invested a lot of time into this thread and I dont want to see it deleted because it docent interest you.

Al, you have completely missed my point. Look at the cartoon. Read the quoted comment above it.

 

What's dull is watching two grown men bicker on the internet about some insignificant point of detail, and both with an utter determination to have the last word.

 

Internet-ability-to-wordsmith-lathe-knowledge willy-waving, that's what's dull.

 

You'd probably agree with each other if you were chatting in the same room.

 

For both of you, as per Bradders:

 

[bradders]

Yes Al, exactly, its a form cutting tool. I used the term tip to try to explain where it cuts. The illustration does use excessive cuts to simply enlarge and demonstrate the cutting action in detail its as simple as that. You are now attempting to introduce a differentiation between cutting and shearing? Why would one side of the tool cut and the other shear?

 

What's all this talk about backing the wrong horse etc etc. I've offered a different perspective and you cant provide a reasoned explanation and are going off at a tangent.

 

Bradders, have a good trip.

 

Thx, made it as far as Doha (for old times sake) next stop Melbourne, then Brisbane

[eldon]

Well thanks for the informative discussion guys from a simple question; big trees from little acorns grow .....or something like that.

 

I am not a machinist by trade although I do have a lathe and have done a few threads in my time so I bow out to the more experienced on here.

 

Strangely I have used/done both methods, compound slide 30 degrees etc and plunge with tipped tools, and both were carried out on a manual machine. I have normally blamed the material or incorrect selection of feeds and speeds for any poor surface finish so here certainly adds a further dimension.

What prompted my question was once when I mentioned to a couple of (manual) machinists why they weren't spinning the compound slide around they unanimously agreed that "Oh you do't need to do that with modern tipped tools, that was in the old days!!!"

 

I walked away unconvinced, so thank you all for the detailed clarification.

[gazzarM1]

 

100%.

This is turbo-dull.

 

This ^^^^ lol