# Threading a long rod and keeping it straight.



## Tim Wescott (May 7, 2020)

I'm trying to make needle valves per the drawing below, and I keep screwing up the spraybar.

Basically, I get a nice machined straight brass rod, but as soon as I thread it I end up with a nice, threaded, gracefully bent, brass rod.

How do people _do_ this?  I'm currently using a die in a holder, held in my hand -- if I made up a die holder to be held in a chuck in my tailstock would it work?  I've considered trying to single-point machine it, my lathe isn't well set up to make such a cut in such confined quarters (but I'll figure it out, if it's the only way to make it work).

(Edit: I'm trying to tap it at 5-44 -- is that just too coarse a thread?)

Thanks.


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## dnalot (May 7, 2020)

Most threading dies are for chasing threads. It would be best to single point machine about 80 percent deep and then chase to the final size using a die holder in the tail-stock. 

Mark T


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## fabricator (May 7, 2020)

dnalot is right, generally split round dies are for cutting threads. Hexagonal dies are for chasing threads. But if you have a tailstock die holder you would stand a much better chance of good results.


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## Tim Wescott (May 7, 2020)

It's a round die, bought as a thread cutting tool.

Mark, I hear what you're saying about single-point threading and then chasing -- but I think I'm going to make me a tailstock die holder anyway and try it, because getting my lathe to cut threads over such a short span is going to be murder.

Then if that doesn't work I'll go back and figure out how to single-point turn threads on something while supporting it with a center.


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## fabricator (May 7, 2020)

I've had good luck using a handheld die holder if I put the piece to be threaded in the chuck or a collet then keep the tailstock up against the die to keep it perpendicular.


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## Tomcat (May 8, 2020)

Tim Wescott said:


> I'm trying to make needle valves per the drawing below, and I keep screwing up the spraybar.
> 
> Basically, I get a nice machined straight brass rod, but as soon as I thread it I end up with a nice, threaded, gracefully bent, brass rod.
> 
> ...


You can also machine a short section and thread it, then reduce the next section and thread it, etc. Also watch the diameter of the rod - a very small reduction on the diameter makes a huge difference in the threading forces required.


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## clockworkcheval (May 8, 2020)

In my experience some finer and longer die-cut threads wil not follow a nice straight path, even if cut with a die held in a tailstockholder. Too many elements can be slighty amiss adding up to scrap. So I fully agree with singlepoint cutting, if possible at all supported with a running support on the saddle.


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## terryd (May 8, 2020)

Hi,
I made myself a taistock die holder and have made a straight 5/32" threaded rod 11.5 inches long.  However in the meantime you can make a thread in the lathe with a die and standard hand held holder very accurately.  How?  With the work centered in the chuck and the end chamfered push the die against the work and lock the tailstock.   Turn the chuck with left hand and use right hand to feed the tailstock just enough to keep light pressure on the die.  The handle of the die holder should be prevented from turning by resting on the saddle or cross slide of the lathe,  I've just been making a series of threads of varying size from M2.5 to M8 (5/16) metric fine using this method as all of my tailstock die holders were full of other dies and I couldn't be bothered to keep changing dies for a few one fs.  I've added a picture to show the set up, this is not a working set up just a demo - N.B.  very important - the lathe must NOT be powered, isolate it.  Note the handle restrained by the cross slide, with a larger die holder it could rest on the bed.

I've also added a picture of my tailstock die holder.  It is very simple and slides on a shaft which has a morse taper for the tailstock.  I usually use it hand held without the screw in handle and under power and when I release the holder it simply spins with (slowly) rotating work piece.

TerryD


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## tornitore45 (May 8, 2020)

A die holder that can slide and stay on axis is mandatory.
If the die starts crooked the result is a "drunken" thread, being the part hollow one side is thinner then the other and the part bends.
Visualize an angle between the part axis ant the die axis.
The thread will eventually get deeper and deeper on one side and shallower and shallower on the opposite side as the thread progresses. This is an exaggerated visualization but it does not take much for the die to attempt to right itself because there is more resistance on the deeper side, in doing so it bends the part.

The smaller the diameter the harder is to start square and smaller error are enough to give trouble.
Tho start a die well aligned I usually turn down 4 or 5 thread pitches to the minor diameter and then cut that stub off.  The die and the part have little choice to move as the thread starts and place an offset force until the first thread is formed.


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## Mainer (May 8, 2020)

You ARE turning the rod down to 0.125" before you thread it 5-44. aren't you? I'm a bit confused by the drawing, as it looks as though the thread is spec'd at 6-32.  Am I missing something?


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## terryd (May 8, 2020)

I just came across this picture of a long thin thread - 5/32 diameter - which I cut under power using my tailstock die holder - it was dead straight.  This is obviousy brass but I've done the same job in mild steel.

TerryD


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## tornitore45 (May 8, 2020)

The fact that the part is hollow and the wall is fairly thin aggravates the situation substantially.


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## terryd (May 8, 2020)

Die holder hand held for small thread (5/32" BSW)  And just to clarify, the Morse taper sliding shaft for die holder to slide on which I didn't show earlier

TerryD


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## terryd (May 8, 2020)

tornitore45 said:


> The fact that the part is hollow and the wall is fairly thin aggravates the situation substantially.



Thread first in lathe then drill (carefully) is probably the best sequence.

TerryD


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## fabricator (May 8, 2020)

terryd said:


> Die holder hand held for small thread (5/32" BSW)  And just to clarify, the Morse taper sliding shaft for die holder to slide on which I didn't show earlier
> 
> TerryD
> 
> ...


The die holder sliding on a shaft is an excellent way to go, I'm going to have to brazenly copy that.


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## terryd (May 8, 2020)

fabricator said:


> The die holder sliding on a shaft is an excellent way to go, I'm going to have to brazenly copy that.



That's fine, I copied the basic design but made up all the dimensions to suit.  If you note there is a hole down the centre of the sliding Morse taper bar which accomodates longer parts.  I actually made another bar, turning an integrated Morse taper which I drilled all the way through so that even longer threads could be produces.  The longest I've made is 11 3/4"


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## terryd (May 8, 2020)

tornitore45 said:


> The fact that the part is hollow and the wall is fairly thin aggravates the situation substantially.



  Of couse another solution is to turn a bar- even hardwood would suffice, close fitting in the hole and Loctite (I use cheap 'superglue' - cyanoacrylate) it in when cutting the thread.  Heat up gently to break down the Loctite, pull out the support bar and clean up.  Smiles all round 

TerryD


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## teeleevs (May 8, 2020)

Tomcat said:


> You can also machine a short section and thread it, then reduce the next section and thread it, etc. Also watch the diameter of the rod - a very small reduction on the diameter makes a huge difference in the threading forces required.


Tim, Tomcat is right, if the rod is slightly under size it will cut easier it will also expand out to the right size, having said that brass is difficult as it will cut tight and the rod will slightly twist which also contributes to bending, a good new die is better than an old one. I know none of this helps you, just keep trying.


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## awake (May 8, 2020)

Tim Wescott said:


> Then if that doesn't work I'll go back and figure out how to single-point turn threads on something while supporting it with a center.



Tim, I pretty much always single-point threads - in part because the only dies I have are only good for chasing threads, not for cutting them from scratch. But I want to call attention to the last thing above - if you go this route, with a long, thin part, you really need the end to be supported by a center; otherwise the threading force will bend the rod, and/or give you lobed threads as the part flexes. DAMHIKT!


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## JohnBDownunder (May 9, 2020)

All the above reminded me of this item for turning slender rod and perhaps if you had a few to do it might be possible to adapt the idea to support the threaded diameter behind the die???

John B


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## terryd (May 9, 2020)

JohnBDownunder said:


> All the above reminded me of this item for turning slender rod and perhaps if you had a few to do it might be possible to adapt the idea to support the threaded diameter behind the die???
> 
> John B




Hi,
The tailstock holder which I posted a picture of earlier has an 8mm hole all the way through to the headstock which controls any whip in long slender rods.  I have batch produced threaded 5/32 rods (4mm) BSW (approx #8-32 UNC) which are 11.5" long without any drunkenness in the thread, so I don't think that this is a problem with a decent tailstock die holder.  I can use this system for up to M8 (5/16") threads, above this I use single point threading.  I wouldn't use single point threading for small threads as quality split dies are available at reasonable prices.  I find that brass cuts beautifully

There is a Youtube video showing a long thin threaded rod (for Meccano use) made using my tailstock holder here







Above - the Meccano coupler on the threaded rod is internally threaded and 1.125" long, thread 5/32 BSW.







Above - here I am cutting an M2 (2mm - just smaller than #2-64 UNF) thread

TerryD


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## JohnBDownunder (May 10, 2020)

terryd said:


> Hi,
> The tailstock holder which I posted a picture of earlier has an 8mm hole all the way through to the headstock which controls any whip in long slender rods.



Hi,
The bit about the 8mm hole through to the headstock had me scratching my head a bit.

Did you mean through to the tailstock end which would work if your tailstock was continuous bore I guess.
My little 7x12 Seig clone has a blind outer end where the screw handle attaches to the tailstock quill. Kinda defeats the through hole idea.

Just trying to picture the process. I don't have the need to thread a long slender rod as yet but if I did I would likely use an ER32 collet chuck and feed 25-30mm a time through the collet and as my little lathe is under-powered at very low revs would be turning the spindle by hand crank so whipping would not be an issue.
Regards,
John B


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## terryd (May 10, 2020)

Hi John,
My Boxford (South Bend clone) also has a closed end on the tailstock but the 'quill' can be wound out as far as needed to accomodate around 5" max of rod and the die carrier is around 5" long and can slide to about 3/4" of the carrier rod which is bored as is it's morse taper giving a total capacity of around 13 - 14" so in total there is quite a lot of leeway for long rods.  Don't get me wrong, I don't use that maximum often, only for special orders such as long Meccano screwed rods which were originally made to an 11 1/2" length. Having said that it is a useful facility when needed.  As you can see from my pics above it is also useful for short tiny threads as well.  I really struggled before I took the plunge to make and I don't know how I would now manage without it.

I should also point out that I keep the main size dies which I use the most permanently in the interchangeable die holders which are interchangeable.  I often make a new holder as I add extra dies rather than swapping them and as there are several sizes of die I make their holders to suit.  They only take a few minutes to make.

TerryD


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## BaronJ (May 10, 2020)

terryd said:


> Hi John,
> My Boxford (South Bend clone) also has a closed end on the tailstock but the 'quill' can be wound out as far as needed to accomodate around 5" max of rod and the die carrier is around 5" long and can slide to about 3/4" of the carrier rod which is bored as is it's morse taper giving a total capacity of around 13 - 14" so in total there is quite a lot of leeway for long rods.  Don't get me wrong, I don't use that maximum often, only for special orders such as long Meccano screwed rods which were originally made to an 11 1/2" length. Having said that it is a useful facility when needed.  As you can see from my pics above it is also useful for short tiny threads as well.  I really struggled before I took the plunge to make and I don't know how I would now manage without it.
> 
> I should also point out that I keep the main size dies which I use the most permanently in the interchangeable die holders which are interchangeable.  I often make a new holder as I add extra dies rather than swapping them and as there are several sizes of die I make their holders to suit.  They only take a few minutes to make.
> ...



Hi Terry, Guys,

One technique that I haven't used for a number of years, was to feed round bar through the headstock and use a die holder in the chuck.  Start the die in the normal way and then transfer the die holder into the chuck jaws.  Taking the tailstock off allowed me to make yard long (36 inches) threaded rod quite easily.  Squirting cutting oil into the end of the lathe spindle to coat the rod.


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## ytrose2 (May 10, 2020)

I wonder if there was a way to modify a travelling steady to hold the die in the correct orientation once the initial thread had been started. The free end of the rod could be lightly held in the tailstock chuck for centring. The saddle could then be allowed to travel feely as the thread is cut along the rod whilst the chuck in the headstock is rotated.
Have not tried this, all theory, but it might be feasible.


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## Tim Wescott (May 10, 2020)

Wow.  I've been away for a couple of days, and I'm getting a huge number of answers -- thank you all (and don't stop helping!)

On cutting & threading in short sections -- d'oh.  I'm already _cutting_ it section by section.

Mainer -- the one reference I found called out 0.122", and I tried that without success.  0.120" also still resulted in a bent rod.  So I have some learning to do.  And the drawing is only representative; I should have pointed that out better.  I'm using the same basic design, but I've got a bunch of engines that take a 1/8" or 3.5mm spraybar, so I need a slightly smaller thread (I've even got a few that are officially for 3mm spraybar, but I think I can cheat a 5-44 down to that by taking the tops off of the threads).  I've seen drawings for similar spraybars with smaller threads, so I'd at least _think_ it's possible.

I think that I'm going to go get a glass of wine and stare at my lathe for a while, to decide if it'll be easier to make a terryd-style tailstock die holder (which I like because it'll be quick) or a JohnBDownunder-style sliding steady rest.  I kind of need a steady rest anyway -- but dang, that tailstock die holder looks nice!

I fly control line model airplanes, and the best cheap engines for that are lightly used plain bearing RC "sport" engines from eBay (mostly Enyas and OS LA series).  The port timing is just about perfect for control line stunt, and the plain bearing engines are lighter than ball bearing engines (and seem to hold up well; I have a couple with over 500 flights). 

Given that I'm scavenging them from a different market, they come with the RC carb (and sometimes the nose of a trainer airplane) attached, and only need to have a venturi and needle assembly machined for them to make a nice CL engine.  Which is a _really long way_ of saying that I need to make a number of assemblies, so having a way to zip out the solution is good.


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## BaronJ (May 10, 2020)

Hi Tim,

Thread first, drill second !

A proper tailstock die holder is the way to go for fairly short lengths under 50 or 60 mm.  After that single pointing in a traveling steady works.


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## JohnBDownunder (May 11, 2020)

Thanks Terryd, Now my head is sorted. I could probably do similar if only I can remember down the years.


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## Tim Wescott (May 11, 2020)

So, the point is that the rod and die should rotate with respect to each other, held concentric, and allowed to move along the length.  But this doesn't mean that the rod needs to be turning and the die steady.

So what if I carefully adjusted my tailstock so that it slides smoothly on the ways, put the rod in the tailstock, and put the die in the chuck?

I'm going to have to give this a try, if for no other reason than I have all the parts I need for it already, unless it turns out that I should have the die in a pot chuck -- and I know how to make those.


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## Tim Wescott (May 11, 2020)

Anyone have a feel for how concentric the rod and die need to be?  I'm wondering if I can just toss everything into a 3-jaw and trust it, or if I need to do everything with a carefully dialed-in 4-jaw.


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## BaronJ (May 11, 2020)

Hi Tim,

The whole point of using a tailstock die holder is that it will be as close to center when the workpiece is rotating in the chuck.

As I said earlier, I used to thread very long lengths of steel and brass rods by feeding them through the spindle with the die holder gripped in the three jaw chuck.  I used to start the thread using the three jaw to turn the rod into the die in the holder, then transfer the die holder to the chuck and continue from there.  You did need to hold the rod with mole grips to stop it rotating, but it worked very well.  Certainly the guy I made them for was quite happy with it.


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## awake (May 11, 2020)

Tim Wescott said:


> So what if I carefully adjusted my tailstock so that it slides smoothly on the ways, put the rod in the tailstock, and put the die in the chuck?



I think that's what BaronJ was describing in post # 24 above - except that if I understood correctly, he starts the die first.

On edit - BaronJ got his post in while I was typing mine!


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## BaronJ (May 11, 2020)

Hi Tim, Andy,

Yes that will work.  The reason for starting the thread into the die first is the run out on the chuck jaws will be less than when the chuck is opened up to grip the die holder. Plus the die will start dead square to the rod and stay square when placed in the chuck.

The only difference is I was passing the rod to be threaded through the spindle, through the die and down the lathe bed. I had removed the tailstock.

At least gripping the rod in the tailstock drill chuck it won't rotate whilst cutting the threads, but do use lubricant, even on brass.  I use diesel fuel as a cutting oil.


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## peterl95124 (May 11, 2020)

sorry, the easiest way to thread a long rod is to go buy some "all thread rod", and then screw it into
what ever part it was supposed to be part of.  my experience threading just the ends of rods to be
used as long studs for the heads of my V12 is that getting the threads "straight" and concentric
with the rod is a hit-or-miss proposition even with a tailstock die holder, therefore something
requiring even longer threads is problematic, and if really necessary will require single-pointing
rather than cut with a die (and since you imply lengthy threads, will also require some sort of
steady-rest, which...).  HTH, YMMV, etc.


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## SmithDoor (May 12, 2020)

I single point first then use a die for finishing. 
For long threads use a follower rest and single point thread

Dave



Tim Wescott said:


> I'm trying to make needle valves per the drawing below, and I keep screwing up the spraybar.
> 
> Basically, I get a nice machined straight brass rod, but as soon as I thread it I end up with a nice, threaded, gracefully bent, brass rod.
> 
> ...


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## BaronJ (May 12, 2020)

Hi Peter, Dave, Guys,

Roller die boxes were made to produce long lengths of thread as were Coventry ones.  The threaded rod or stud bar as it is sometimes called is made in this way.

Single pointing wins hands down for odd size threads but does require special techniques to be used for slender or long pieces.


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## SmithDoor (May 12, 2020)

That type good but cost setup is great.
But most of work here is ones and two's. Maybe a haftdose parts. So a die works esely do 100 part run even 1,000's parts.

Single point works great for hand full parts but most time you find dies that are low cost. 

Dave




BaronJ said:


> Hi Peter, Dave, Guys,
> 
> Roller die boxes were made to produce long lengths of thread as were Coventry ones.  The threaded rod or stud bar as it is sometimes called is made in this way.
> 
> Single pointing wins hands down for odd size threads but does require special techniques to be used for slender or long pieces.


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## terryd (May 13, 2020)

peterl95124 said:


> sorry, the easiest way to thread a long rod is to go buy some "all thread rod", and then screw it into
> what ever part it was supposed to be part of.  my experience threading just the ends of rods to be
> used as long studs for the heads of my V12 is that getting the threads "straight" and concentric
> with the rod is a hit-or-miss proposition even with a tailstock die holder, therefore something
> ...




Hi Peter,

I would agree with you generally but I make my long threads for Meccano users.  The thread is 5/32" BSW and I believe that the stuff now made in Calais is now metric M4.  Many users, collectors and builders of traditional Meccano need these threaded parts and it is almost impossible to buy the stuff apart from us specialist makers.  Meccano threaded rods were made in varying lengths up to 11 1/2" hence my manufacturing technique and of couse with my tailstock dies I can die cut any thread up to 8mm (5/16) up to that length and they are very straight and take a couple of minutes to set up and make.  No sorting out gear ratios, wrestling with setting them up, perhaps finding an interposing conversion gear for another system, grinding tools  or finding a stockist, driving around to collect or waiting on some courier to deliver.  I simply make what I need, when I need it.

By the way my tailstock die holder has never produced a non concentric thread in years of use and there is a reason for that but I will keep that reason to myself.


Best regards and keep safe,

TerryD


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## terryd (May 13, 2020)

Tim Wescott said:


> Anyone have a feel for how concentric the rod and die need to be?  I'm wondering if I can just toss everything into a 3-jaw and trust it, or if I need to do everything with a carefully dialed-in 4-jaw.



Hi Tim,

Depending on how you make your tailstock die holder the die should be self centering on the work in a 3 jaw chuck (hint don't make the die holder too precise a fit on it's slider - allows for self centering).  There is no need for a super precise 4 jaw set up.  That's just faffing about for the sake of it.  Some folk like to spend large amounts of time on super precision even when it's not needed and that's ok if it's your bag.  Me, I just like making stuff that does a job and does it well.  I don't have enough years left to waste them on uneccessaries


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## BaronJ (May 13, 2020)

Hi Terry,

Where about in the world are you ?


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## terryd (May 13, 2020)

Hi GOG  ,

UK Midlands,  Probably due South of you

Terry


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## BaronJ (May 13, 2020)

Hi Terry,



terryd said:


> Hi GOG  ,
> 
> UK Midlands,  Probably due South of you
> 
> Terry



Thank you.
The reason I asked was that it occurred to me that you might have been the guy that I made those long threaded rods for.  Its been a long time.

I'm near York.  The guy I remember was called Terry, he lived in Lichfield.


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## Ken Brunskill (May 24, 2020)

Interesting discussion, lot of ways to "skin the cat" are'nt there? So I served a Tool & Die Apprenticeship 1961-1965, as was the custom back then, we were allowed/encouraged to make our own tools, the attached photos show the 'Die Holder' and a 1/2" dia. drill blank, this is very similar to terryd's unit. Having read all the posts, it reminded me of using my 'Die Holder' with the die toward the headstock, once the thread has become as long as can be supported by the Drill Blank, acorrectly sized (for the major dia. of the thread being created) is placed in the opposite end. Worked fine for threads up to 9" in length, don't see why it would not work for longer rods.
As shown the 'Die Holder' has two (2) bore sizes for the popular split die sizes.

Good luck, stay well all.


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## terryd (May 24, 2020)

Hi Ken,

Great minds thinking alike

TerryD


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## Longboy (May 25, 2020)

Tim Wescott said:


> How do people _do_ this? I'm currently using a die in a holder, held in my hand -- if I made up a die holder to be held in a chuck in my tailstock would it work?


Reverse procedure. Put your Jacobs in the tail stock. Your brass rod in the chuck and the die in the 3 jaw chuck in head stock. Automatically squared up, stock to die. Power up after releaseing the tail stock from the ways. At least, this works well for smaller mini lathes.


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## Ken Brunskill (May 25, 2020)

Longboy, I like that idea for 1/4" (6mm) diameters and above for small lathes with light tail stocks. Depending on the the material being threaded and desired thread quality results, that approach could result in loose fitting threads as it is putting quite a axial load-bias on the thread cutting die. Suspect that a larger lathe   (13" +) certainly would in my opinion/experience. Of course we are not making mil. spec. parts here are we?  

All in all, this thread has shed a lot of light on a seldom discussed topic.


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## Longboy (May 25, 2020)

That was my best guess.....larger machines make these small dia. rounds & rods look frail. Brass rod can get the twisty in threading. Shouldn't have any axial load as the die drawing on the brass rod pulls the tail stock forward but may depend on the weight and drag of your machine tool size. You haven't much length of thread to do and Loctite cures underclass threading......let us know how you proceeded.


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## Ken Brunskill (May 25, 2020)

Must be some kind of serendipity as I just came back from the shop a few minutes ago, I am in the end stages of building an model Atkinson Differential  (See thread (Another Atkinson Differential), any way one of the very last pieces to fabricate was the 'Needle' for the carburetor. I did not have a traditional #2-56 split die, so I had to revert to the dies may father gave me._ I am so fortunate to have had a fantastic dad, who was a Maintenance Machinist for Friden Calculator Co, he was their ace on repairing their Automatic Screw Machines. _The tool seen in the photo was something he made to hold the Automatic Screw Machine Dies, he designed and built it with a precision .375" hole in the back that as the photo shows keeps it centered similar to the device I made in my apprentice ship. 

The thread cut in the photos is a #2-56 X 5/8" (.625") and the turned out well, not as straight as the Aluminum tool which has a longer guide component to it, (Shaft - Hole in Die Holder) than this tool does, as can be seen. I measured the wobble after threading and it was .007" TIR.


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## terryd (May 26, 2020)

Longboy said:


> Reverse procedure. Put your Jacobs in the tail stock. Your brass rod in the chuck and the die in the 3 jaw chuck in head stock. Automatically squared up, stock to die. Power up after releaseing the tail stock from the ways. At least, this works well for smaller mini lathes.



Hi Longboy,
That's a good idea as long as you have solid dies, which are mostly used for 'chasing' here in the UK.  Here, for threading the dies are invariably split dies which of course are adjustable so that threads can be adjusted to fit specific parts.  These would have to be held quite tightly in the chuck to prevent them from being pulled out by the drag of the tailstock = this would cause undersized threads surely?  With the tailstock die holder the die is held in place by the three grub screws which are also used for adjustment.

TerryD


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## justisla (May 27, 2020)

Put a shim in the split?


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## BaronJ (May 27, 2020)

Hi Guys,

?? Why put a shim in the gap of a split die ?  A correctly made die holder will have three pointed screws in it.  Two to hold the die and one to prevent the gap from closing up too far.

The two screws holding the die are used to close the die to size as well as hold it, the third screw besides holding the die prevents the die closing up any further than what ever you have set.

American style dies with the internal adjusting screw use all three holder screws to secure the die.


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## goldstar31 (May 27, 2020)

I agree with John B. What on earth will improve. what is probably a gimcrack solution anyway.

I was writing a hopefully nice letter. to one of our younger btretheren who was making steadies for sale.

Ye Gods wgat's next?

Well, I have got a pair of steadies for my sold Myford ML10 for sale. Well then I suggested that he consider Martin Cleeve's solution in those forgotten days.
He was a bit like an even older writer who sketched a steady made out of--- wood. He is the long gone geyser that everybody is copying- or nearly every one copies.
So I looked at  my Super7B one and then  the unused  one on the Chinese C4.  The bearing fingers bearing surfaces are tiny and virtually useless.
Cleeve, who not only wrote but MADE special  screws, made something solid in metal and added correct collars of and inch and a half and called it ' his fixed bushing steady'.
I his almost forgotten write ups he  held an 11 foot standard of steel in in his lathe- which poked out into his garden through a hole.
You  think about it, held accurately in an independent chuck on 'waving about' in the garden.

Clever?


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## justisla (May 27, 2020)

Baron J
Perhaps i should have included the quotes. I seem to have problems getting them to come out in the post.
The suggestion made earlier was to put the die in the 3 jaw chuck & the rod in the jacobs chuck such that the rod passed through the headstock. The follow up to that was that the 3 jaws would compress the die too much & may produce a thread that was too loose. I just made the suggestion that to prevent a split die from closing too much in such a set up one might perhaps shim the split. I have no idea if that would solve the issue, so i put a question mark after the remark.
Apologies if I mislead anyone. Perhaps my inexperience at such activities should have precluded me from commenting in the first place. However, if I do come upon the problem sometime in the future I may well try it.


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## BaronJ (May 28, 2020)

justisla said:


> Baron J
> Perhaps i should have included the quotes. I seem to have problems getting them to come out in the post.
> The suggestion made earlier was to put the die in the 3 jaw chuck & the rod in the jacobs chuck such that the rod passed through the headstock. The follow up to that was that the 3 jaws would compress the die too much & may produce a thread that was too loose. I just made the suggestion that to prevent a split die from closing too much in such a set up one might perhaps shim the split. I have no idea if that would solve the issue, so i put a question mark after the remark.
> Apologies if I mislead anyone. Perhaps my inexperience at such activities should have precluded me from commenting in the first place. However, if I do come upon the problem sometime in the future I may well try it.



Ah I see, no problem.  Its a bad idea anyway to put a bare die directly in the lathe chuck.  You should use a proper die holder.  Also pulling the tailstock along on those thin threads won't do the threads any good, it will cause them to stretch.


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## justisla (May 28, 2020)

BaronJ said:


> Ah I see, no problem.  Its a bad idea anyway to put a bare die directly in the lathe chuck.  You should use a proper die holder.  Also pulling the tailstock along on those thin threads won't do the threads any good, it will cause them to stretch.


Would it not be simple to apply pressure to the tailstock with one's hand?


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## Longboy (May 28, 2020)

justisla said:


> Would it not be simple to apply pressure to the tailstock with one's hand?


That is the right answer! Laying the book down and  doing the set task with the tooling one has available most likely will get you there.  Easy set up to try.  No need to make or purchase specialize holders. Will not be a time / cost consideration if results are not satisfactory for this part.  You certainly can get around stretching threads helping the tail stock along as the rod moves thru the die. 
As for torque twisting the brass rod for a 5-44 threads.......then the split die gets around that.  Also it is unlikely that the "Committee for the Proper Use & Procedures of Machine Tools" will  come to your shop and issue citations for going rogue. ( just in case you were wondering!)
But I still can't imagine doing 5-44 single point.....not even on a mini lathe!


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## terryd (May 28, 2020)

The problem with shimming the die is how thick should the shim be?  The obvious answer, as thick as the slot!  However at 'full stretch' i.e. die at the max opening, it will give an oversize thread, I always have to compress the die a little using the adjusting screws of the holder to tune the thread once the initial cut has been made. 

As I said in a much earlier post the tailstock die holder I made, not my design - I just tweaked it a little - can cope with threads up to 3/8" dia x 12" long.  The length of screwed rod which iI can make is because of the length of the hollow die holder itself.  The support bar and its morse taper are turned from one bar and drilled through 10mm with a long jobbers twist drill I bought for the job.  If I need longer than 12" I buy a metre of threaded rod.

It took an evening to make and has saved me an immeasurable amount of time and has given accurate results every time.  The actual die holders are interchangeable with one grub screw to loosen and I keep each of my most used sizes in their own holder only changing one when I need an unusual thread.

I wouldn't be without it.

Stay safe

TerryD


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## justisla (May 28, 2020)

Surely one can use a relatively "soft" shim & if the thread is tight one can just tighten the chuck jaws in a similar way to adjusting the screws on a die holder. Is that any harder in the grand scheme of things?


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## terryd (May 29, 2020)

Longboy said:


> That is the right answer! Laying the book down and  doing the set task with the tooling one has available most likely will get you there.  Easy set up to try.  No need to make or purchase specialize holders. Will not be a time / cost consideration if results are not satisfactory for this part.  You certainly can get around stretching threads helping the tail stock along as the rod moves thru the die.
> As for torque twisting the brass rod for a 5-44 threads.......then the split die gets around that.  Also it is unlikely that the "Committee for the Proper Use & Procedures of Machine Tools" will  come to your shop and issue citations for going rogue. ( just in case you were wondering!)
> But I still can't imagine doing 5-44 single point.....not even on a mini lathe!




Good job the engineers in the past didn't take the attitude " _doing the set task with the tooling one has available most likely will get you there",_ if they had we would still be making stuff with hand tools which in turn had to be hand made such as files made with chisels and charcoal case hardening as they would be happy making stuff with the "available tooling". 

Personally I'm really glad that people like Henry Maudsley, Brunel, Whitworth and James Watt et. al. were inquisitive, adventurous and ambitious enough to push the envelope and develop new tools and methods - and spend the time and effort to make them.  Still as the Beatles said:

He's as blind as he can be
Just sees what he wants to see 

TerryD


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## justisla (May 29, 2020)

terryd said:


> Good job the engineers in the past didn't take the attitude " _doing the set task with the tooling one has available most likely will get you there",_ if they had we would still be making stuff with hand tools which in turn had to be hand made such as files made with chisels and charcoal case hardening as they would be happy making stuff with the "available tooling".
> 
> Personally I'm really glad that people like Henry Maudsley, Brunel, Whitworth and James Watt et. al. were inquisitive, adventurous and ambitious enough to push the envelope and develop new tools and methods - and spend the time and effort to make them.  Still as the Beatles said:
> 
> ...


With due respect you have just contradicted yourself. Longbow suggested an alternative idea. -- He suggested a different method-he pushed the envelope. & you are saying he should not. Is one "blind" not to accept that? Nobody has actually said WHY one cannot put the die in the chuck with soft shims. Then push the tailstock along. I do not know why not, but I am certainly not going to accept, " well because it is not the done thing" as an answer. Furthermore, if one has only a single item to make can one tell me why one would want to waste time on an uneccessary task constructing a tool - other than the interest in making something. If that is what you like doing then there is nothing wrong with that, It is a hobby for most people anyway. I sometimes make things to solve a problem that never exists. But, hey, I was having fun !!!
Henry Maudsley, Brunel, Whitworth and James Watt Were on a different path for a different reason. So I do not accept those as relevant examples.


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## goldstar31 (May 29, 2020)

I wrote earlier about 'steadies and fixed bushing steadies' but doubt that you have read it up or perhaps haven't got them.
Again, I don't quite get my head around 'soft shims'. However I have two sets of soft jaws  for my Sieg C4 whereas I have 'umpteen' assorted chucks and collets especially for my Myford. I'm  a bit 'iffy' about using a split die in a self centring 3 jaw chuck and slightly happier about a 4 jaw SC. You DO get a lot more grip with a set of soft jaws but my thoughts are that without all this the chances of a broken die are high and if you are prone to holding the end of a rod by hand without any other assistance, you are probably risking severe  injury.

I'm not going to join the ebdless discussion on the old masters apart from mentioning my name is Norman Atkinson and there fore the same as the biographer on Joseph Whitworth and an E-mail requesting details of Whitworth's sex life

So cheers from the other Norman who isn't a dead Labour Member of Parliament.


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## Longboy (May 29, 2020)

terryd said:


> Good job the engineers in the past didn't take the attitude " _doing the set task with the tooling one has available most likely will get you there"..................
> 
> Personally I'm really glad that people like Henry Maudsley, Brunel, Whitworth and James Watt et. al. were inquisitive, adventurous and ambitious enough to push the envelope and develop new tools and methods - and spend the time and effort to make them. [/URL]
> 
> ...


_
OK Terry!  They would be glad that you depend on them to lead the way and one can run to the library for their insight..........but I am not familiar with their monopoly on thread cutting procedures. As inquisitive engineers, it would be unlikely they would be disappointed when one finds an alternative to reach the same end.  Seems like they would foster that approach looking for ideas and asking questions as justila has.

"Reading a lot of golf magazines and having lots of golf clubs...... doesn't make a good golfer."  (author unknown).
Dave._


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## Tim Wescott (Jun 20, 2020)

Yahoo!

You guys are officially the best.

I thought long and hard about all of the advice I got.  I decided to try terryd's suggestion first, because it'd be quick, because I have some brass* rod sitting around that's about the right size, and because if it worked it't fit really well with my process.

I _also _figured out how to turn long thin rod adequately using a center -- it's kind of stupid, but I'd been so hard over on "keep it rigid" that I didn't think about the fact that I can have a couple of inches on the chuck side of things, as long as I'm not turning too great a length on the supported end.  So -- yahoo twice.  And it's still a crappy lathe.







So I turned the end of a rod down to 0.122 & change (0.1227 is supposed to be the "correct" number; I wanted to be a bit small, if anything).  I made up the holder that terryd suggested, turned a thread, and voila!  I measure less than 0.001" of runout.  So, I'd say it's a success.


















* Of unknown alloy.  I got it as a joke, because I'm working with some students who handed me a drawing calling out "brass" as the material.  Clearly, if you get a drawing that calls out "brass" without an alloy, then you should go get some brass of unknown alloy to do the work -- right?  So I happened to be at Clackamas Steel, wandering through their "brass & copper" shed, and this bar of brass called to me.


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## Charles Lamont (Jun 21, 2020)

Well, that looks as though you have it cracked.

Turning small parts with tailstock support is never easy because bits of lathe get in each others way. When I put my indexing QC toolpost on the web, in 2003 if memory serves, I fondly imagined that I had invented the extended toolholder for the purpose:



			Charles Lamont's Model Engineering Pages -> IQC Toolpost -> Toolholders
		


I had never seen one before, but now they are available commercially for some QC systems. I have never been able to get on with the 4-tool turret toolholder your lathe has. I even sold mine.


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## BaronJ (Jun 22, 2020)

Hi Guys,

I sold my Dickson QCTP, far too expensive !  I made the Norman patent one and have never looked back.  It was good enough for Rolls Royce, and its more than good enough for me.

I no longer have any of the problems that seem to be associated with other tool holders and posts.

I do note that some of the articles and drawings for more recent designs don't actually stick to the original design and use a slit instead of the split collet to secure the tool block.  Having said that mine doesn't either, I used a slot to hold the tool bit,  Where the original used a broached square hole.


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## terryd (Jun 22, 2020)

Longboy said:


> _OK Terry!  They would be glad that you depend on them to lead the way and one can run to the library for their insight..........but I am not familiar with their monopoly on thread cutting procedures. As inquisitive engineers, it would be unlikely they would be disappointed when one finds an alternative to reach the same end.  Seems like they would foster that approach looking for ideas and asking questions as justila has.
> 
> "Reading a lot of golf magazines and having lots of golf clubs...... doesn't make a good golfer."  (author unknown).
> Dave._




It wasn't really about thread cutting monopolies or otherwise per se. nor about reading whether magazines or library books. 

I'll leave you to reread my posting and work out what I was getting at.

Best regards

Terry


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## terryd (Jun 22, 2020)

Duplicate


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## Bentwings (Jun 26, 2020)

Tim Wescott said:


> I'm trying to make needle valves per the drawing below, and I keep screwing up the spraybar.
> 
> Basically, I get a nice machined straight brass rod, but as soon as I thread it I end up with a nice, threaded, gracefully bent, brass rod.
> 
> ...


I was tasked with making an almost identical parent out of stainless steel when I started a new job as tool maker. Basically it was a 5-56 thread in the middle or a long shaft. we had a brand ne Hardinge tool room lathe with every option. So tooling was available. Aft several failures I made a fixture that mounted on a tool holder that had a hole tha the first few threads rode on. Well lubricated. Also used a modified steady rest.  I did try a die but it failed miserably. I even resharpened it going so far as helping the jug grinder make tooling and dresser for his jig grinder to grind or finish grind these threads. There was a totally rediculous and unnecessary tolerance on the threads. Something I changed when I was promoted to the engineering dept. 
id have to sit on a stool at the lathe to re do this stuff as it’s been 30 years in the past. 
the bottom line is to support the work however possible.  It’s hard to thread a small rod with a die even if it is precision made. Purchased dies today have a hard time cutting straight  on much larger rods.  I’m not sure of the dynamics as I never ran any analysis of this nightmare. I just remade the device so it didn’t need this piece at all. Saved the co. A huge bundle and got a beautiful custom made pocket knife as a reward.


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## roncohudd (Mar 8, 2022)

terryd said:


> Hi Tim,
> 
> Depending on how you make your tailstock die holder the die should be self centering on the work in a 3 jaw chuck (hint don't make the die holder too precise a fit on it's slider - allows for self centering).  There is no need for a super precise 4 jaw set up.  That's just faffing about for the sake of it.  Some folk like to spend large amounts of time on super precision even when it's not needed and that's ok if it's your bag.  Me, I just like making stuff that does a job and does it well.  I don't have enough years left to waste them on uneccessaries


If I'm threading most round stocks I use collects rather than chuck. I machined a 1 inch die holder many years ago. Don't know any more than every one else but sometimes I get lucky.


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## Bentwings (Mar 9, 2022)

I agree unknown time left so I make and use what works for me as long as it’s safe to use. If I threaded a foot long shaft I’d have to visit my neurologist to see if I still had a mind left .  It’s bad enough tapping a 2mm hole in soft aluminum by hand I imagine at one point I would have power tapped with the small tapping head or even cut the thread with cnc  but today just getting it done is more important if the screw fits great I’m happy . 
this steamer has bags full of screws 2an 3mm I YHINK there is one or two m4 screws . Those m 3 grub screws really inhale . I’ve come up with a work around so I don’t even have to use them . All of the eccentrics and flywheels will have much stronger and secure mounting. I’ll take pictures as I get these parts ready for installation I finally got the correct beam coupler ordered. It should be her Fri. It a bit longer so I’ll not re locate second engine yetis it’s a bit longer than I expected but I couldn’t get the very short one . Don’t need it anyway. 
byron


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