# Choosing the right alloy steel - and make a quill



## graham-xrf (Dec 19, 2019)

This is about attempting to machine a new quill, in a case of using one lathe to fix up another. I searched the net, and found that quills can be made of alloy steel, or high strength cast iron. My thoughts were that it needs high strength and be able to take impact, easy machining, not ultra-hard, corrosion resistant would be nice. The older South Bend 9C is in good condition, but the South Bend 9A tailstock quill has been greviously mangled. The MT2 taper was partly drilled out off center. Amazingly, what remains of the MT2 still grabs onto a taper, but is not properly supported. It needs a new quill!




Parted-out South Bend tailstocks turn up on eBay, but the risk is repeatedly shelling out for a banged-up old part of unknown internal condition, so I was thinking to use the SB9C to make a new quill for the SB9A. (There is a kind of poetic justice in that)! We get to choosing the steel.

I thought 4140. More easily available in UK is EN19T and EN24T. I found some specifications and set them together as a compare list. The info I have on 4140 mentions "0.2% Proof Stress" which may be yield-related, but the other two steels show "yield" instead. I tried to convert units, but not guaranteed to be error-free. Mpa is the same as N/mm2. KSI is "kilo-pounds per square inch".

The steels all seem very similar, and I guess a quill could be made out of any of them. 4140 seems more tightly controlled when it comes to impurities. EN19T is readily available, slightly lower cost than the other two. EN24T looks kind of similar to 4140, except it has a bigger dollop of nickel, and is a bit stronger.
Enough EN24T to make two quills is £16.50 (about $20).




So where am I going with this?  First is to just ask which would be your preference. Would you use something else? Does anyone know what the South Bend quills were made of in the first place?

The next thing, given my relative inexperience,  is to seek advice on actually making it. The quill measures 5.125" long x 1.070" diameter, so I guess around 28mm, or 1.125" is the starting out raw size. A precision centered taper and a 1/2" x 10 ACME thread on a alloy steel quill is not a trivial thing, and it may take me a couple of tries before I get it right. I could use an ACME tap, but I was thinking to just use a ready-made bronze ACME nut insert turned to fit and secure into the back of the quill, just like was done for the SB9C.




I don't have a mill, so I have no idea what to do to cut the anti-rotation slot. I may have to find some milling help from a pal. I did see some dude on YouTube use an angle grinder with a cutting disk to hack out most of a quill slot, and then finish with a file (shudder)! Maybe I can clamp a tool sideways, and move the saddle to carve the slot out. Hmm - is that a crazy notion?


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## john.k (Dec 19, 2019)

I made a (missing) quill for a Colchester Bantam out of (I assume) 4140 PH......I made it somewhat like the SB pictured,but the thread nut simply screwed into a pipe taper....Whereas the Bantam has a cross hole with a movable bronze thread.......Anyhoo,it was wanted to use the lathe urgently,no time for frills.....Made a tap for the thread,IIRC was 1/2x10 LH .....still had the handwheel and screw........The little scrote who stole the quill didnt get the wheel.....Would have been an apprentice,so he probably didnt know how to unscrew a hex screw..............edit ,you have a lathe working,use it as a horizontal mill.....slow cut in PH tho,plenty of suds,or cutter will burn.


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## GrayTech (Dec 19, 2019)

If you're going to harden it, which is the most stable? Which will be the essiest to get a good finish on your machines. I'd use the seperate nut idea, you could have a go at making that too without risking the spindle.


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## benmychree (Dec 19, 2019)

Definitely use the separate bronze nut SAE grade 954 would be a good choice, it would be simply lightly pressed in and secured with setscrews as it the one in your pictures. For the quill, any of the choices that you presented would be fine without further heat treatment.


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## Tim9 (Dec 19, 2019)

Yeah...I’d do it as Ben says above. 4140 machines nicely. Many more experienced machinist love that stressproof steel. They all say it’s more stable and machines nicely. I’ve never used it but have used 4140 and like it a lot.
https://www.speedymetals.com/information/Material37.html
Only thing I would probably do differently is I’d press the bronze nut in place with a little loctite and then lock in place with the set screws.


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## benmychree (Dec 19, 2019)

Stressproof is a positive joy to machine, but not so hard as 4140HT, but would be fine for a tailstock quill.


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## graham-xrf (Dec 20, 2019)

benmychree said:


> Stressproof is a positive joy to machine, but not so hard as 4140HT, but would be fine for a tailstock quill.


Guys - thanks so much for the replies. Try not to laugh when I admit to being somewhat "YouTube-Trained". I know there is all sorts of potential for messing up doing that, but there are also lots of eye-openers for one like myself.
Dudley Toolwright has two videos where he explores the cutting of 4140 in 3 stages of hardness, two cutting speeds, for both negative and positive rake cutters.










For great entertainment on a property of 4140, WBF777 publishes how to chop up a big chunk of 4x2 with a 4140 tomahawk, then shave hair with it (the tomahawk)! It makes me think the average Gillette could be made of better stuff!





I don't know how hard a quill should be, but my internal reasoning suggests that drill male tapers are plenty hard already, and maybe want to be set into a not-so-hard quill. The friction in there would be better if one of the surfaces was slightly more compliant. I will be going with the temper standard as supplied.

In my internet searches, I came across a new thing to learn about. From the sentence..
_"Blaze or consecration hardening of EN24T can accord a case acerbity of 50 HRc or higher."_

OK -so I don't yet know what on Earth is "consecration" hardening, and "acerbity" is a new word for me. The mischief in my cartoon mind is right now showing a guy with a blazing torch in one hand, Bible in the other, offering up a prayer before applying the fires of Hell!
Surface flame hardening - right?


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## Tim9 (Dec 20, 2019)

I don’t think a tailstock quill needs to be hardened. I’ve seen quite a number of experienced YouTube machinist with big followings make quills and they just used a decent steel. Nothing that special about quills in my opinion. The MT adapters don’t seem that hard to me. Most of my MT stuff doesn’t appear that hard either. 
    Honestly, I think you’d be just fine using any decent steel... Leaded steel or 4140. I doubt it will make much difference one way or another for most hobby guys.
    My old SB quills steel seem kind of soft also. I wouldn’t overthink this project.


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## graham-xrf (Dec 20, 2019)

john.k said:


> I made a (missing) quill for a Colchester Bantam out of (I assume) 4140 PH.....


Decoding "PH". Does that mean "Partly Hardened"? Do I need to know something?
edit .. Ah.haa - would that be "Precipitation Hardening"?


> The little scrote who stole the quill didn't get the wheel.....Would have been an apprentice,so he probably didn't know how to unscrew a hex screw....


John, I do feel for you. I know that among folk in this forum we can expect that some thieving git making off with an essential part of a working machine (especially your Colchester), will evoke more than average disgust! He deserves a special spot in that place where "consecration hardening" is done!


> ..........edit ,you have a lathe working,use it as a horizontal mill.....slow cut in PH tho,plenty of suds,or cutter will burn.


So that would be .. clamp the quill up in V-blocks onto a right-angle plate or something, in place of the compound, and put a MT3 mill cutter into the spindle? A main question right now is, does one complete all the ACME thread bushing, except for final assembly with Locktite and side screws _before_ milling the slot, or can we mill the slot first?


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## graham-xrf (Dec 20, 2019)

Tim9 said:


> My old SB quills steel seem kind of soft also. I wouldn’t overthink this project.


 Thanks Tim.
I do agree that the SB quills, though tough, also seem kind of soft, which is why I was asking if anyone knew what they were made of. I am sure that any of the replacement steels we have been discussing would be an "upgrade" anyway.

"Overthinking" the project is the natural compensation for one who starts out not knowing very much. I guess I am also prone to ending up with "over-designed" solutions to most things I attempt.


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## machPete99 (Dec 20, 2019)

4140 PH is Pre Hardened. It is usually a "medium level harness, around RC 30, so is still readily machinable with carbide and better HSS.


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## benmychree (Dec 20, 2019)

The suffix PH, supposedly meaning pre hardened is not at all a familiar term to me, have never seen it in steel catalogs, the term normally means precipitation hardened, a technique in heat treating; the commercial suffix is HT (Heat treated), that is what I always have seen in catalogs, and when I order that material, that is what I specify.  It is quite tough, but not so very hard, and machines fairly easily with HSS or carbide, I would suggest that its use is overkill for a small lathe, if I had Stressproof on hand, it would be my choice due to it's machinability and also it's strength.
One suggestion: before embarking on the project, buy a Morse taper reamer to FINISH the bore, it will be money well spent, and available for touch ups if needed.


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## benmychree (Dec 20, 2019)

graham-xrf said:


> Guys - thanks so much for the replies. Try not to laugh when I admit to being somewhat "YouTube-Trained". I know there is all sorts of potential for messing up doing that, but there are also lots of eye-openers for one like myself.
> Dudley Toolwright has two videos where he explores the cutting of 4140 in 3 stages of hardness, two cutting speeds, for both negative and positive rake cutters.
> 
> 
> ...


The only thing wrong with the videos is that there is no accurate hardness known for the various samples, the way the heat treatment was done lends little credibility to the purported results, in my view, I doubt that the hardest sample is as hard as represented.


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## macardoso (Dec 20, 2019)

john.k said:


> The little scrote who stole the quill didnt get the wheel.....Would have been an apprentice,so he probably didnt know how to unscrew a hex screw..






Love it!    Have to save that for later use


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## mikey (Dec 20, 2019)

benmychree said:


> ...  if I had Stressproof on hand, it would be my choice due to it's machinability and also it's strength.



I would use 1144 Stressproof, too, for the same reasons.


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## Bob Korves (Dec 20, 2019)

The higher carbon and higher alloy steels can become problems from work hardening if you are not quite careful to keep them cutting, not rubbing.  Once those metals get work hardened, the job often goes bad.  High tensile steel also can move with machining, warping into something unusable as the stresses are relieved.  I think something like the 1144 Stressproof that mikey suggested would make more sense all around.  Reasonably hard and strong, but also tending to not warp and move as material is removed.  1144 is commonly used for shafting and is very nice to work with.


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## MrWhoopee (Dec 20, 2019)

All good suggestions, but in the final analysis you'll have to use what you can (afford to) get. Stressproof, being a LaSalle product is probably not available at a reasonable cost in the U.K.  No need to get down in the weeds, use any of the 3 you mentioned and the bronze nut insert.

Next question.


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## graham-xrf (Dec 21, 2019)

benmychree said:


> I would suggest that its use is overkill for a small lathe, if I had Stressproof on hand, it would be my choice due to it's machinability and also it's strength.
> One suggestion: before embarking on the project, buy a Morse taper reamer to FINISH the bore, it will be money well spent, and available for touch ups if needed.


John: You are absolutely right about overkill!
I ended up following the MrWhoopee-style line of least resistance, (which means I came across a low-cost 300mm chunk, 30mm diameter in EN24T), and rub into that I count the chromium and nickel content as making it somewhat more corrosion resistant. Only based on convenience and economics, this unreasonable tendency I have to go for overkill wins out!

Re: The suggestion about the Morse taper reamer. Already done Sir! I am looking at the MT2 twin-piece kit right now. I also have the MT3 (came with the MT2 as part of the package deal). I plan to use that one to very gently clean the crud out of the spindle, and peek in there for any dings. I think the lathe was mainly used with chuck for most of it's life, so I don't expect the spindle needs any more than a cleanup and some anti-corrosion (ACF-50).

P.S. The door chime with that fragment of a Strauss waltz just went off. It was the Postie!
Unbelievable! It was only ordered yesterday. It is going to be a bit of a fight to release it from the packaging. Those are big big bent-over staples in the cardboard.

£16.50 ($21.45) and free postage. (Clench fist - punch air a little) Yeah!!


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## MrWhoopee (Dec 21, 2019)

As for cutting the alignment keyway, I'd be looking for a way to mount the part on the carriage of your lathe with an endmill held in a collet. If no collet capability, probably best to find someone with a mill. It's not a critical feature, but we're still (trying to be) machinists.


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## SLK001 (Dec 21, 2019)

graham-xrf said:


> I do agree that the SB quills, though tough, also seem kind of soft, which is why I was asking if anyone knew what they were made of.



South Bend lathes had two options for their quills - standard and hardened.  For standard quills, I wouldn't be surprised that a leaded steel was used, since it machines so nicely.  For the hardened variety, some low cost, high carbon alloy was probably used, like 4140.


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## SLK001 (Dec 21, 2019)

You can cut the alignment keyway with the carriage and a tool bit with the proper profile held horizontally.


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## MrWhoopee (Dec 21, 2019)

graham-xrf said:


> In my internet searches, I came across a new thing to learn about. From the sentence..
> _"Blaze or consecration hardening of EN24T can accord a case acerbity of 50 HRc or higher."_
> 
> OK -so I don't yet know what on Earth is "consecration" hardening, and "acerbity" is a new word for me. The mischief in my cartoon mind is right now showing a guy with a blazing torch in one hand, Bible in the other, offering up a prayer before applying the fires of Hell!
> Surface flame hardening - right?



This is obviously a direct translation from the Chinese by someone who is not a native English speaker but possesses a Chinese-English dictionary. We've had hours of hilarity from reading entire machine manuals translated in this manner. I have a friend from the U.K. who has made a nice living writing manuals for a Japanese equipment manufacturer.


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## Mitch Alsup (Dec 21, 2019)

MrWhoopee said:


> This is obviously a direct translation from the Chinese by someone who is not a native English speaker but possesses a Chinese-English dictionary. We've had hours of hilarity from reading entire machine manuals translated in this manner. I have a friend from the U.K. who has made a nice living writing manuals for a Japanese equipment manufacturer.



A very long time ago, IBM thought that they had cracked the language translation barrier. So they went to Boeing and took and Aircraft maintenance manual and translated it to Germain and back. Most of the translation went well, but there were dozens of cases when the doubly translated manual had the phrase "water goat". It ended up that the original word pair was 'hydraulic ram' which, without context, had been translated into "water goat".


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## graham-xrf (Dec 21, 2019)

SLK001 said:


> You can cut the alignment keyway with the carriage and a tool bit with the proper profile held horizontally.


In the spirit of using one machine to fix the other - or even using a machine to fix itself, you can bet I am going to attempt this. If all else fails, I have a pal who is a member of a model machinist club, but I am not anticipating going that route unless I mess up really badly.


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## graham-xrf (Dec 23, 2019)

Regarding the poorly translated specification _..
"Blaze or consecration hardening of EN24T can accord a case acerbity of 50 HRc or higher."_

 It is not hard to see that "acerbity" means "hardness", simply because it has Rockwell units, and among it's definitions, there is "forceful, trenchant, disagreeable.

More speculative is that "blaze or consecration hardening" is the attempt to translate "flame or induction hardening".
This because "induction" is also a religious ceremony done for Buddhist and other monks, and the association between "blaze" and "flame" is more or less obvious.

Even so, if I ever get up to hardening anything some day, I will not be able to think of it as anything other than "consecrated". I suppose if the quench goes wrong, we might add "cremated"!


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## graham-xrf (Dec 24, 2019)

Darn! It looks like turning into a "Tailstock TLC thing". All you folk were absolutely right about the slippery slope! The pressure of "mission creep" is now overwhelming. It seems the only way to duck it is not to look!

The ACME external thread from the SB9A flops about like a stirrer in a tall glass! I offered it at both quills. The SB9C thread fits it's own brass insert rather better, but even that "good" one could not be described as great.
View attachment Worn ACME Threads2.mp4

















Left hand 10 x 1/2" ACME as a ready cut stock is thin on the ground here (UK). I suppose I could cut off the threads and salvage the back end with the 3/4" thrust disc part, turn it down some, and join it onto a new threaded section with Locktite and a small pin. OR - just turn up an an entire new part. Right now, it is looking like this might be the best way.

I have invested in one of these ACME tool grind assist gauges.


Whichever way this goes - it is going to be interesting! I can (sort of) grind a HSS tool to cut OK. Accurately getting 29°, with the front cut back to the correct width, with correct side and back rake clearance and all? Er.. OK. Let's give it a try. I will likely not be posting a video of the attempt. The fumble limit has been reached!

P.S. It is that time of year. Have a good Christmas folks!


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## MrWhoopee (Dec 24, 2019)

And so it begins. 1/2-10 Acme is not going to be easy to cut, hopefully you have a follower rest. Without one it will be damn near impossible. You can get the threaded rod off eBay for under $40 US delivered to the UK. Not nearly as educational, but you will probably end up buying it anyway.








						304014-3-LH 1/2-10 x 36 inch 1 start Acme threaded rod for lead screw LEFT HAND  | eBay
					

A 1 start has only a single thread cut. A 2 start has 2 threads and. What is Alloy Steel?. Alloy steel is pre-heat treated 4140 alloy. Harder to machine and also tougher. Hardness is 271 Brinell. Alloy lead screws are black-oxide finish.



					www.ebay.com
				




Merry/Happy Christmas/Chanukkah to all.

edit: Just watched the video. Given the fit in the bronze inserted spindle, the wisest course might be to live with it. It's not that sloppy and will not affect the function or precision of the lathe.


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## Tim9 (Dec 24, 2019)

I made a really rough follower rest when I cut an acme for my large dial upgrade on my little SB-9”
  I’ve even seen some people make one off wood followers for a one time use when cutting Acme threads. My attempt was a 3/8”-10 LH acme... and although it took a while to tweek my aluminum follower...the screw came out surprisingly well.
  Tex-va on PM site did a wonderful write up of that acme thread job and it’s still there but all of the awesome pictures have now been blurred by those photoshopped bastards. I hope they rot in hell.


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## BtoVin83 (Dec 24, 2019)

Well you're down the rabbit hole for sure now. Trying to make the internal thread is going to be a tussle and the taps or tools needed to make it don't seem financially feasible. But 1/2 -10 LH nuts are available in cast iron or bearing bronze. Use that as an insert in the tail end secured with maybe set screws (or as the English prefer "grub screws").  The diameter and length of the spindle is going to give you some difficulty but  is doable. You already have the material but my opinion you want something tuff not hard, big difference. When cutting an Acme turn you compound parallel  to the spindle, cut a register on the end to the bottom diameter of the thread. With your tool ground a tad narrower than called for when the tool touches the bottom diameter you now use the compound to widen the thread until the nut achieves the fit you desire. If careful you shave both sides of the thread this way and get a nice finish. I've been around enough machinists to now you are going to say this is rubbish but the skills needed to fix it this way is not beyond the beginner if you take your time.


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## BtoVin83 (Dec 24, 2019)

OH! Solve one problem at a time and don't try and solve them all at once. When one solution is achieved you can now focus on the next and solutions become more obvious. Unless it leads you farther down the hole, been there dun that !


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## BtoVin83 (Dec 24, 2019)

These are the things you learn in 30 years of machining that are hard to communicate. In cutting an Acme the way I described the high flank pressure especially are large Acme threads can sometimes cause the carriage to float and not cut much then all of a sudden dig in a bunch. Rest your left hand on the carriage hand wheel and cause some friction and it won't want to float.


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## graham-xrf (Dec 25, 2019)

BtoVin83 said:


> Rest your left hand on the carriage hand wheel and cause some friction and it won't want to float.


 That effect is just a bit subtle!  I think it likely would not happen if the cut was the more usual straightforward kind, straight in at 90°, just getting deeper until the core diameter is reached.

In your variation, with the slightly narrower 29° tool, I get it that when you are cutting on one side of the ACME thread at a time, the lathe lead screw has taken up the backlash without the benefit of anything to prevent "flopping back" a bit. I think you are saying to hold on to the carriage hand wheel as it travels, slightly "helping it along", so it does not drift back into "backlash space" - right?


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## Tim9 (Dec 25, 2019)

graham-xrf said:


> That effect is just a bit subtle!  I think it likely would not happen if the cut was the more usual straightforward kind, straight in at 90°, just getting deeper until the core diameter is reached.
> 
> In your variation, with the slightly narrower 29° tool, I get it that when you are cutting on one side of the ACME thread at a time, the lathe lead screw has taken up the backlash without the benefit of anything to prevent "flopping back" a bit. I think you are saying to hold on to the carriage hand wheel as it travels, slightly "helping it along", so it does not drift back into "backlash space" - right?


I usually just rest my hand on the carriage wheel....which I’m guessing keeps it from flopping around. Just a tad bit of drag.


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## graham-xrf (Dec 25, 2019)

Tim9 said:


> I usually just rest my hand on the carriage wheel....which I’m guessing keeps it from flopping around. Just a tad bit of drag.


Yes, of course it is. Backlash is taken out from a forward advancing thing by giving it some friction drag. Sorry about that.

Into the weeds I may be getting, and with apologies to MrWhoopee, I have been allowing myself to keep digging about thread turning, even to the extent of the advice on page 11 of the 1936 South Bend Lathe Works Bulletin No. 36A where one can get diverted by why we should use _lard oil_, or better still, _lard oil with some sulphur added_, for a smooth finish. (It's Christmas, and I've had a nice lunch)!

Try not to call me out on that Teddy R simplified the spelling in 1906 to read "sulfur", but I guess the message had not quite got through to Indiana 3 decades later - or maybe the county around South Bend voted Democrat, but I assure you that "sulphur" is the spelling used.

We pass by page 11, (backwards) where on page 8 there lurks this gem..


Now this is altogether different to the thread turning styles I have been seeing on YouTube, and discussing here. It seems halfway nearer to the BtoVin83 and Tim's method. The compound is rotated 29°, but note that the tool is actually ground 60° for 30° half-angle to the face of the cut.. Hmm.. hardly making sense when I look at the diagram, but anyway, the tool is advanced along to finish one side of the thread, the cut apparently getting thicker until one arrives at the other side, (and correct depth). The other side is made with the whole (here the left) side of the tool as it gets to depth.

OK - now I have got it! The tool angle is 1° beyond the 29° setting of the compound feed direction. The (right) side starts with a very small cut, and it stays quite thin, but always cutting more of the right side, because of the 1° wider tool always taking that bit more, instead of just rubbing along the already cut right side. When it arrives at depth, we have inevitably the full 60°. The way to get a shiny thread!

All earlier pages are about American National Screw Threads being 60°, and also grinding the tools 60°. I can see how the customary setting of the feed in direction to 29° would produce the nice finish. Is the choice of 29° influenced by the 1894 ACME 29° trapezoidal power thread design that predated the South Bend manual writers? Something must have motivated the choice of 29° from face to face for ACME threads. Nah - probably coincidence!

I have to admit, I kind of lost it when I came across the lard oil + sulphur. I can find weeds like no other! It cracked me up laughing. I am going to find some old bolt, and try this out (the cut method, not the lard)! But not yet. It was a great lunch, and 1 x 125ml glass of Prosseco, and I never do that! I don't want to make machinery turn, and reading measurements and doing arithmetic does not go as well as it should - spoils the mood even!




This whole discussion has made me want to have a go at cutting some ACME - so my thanks to all of you. This even if in the end (Oh - the shame of it!) I end up with store-bought 10x1/2" LH ACME, and a bronze nut import from McMaster-Carr, and a little pile of "attempts" awaiting the day they can join a meltdown!


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## MrWhoopee (Dec 25, 2019)

BtoVin83 said:


> These are the things you learn in 30 years of machining that are hard to communicate. In cutting an Acme the way I described the high flank pressure especially are large Acme threads can sometimes cause the carriage to float and not cut much then all of a sudden dig in a bunch. Rest your left hand on the carriage hand wheel and cause some friction and it won't want to float.



I have had to use this same technique with coarser thread pitches. Very worn half-nuts may require a lot of drag to prevent "pitch wander", particularly at the beginning of the pass. I do it without even thinking now.


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## MrWhoopee (Dec 25, 2019)

I keep a copy of SB's "How to Run a Lathe" in the "reading room" for the sake of nostalgia and the occasional tidbit of overlooked info. Since I'm running an SB Heavy 10, it is particularly pertinent. I understand that bacon grease mixed with kerosene makes a good substitute for lard oil in certain situations, but I imagine it would drive me to the kitchen fairly quickly for a BLT.

In school,  I was taught to set the compound at 29.5 deg., as if we could interpolate the graduations that closely. In addition to improved finish, it provides for better chip flow since there are not equal, competing chips coming off the tool. Many people poo-poo the whole notion and simply feed straight in. They seem to get equally good results, though it helps if you are using a newer, tighter and more rigid lathe.

I only recently became aware that TR was responsible for the simplified spellings used in the U.S. As these were not officially adopted, it probably took quite some time before "center" became the standard instead of "centre". I scarcely notice the spelling of "sulphur", as that's how it was spelled in my first chemistry set.


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## BtoVin83 (Dec 25, 2019)

Usually the size hobbiests make dragging the hand wheel is not a requirement, I'm talking about cutting 2-3 inch diameter 2 pitch Acmes and they can float a carriage. But the habit carries over and I find myself doing it without thinking. The idea is create drag on the carriage and forcing it to the backside of the half nut, now the carriage doesn't want to wander.


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## BtoVin83 (Dec 25, 2019)

My dad taught me to cut the register for both internal and external acmes. That way when the tool touches off you know you are to proper depth. The tool is cutting on 3 sides until getting to depth that's true but when you widen it out with  the compound you are only cutting on one side. Cutting a 3 inch 2 pitch Acme even following the flank of the screw can be give you fits.


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## graham-xrf (Dec 25, 2019)

MrWhoopee said:


> I only recently became aware that TR was responsible for the simplified spellings used in the U.S. As these were not officially adopted, it probably took quite some time before "center" became the standard instead of "centre". I scarcely notice the spelling of "sulphur", as that's how it was spelled in my first chemistry set.


Only partly is the story so. Theodore was home schooled, and (hearsay), may have had a hard time with spelling. He was influenced by zealots with a mission to really mess with the spelling, and who were self-convinced and selectively rationalizing their obsession (Andrew Carnegie, Mark Twain et al.) The attempts to spell "fixed" as "fixt", "rhyme" as "rime", and similar extremes were headed off by Congress.

After attempts to "sneak the changes in and get them established in some Government documents, Congress forced that  the right to mess with the language by Presidential order was disallowed. Hoping to get re-elected, Teddy abandoned the attempt. The Congress action had already set out that Webster's and other accepted dictionaries be used. These change over time, so some of the more obvious phonetic spellings did get adopted - except, it seems, by the writers of the South Bend Lathe Works publications. It may have been a generational thing. Some may have been at school before Webster's and others had moved on.

P.S. I have been trawling through the drawers of the SB9C bench (that came with the lathe), and what do I find? About 14" long bar of 1" brass-looking material. Brass, bronze, phosphor-bronze, tin-bronze, who knows? Too late that I already ordered the quill material, including the bronze for the ACME nut. Oh well. If you do what we do, you can't ever be too rich, and you can't have too much spare 1" rod material.


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## graham-xrf (Dec 25, 2019)

*THE QUILL CONSTRUCTION PLAN (sort of)*
I am thinking through the sequence for making the quill.

1. Face off both ends, and give them centres.

2. Get one end into a 4-jaw, and the other onto a MT2 (dead?) centre, and turn a quill length to outer size.
   We notice here that the older lathe (about 1938 or so) has a slightly thicker quill.
   The worn target quill measures 1.055" (26.79mm) and the SB-9C quill measures 1.070" (27.178mm)
   The fatter one does not fit up the thinner tailstock. It raises a question.
   Does one machine a new quill to 1.055, or should there be an attempt to "fit" it, making the final cut such that it slides in snug, perhaps compensating for tailstock wear?

3. We use a MT2 shank drill set direct into the tailstock, avoiding using a tailstock chuck . A little unsure of the size here. For quills with a bronze nut back there, the through drill hole does not have to be smaller than the internal ACME 2G 1/2" x 10 Minor diameter 0.4000", so we are OK with the smallest hole the taper needs to have at the back. We need it  good for a MT2, at a depth where the proper amount is sticking out the front of the quill.

Apparently the depth should be 2" + 39/64ths deep. The small end down there is apparently 0.572" but I still have to figure out how a taper per inch of 0.04995 x 2.60975" = 0.13034" gets us to 0.572". There are tolerances, and 0.5696 is -0.0023" adrift.
The tables are a bit confusing. OK - so we get a hole deep enough to part into later.
The drill looks like it needs to be 9/16" as a starter, and it has to be long enough

4. We bore out most of the taper, done with much trawl of YouTube. I am sure there is a "best" way to do this, and I hope folk will tell.
We open it more with a MT2 HSS cutter, with the back of the cutter supported in a tailstock dead center, and carefully using a spanner to turn it, keeping the whole lot together with a little squeeze from the back. Use cutting oil, and make sure we don't cut too deep, allowing the reamer is to follow. How close do we go?
Follow with the finishing reamer.  Again, we stop short of making it too deep. Stop where a MT2 anything is supposed to end up.

5. We part it off at the correct length. Then turn it around, re-chuck it, and drill the wider hole into the back, just deep enough to accept the bronze nut, which was made/acquired in a separate operation.

7. We fit the bronze nut, and secure it with 2 more holes, like the one the SB-9C has, or we use 3 holes at 120° apart, tapped to secure a flange on the bronze nut. Glue in with Loctite as well.

8. Chuck again at the nut end, and put an MT2 arbor into the taper to enable to support the other end in a tailstock chuck. Mount a tool ground to be as wide as the quill slide anti-rotation slot, and set it on it's side. Apparently 0.185" wide. Was that an attempt at 3/16"?

Is the quill slot supposed to be slightly wider at the top than at it's depth? Does the cutter have to have a slight trapezoid shape? Not known yet, but I will find out.

Anyway, with the tool at the right height, we repeatedly move the saddle across, with little planing cuts, to eventually scoop out 0.1" deep from the full radius start point. Alternatively #1, we consider some way to mount it up, and use a MT3 milling cutter in the spindle. Alternatively #2, we take it to the friend, who is member of a model engineering club, where it finds it's way to a Bridgeport mill.

9. There is a final little groove, a bit roughly scooped out on the side opposite to the full length slot, at the nut end.  It is 0.1" wide, 1.2" long starting from where it finds it's depth, which is not much. Is than an oil channel?
The same groove on the SB9C quill is only 0.08" wide, and much better made, looking "engraved". I am thinking that whatever method was good for the main slot will also be OK for the little one.

This is, of course, just a first think-through, and I fully expect some bits may have been left out, or in the wrong order, or simply not a good plan in the first place. If anything spectacularly crappy happens, I will post it anyway. For all I know, maybe someday, someone who has never done it before will come across it, and see the advice from those with 30+ years experience, after they figured out how to type while laughing!


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## MrWhoopee (Dec 26, 2019)

Sounds like you've thought it out pretty well. Make the diameter of the quill a close sliding fit, somewhere around .001-.002 smaller than the bore. Check the bore in multiple locations. The anti-rotation slot on the bottom is not critical, just needs to be a free sliding fit. Trying to cut it with by "shaping" with carriage will be tedious at the least. I just tried to broach a 3/16 keyway in a gear recently using this method, I ended up moving it to the mill, cranking the knee up and down. The handwheel on the carriage did not provide enough mechanical advantage. Try to work out a mount perpendicular to the spindle with a 3/16 endmill in a collet (if such you have). Retention of the bronze nut is no big deal, two set-screws will be quite adequate.


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