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John Stevenson
12-23-2009, 10:19 AM
[EDIT] This idea was originally by Mike Cox, then picked up by John Moore, John did give credit to Mike Cox, I missed it, my mistake.

First off let me give credit where it is due as the design concept came from John Moore over in the UK, my only input was suggesting the use of a key to locate the tool.

John's initial design was for a swinging holder to hold a replaceable brazed tip tool.

I cheated and used the tool as the swinging element.

I have some spare blank holders for my quick change system on the lathe, some full ones and some narrow ones for things like parting blade holders.

http://www.stevenson-engineers.co.uk/files/retracttool5.jpg

The one in the foreground was made as a threading tool and it works but in practice if you need a tailstock centre you can't get close enough so I was going to use John's design and this threading tool but then after a sort out I found a big old brazed tip tool and decided to use this as both the tool and the swinging holder.

The tool was accurately marked out for the pivot hole and then drilled thru into the holder and tapped.

http://www.stevenson-engineers.co.uk/files/retracttool6.jpg

It was then turned upside down and again accurately marked out for the location key to fit.

http://www.stevenson-engineers.co.uk/files/retracttool7.jpg

The tool was bored out and a brass bush fitted that extended by about 5 thou and a keep plate was screwed to the bottom, again with a 5 thou shim fitted whilst drilling and tapping the holes.

http://www.stevenson-engineers.co.uk/files/retracttool10.jpg

End of first post because of 4 picture limit, please don't reply until second post appears to keep continuity.

.

John Stevenson
12-23-2009, 10:30 AM
Second post.

Two more pics of the finished tool, this took literally 1 1/2 hours to make but I did have the holder already done, no drawings, just typical weld it where it touches and no microns were harmed in the making of this tool.

http://www.stevenson-engineers.co.uk/files/retracttool11.jpg



http://www.stevenson-engineers.co.uk/files/retracttool12.jpg

In use you turn a run out groove at the end of the thread and when the tool gets into this you just reverse the machine with the cross slide untouched.

You would think that it would tear the thread but what happens is that it lifts and runs back down the thread out of the cut.
You can even put the new cut on as you are going backwards !!

Then select forward and do the next cut.

Video here. http://www.youtube.com/watch?v=2F_AVx_JRlE&feature=related (http://www.stevenson-engineers.co.uk/files/P1000910.MOV)

And shot of the finished thread .

http://www.stevenson-engineers.co.uk/files/retracttool1.jpg

This was 2mm pitch, [ about 13 tpi ] cut at 135 rpm.

OK done now, flames, bricks etc but it was the fastest thread I have ever cut.

.

Black_Moons
12-23-2009, 10:46 AM
Very cool, I like how you left it free to swing up a LOT, the other tool posted here looked like it would fail to lift up enough on large diamiters with low TPI's

Crazy backwards QCTP system.

Frank Ford
12-23-2009, 10:50 AM
Terrific! My only question is "Why doesn't everybody do it that way?"

That's the same question I asked when I first encountered the Hardinge HLV threading system. The instructions for my Hardinge clone say "please do not thread above 1000 RPM." At first I thought it was a bit silly, but once you have a nice mechanical system like that, you can really rip.

Bill Pace
12-23-2009, 11:10 AM
That is just soooo kewl, I love it!

The brazed tip tool -- did you get the thread profile by regrinding a common existing profile (using carefully marked out dimensions of course!!) or -- how did you get it?

lazlo
12-23-2009, 11:29 AM
Terrific! My only question is "Why doesn't everybody do it that way?"

Well... this is Bogstandard's design, that we discussed last week -- he was trying to replicate Martin Cleeves' swing toolholder with a much simpler design:

http://www.hemingwaykits.com/acatalog/HK_1630_Positional.jpg


With Bogstandard's design, you have to reverse the spindle to lift the threading tool out of the cut. A bit of a kludge, IMHO.
The Hardinge flying dog clutch and the retracting toolpost is the ultimate answer, but how many actually have that? :)

John's thread looks superb, obviously, but John could cut a good thread with a plastic fork ;)

dp
12-23-2009, 11:40 AM
No criticism from me, but I am curious how well it does with a left hand thread. I realize that is the purpose of the lug and slot so left hand threading was a design consideration.

What is the concern level for trapping swarf under the cutter?

Timewarp
12-23-2009, 12:15 PM
I really like this setup. Who wouldn't? My question is what is the best method of adding a responsive brake to a lathe without one?
Paul

gzig5
12-23-2009, 02:42 PM
No criticism from me, but I am curious how well it does with a left hand thread. I realize that is the purpose of the lug and slot so left hand threading was a design consideration.

What is the concern level for trapping swarf under the cutter?

Since the key/lug in the bottom takes up the cutting force equally in each direction, I would think that LH threads would work just as well. A piece of carboard or the back of a note tablet with an X cut into it, placed over the bit and bent back over the top of the assembly would do a pretty good job of keeping the chips out of the works.

Davidhcnc
12-23-2009, 04:19 PM
I wonder would it work without the key?

motorworks
12-23-2009, 06:24 PM
John
Nice work.
I think I can fit one on the outside of a toolblock that I am using now.
Almost as fast as CNC :)
e2die
ps Merry Xmas. You do still have Xmas in the UK?! :D

oldtiffie
12-23-2009, 07:25 PM
Nice thinking and nice job too John.

It actually gets better and better as there is no need for a threading dial either so it will work whether the thread is left or right-handed or an inch or metric thread on either an inch or metric lathe with no having to retract or (re)set the tool depth.

It seems that all bases are covered.

gary hart
12-23-2009, 07:29 PM
I like it. Thanks John Moore and John Sir.

Made it today's project. First had to make insert holder for a box of inserts that had but no holder for.

For the swing tool milled out a little on tool holder for clearance to swing.
Drilled thru insert holder and tool holder. Reamed tool holder for 1/4 press fit and reamed insert holder for slip fit and drove 1/4 dowel pin into tool holder.

Took advantage of the little bit left of the front set screw hole. Drilled a 1/8 hole in 5/16 socket head screw held in lathe chuck.

Placed insert holder in tool holder and screwed in the drilled socket head screw. Using socket head screw as drill guide, drilled thru insert holder and bottom of tool holder.

With needle files and Dremel tool made hole in insert holder elongated for up down movement.

Silver brazed 1/8 hunk of high speed steel from broken long center drill that had on hand into the 5/16 socket head screw.

Gave it a try, Wow that is neat. Hard part is not disengaging half nut.

http://img.photobucket.com/albums/0903/ghart3/Threadingholdertool006.jpg

http://img.photobucket.com/albums/0903/ghart3/Threadingholdertool010.jpg

http://img.photobucket.com/albums/0903/ghart3/Threadingholdertool008.jpg

beanbag
12-23-2009, 07:36 PM
Is the slight floppiness an issue?

Black_Moons
12-23-2009, 07:40 PM
I really like this setup. Who wouldn't? My question is what is the best method of adding a responsive brake to a lathe without one?
Paul

a VFD would be a good option! Not super fast stop, but pertty close with a good braking resistors. I wonder if some VFD's can slam it into reverse a little to incress braking power.

Tony Ennis
12-23-2009, 07:48 PM
how much is that video sped up?

lakeside53
12-23-2009, 07:51 PM
a VFD would be a good option! Not super fast stop, but pertty close with a good braking resistors. I wonder if some VFD's can slam it into reverse a little to incress braking power.

In addition to aggressive use of braking resistors, DC injection at the last part of the deceleration will stop it dead. Bit fussy to setup though and you can overheat the motor if not careful.

I'm spoiled. on my big lathe .. by an electromagnetic clutch in the main gear box. Stops the lathe on a dime. I'll be adding a mechanical brake to my other lathe - just a drum with a belt around it on the rear end of the spindle - foot operated...

John Stevenson
12-23-2009, 07:54 PM
Gary,
Nice work, just proves the concept isn't tied to any set design other that it has to pivot.

I had though about making a holder for some inserts but to be honest I don't have any decent ones but perhaps later, as I say it's very open ended.

Quick answers to previous questions:-

Black Moons, Crazy backwards QCTP [ smile ]
Covered this ages ago, these toolposts were made well before cheap imports appeared and I wanted a design that allows easy manufacture of the holder, being reversed means I can mill a long 24" strip on the horizontal and cut off as needed.

Bill Pace,
The tool was a parting tool with one chamfer on it already, I just ground it up freehand on a diamond wheel mounted on the end of a small motor. I did follow a sharpie line !

Dennis:-

Tried a left hand tonight, absolutely no difference to doing a right hand as regards cutting etc. Same thread as before 2mm pitch

Video here:- http://www.youtube.com/watch?v=-tIvwDG9zd0

Finished thread.

http://www.stevenson-engineers.co.uk/files/retracttool2.jpg


Heres a fine thread done in steel, about 50mm diameter [ 2" ] and 1mm pitch, so 25.4 tpi. Not quite full depth so it has flats on the top but i was just playing,
Did a 2mm pitch on the same bar previous to this but forgot to take a picutre before I turned it off to do the fine thread, very acceptable.

http://www.stevenson-engineers.co.uk/files/retracttool8.jpg


These are all just plunge cut as this machine has no top slide to setover, well it does but I have swapped if for a big solid block for rigidity.



[EDIT] Just put a rider in the first post to say that this idea was originally by Mike Cox, then picked up by John Moore, John did give credit to Mike Cox, I missed it, my mistake.

John Stevenson
12-23-2009, 07:57 PM
how much is that video sped up?

It's not, that's true speed.

lazlo
12-23-2009, 08:11 PM
These are all just plunge cut as this machine has no top slide to setover, well it does but I have swapped if for a big solid block for rigidity.

John, what machine is that, that can reverse almost instantly? It looks like you're winding the infeed as you're hitting the spindle reverse -- does your lathe have a spindle control on the apron?

rockrat
12-23-2009, 08:42 PM
I love it!

The only issue I could imagine might be the end relief angle, it must be there. It seems that I have seen threading tools with minimal end relief. If this is not noted, the hypotenuse of the near 0 end relief could climb into the thread on the reverse depending on where the axis of tool rotation is. Would probably be evident the first time it was tried. :)

But then again, I dont have a tool with that type of relief so I might just go out and copy Sir Johns tooling tomorrow.

Thanks for sharing
rock~

S_J_H
12-23-2009, 09:20 PM
Jiminey Christmas!! What's the big deal with turning the cross slide dial a turn out when retracting?
dag-gummit, pretty soon you guys will be hooking up motors and computers to your machines!

Steve

John Stevenson
12-24-2009, 05:26 AM
John, what machine is that, that can reverse almost instantly? It looks like you're winding the infeed as you're hitting the spindle reverse -- does your lathe have a spindle control on the apron?
TOS 14 x 40 with forward and reverse clutches and brake in the neutral position so you can just bang if from forward to reverse with no problem.
I put the new feed on whilst it's running back, right hand on the cross slide, left hand on the clutch lever.

A lot of this East European gear has beeen ridiculed in the past, glows in the dark etc, but they make very good machine tools, built like brick $hithouses and very accurate. I now have 3 machines from Eastern Europe, two TOS and one with no markings other than it just says made in USSR, it's a 10" x 20, same size as a South Bend but has pressure oiling, 24 speed pre-selector gearbox 3 HP, and weights close to two tonnes, the bed and cabinet are all one big iron casting.

The 14 x 40 is an all metric machine which is what I bought it for. I make imperial parts on the CVA / Monach 10EE copy and metric parts on this one.
It was supplied as new with no thread dial and no way to fit one, full leadscrew cover, I complained and the importer got me a dial and I split the cover to allow fitting.

Used it about 3 times and it now hangs in fresh air not running on the screw because it's far quicker to leave the half nuts in and reverse the machine.
It is helped by the fact that reverse is 1.3 times faster than forward, a nice touch.

It is because of this that this tool suits the way I work, probably won't suit others but you start off at zero on the dial and every move made is an infeed move in the same direction, no remembering where you were, so quick as I think the video shows, what was it something like 1 minute 15 seconds to do a course thread.

I may change the tool at a later date to a holder for inserts, have to see how things go but I reckon there were about 4 or 5 similar tools lurking in the bottom of the box it came out of so probably not given I have the tooling and sharpening brazed tooling is no problem to me.

.

Ian B
12-24-2009, 05:46 AM
I liked the references in the first couple of posts to "accurately marking out" - does your felt tipped marker pen have sub-micron sized ink particles John?

Ian

Your Old Dog
12-24-2009, 06:17 AM
Slicker then Owl Dew :D

EVguru
12-24-2009, 06:47 AM
Jiminey Christmas!! What's the big deal with turning the cross slide dial a turn out when retracting?
dag-gummit, pretty soon you guys will be hooking up motors and computers to your machines!

Steve

Please post a picture of your treaddle lathe, or do you have street urchins cranking a handle?

Perhaps your lathe is powered by one of those labour saving electric motors.:p

20+ years ago I did a year at College on a combined Electronic/Mechanical engineering course. I was bored rigid on the electronics side (I knew far more than the lecturers) and frequently frustrated on the engineering side. Machine shop practice was from 7pm one evening. We were taught to make a cut, zero the dial, wind clear, make a measurement, wind the tool back in to zero and put on a cut.

That would have been fine if the machines weren't well worn and badly adjusted. Once when machining a 'stepped bar' task (in 1.5" leaded steel) I took a slightly heavier cut and the topslide shifted on it's bolts, the tool digging in and ruining the job. After having been given a thourough dressing down for abusing the machine, I watched the topslide being re-attatched with the same mostly stripped bolt and nut as before.

At that point I would only take very light cuts and adpoted the technique that I'd learnt at school from a teacher who made model steam engines. I'd knock off the feed, stop the spindle, reverse the feed, start the spindle and cut back out. I still managed to finnish before anyone else (I don't think anyone else had been allowed to use a lathe unsupervised before).

When the work came to be marked, I handed it over with a micrometer and insisted that it was used to measure the job. All the diameters were spot on, which certainly wasn't the case with the Lecturers mike.

John Stevenson
12-24-2009, 08:27 AM
Please post a picture of your treaddle lathe, or do you have street urchins cranking a handle?

Perhaps your lathe is powered by one of those labour saving electric motors.:p

.

Paul,
A bit of a tongue in cheek reply from Steve given that he's probably got the nicest CNC home made lathe and mill bar none. :rolleyes:

.

lazlo
12-24-2009, 10:46 AM
TOS 14 x 40 with forward and reverse clutches and brake in the neutral position so you can just bang if from forward to reverse with no problem.
I put the new feed on whilst it's running back, right hand on the cross slide, left hand on the clutch lever.

Ah, that's a great setup for your threading tool.

It occurred to me last night that something like the 10EE's ELSR (electric leadscrew reverse), would be killer for this swing threading tool. For those who aren't familiar, the 10EE's ELSR was Monarch's answer to Hardinge's flying dog clutch for high-speed threading up to a shoulder: like the Hardinge, you set forward/reverse stops on the feed shaft (below the leadscrew). But on the Monarch, there's no dog clutch on the leadscrew: the stops trigger limit switches that reverse the direction of the spindle.

So combine that with John's threading tool, and the carriage will move back and forth across the thread, and all you have to do is set the infeed. Almost CNC :)


A lot of this East European gear has beeen ridiculed in the past, glows in the dark etc, but they make very good machine tools, built like brick $hithouses and very accurate.

I like the old TOS'. Typical Eastern European design -- you can drop it out of a helicopter and it'll still turn to a tenth :)

The new TOS's look suspiciously like mainland China lathes, but I haven't seen one in the flesh.

quasi
12-24-2009, 02:43 PM
I believe TOS-Trenchin manual machines are made in China now. TOS in the Czek republic makes Harrisons CNC stuff.

Boucher
12-24-2009, 07:16 PM
This just screwed up my priority to do list. I am not anywhere near as fast as Gary is, but I have got to do what he did. The Spindel control on the Nardini will make this work fantastic. The other things on the to do list are just going to have to wait a little longer. I really do like those NV insert holders, but one of them is about to be sacrificed in the name of threading progress.

Thanks John for posting this and thanks Gary for your rendition.

Ian B
12-25-2009, 05:13 AM
John,

The "traditional model engineering" method for increasing depth of cut when screwcutting has always been to set the compound slide to the thread flank angle, and feed with the compound. Reasoning being that this causes the tool to cut on the left hand edge, rather than both.

You're feeding with the cross slide, and (apparently) having no troubles with surface finish etc.

Any thoughts on this? It's a pain having to set the compound over and then reset the quick change toolpost to be square. If you're cutting a thread in a couple of minutes, this would obviously significantly increase the time taken.

Is it worth the trouble?

Ian

mardtrp
12-25-2009, 07:32 AM
You DO NOT have to set the compound slide to that stupid angle AT ALL.

Now some on this forum will say that you do, I'll say Bu!!$#it to that stupid totally outdated theory, so will lots of others, who don't use that outdated confusing stupid crud.

If you just use the infeed to add to the cut, it works, and exceptionally well.
You just watched a video made by somebody who actually "does it for a living" and did you see him stuffin' around setting a compound slide to some stupid angle, no you don't, so it does work.

Now I got to ask the 'naysayers', how does a CNC do the thread cutting, well it just plunges straight in, none of this set over crud.

Don't believe that it will work for you when your threading, well go right ahead and try it, you'll wonder why you have never used it previously, and now you wont get all confused and bugger it up any more.

Mark

Peter N
12-25-2009, 07:45 AM
You DO NOT have to set the compound slide to that stupid angle AT ALL.

Now some on this forum will say that you do, I'll say Bu!!$#it to that stupid totally outdated theory, so will lots of others, who don't use that outdated confusing stupid crud.

If you just use the infeed to add to the cut, it works, and exceptionally well.
You just watched a video made by somebody who actually "does it for a living" and did you see him stuffin' around setting a compound slide to some stupid angle, no you don't, so it does work.

Now I got to ask the 'naysayers', how does a CNC do the thread cutting, well it just plunges straight in, none of this set over crud.

Don't believe that it will work for you when your threading, well go right ahead and try it, you'll wonder why you have never used it previously, and now you wont get all confused and bugger it up any more.

Mark


Do you by chance have any views on knurling? :D :D


Peter
(who plunge cuts threads as well)

Merry Christmas Everyone!

mardtrp
12-25-2009, 08:05 AM
Do you by chance have any views on knurling?




:confused: This post is about threading, how about gettin' it back on track, eh. :confused:


Mark

Glenn Wegman
12-25-2009, 08:40 AM
Now I got to ask the 'naysayers', how does a CNC do the thread cutting, well it just plunges straight in, none of this set over crud.

Mark

Perhaps a refresher course in CNC threading.

http://technology.calumet.purdue.edu/met/met/285/handouts/lecture12.pdf

Carld
12-25-2009, 08:41 AM
I'm not a CNC person but it seems I was told that the program in a CNC moves the carriage and crossfeed in a manor that it still cuts on the leading edge of the thread, not both sides as would happen on a manual machine doing a plunge cut.

Plunge cutting a thread will work but it does have problems with tearing the metal and a heavy load on the lathe and work. I never have liked the results with plunge cutting on anything but a fine thread, maybe 18 tpi and finer.

EDIT: mardtrp, look at page 18 of the above linked pdf file.

Peter.
12-25-2009, 08:46 AM
Great thread :D

I'd like to know where those threading tips in Gary Hart's photos come from. Can't find anything like them online!

Peter N
12-25-2009, 09:15 AM
:confused: This post is about threading, how about gettin' it back on track, eh. :confused:


Mark

You're a NOOB, so the humour is lost on you, but the others know what I meant ;)


Peter

Glenn Wegman
12-25-2009, 09:22 AM
mardtrp,

It's all a matter of how much pressure the tool tip can stand before tip breakage/chipping or chatter. Some threads in free machining materials will plunge with no real problem. Try plunging 8 tpi in harder to machine metals or gummy metals and you may understand better the reason for cutting primarily on one flank.

pistonskirt
12-25-2009, 09:35 AM
A very interesting design indeed, thank you John for taking the time to document the procedures in such excellent detail.

Certainly reducing the number of individual (mental & physical) actions in a threading sequence is of great benifit to even the sharpest operator. Almost every time I have made a balls up of a thread it has been when using the threading dial, a moments lapse in concentration & all is lost.


You DO NOT have to set the compound slide to that stupid angle AT ALL.
Mark

I have tried all methods but have never found any benefit from pissing about with the compound slide, if anything I tend to get a better overall finish when straight plunging the cross slide, added to which being able to glance at the DRO rather than squinting down at the compound scale helps reduce the mental agility demands whilst eliminating another hand move sequence from the procedure.

Possibly a lighter lathe may benefit from the compound tool advance, but any 3 phase industrial lathe should take the plunge feed with impunity.

regards

Brian

Merry Christmas to all

Carld
12-25-2009, 09:40 AM
I can bet mardtrp hasn't tried to plunge cut a thread in Monel or Hastelloy, especially Hastelloy.

Boucher
12-25-2009, 11:20 AM
Great thread :D

I'd like to know where those threading tips in Gary Hart's photos come from. Can't find anything like them online!

I think these people originated the design. They won't sell to you direct. They referred me to C W Rod Tool co in Houston
http://www.toolflo.com/cats/On%20Edge.pdf

ENCO p/n 347-4329 will get you into their similar parts

lazlo
12-25-2009, 11:49 AM
I think these people originated the design. They won't sell to you direct. They referred me to C W Rod Tool co in Houston
http://www.toolflo.com/cats/On%20Edge.pdf

ENCO p/n 347-4329 will get you into their similar parts

That's a standard on-edge threading insert. All the usual suspects carry them.

gary hart
12-25-2009, 12:21 PM
Like to say Thanks again to you John for showing this.
I'm so happy with it, makes feel like a little kid with a new neat Christmas toy.
Works so slick with a VFD's braking and reversing.

Peter, looked at my inserts and they are TNMA 32NV Enco # 347-3209.
Just looked in there catalog and they still have them but at a sale I paid less for ten then what one costs now.

dockrat
12-25-2009, 12:59 PM
You're a NOOB, so the humour is lost on you, but the others know what I meant ;)


Peter

"Oh Yeah", he says as he wipes the coffee of his monitor:D

dp
12-25-2009, 02:45 PM
You DO NOT have to set the compound slide to that stupid angle AT ALL.

Now some on this forum will say that you do, I'll say Bu!!$#it to that stupid totally outdated theory, so will lots of others, who don't use that outdated confusing stupid crud.

There's another thread running here where going ballistic is more appropriate :D.

It comes down to choice - either way you have to turn a crank to get the job done. Doesn't matter to me which crank it is.

John Stevenson
12-25-2009, 05:39 PM
I have tried all ways to thread, by the book, not by the book and winging it.
I don't think there is a right and wrong to thread but more a way that works for you.
What you have to remember though is nothing is new in engineering except materials and electronics.
What was written in textbooks years ago is still repeated parrot fashion today.

As an apprentice you were taught one way, usually from the same 3 or 4 set textbooks and whoa betide anyone who decided to try any other method. As most set exercises were markable exercises you HAD to stick to the book to pass and there was no time to try other methods.

The only way to find out is to try other methods, in the homeshop / self employed situation NOTHING is written in stone.

I must admit it does make sense to set the top slide over when doing course threads to reduce the cutting forces.

I make a lot of short worm with an 8tpi thread left hand on them.
I use a carbide tip ground to the correct Acme profile and swing to top slide over to 14 degrees, just less than half the 29 degrees Acme angle from the perpendicular. Been doing these for years and it get a beautiful finish on the flanks due to the material, high tensile, and pure cutting oil.

It was only recently I realised that because these worms were left handed I was feeding on the trailing flank and not the leading flank.
A big no no in terms of text book screwcutting but again something that has worked for me.

I have had another idea today to improve / alternate design / knacker up the swing threading tool but I'd not like to comment on this until I do some more testing. After rushing out to Wilko's at 10 minutes to 6 on Christmas eve to get Gert chrissy box and spending £4.25 in the process I reckon I can get me passport stamped and shoot into the workshop tomorrow, watch this space !!

.

Limy Sami
12-25-2009, 05:52 PM
You DO NOT have to set the compound slide to that stupid angle AT ALL.

Now some on this forum will say that you do, I'll say Bu!!$#it to that stupid totally outdated theory, so will lots of others, who don't use that outdated confusing stupid crud.

If you just use the infeed to add to the cut, it works, and exceptionally well.
You just watched a video made by somebody who actually "does it for a living" and did you see him stuffin' around setting a compound slide to some stupid angle, no you don't, so it does work.

Now I got to ask the 'naysayers', how does a CNC do the thread cutting, well it just plunges straight in, none of this set over crud.

Don't believe that it will work for you when your threading, well go right ahead and try it, you'll wonder why you have never used it previously, and now you wont get all confused and bugger it up any more.

Mark

Oh dear! :rolleyes:

Carld
12-25-2009, 05:55 PM
John, I too experiment to hell and back and found what I sure as hell don't want to do again and what will work most the time. I have to agree that what may not work for me does for someone else and that's why I always try to present the other side of the argument.

I have had some OMG :eek: incidents while threading and have learned to be very careful and plunge threading above a certain pitch was one of them. BUT, if someone can get a real good looking thread plunging a 10 tpi or coarser then go for it but I can't.

As to a CNC cutting a thread, the program advances the tool to only cut on the leading side of the thread as far as I understand it as I have been told. It don't care how it does it because I don't use a CNC.

John Stevenson
12-25-2009, 06:46 PM
Carl,

I don't advocate one way over another, I much prefer to suggest that people find what suits them best.

Just because I can do this on a decent sized rigid lathe doesn't mean that a newcomer can do it on a 7 x 12 lathe. It depends on many variables.

Most CNC lathes I have come across have variables where the infeed angle can be altered for different threads, no good having a 29 degree angle written in stone if you are cutting a 55 thread or an acme.
It can also be canceled if needed for plunge cutting.

.

pistonskirt
12-25-2009, 07:38 PM
BUT, if someone can get a real good looking thread plunging a 10 tpi or coarser then go for it but I can't.


On reflection I should qualify what I said in my earlier post with the fact that I never cut any threads above 1.5mm pitch, coarser pitches do not occur in my normal work. The only "large" coarse threads I have ever cut were done on a big DSG or Holbrook over 20 years ago & I have no memory of what techniques I used.
I certainly take your point about the excessive tool load when attempting plunge feeding such a heavy cut.

regards

Brian

Ian B
12-26-2009, 05:41 AM
Peter,

Mmm, knurling; now that I think about it, maybe I should set the compound slide over to the angle of the flanks of the knurling wheel, and infeed it that way.

Once I've calculated the right diameter of the work to be a whole number of knurled teeth, that is...

(Running for cover)

Ian

Timleech
12-26-2009, 06:56 AM
On reflection I should qualify what I said in my earlier post with the fact that I never cut any threads above 1.5mm pitch, coarser pitches do not occur in my normal work. The only "large" coarse threads I have ever cut were done on a big DSG or Holbrook over 20 years ago & I have no memory of what techniques I used.
I certainly take your point about the excessive tool load when attempting plunge feeding such a heavy cut.

regards

Brian

I usually have the compound parallel with the lathe axis, and when cutting large threads may put a shift of a few thou on the compound between cuts. Rough & ready and 'seat of the pants' so there's always the risk of making a b*lls of the job but it does make for an easier cut and yet allows simple control of cutting depth via DRO or cross feed dial.
It wouldn't be too hard to draw up a scale for axis feed vs cross feed to get whatever your chosen infeed angle might be.

Tim

John Stevenson
12-26-2009, 06:59 AM
Peter,

Mmm, knurling; now that I think about it, maybe I should set the compound slide over to the angle of the flanks of the knurling wheel, and infeed it that way.

Once I've calculated the right diameter of the work to be a whole number of knurled teeth, that is...

(Running for cover)

Ian

How about a swing knurling tool so you can go back for a second cut without loosing pitch ? :p ?

.

pistonskirt
12-26-2009, 08:35 AM
I usually have the compound parallel with the lathe axis, and when cutting large threads may put a shift of a few thou on the compound between cuts. Rough & ready and 'seat of the pants' so there's always the risk of making a b*lls of the job but it does make for an easier cut and yet allows simple control of cutting depth via DRO or cross feed dial.
It wouldn't be too hard to draw up a scale for axis feed vs cross feed to get whatever your chosen infeed angle might be.

Tim

Which would indeed seem to achieve a similar cutting flank bias as with the half included angle compound feed method, as you say it just requires care not to advance the compound too far.

On every other lathe I have owned or used I would always have the compound "parked" parallel with the bed axis, however my present "daily use" lathe is an S&B 1024VSL on which the compound slide assembly is so long that one would be forever clouting the tailstock drill chuck with it, so it usualy sits at 45 degrees for whipping on a quick chamfer.

regards

Brian

Glenn Wegman
12-26-2009, 08:53 AM
My compound just lives a 29° for 60° threading so it is out of the way of the tailstock or the crossfeed handwheel. Makes threading a non-event, as all I do is set the gearbox for the proper pitch and drop the threading tool onto the QCTP. The compound has a gib lock, which stays locked for turning and facing for rigidity reasons, and unlocked for threading.

Tim's method is interresting, but complicates the issue as it's basically the same as setting the compound to 29°, but adds to the confusion with the need for a chart or guess work to end up with the correct thread form.

Threading is not as difficult as some seem to make it out to be! :)

Threading, parting, knurling, and using a DTI seem to be huge stumbling blocks for home shops. Just takes a little practice, that's all!

DICKEYBIRD
12-26-2009, 08:56 AM
My compound stays "parked" in the 2nd drawer down in the lathe stand.:D

Makes my little lathe think it's much bigger. Way less chatter, takes (relatively) huge cuts and there's no comparison in the parting off performance.

It only comes out t'drawer when absolutely necessary for tapers or threads.

OK, now back to our regularly scheduled thread content.:)

Timleech
12-26-2009, 08:58 AM
My compound just lives a 29° for 60° threading so it is out of the way of the tailstock or the crossfeed handwheel. Makes threading a non-event, as all I do is set the gearbox for the proper pitch and drop the threading tool onto the QCTP. The compound has a gib lock, which stays locked for turning and facing for rigidity reasons, and unlocked for threading.

Tim's method is interresting, but complicates the issue as it's basically the same as setting the compound to 29°, but adds to the confusion with the need for a chart or guess work to end up with the correct thread form.

Threading is not as difficult as some seem to make it out to be! :)

Threading, parting, knurling, and using a DTI seem to be huge stumbling blocks for home shops. Just takes a little practice, that's all!

It makes no difference to the thread form, unless you c*ck it up, because the last couple of cuts will just be shavings with direct infeed (they will be if I do it, anyway!), the thread form is determined my the tool form.

Tim

Glenn Wegman
12-26-2009, 09:18 AM
Tim,

Agreed, but the possibility exists of cutting too wide in relation to the depth with the compound for someone just learning or that struggles with thread cutting already.

The point is, if you are going to use the compound, why not just use 29°? Makes it easier to keep track of thread depth withut having to guess.

I always sharpen up the tool and plunge the last .001" or .002" as well to clean up the threads. Makes a nice finish.

John Stevenson
12-26-2009, 09:57 AM
That's the problem with most lathes and the main reason why I decided to store the topslide on the small TOS until needed and instead opt for rigidity in the shape of a big packing block with a cutaway made to miss the tailstock.

http://www.stevenson-engineers.co.uk/files/toolblock.jpg

In it's lifetime it has probably been fitted about 10 times for the odd taper. Chamfering is done by a ground tool in one of the QCTP holders which is ground to do both internal and external chamfers at the same setting, handy for the quick deburr.

http://www.stevenson-engineers.co.uk/files/chamfertool.jpg

Looking at this picture makes me realise I need to start looking for a new tool, not muck life left in this old girl but it has been in use for about 20 years .

.

Timleech
12-26-2009, 10:28 AM
Tim,

Agreed, but the possibility exists of cutting too wide in relation to the depth with the compound for someone just learning or that struggles with thread cutting already.

The point is, if you are going to use the compound, why not just use 29°? Makes it easier to keep track of thread depth withut having to guess.

I always sharpen up the tool and plunge the last .001" or .002" as well to clean up the threads. Makes a nice finish.

I don't have to guess, just read the depth off the DRO!
besides, we in the UK regularly have more than one thread angle to deal with ;)

Tim

John Stevenson
12-26-2009, 10:38 AM
Plunging in means you can use the thread depth from standard tables, using the top slide the infeed is totally different and not in standard tables.

I dare say there are tables printed for this but American / Metric, 60 degrees, British at 55 degrees and Acme at 29 plus a few more like Trapezoid at 30 and BA at 47.5 means an overload of information.

.

GadgetBuilder
12-26-2009, 10:39 AM
....

Tim's method is interesting, but complicates the issue as it's basically the same as setting the compound to 29°, but adds to the confusion with the need for a chart or guess work to end up with the correct thread form.
...

Tim's method is a variation of Martin Cleeve's method for 60 degree threads. Cleeve suggests leaving the compound parallel to the ways and advancing it half the distance the cross slide is advanced for each cut. This effectively moves the bit down the thread flank, just like setting the compound over, so the tool cuts easily.

One feature of this method hasn't been considered so far in this thread: the width at the bottom of the thread should be a fraction of the thread pitch. With Cleeve's method one hones the threading tool's tip width for the finest thread one expects to cut. For coarser threads when one arrives at thread depth then the compound is advanced to widen the thread bottom without affecting thread depth. This doesn't produce the correct radius at the bottom but it's close enough for my home shop and the threads work well with commercial fasteners.

Cleeve's method does require knowing the target thread depth but it seems one would need to know this with the compound at 29 degrees also.

I was wondering how to cut the correct thread form with the compound set to 29 degrees other than grinding a bit for each thread pitch? I adopted Cleeve's method because I don't understand how to handle this other than multiple threading bits or re-grinding my one threading bit when changing pitches.

John

Carld
12-26-2009, 11:12 AM
GadgetBuilder, if your talking about having to grind the right flat on the tip of a threading tool for each pitch what do you do if your using a carbide insert to thread with? I don't recall seeing threading inserts listed for each pitch of thread.

I have been cutting threads since 1962 and I seldom if ever put a flat on the end of the cutter. I use HSS Cobalt tools and a Dorian vertical insert holder to thread with. All I ever do with the Cobalt cutter is put a slight flat on the tip and I never grind or dress the carbide inserts at all.

I have cut all the class threads including interference threads where heat was required to assemble and I have never had an issue or interference with the tips not conforming to the specs in the MH or other sources. All this is on external threads of course and I file a flat on the OD of the external thread although I have used a scraper I made to dress the flats of an internal thread.

With internal threads I always do the bore so it ends with a flat on the finished thread. The reason I do it this way is I can't file the ID of the bore But I have and do scrape them. I also use a sharp tip with slight dressing on it for internal threading and I don't use inserts for internal threading.

I thought a lot about all this flat tip stuff years ago and after a lot of reasoning it out saw no real reason for concern about a sharp tip on the cutter. It's not the bottom of the V that is important it's the V that fits into it. If your cutter is a sharp 60 deg V then any sharp 60 deg V will fit because you always put a flat on the outside of the thread, that's the OD of an external thread and the ID of an internal thread.

Having the full V at the bottom of a thread has benefits as I see it and the only real concern is having a stress riser at the bottom of the thread. In the case where the thread has to have the highest strength then a round tip on the cutters is needed.

I think most go to extremes about the flat tip issue. That's my opinion, it's worked for, ummm, 47 years and I am sticking to it.

Glenn Wegman
12-26-2009, 11:47 AM
Plunging in means you can use the thread depth from standard tables, using the top slide the infeed is totally different and not in standard tables.

I dare say there are tables printed for this but American / Metric, 60 degrees, British at 55 degrees and Acme at 29 plus a few more like Trapezoid at 30 and BA at 47.5 means an overload of information.

.

You divide the required thread depth by the cosine of the compound angle to get the proper compound infeed. If the single straight in depth is .035" and the compound is set to 29°, the cos of 29° is .8746, so divide .035 by .8746 and you get .040" compound movement. No charts, just 15 seconds with a pocket calculator.

Subject to error though as tool tip and od of part effect the outcome.

I use thread wires.

I cut BSF and BA threads too! Not just UN.

TGTool
12-26-2009, 12:06 PM
Or use Marv Klotz's DOT (depth of thread) program to give you the compound travel for any thread pitch, compound angle, and flat/sharp top/root.

mardtrp
12-26-2009, 05:01 PM
You divide the required thread depth by the cosine of the compound angle to get the proper compound infeed. If the single straight in depth is .035" and the compound is set to 29°, the cos of 29° is .8746, so divide .035 by .8746 and you get .040" compound movement. No charts, just 15 seconds with a pocket calculator.

Subject to error though as tool tip and od of part effect the outcome.

I use thread wires.

I cut BSF and BA threads too! Not just UN.


WOW, and all this for just cutting a simple thread. :eek:

Why bother? :rolleyes:

Go straight at it, much easier, EXACT same result, try it out, you'll still cut a thread.

Mark

Ian B
12-27-2009, 03:48 AM
Carl,

Inserts do come in a range of pitches:

http://stores.shop.ebay.co.uk/The-Tool-Shop__W0QQ_sidZ106928419?_nkw=threading+iso&submit=Search

Ian

Ian B
12-27-2009, 03:55 AM
John (and others who've removed the compound slide),

Have you also tried adding a rear toolpost? Modern cross slides are pretty long, and a rear toolpost comes as an option on some lathes. Mine has vee grooves down both sides of the cross slide, allowing various bits of kit such as hydraulic copyers and rear toolposts to be attached.

I have a spare T3 toolholder block, and was wondering if it's worth the effort of making a rear toolpost. Would it be handy, or will it just get in the way?

Also, as cutting forces will be upwards, any issues with the toolholders moving upwards?

Ian

Circlip
12-27-2009, 04:10 AM
Problem with upward cutting forces is that gravity acts downwards.:D

Regards Ian

ptjw7uk
12-27-2009, 05:02 AM
It wont work on a rear toolpost as gravity will hold it down, needs a spring to push it up.
Not to sure if it will be worth the trouble on a rear toolpost.
I always thought the whole point of a rear toolpost was that if a parting tool is fitted then it is always available to cut of the part, in so doing making small production runs that bit easier.

Peter

Peter.
12-27-2009, 05:32 AM
It'd work on a rear toolpost if you ran the lathe backwards surely?

Ian B
12-27-2009, 07:48 AM
I was thinking about running the lathe in the normal direction and mounting the rear toolpost higher than the front one. Then, mount the tools upside-down. Typical jobs would be parting off, chamfering etc, with the bulk of the turning still being done with the front toolpost.

This would cause the cutting forces to try to lift the toolholder.

Ian

Timleech
12-27-2009, 08:25 AM
I was thinking about running the lathe in the normal direction and mounting the rear toolpost higher than the front one. Then, mount the tools upside-down. Typical jobs would be parting off, chamfering etc, with the bulk of the turning still being done with the front toolpost.

This would cause the cutting forces to try to lift the toolholder.

Ian

Rear upside-down parting tools do generally work well. Colchesters used to do a one-sided Dickson post with a raising block for rear use.
I've got a spare, slightly knackered T3 toolpost, you have set me thinking & I might look into setting that up on my big lathe as a rear post using its best face. It would need to be easily removed as I use the power drilling bracket quite often.
Mind you, changing tools is so simple with a QCTP it only takes a few seconds to slot in a parting holder to the main toolpost. The advantages of the rear post were greater before QC posts became more or less the norm.

Tim

John Stevenson
12-27-2009, 08:35 AM
I have an insert parting tool that's a bit lumpy and needs a bit of work on it to get it to fit correctly, I can't get it low enough to get on centre so I have fitted it upside down and run the lathe in reverse, bolted chuck so no problems there.

However it could lend itself to lifting as there are no stops etc to register on. So far it has never been a problem the wedge type QCTH being sufficient to hold it in position.

It has made parting easier as the chips fall away and don't build up on the top so I'll probably leave it as is.

.

Carld
12-27-2009, 11:16 AM
Hmm, interesting but have not seen them in the catalogs I use. On the other hand, I don't buy machine supplies from ebay nor do I visit the major insert companies sites. Maybe I should have a look, not that it would change my mind about the sharp V but the insert list may be interesting.

Recently I ordered a catalog from Micro 100 and was impressed with how many different things they have for sale aside from the brazed Micro 100 cutters.

JTToner
12-27-2009, 11:42 AM
For threading unsupported workpieces, I frequently use an inverted tool and run in reverse. That allows me to cut threads at high rpm without risk of colliding with anything. One time I had to cut threads on 36 303 rods. Got them finished, then was told to do 36 more. Was a piece of cake. (Obviously, not to be attempted with a threaded spindle unless using collets!)

Johnny

pistonskirt
12-27-2009, 06:23 PM
Carl,

Inserts do come in a range of pitches:

http://stores.shop.ebay.co.uk/The-Tool-Shop__W0QQ_sidZ106928419?_nkw=threading+iso&submit=Search

Ian

Because those are full form inserts......a partial insert will cover a broad range of pitches governed by the physical size of the insert & holder.

regards

Brian

Peter S
12-27-2009, 09:54 PM
Not sure if I could do without a compound slide, I use it all the time for accurate shoulder turning. I presume you guys that remove your compound have a DRO on carriage travel? (I don't).

Not wanting to enter into a thread-fight....but getting thread depth with angled compound can be easily done without calculation by:

-Touch off on job.
-Zero cross slide.
-Zero angled compound.
-Move carriage so tool is clear of job.
-Look up thread depth and wind in full depth of thread with cross slide.
-Re-zero cross slide without moving it.
-Back off compound until tool is just touching job.
-Start thread cutting.
-Retract tool with crosslide at end of pass (unless you have the super swing-lift tool!) and return it to zero each pass.
-Apply cuts with compound until you reach zero.
-Hard to get it wrong!

John Stevenson
12-28-2009, 07:32 AM
Not sure if I could do without a compound slide, I use it all the time for accurate shoulder turning. I presume you guys that remove your compound have a DRO on carriage travel? (I don't).

I do have a DRO fitted but that long axis doesn't have a scale fitted yet, I got a good deal on a two year old NIB readout / old model and just bought a scale for the cross slide. To me and the work I do diameters are very important [ bearing fits ] but lengths aren't so important.

Being a metric lathe the rack is module so it moves in easily divisable amounts, one turn is 80 mm and the hand wheel is graduated in 1/2mm's, you can further split this by eye to 1/4mm's which is about 10 thou

Anything better and it sometimes happens, I use a chuck backstop and a micrometer bedstop, using this method you can get to 3 tenths of a gnats foreskin on a good day, with the door shut and no wind.

My way isn't the best way, it's just what suits the way I work and I'm comfortable with. Machining and machining practices is like doing the lottery, any 8 from 100 choices, take your pick and what works on one machines may not work on another.

.

Glenn Wegman
12-28-2009, 07:52 AM
WOW, and all this for just cutting a simple thread. :eek:
Why bother? :rolleyes:
Go straight at it, much easier, EXACT same result, try it out, you'll still cut a thread.
Mark



what works on one machines may not work on another.
.

Exactly as John stated.

That is why there was an attempt at an intelligent discussion concerning different methods of thread cutting that may suit different machines.

A machine that experiences difficuty using a 1/16" wide parting tool without chatter would most likely not be a very good machine for plunge cutting threads.....

GadgetBuilder
12-28-2009, 11:05 AM
The original swing threading tool by Mike Cox (shown below) was developed on an Asian 7x12 which has electronic speed control.
http://img187.imageshack.us/img187/8866/swinguptoolholder.th.jpg (http://img187.imageshack.us/i/swinguptoolholder.jpg/)

Mike's approach uses a carriage activated switch to stop the carriage; this repeats within a fraction of a spindle turn. A runout groove must be cut prior to threading to avoid swarf buildup at the thread termination point.

The 7x12 enforces a soft start so the multiple forward and reverse starts required when using the swing up tool have little heating effect on the motor. I'm wondering if this is true for lathes that don't use electronic speed control.

That is, with two starts per threading pass one might make 20 or more starts in just a few minutes. Would this affect the motor as well as the start capacitor and switch due to the repeated starting surge?

John

Keith Krome
06-06-2010, 03:35 PM
First, thanks for the swing threading tool. Looks really neat, I'll have to make one myself.

As far as the compound angle is concerned, I'm in the 29-30 degree group, cutting with the flank.

Regarding how it is done on a CNC, one should not make generalizations regarding techniques used. I have used an Anilam control (1200T IIRC) and it had options to do straight in, arbitrary flank angle, and alternating left/right flank cutting to balance the wear on the left and right flanks (this is for the same thread being cut). So in CNC, it depends on the control (and possibly the CAM package being used.) I usually used the alternating left/right flank mode.

John Stevenson
06-06-2010, 06:19 PM
You can also use the tool with a Coventry die insert so that it forms a full thread with the correct root and crest radii.

http://www.youtube.com/watch?v=6TR0ssQrmI8

This was done on a piece of 16mm rebar on purpose just so I could see what the quality was.

To be honest it came out a lot better than I expected.

http://www.stevenson-engineers.co.uk/files/swingfinal4.jpg

This was the finished thread 16mm x 2mm pitch, about 13 tpi, there is a bit of tearing but this has got to be the worst material for cutting on a lathe.

Since this post was first done I must admit I have used this tool all the while, either with the single point or with the die piece holder.
I have threaded quite a few ballscrews and these can be tough if you are still at the root diameter.

Last weeks job was 20 titanium bolts 10mm diameter x 80 mm long with 15mm of thread from solid round, the material was bloody expensive so no mistakes, every thread came out nice.

.

J Tiers
06-06-2010, 06:35 PM
The video seems to be gone...... I missed the thread while it was active, I guess...

But I am not clear on why a swing-up tool makes anything easier..... elsewhere it was suggested that it would make metric threading a breeze....... didn't see why on that eitehr.

It seems that it gives you a way to "retract" quickly.... similar to the 'pull-out" toolholder that Metal Lathe Accessories sells a kit for.

But to "not need a threading dial".... that would suggest you are just winding back with the leadscrew..... otherwise I don't see why the holder, however nice it is, makes a difference.

I DO see that all the threads seem to have a relief... what if you don't get that? Does it still make everything a breeze? and why so?

As for "marred-up" and his comments, he, and the others advocating straight-in threading probably have large heavy lathes.....

if you have a lighter lathe, the thread can "take charge" and PUSH the carriage ahead, giving you a drunken thread.....

if you have a heavier one, then most threads are too small to do that, and you will be wondering about all the "wusses" who say it doesn't work well.

Black_Moons
06-06-2010, 06:52 PM
the point of the swing up tool is you can reverse the lathe *WITHOUT* retracting the tool, the work just pushs the tool outta the way when it rotates the 'wrong' (reverse) way.

So basicly your threading ops are just:

run forward, stop, reverse, advance X mils, repeat.
Insted of
Run forward, Stop, retract, reverse, advance back to 0, advance X mils, Repeat.

Basicly removes 2 operations to 'screw up' on and brings it back to a simple 2 handed operation with no movement beween diffrent controls or trying to remember the exact last value.

John Stevenson
06-06-2010, 07:00 PM
Jerry,
You need to go back and read it all again, I think you have missed the whole concept of not being able to get crossed threads thru selecting on the wrong number.
If you have an imperial lathe you can do metric without having to worry about it lining up.

First link has been repaired.

http://www.stevenson-engineers.co.uk/files/P1000910.MOV

.

J Tiers
06-06-2010, 07:02 PM
Jerry,
You need to go back and read it all again, I think you have missed the whole concept of not being able to get crossed threads thru selecting on the wrong number.
If you have an imperial lathe you can do metric without having to worry about it lining up.


.


I was looking for that, care to gimme a hint on where the details are?

John Stevenson
06-06-2010, 07:10 PM
Sorry Jerry not sure what you want, everyone else gets it, Gary even built one in a night just from seeing the pictures.

You engage the half nuts and don't disengage them until you are done so no way to engage at the wrong point.

PeteF
06-06-2010, 07:27 PM
I was looking for that, care to gimme a hint on where the details are?

I think it's extraordinarily generous that people like John make so much effort to put up these things so the whole community can benefit. I know a lot of us are very grateful. I can imagine it takes quite a lot of time to do so, time he could easily spend on other efforts. Surely that's worthy of a little more respect in simply asking anyone interested to READ the thread before launching off with comments then asking for a synopsis since you can't be bothered reading through a few pages to get the COMPLETE details. :mad:

John, I read it, watched the videos and, unremarkably, "got it". Thanks again for posting. I was wondering if the tool came down to rest on a simple pin sticking out from the holder it would have enough rigidity? ie instead of a "ledge" the tool rests on, just a decent sized pin. It would make machining one up even simpler, but wondered if either the pin would flex or the tool itself cantilever on the pin and give rigidity issues? However maybe the cuts simply aren't heavy enough for this to be an issue when threading?

Pete

BobWarfield
06-06-2010, 07:51 PM
You engage the half nuts and don't disengage them until you are done so no way to engage at the wrong point.

Eureka! And that's why you don't need a threading dial, which is why it works well for metric.

Cheers,

BW

J Tiers
06-06-2010, 08:51 PM
Sorry Jerry not sure what you want, everyone else gets it, Gary even built one in a night just from seeing the pictures.

You engage the half nuts and don't disengage them until you are done so no way to engage at the wrong point.

Well, heck, I was looking for details that DO NOT EXIST....

YOU described it fine, and I assumed (I think I asked if that wasn't true) that you left the halfnuts engaged.....

It's the OTHER folks that were giving it near-magical properties.......

Looks like I GOT IT the first time, but got confused by the OTHER folks......


Surely that's worthy of a little more respect in simply asking anyone interested to READ the thread before launching off with comments then asking for a synopsis since you can't be bothered reading through a few pages to get the COMPLETE details.

You lose, chump..... but thanks for the slap anyway.:mad: :rolleyes:

I READ the thread, and the way everyone was talking, there had to be something "else".... and I couldn't find it

Talkin about "keys" and whatever.... looks like I saw them already......

Nope... NOTHING else special....

Same thing you get by retracting the crosslide and using a "threading stop"...... except that yo may not need to be as co-ordinated, and you CANNOT use it with no runout groove....

I got no problem with John S.....

It's the rest of you that were ascribing magic to it................ ain't no magic... which does not make it a bad thing...... just over-hyped by the peanut gallery....

PeteF
06-06-2010, 11:52 PM
The fact the half-nuts remained engaged was mentioned at least twice in the thread, quite apart, one might have thought, as being bleeding obvious! But of course having read the thread you would know that, which is why, I guess, you asked :rolleyes:

The Artful Bodger
06-07-2010, 09:13 PM
Someone(?) mentioned floppyness and what problems that might cause.

I made a very simple flip up by drilling a hole in a carbide tool holder and fixing that to a block that fits in the 'lantern' stype tool post.

The tool holder is free to flip up and it can wobble a little, obviously it is stopped from falling below spindle centre line.

Floppyness is not a problem when using the 29 degree offset compound to feed as that forces the tool holder against the block. I am not an experienced thread cutter but I cut my best thread ever using this floppy device.

Black Forest
02-25-2011, 03:35 PM
Early on in this thread John you mentioned you had a thought on an improvement for your swing up tool. Did you ever work on that?

noah katz
02-25-2011, 06:12 PM
I don't thread enough to make it worthwhile to make this very cool tool.

Any reason not to do the same thing manually by just loosening the QCTP toolholder and lifting the tool during the backup part?

miker
02-25-2011, 09:15 PM
Someone(?) mentioned floppyness and what problems that might cause.

I made a very simple flip up by drilling a hole in a carbide tool holder and fixing that to a block that fits in the 'lantern' stype tool post.

The tool holder is free to flip up and it can wobble a little, obviously it is stopped from falling below spindle centre line.

Floppyness is not a problem when using the 29 degree offset compound to feed as that forces the tool holder against the block. I am not an experienced thread cutter but I cut my best thread ever using this floppy device.

Could you post some pics of this set up when convenient?

Rgds

Forrest Addy
02-25-2011, 09:27 PM
I got the Multifix outside and inside threading tool holders. They are neat looking and beautifully made. They work well: flip a lever and the tool backs clear. Flip it back and the tool pops out to original postion within 0.0001" or so. Problem is they are a little bulky and cumbersome.

I think Sir J's approach would be more compact if well executed for the particular machine it's intended for.

Boucher
02-25-2011, 10:10 PM
The usefulness of this swing up tool is somewhat related to the lathe being quickly reversible. My Nardini has the magnetic brake and works great when the apron control is slammed from forward to reverse. My version of this tool is not keyed and works fine for turning right hand threads.
http://i109.photobucket.com/albums/n50/boucherbyron/SwingThreaderSmall.jpg
http://i109.photobucket.com/albums/n50/boucherbyron/BackSideSwingThreaderSmall.jpg
I used the vertical insert tool holder because I had several and like them. I seldom use left hand threads and thus have not been motivated to incorporate keying or support for cutting in that direction. This tool works easier and faster than the old way and I don’t have to drag out the threading stops. You just add the cut for the next pass as the carriage is returning back to the right. I have not purchased the thread type cartridges but I am sure that concept will produce better finish quicker. I am very pleased with the way this works and appreciate Sir John’s effort in documenting it.

John Stevenson
02-26-2011, 05:56 AM
Early on in this thread John you mentioned you had a thought on an improvement for your swing up tool. Did you ever work on that?

I made a new holder that holds an insert from a Coventry Die head,
You can see it in this video.

http://www.youtube.com/watch?v=6TR0ssQrmI8

I posted a picture of the finished thread earlier but never thought to cover the threading tool.

http://www.stevenson-engineers.co.uk/files/swingfinal1.jpg


http://www.stevenson-engineers.co.uk/files/swingfinal2.jpg


It has it's uses but not as useful as the single point tool.

Black Forest
02-26-2011, 06:51 AM
Danke John

lugnut
02-26-2011, 12:08 PM
I made one of the swing up threading tools after seeing Johns post here. I don't do a lot of threading but it does work very well., I used a carbide insert threading tool and one of my QC holders. The Treadmill motor I put on my lathe allows me to reverse on the go.

http://img.photobucket.com/albums/v671/lugnut/Treading%20tool/Jan011998001-1_edited-1.jpg

http://img.photobucket.com/albums/v671/lugnut/Treading%20tool/Jan011998002_edited-1.jpg

http://img.photobucket.com/albums/v671/lugnut/Treading%20tool/Jan011998001_edited-2.jpg

http://img.photobucket.com/albums/v671/lugnut/Treading%20tool/Jan011998002-1_edited-1.jpg

The Artful Bodger
02-26-2011, 01:44 PM
Could you post some pics of this set up when convenient?

Rgds

Hi, I dont have pics handy right now but mine is very similar to what Lugnut posted, except I did not put the spring in and instead of the QC tool holder mine is just a block that fits in the tool post.

John