# Where's Harry Potter when you need him ..... the Dark Arts ......  Grrrrr.. SPT



## CrewCab (Sep 14, 2008)

or ................. *S*ingle *P*oint *T*hreading ??? ......... and how I broke all my cutting tools in one afternoon :-X

OK ..... this is my first attempt at said "Dark Art" ...  :wall: .......... I've chosen an M12 x 1.75 thread .......... cos' that's what I need ..... I've abandoned practising on mild steel bar and am now using Delrin ... much easier on the tooling ;D ......... but .......


why is my 1.75 pitch thread ending up at about 1.75 plus a bit ......... or around 1.8 ish ???

Confused.com CC


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## Brian Rupnow (Sep 14, 2008)

You may have the wrong change gears installed, or it may be a case of having a British Imperial lead screw that will not cut a metric thread.


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## CrewCab (Sep 14, 2008)

Brian Rupnow  said:
			
		

> it may be a case of having a British Imperial lead screw that will not cut a metric thread.



.0254/.025 x 1.75 = 1.778 ??? ............. Dammit Brian  .......... you may well be right :-\

 :wall: CC ???


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## Bogstandard (Sep 14, 2008)

Dave,

As you have found out the hard way, you are now in the world of the black arts. 

There has been a lot of discussion on this over the last month or so about this weird phenomononomonon. 

Marv is the one who is having bad indigestion over this one, and already I have put my head thru a brick wall because of it.

It all seems to stem, as Brian said, from the changeover from imperial to metric leadscrews, or the non changeover in some cases.
With an imperial leadscrew, it is normally very easy to cut imperial threads, and only (but sometimes very close) approximations of metric threads.

With a metric leadscrew, up to now, you are on your own. 
Both Marv and myself are still working on that one. 

On the lathe I have just bought, that has a new fangled metric leadscrew, even with a lot of gear swapping, a majority of the metric and imperial pitches are only approximations. 
So it looks like progress has sent us back to the start of the industrial revolution.

I might have a bit more helpful info when I get my new machine delivered. As I am going to give it the full range checkout, just to see what it can and can't do, with reference to cutting threads. I have loads of delrin in stock to try it out. That might then shed some light on the metric thread syndrome. The machine might end up where the salesman doesn't want it to be (if you have seen the Hancock film, you will know where), depending on the results.

John


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## CrewCab (Sep 14, 2008)

Bogstandard  said:
			
		

> you are now in the world of the black arts.



Not Kiddin' Dumbledore 

I bow to others who have gone before ........... or ...... who are at least on their travels ........... good luck guys  

Anyway ............. I will, when time allows, try and cut a 1.778 female thread ...........just so something can be salvaged ;D

Good luck gang ....... seems like I need to re-visit my tailstock threading do -dad  ........ but can anyone help, large threads using steel are ........... to say the least........... not easy   ................ in fact 12mm is a (female dog) 

CC


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## Bogstandard (Sep 14, 2008)

Dave,

What you can do, is cut the thread say to half depth using single point. Then finish off using a die. The die should be able to put the slight off pitch right, it won't be so hard to cut because of some of the material is already gone, and the thread will be guaranteed straight because it was started as a single point.

John


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## tel (Sep 14, 2008)

That's how I'd go about it as well John. AND make a tap the same way while you're set up for the pitch (just in case).


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## CrewCab (Sep 15, 2008)

Bogstandard  said:
			
		

> The die should be able to put the slight off pitch right,



Tried that guys, but It looks like the pitch is a little too far off for the die to put it right 

CC


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## Bogstandard (Sep 15, 2008)

You are definitely in need of a few new spells.

John


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## CrewCab (Sep 15, 2008)

Bogstandard  said:
			
		

> You are definitely in need of a few new spells



 :big: ;D :big:

That cheered me up after a crap day ................. Thanks John ...... ;D .............. and ........   .......  I think your right 

CC


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## Bogstandard (Sep 15, 2008)

I had a thought after I had posted about straightening it up. That would only really work for a short run of threads, anything over say 12mm (1/2") the overpitch would be running into where the next thread should be.

Don't worry, you are not alone, and I think in the short term the manufacturers will get the better of us, but somewhere along the line, someone, somewhere, will come up with a final solution.

Using my old Atlas imperial machine, I managed to find some gearchange charts in the fantastic manual, that gave me useable metric threads up to whatever length I wanted. Almost perfect pitches with the change gear set I already had. Weird setups, but they worked.

Maybe some sort of web search might come up with a few answers.
I did find that downloading the 'Grizzly' PDF files for lathes similar to mine showed me the way to an understanding of how threads were cut. Maybe they have similar ones for your lathe, to give you a workaround to the problem.

John


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## CrewCab (Sep 15, 2008)

It's not an insurmountable problem as I'm sure imperial threads will be no problem, however I will check that in the near future  ...... it's just I needed an M12 thread at the time, so M12 die to the rescue on this occasion ........ dam hard work mind ??? ........ I'm happy working in either imperial or metric, or even both so I can cope with using the nearest imperial thread without any real problem ............ tis' a bit of a beggar for the younger guys though where imperial measurement is a bit of a mystery.

CC


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## John S (Sep 15, 2008)

CC,
What lathe do you have ?

.


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## Bernd (Sep 15, 2008)

Bogstandard  said:
			
		

> I did find that downloading the 'Grizzly' PDF files for lathes similar to mine showed me the way to an understanding of how threads were cut. Maybe they have similar ones for your lathe, to give you a workaround to the problem.
> 
> John



You know John when I first got my Grizzly (model G4000) I tried cutting threads on it. The standard 20 threads per inch and they didn't come out right, come to think of it now. I never did try cutting threads on that "darn" machine again. I also didn't dive into why the threads didn't turn out right since I didn't buy it to cut threads. I'm thinking I should try to go through and set it up again to see if I can cut a simple 1/2-20. 

The Grizzly's mini mill's lead screw are some odd pitch. IIRC if you turned the dial 1" it actually traveled a few thou further if you put and indicator on it. I finally changed those over to true standard thread by buying the change over kit from Micro-Mark. 

Bernd

Regards,
Bernd


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## mklotz (Sep 16, 2008)

Bogstandard  said:
			
		

> Using my old Atlas imperial machine, I managed to find some gearchange charts in the fantastic manual, that gave me useable metric threads up to whatever length I wanted. Almost perfect pitches with the change gear set I already had. Weird setups, but they worked.



For the benefit of others who may wish to do what John suggests, take a look at the CHANGE program on my webpage. It was written expressly to address this problem.

Basically, you feed it (via a data file) all the change gears you have as well as the pitch of the leadscrew. When it runs, you input the thread you want to cut (Imperial or metric) and the maximum pitch error you will accept for cutting that thread.

It then proceeds to write a file which contains all of your change gear permutations that will cut that thread with an error less than or equal to the maximum you specified. Print the file, take it to the shop and get to work mounting gears.

Some of the old, grizzled pros may be saying, "Feh! We don't need no steenkin' computer program to run a lathe." Try figuring out what gear combination you need to cut 11-1/2 tpi with 0.01% pitch error by hand and you may revise your feelings about this program.


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## Bogstandard (Sep 16, 2008)

Marv,

I had forgotten all about your little elegant prog, and I am positive that anyone who has a change gear machine would benefit from its use.

My problem, with this new machine, I only have the basics that changes over from metric to imperial, everything else is done in the gearboxes, which I have no control over whatsoever. When I want to 'play' and make something special, as in the columns on my mine engine, I think now I have taken a major step backwards on that one.
Make it easier to do, but lose the independence of being able to make whatever you want.

Change gears rule!

John


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## DickDastardly40 (Sep 16, 2008)

Crew Cab,

Your post raises 2 points, the first being that you've broken all your cutting tools.

I would be interested in how they have failed as you shouldn't be getting close to putting too much pressure on a vee thread tool on only a M12 thread to break one.

How deep was your cut on each pass and what speed were you turning at, did you use coolant and were you using the direct approach with the compound parallel to the lathe bed or angular approach with the compound at 30 deg?

Were your thread tools hand ground, did you take the side clearances required into account and did the tool tip have sharp, small flat or rounded profile.

Brass is a good medium for practising thread cutting; no coolant is required and you can see how the chips come off. Practising on delrin may not show how the chip forms as it shaves and you get big swathes of candyfloss.

As to the pitch of the thread being off by a small but apreciable margin I can offer no suggestion if you wish to use a proprietry fastener to a thread you have cut, however an alternative way could be to cut both the male and female threads the same (but non-standard) pitch. I appreciate cutting a 12mm internal thread is a pain especially for a novice.

I rarely cut a thread if a tap and die is available and the fit is not critical.


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## John S (Sep 16, 2008)

Once you can get by the basics of screw cutting it becomes a pleasure. No more rough looking threads and more to the point they are parallel to the rest of your work.

It's not that hard and with just one or two cheap reground tools you have every die ever made [ and unmade  ]

I screwcut even simple everyday threads to but one dodge I use is to use a single piece out of a Coventry die head.







This shot is of a part completed 14 x 2mm pitch thread being cut on a piece of silver steel [ drill rod ] which as we know isn't the best material to thread. The advantages of this method are that it puts the correct root and crest radii on in the same pass.

One die piece will cut any thread of that pitch and for some reason ? it doesn't seem to affect it just plunge cutting as opposed to going in at an angle with the top slide. This suits me as I have removed the top slides from by two big machines and replaced then with solid steel blocks as rigidity is worth more to me than the angular feature used about every 3 months.

.


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## steamer (Sep 16, 2008)

Marv,

The program is great as long as you know the pitch of the leadscrew.
Based on the above it would appear to have something not quite english or metric? What are you using for leadscrew pitch as part of your program?

Dave


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## CrewCab (Sep 16, 2008)

John Stevenson  said:
			
		

> CC,
> What lathe do you have ?



John,

My lathe is a Chester 9 x 20 (Imperial I believe) *This One*

CC


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## John S (Sep 16, 2008)

CC,
Found the manual for the same lathe from Grizzly but not a lot of help as it's only imperial and they don'y know what metric is over that side.

What gear wheels came with the lathe?
.


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## CrewCab (Sep 16, 2008)

John Stevenson  said:
			
		

> What gear wheels came with the lathe?



28, (2x) 30, 36, 42, 45, 60, 80, 120, & 127


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## mklotz (Sep 16, 2008)

steamer  said:
			
		

> The program is great as long as you know the pitch of the leadscrew.
> Based on the above it would appear to have something not quite english or metric? What are you using for leadscrew pitch as part of your program?



Leadscrew pitch is one of the inputs to the program. You supply the proper value for your particular lathe.

I have to believe that every commercially available lathe today has either an Imperial or metric leadscrew as opposed to some bastardized thread. The errors that some folks are experiencing when trying to cut a given thread pitch are probably due to errors in setup that result from poorly written instructions and the fact that some makers may be claiming that the lathe cuts a given pitch when, in reality, it cuts only an approximation to that pitch.

This is why I'm so vicariously interested in the problems that John is experiencing. If we can really nail down what is going on there, we'll be in a good position to write a clear description for the newcomer explaining what he needs to do to fully understand threading on his machine.


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## Dhow Nunda wallah (Sep 16, 2008)

Errm, sir?
Has no one considered a tailstock die holder?


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## DickDastardly40 (Sep 16, 2008)

127 is the likely 'magic' number for imperial to metric conversion in this instance. I think now we need to know what pitch the leadscrew is.


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## CrewCab (Sep 16, 2008)

DickDastardly40  said:
			
		

> I think now we need to know what pitch the leadscrew is.



So do I ??? .................. from a trawl it looks like it's (supposed to be) 16tpi, here's a quote from the 9x20 Yahoo group .......... 

_"they are generally a metric diameter,15mm and an imperial pitch, 16tpi."_  :wall:

but no matter how many times I try it, using a steel ruler and a pointer I count 17tpi, plus my 1.5 thread pitch gauge is a bloomin' good fit (which works out at 16.9tpi)

DD40 ......... in answer to your earlier questions 
Carbide tipped 60o spt tool, between 5 and 10 thou, 100rpm, cutting steel rod, new lathe tool and the end of the tip broke off, spray on cutting fluid (aerosol) .............. direct approach ........... cross feed parallel to bed.


hth

Dave


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## John S (Sep 16, 2008)

CrewCab  said:
			
		

> but no matter how many times I try it, using a steel ruler and a pointer I count 17tpi,
> 
> Dave



Aaahh there's the answer.
You count from the start of one tooth to the start of the last tooth at a 1" spacing BUT you don't count that tooth.

Using a ruler with 1/16" graduations they should line up every tooth.

Tea time calls [ Broken leg of lamb - yummie ]

I'll pick this up after tea, it's all in the setup.

.


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## mklotz (Sep 16, 2008)

DickDastardly40  said:
			
		

> 127 is the likely 'magic' number for imperial to metric conversion in this instance. I think now we need to know what pitch the leadscrew is.



127 is indeed the magic number. The trouble is, it can be approximated in many different ways*, and it may be just such an approximation that's the root of the problem here.

--------------------
* the most common two gear approximation on these import lathes is 47/37 = 1.27027 or an error of about 0.02% but, by going to a four gear approximation one can get a lot closer as this sample output from GEARFIND shows... 

Desired ratio = 1.27

17:18-39:29- 1.27011 (0.00905059 %) **
17:29-39:18- 1.27011 (0.00905059 %) **
19:17-25:22- 1.27005 (0.0042107 %) **
19:22-25:17- 1.27005 (0.0042107 %)
22:19-34:31- 1.26995 (-0.00401053 %) **
22:31-34:19- 1.26995 (-0.00401053 %)
25:17-19:22- 1.27005 (0.0042107 %)
25:22-19:17- 1.27005 (0.0042107 %)
25:22-38:34- 1.27005 (0.0042107 %)
25:34-38:22- 1.27005 (0.0042107 %)
26:24-34:29- 1.27011 (0.00905059 %)
26:29-34:24- 1.27011 (0.00905059 %)
30:23-37:38- 1.27002 (0.00180183 %) **
30:38-37:23- 1.27002 (0.00180183 %)
31:28-39:34- 1.26996 (-0.00330841 %)
31:34-39:28- 1.26996 (-0.00330841 %)
34:19-22:31- 1.26995 (-0.00401053 %)
34:24-26:29- 1.27011 (0.00905059 %)
34:29-26:24- 1.27011 (0.00905059 %)
34:29-39:36- 1.27011 (0.00905059 %)
34:31-22:19- 1.26995 (-0.00401053 %)
34:36-39:29- 1.27011 (0.00905059 %)
37:23-30:38- 1.27002 (0.00180183 %)
37:38-30:23- 1.27002 (0.00180183 %)
38:22-25:34- 1.27005 (0.0042107 %)
38:34-25:22- 1.27005 (0.0042107 %)
39:18-17:29- 1.27011 (0.00905059 %)
39:28-31:34- 1.26996 (-0.00330841 %)
39:29-17:18- 1.27011 (0.00905059 %)
39:29-34:36- 1.27011 (0.00905059 %)
39:34-31:28- 1.26996 (-0.00330841 %)
39:36-34:29- 1.27011 (0.00905059 %)


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## CrewCab (Sep 16, 2008)

John Stevenson  said:
			
		

> Using a ruler with 1/16" graduations they should line up every tooth.



Does this help 







It appears the pitch is slightly less than 16 .............. and if it helps the gear wheels recommended for 1.75 pitch are 42 and 36

CC


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## John S (Sep 16, 2008)

Shot down in flames 

I make it 17 as well. Can we have another picture with the metric side of the rule now please ?

1 divided by 17 is 0.0588" per pitch, now multiply this by 25.4 and we get 1.4941 which is bloody close yo 1.5mm pitch given the 17tpi was only an eyeball figure.

So have you got a metric lathe or an imperial one with a wrong screw fitted ?

What does the chart say on the gearbox / end cover or wherever, another pic please.


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## CrewCab (Sep 16, 2008)

Looks like it's Metric John .............. good call 






So the leadscrew seems to be 1.5 pitch .............. but where does that leave (or take) me in terms of SPT ???

The hand wheels are calibrated in thou's (or 0.0254mm) hence the reason I believed it to be an imperial machine.

CC


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## John S (Sep 16, 2008)

Need a picture of the gearbox chart but I do have an idea now.

.


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## CrewCab (Sep 16, 2008)

John Stevenson  said:
			
		

> Need a picture of the gearbox chart but I do have an idea now.


Bear with me  

David Bailey  : CC

 ;D


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## John S (Sep 16, 2008)

OK going to jump the gun as I'm certain I have it sussed.

It was what you said about using 42 /36 for 1.75 pitch.

Here's the chart from the Grizzly manual.





If yours is like this then you have the wrong leadscrew.
looking at the top section of the chart and given that you SHOULD have a 16 tpi screw then you can see that the 40 and 40 gears cancel out and as a and b are both 30 they also cancel out, basically in this configuration you have a 1:1 drive train.

Now 16 tpi is in slot 1 so slot 1 is a direct drive.

The proof now is setup the train as shown drop the box into slot 1 and for every turn of the chuck the saddle will move 1/16" on an imperial machine but I'll bet you that yor machines moves 1.5mm

Best to do this over a longer distance, say 4 turns which will be a 1/4" or 6mm Turning by hand will be best.

.


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## CrewCab (Sep 16, 2008)

JS
This is the chart on my lathe ............ which I believe is the same as you have posted 






Sorry for the delay but we are running a bit late here tonight due to FIL problems : ........ so I'm eating tea with one hand and typing with the other 


OK so if I understand this correctly I'm attempting to cut a 16 tpi thread by using the 2 x 30 change gears ???  .............   ........ so ......... now we come to the next minor problem ???

The theory is ..................






Unfortunately, at present, the "removable" boss on the shaft with gear "B" is proving a nad's awkward to remove so ......... gear B can't move "inward" to line up with gear "A" and mesh with the same wheel ............. please bear with me while I gradually move up the scale of "persuader's" :wall:

CC


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## John S (Sep 16, 2008)

CC,
You have a metric lathe.

Look carefully at the pictures of the gear trains on my pic [ imperial ] and yours.

They are transposed, on 'mine' [ read grizzly ] the straight train is for imperial thread but on yours the straight train is for metric.
The 127 on yours is to cut imperial as it should be with a metric screw.

So to cut a 1.75 thread you bneed a 40 thru a 80 to another 40, coupled with a 42, driving a 36 thru an idler.

.


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## CrewCab (Sep 16, 2008)

I see what you mean John 8) ......... now ........... once I can persuade this boss to co-operate we might be threading 











At this moment in time I'm struggling to get the little beggar off the shaft ??? ...... If anyone has already "got this Tee Shirt" I'd appreciate any pointers 

CC


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## John S (Sep 16, 2008)

small blowlamp, then a pry bar, then oh sod it , it's bedtime.

.


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## CrewCab (Sep 16, 2008)

John Stevenson  said:
			
		

> small blowlamp, then a pry bar, then oh sod it , it's bedtime.



I've tried 
1) gentle persuasion
2) "less than" gentle persuasion ............... that's basically a "slightly" bigger tapping stick :
3) all sorts of levering and prying coupled with gentle prying :-X
4) foul language and associated devil worship threats :big:
5) spitting and eye poking :-[

OK ............ we need help here guys 8) ........... It's late so I'm off to bed, I'll check back in tomorrow and I'm sure one of you bright sparks will have the problem solved by then 

CC


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## kf2qd (Sep 16, 2008)

CrewCab  said:
			
		

> I've tried
> 1) gentle persuasion
> 2) "less than" gentle persuasion ............... that's basically a "slightly" bigger tapping stick :
> 3) all sorts of levering and prying coupled with gentle prying :-X
> ...



Sounds about like you've got the process down.

Actually - it might be rather tight on the key as well as the shaft, so it might be easier - at least the first time... to loosen things up so the shaft can move through the collar and then finish up by prying the collar off.


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## Hilmar (Sep 16, 2008)

CC 
go to the 9 X 20 group and look for message 52133.
Same problem and solution .
Hilmar


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## BobWarfield (Sep 16, 2008)

Oh my, all this metric versus imperial versus 8 million gear combinations and which ones will fit on the banjo, yada, yada. So much pain.

And now, for the real black art secret: it's all so unnecessary and so last millenium (he said with tongue somewhat in cheek). After all, the computer can do for lathes what it has done for the phonograph.

CNC, of course, makes all of this easy. But CNC is such a religious issue. Many don't want to deal with CNC and all of it's learning curve and cost. But there is a waypoint between the mechanical and the full CNC that is pretty nice. It's called an "Electronic Lead Screw". Here is a YouTube video:

[ame]http://www.youtube.com/watch?v=RRaVIBhLgF0[/ame]

So what you do is mechanically use a stepper motor to drive your leadscrew. It's not hard to lash one on there. You attach a little sensor to the spindle, which enables the little computer (it's all in a box, you don't need a separate PC, just mount the little box right on your lathe next to you VFD) to create an infinitely variable simulated gear train. Now you can dial in any thread or feedrate you might want. 

If you are more ambitious, the ELS can control both axes and do tapers of any kind, but now you really are starting to get more down the road to CNC. I just love the idea of an infinitely variable electronic gear box that is cheap and cheerful to put in place on almost any lathe. 

Here is the Yahoo Group for the thing:

http://tech.groups.yahoo.com/group/E-LeadScrew/

There are professional "manual" lathes that have this feature. A Hardinge clone is pictured on the site. John Danmeyer manufactures the little kit and frequents the HSM boards. He may even be lurking here.

Worth a look see. Short of CNC I can't imagine a more versatile answer to this vexing problem.

Cheers,

BW


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## Bogstandard (Sep 17, 2008)

Dave,

With this problem, IMO you are doing the right thing. Hanging on to the bitter end, until you have proved either success or failure.

By doing it this way, unlike a lot of others, who would have given up and reverted to taps and dies, you are deep into a major learning curve. Get it cracked, and you will be whistling and grinning for all time. You should be able to accurately cut threads on your lathe.

If it doesn't work out, and you can't get good results because of machine limitations, at least you will know it is not your fault, but you will know how a screwcutting gear train works, and the next time, on another machine, you might have more favourable results.

Keep at it mate.

John


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## DickDastardly40 (Sep 17, 2008)

CrewCab  said:
			
		

> DD40 ......... in answer to your earlier questions
> Carbide tipped 60o spt tool, between 5 and 10 thou, 100rpm, cutting steel rod, new lathe tool and the end of the tip broke off, spray on cutting fluid (aerosol) .............. direct approach ........... cross feed parallel to bed.



I can't see why you should get tool should breakage using the above method. At which point in the cutting process did the tool break. 100 RPM is possibly the slowest speed possible on your lathe yes? Is the steel rod mentioned silver steel drill rod? (as John says, this threads awfully).

I always try to have a recess at the shoulder end of the thread to run the tool into. Others back the tool out swiftly at the end.

Possibly if you are not running the tool into a recess at the end of the thread and you don't either manage knock out the leadscrew feed or stop the lathe (if not disengaging the half nuts) at the same time every time, the pressure on the tool as it reaches the end of thread and tries to cut full depth could cause it to break. 

Winding the spindle by hand for the last turn to get a dead nuts on stop has been covered before; Marv and Tel have both posted pictures of their respective 'mandrel handles'.

Hope the above helps. Lots of cracking information in this thread already.

Al


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## bob ward (Sep 17, 2008)

To remove the boss, will a puller along these lines work?
http://www.justoffbase.co.uk/Bearin...970e9dd33f599c3e.e3eTaxaQbxmTe34Pa38Ta38Mahb0


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## John S (Sep 17, 2008)

I had one similar some years ago on a new lathe where I had to pull the gear off with a puller and the sleeve wouldn't move.
After trying numerous tricks I drilled down it from the face and split it off then made a new sleeve with clearance.
They don't need to be dead nuts tight it's only a spacer and often the most destructive way does the least damage, read bent shafts, and is quicker in the long run.
If you get a blank, doesn't even have to be steel, any free machining material will do, mark out where the key goes, drill a hole then bore the centre out, clean up with a file.

Don't worry about a fit , it's only a spacer. Depending on what spare gears you have with the machine you may be able to use one of these as a spacer to save making one.


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## CrewCab (Sep 17, 2008)

Thanks guys, seems like it's a common problem then ???

I'll have a go with a puller etc, failing that methinks sacrificing the sleeve may be the best way forward, could well be the weekend before I get chance to have a look but I'll keep you all informed 8)

CC


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## CrewCab (Sep 17, 2008)

CrewCab  said:
			
		

> could well be the weekend before I get chance to have a look



 ;D ............. OK ............. I lied :big:  :big:

Just snuck half an hour off to have another go at the lathe ............. it seems the "thorough" talking to I gave the Darn boss, ........... perhaps coupled with the penetrating oil ............. has had an effect, the bloomin thing virtually fell off of it's own accord as soon as I showed it a puller :

So, quick tidy up of the woodruff key with a file and both boss and gears slide on & off just fine ............ 


and ...... Problem Solved, it is a Metric Lead screw and now it's cut a first class 1.75 pitch thread in Delrin :bow: Thanks for all the help guys 8)







I'll try some aluminium at some stage before working back up to steel 

CC


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## mklotz (Sep 17, 2008)

CC,

Congratulations on your success. If nothing else, you probably have learned a bit about threading; though I expect you would have preferred a less taxing education.

Somewhere along the line, I've lost track. What exactly was your original problem with cutting the thread? Was it that you were misreading the gearing charts on your lathe or something else?


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## CrewCab (Sep 17, 2008)

To be fair Marv, I've enjoyed it as I've learnt a lot 

As regards loosing the plot, don't worry your not alone ??? .......... The main problem was self inflicted, I thought my lathe was imperial, but as we now know it has a metric leadscrew and, having now resolved the seized bush and fitted the correct combination of gears it works just fine.

I've used a lathe quite a lot but that was many years ago, but I've never before attempted single point threading, without the help of the guys on here, particularly JohnS, I suspect I'd have been weeks getting to the bottom of the problem, but with all the help on this forum it's taken a couple days :bow:

CC


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## mklotz (Sep 17, 2008)

I guess my question is: Had you fit the gears indicated on the charts for the pitch you wanted to cut (1.75 mm IIRC), would it have worked correctly? What I'm after here is whether we need to warn other users of this lathe about a possible chart problem?


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## Bogstandard (Sep 17, 2008)

Well done Dave,

Problem solved, lesson learned, the hard way maybe, but you can be damned sure you won't forget what you have learned.

John


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