# On turning     your own threads



## avbill (Nov 22, 2008)

I assuming that most of you are using a metal lath to turn your own threads on your pens?  Am I correct ?  


Can a mini wood lathe [rikon]  work?   If not guidance would be helpful


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## Russianwolf (Nov 22, 2008)

It can be done three ways from what I understand.

1) metal lathe. set up properly and with a little knowledge on the technique and you can do any type that you have gears for.

2) Wood Lathe. Need VERY slow speed to do it accurately by hand. There is a thread chasing tool listed in CSUSA's catalog that recommends 100-300rpm.

3) tap and die. The easiest method and the cheapest. everything is powered by hand.


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## dogcatcher (Nov 22, 2008)

Using taps and dies the Rikon will work.  You will need a die holder and a Jacobs chuck for the tailstock and a chuck to hold the blank on the headstock.  I found the die holders at ENCO.


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## Daniel (Nov 22, 2008)

Mike, I had this idea on my mind last night. I have a metal lathe and know I can cut threads with it I have never done this but i am aware that with just a little homework i could get the math needed to figure out the gears etc. thinking about cutting my own threads on pen parts (require that I get it right the first time every time) lead to me thinking why not make my own tap and die? From the little I know it requires starting with something like raw M2 tool steel. cutting the tool and then annealing it. never done the annealing part or worked with M2 steel. For me it one of those ideas that has so much side work involved I eventually go $200 is cheap. Anyway I am jsut throwing this one out there to see if anyone has ever even attempted it and what was the outcome.


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## BRobbins629 (Nov 22, 2008)

I think Bruce Boone once made a multi start set (he was not interested in making them for a group buy).  I have already cut metal threads in soft steel and aluminum with my set for some jigs and thought maybe I could make a set in mild steel with the tap and die.  If I was careful I probably could cut threads with the mild steel in some of the plastics or hard rubber I use.  I would probably try this with a standard set first, but for now, its just one of those things on the list.


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## Daniel (Nov 22, 2008)

Bruce is way off the charts when it come to ability to make anything. I did have a flash of Titanium taps and dies there for a second though. I think I am only about $300,000 behind him just in equipment. I'll poke around and see if i can figure out anything. I do have access to a couple of machine shops at work. One is in a physics department. they make things like parts for Nuclear reactors and Proton accelerators. They like to see me coming cause they all know they will get a good laugh out of my questions. they actually made my first custom pilots for my pen mill for me. gave them something to do in there slow time. told me what metal to use when I wanted to make more and even where to get it. They have two rooms in there shop one where everyone can go and then the "Back Room" where all the real toys are. they let me in the back room. But they won't let me touch nothin.


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## randyrls (Nov 22, 2008)

avbill said:


> I assuming that most of you are using a metal lath to turn your own threads on your pens?  Am I correct ?
> 
> Can a mini wood lathe [rikon]  work?   If not guidance would be helpful



Although threading under power *CAN* be done, I would suggest using a hand crank on any lathe.  Using a Tap and die consists of turning the piece about 1 turn, then reversing and turning back 1/2 turn, then forward 1 turn.  Repeat until bored out of your skull!

With a metal lathe outside (nib) threading is fairly easy, with a threading point tool, inside threading is more challenging.   Multi start threading is another challenge.


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## pipecrafter (Nov 22, 2008)

I was discussing making a multi-start tap with a machinist friend the other day and, given my tools and equipment, he suggest the following:
 - use hardened O1 drill rod stock turned to the appropriate diameter (because I have experience working with O1 and heat treating it)
 - make sure you relieve an area behind where the threads will be so that it is a reduced diameter - not strictly necessary, but helps you go deeper into the hole than the tap's thread depth if needed
 - using a collet chuck, secure the workpiece on the lathe
 - set your thread cutting tool to the right depth for a 36 tpi thread
 - since the steel is already hardened, a carbide cutter is pretty much needed
 - set the carriage feed rate for 12 tpi
 - cut the threads
 - leave the thread cutting tool where it is, and reverse the lathe allowing it to power feed backwards
 - do not disengage the lead screw, do not rotate the spindle, do not retract the cutting bit
 - loosen the collet, and rotate the workpiece by 120 degrees (which you marked earlier) and tighten it down again
 - cut the second set of threads
 - repeat the above few steps to cut the third set of threads
 - using my grinder, carefully grind out three flutes (he was sort of vague on details, but I think I have it sorted out)

Now, neither of us has actually done this, but this is what he suggested knowing my tools, skills, and knowledge of a particular metal.  You can use whatever steel you like, even a simple carbon steel like 1075 if that's what you have available.  Since you're not cutting hard metals, just about any heat-treatable steel will work.  

He did say that a lot of taps are made by grinding the threads in to steel rather than cutting them.  But, that's beyond the abilities of my equipment. 

Then, once you've got the tap, make the die.
 - using hardened O1, temper it down to a Rockwell C of less than the tap
 - drill 4 holes in a radial pattern around the center so that, once you drill the center for threads, you have 4 flutes.  This is way easier to understand when you look at a tap and see how it's shaped.
 - drill the center slightly larger than the spec'd size for the given thread depth (but only by a few thousandths)
 - using your tap, make the threads in the die CAREFULLY

He did say that this is probably the single most complicated thing I could try to do in my basement workshop.  And that I might not get it right on the first try.  He did show a keen interest in it though, so it's obviously possible.


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## Daniel (Nov 22, 2008)

Kurt, It all makes since to me even the 4 holes in the radius of the die. I had not thought my way that for through the die yet. The greatest work for me would be knowing the heat for a given metal to get the hardness desired. That is largely homework. Nice to know that it "can" be done though.


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## pipecrafter (Nov 22, 2008)

If I can turn out pipes and knives from my basement workshop on a regular basis, this is eminently possible.

The hardening temp for O1 is about 1450-1500 degrees F, with an oil quench.  Then a temper of 300 to 400 degrees F twice for an hour each time - depending on desired hardness.  Other steels will have different specs - but it's easy to dig them up.


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## Daniel (Nov 23, 2008)

Kurt. The 300-400 degrees I can do on my toaster oven (dedicated for the shop not cookies) the 1450-1500 is the one I have trouble with. I know it has to do with the color the steel gets but have never done it. I would also hate to try it one way and find out I cannot get it hot enough. I have also never done an oil quench as I understand it though you use plain old motor oil and just drop the piece in when it is at temp. sounds like a recipe for a nice long fire to me lol.


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## Daniel (Nov 23, 2008)

By the way. I have looked through the MSC catalogue and seen there drill rod. they have three types. Air, water and oil hardened. they give all the temps needed etc for each one. I have read in other palces about how to gauge the temp of metals by the color they get, red hot, white hot. dripping on your boots, etc. I don't have all those stored away in my head though. I've seen designes for some really little forges recently and was talking to someone at the PNWPA not to long ago about metal forging. might be a good time to put one together.


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## dogcatcher (Nov 23, 2008)

Instead of hardening the tap and dies yourself, you might look into a local machine shop doing it for you.  Another option is some of the knife maker have the equipment and I know of one knife maker supplier that does the hardening.

I would hate to go through that much work and take a chance on hardening them with a homemade version.  The costs to do a knife are reasonable, and if you find a local knife maker a pen would probably cover the cost.

Marvin


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## pipecrafter (Nov 23, 2008)

Daniel,  I figured quite a bit out just from trial and error.  I settled on using O1 and 10xx series steels because of their ease of heat treating.  I used to send my blades out for heat treating, but I got a wild hair about a year ago and built myself this:
http://www.loneadmin.com/forge_build/Welcome.html
Yes, that's my little forge.  It cost nearly nothing to build.  It works well for 10xx and O1 where you don't have to soak at temp for very long, and just need a rising heat to harden.  It has it's shortcomings, like the fact that it's tiny, and the heat can be very uneven from front to back.  But it works, and works well.

The air hardened steel is probably A2, the water W2, and the oil O1.  The problem with water hardening steels is that, sometimes, they crack when quenched if you heat isn't absolutely perfect.  Air hardening steels tend to require a long soak at a precise temp, and any deviation can mess it up big time.  O1 is one of the most forgiving of tool steels though, and you can even harden it with a MAPP gas torch.  The first couple knives I made, I used a couple MAPP torches and stuck the blade between them in the open air.  It worked, but it took a while.

Used motor oil is okay, and will get the job done.  It stinks to high heaven, however, so don't do it in your house.  You can really use any kind of oil for O1 for this project, and get acceptable results.  Peanut, soy, canola, or even corn oil will all work.  Transmission fluid, which is mostly mineral oil, also works well.  The important bit will be to get the oil warm so that it's viscosity is reduced, and it can "wet" the steel better as it's cooling.

But, this project is so easy that it would be tough to screw up the heat treat of these things.  No matter how you go about it, it's going to end up harder than when you started, and more than hard enough to cut threads in rubber and plastic.

I'll toss out the same advice that was given to me a couple years ago - don't trust your eyes, use a thermocouple to see what the temp of the steel is.  It takes a while to really be able to judge the temp of a steel by color.  I still can't, since it just doesn't appear red to me at the temp that it's supposed to be "red".  It looks more orange to my eyes.


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## pipecrafter (Nov 23, 2008)

dogcatcher said:


> Instead of hardening the tap and dies yourself, you might look into a local machine shop doing it for you.  Another option is some of the knife maker have the equipment and I know of one knife maker supplier that does the hardening.



Texas Knifemakers Supply is great, but they don't do oil hardening steels.  I can understand that though - it's a big liability for them to deal with the possibility of a fire.  And if you use electric furnaces like they do, heat treating air hardening steels is fairly easy, and difficult to mess up.  In that case, you'd have to use an A-series steel.


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## Daniel (Nov 23, 2008)

Marvin. Right now I have an idea forming that sort of has a lot of people doing little bits of the total job. If you have seen some of the things I have actually done you would realize you don't want to know just how crazy the ideas can start out lol. Ideas are free and easy so what not use lots of them. 
a list is forming for me. after that it is all hunting and gathering.


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## Daniel (Nov 23, 2008)

I went out to my shop and got a 1/2-13 Die just to give it a real careful inspection.
It has 5 holes drilled in the Radius that look to be about 3/16ths inch in diameter. creating 5 "Flutes" the tap has 4 flutes and looking at this it might be important that it si done this way. if you have a 4 flute die and a 4 flute tap. there will be a point when you are tapping the die the flutes of the tap will all be aligned with a gullet in the Die. this might make it either really hard to keep the threads going and might even make it impossible. In other words every 1/4 turn of the tap would have a point that the cutters in the die are touching no metal. With the 4 flute tap 5 flute Die combo you always have at least 3 flutes in the tap cutting at any given time. hope all that makes since. Anyway there may be some geometry to keeping everything working as it should.
More of what I noticed on the die. It has a right side and a wrong side to start cutting threads from. the side you start with is reliefed for about the first three threads. sort of the opposit of how the Tap is tapered for the first few threads. so this would also have to be made when drilling etc.


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## Russianwolf (Nov 23, 2008)

Daniel said:


> In other words every 1/4 turn of the tap would have a point that the cutters in the die are touching no metal. .



It would depend on the width of the flute compared with the width of the cutter. As long as the width of the cutter is greater than the width of the flute, it shouldn't be an issue as to front of the cutter would engage the next cutter on the die before the cutter left the previous cutter.


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## Daniel (Nov 23, 2008)

Mike, in that case the flutes in the tap would simply have to be wider than the gullet in the die. that would actually be pretty easy to figure. this would allow each flute to bridge across the gap and each flute would then always be in contact with the die.
I only see one thing about this. looking at the tap I have here. the flutes are pretty narrow. The die already has 5 flutes and still leaves gullets wide enough for the 4 flute tap to fit into. making a Die with only 4 gullets that are still small enough to be bridged might be a problem. I just took another look to get an idea of ratio of cutting versus gullet there is on these tools. for the tap only about 1/3 of the radius is cutting threads while the die it is over half. I am just wondering at what point you would end up with a tap or die that does not have enough chip/swarf clearing ability.


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## Daniel (Nov 23, 2008)

This is off topic but time is limited, as in real limited and I want as many people as I can to see it. so sorry but it's easier to ask forgiveness than to ask permission.
anyway i am making a last minute push in  he group buy for 7 more orders. those orders will make the price drop for everyone to about $188 total cost. So I have made a special deal that basically is this If you want in at the $188 price but not at the $209 price, PM me that you are in at 177 (don't ask about the 177) I will only put you on a list. If and only if i get 8 people to join that list i will send payment notices for the Approx. $188. Payments will have to be made immediately. and all 8 payments will have to have cleared my pay pal account by Nov 26th when I place the order. failure for even one payment to clear will cancel all 8 orders on that list. I know this is confusing but look at it as a mini group buy within a group buy that needs a minimum of 8 orders. I have 1 of the 8 at this time. OK well thank you for this commercial break we will now resume our regularly scheduled program.


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## Daniel (Nov 23, 2008)

George just posted a link to a HF set of taps and dies in another thread. Just looking at the photo it is easy to see that dies are made with at least 3, 4 or 5 holes drilled in the radius. with a little luck one might prove easier to get tapped than the others. Are those rose colored glasses that just fell over my eyes? At any rate that might be something worth playing with. I am going to watch for this set to go on sale. If it gets as low as the $20 George mentioned it would be worth having and I could use some of them as templates for laying out any future custom pieces. the link to the set he showed is here and includes the elusive M10-1.
http://www.harborfreight.com/cpi/cta...emnumber=35407


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## dogcatcher (Nov 23, 2008)

Here is another set from HF that has the M10-1 for $25.99.

Marvin


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## Daniel (Nov 24, 2008)

I noticed there where two sets also. In comparing them for the price difference one says it is "Alloy Steel" since it costs more I am thinking that the Alloy steel is harder.


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## Daniel (Nov 24, 2008)

Well I am bored so everyone gets to suffer. just kidding.
I am trying to put together some sort of a list of tools equipment etc for making kitless pens from all the threads the last few days.

On this thread I also wanted to make something of a shopping list for making a Tap and Die. this is only my ideas from the conversation and comments suggestions etc are welcome.
EQUIPMENT:
Metal cutting band saw or other means to cut drill rod.
Metal Lathe
Carbide tipped or indexed cutters for lathe
Collet chuck or other means to accurately hold drill rod for tap in metal lathe.
Milling machine or grinder that will grind the flutes of the Tap.
Drill press
Frill bits for drilling the holes for gullets in the Die as well as the threading part of the Die.
Reliable drill bits for both operations above.
Grinder for Misc shaping of Tap and Die such as beveling etc. to avoid sharp edges
Forge for heating Taps and Dies for Hardening
Container of oil to quench Taps and Dies.
Oven or Forge for Annealing Taps and Dies.

Materials:
1" dia. O-1 Drill Rod for Dies
12mm O-1 drill rod for taps. (I am not sure on this one. Just what size rod would you want to start with to end up with a 12mm tap?)

Here are some questions I still have.
I was thinking that the 1" drill rod would leave you with a 1" dia. Die that is round. and not try to create the 6 sided Die.

Next what size drill bit would be needed to drill the Die for a 12mm thread. I know I can find those answers just have not gotten that far in my search.

for the specific use of making pens does the Tap need to be relieved behind the threads?

Finally if one die was made and hardened could it be used to cut the threads on the taps? I know there needs to be a slight difference in the threads on the tap and the die to give a little wiggle room. My thought was to make one tap that will then make 1 die that would then cut the correct threads on every other tap. Thinking along the lines of how to get something like 100 taps and dies made here. I know that carbide cutters where recommend for cutting that much hard steel. But I have also seen machines that can cut an aweful lot of threads in a big hurry. I simply had the idea that if one or two Dies that are quality enough to thread about 25 feet or so of drill rod in one of those machines could be made. It would save a whole lot of lathe time.
of course once you have a system down at the lathe it prety much becomes repetition. I am just worried about being able to turn the drill rod 120 degrees reliably and repeatably.

I already know that the 1" O-1 drill rod is just over $36.00 for 3 feet which woudl be just about 50 cents per Die or so.

12mm O-1 drill rod is about 4 dollars a foot and for 3" taps woudl only be about $1.00 per tap.

The real cost would be in the shop. So making things happen faster and with less labor could make these things very low cost.


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## Daniel (Nov 24, 2008)

I have a couple of questions.
First I would like some input as to what would be the correct drill bit for the Die in order to make a M12-0.8-2.4L Die?

I have found drill rod at what seem like good prices at MSC. But if anyone knows of anouther good source please pass it on.

any good sources for really good quality drill bits?

Finally anyone know where to find a thermocouple that I could use in building a forge so that I can measure the temp?

I have a really good place to scavange for parts to make a Forge/kiln whatever it is called. will have to experiment to get temp control down etc but I really like the home made one shown in the earlier post.

At this time I have the idea in my head to try and make 100 Dies at one time. i was also thinking of heating all 100 at one time. any reason I should not do that other than space?


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## Paul in OKC (Nov 24, 2008)

pipecrafter said:


> I was discussing making a multi-start tap with a machinist friend the other day and, given my tools and equipment, he suggest the following:
> - use hardened O1 drill rod stock turned to the appropriate diameter (because I have experience working with O1 and heat treating it)
> - make sure you relieve an area behind where the threads will be so that it is a reduced diameter - not strictly necessary, but helps you go deeper into the hole than the tap's thread depth if needed
> - using a collet chuck, secure the workpiece on the lathe
> ...



This is a no-no. You will break off the tip of your threading tool, if for no other reason than unless you have zero backlash in your lead screw the slack will make the tool not line up on the 'return'.



pipecrafter said:


> - loosen the collet, and rotate the workpiece by 120 degrees (which you marked earlier) and tighten it down again
> - cut the second set of threads
> - repeat the above few steps to cut the third set of threads
> - using my grinder, carefully grind out three flutes (he was sort of vague on details, but I think I have it sorted out)



Tough to do exactly. I would tend to see about disengaging the gear set just enough to skip a tooth or two, depending on ratio to get a more precise index.




pipecrafter said:


> Now, neither of us has actually done this, but this is what he suggested knowing my tools, skills, and knowledge of a particular metal.  You can use whatever steel you like, even a simple carbon steel like 1075 if that's what you have available.  Since you're not cutting hard metals, just about any heat-treatable steel will work.
> 
> He did say that a lot of taps are made by grinding the threads in to steel rather than cutting them.  But, that's beyond the abilities of my equipment.
> 
> ...



I would reverse this order. Drill the tap drill first, then tap, then cut the reliefs.  Cutting threads in an 'interupted' cut WILL break your tools, whether single pointing or with a tap.



pipecrafter said:


> He did say that this is probably the single most complicated thing I could try to do in my basement workshop.  And that I might not get it right on the first try.  He did show a keen interest in it though, so it's obviously possible.



I agree with that one. I agree about the using something other than drill rod as well, a high carbon steel would work for a while doing woods and plastics.


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## Daniel (Nov 24, 2008)

Paul, I was wondering about trying to tap after the radius hols where there. it sort of just keeps coming up not working very well for me and how I know taps and bits have worked for me in the past. I've never used the lathe to control the tools though.

I just went over and talked with one of the machine shop guys. And once he realized I didn't really care if he thought I was doing this the hard way his final suggestion was this. Buy a professionally made tap and die and then use that to make one tap and die out of drill rod. harden those and then use them as the tap and die to make all the rest out of drill rod. when the original two tools wear out you still have your "Master" professionally made Tap and Die to make a new set. So say Hardened O-1 tap was good for making 25 dies. and the Pro Die was good for making 100 taps. you would be able to get 2500 dies from one High priced Die.
By the way he thought the price we are getting for a triple lead Tap and Die in the group buy was a pretty fair price. He would expect to pay 40 - 50 dollars for a single lead.


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## Daniel (Nov 24, 2008)

Paul I was thinking a little on your don't back up the lathe thing. This was on my mind considering the M12-0.8 has such a fine thread. I know I have read in other places that they do reverse the lathe out and actual get a second cut of the thread when they do. But I tend to agree with you on such fine threads.
Anyway my thought was this. and I am not even sure how really doable it is cut thread 1
back cutter out disengage everything and loose all reference of any kind. move cutter back to the very beginning of the first thread and set everything up as if yo are going to re cut that same thread. this is where the math starts since 0.8mm is the distance from one thread to the next with the cutter inexact position a the start of thread one. You could simply move the cutter away from the work 0.8mm and turn the lathe on. with everything else the same the cutter will meat the rod 120 degrees from the start of thread 1 and be cutting thread 2. hope any of that makes since because I am not sure how to differentiate between the various movements you make with the tool holder.


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## Paul in OKC (Nov 24, 2008)

With metric threads on most lathes, leaving the half nut engaged is the way to do it. The gears are not exactly a 1:1, 4:1, etc., ratio. However, you must back the tool away. What I do when metric treading is when I get to the end of the thread, back the tool away from the part and kick the machine into reverse. let the tool get away from the end of the part, stop the spindle, dial in to the next cut, then turn it back on forward to make the next cut.


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## BRobbins629 (Nov 24, 2008)

Daniel said:


> Paul, I was wondering about trying to tap after the radius hols where there. it sort of just keeps coming up not working very well for me and how I know taps and bits have worked for me in the past. I've never used the lathe to control the tools though.
> 
> I just went over and talked with one of the machine shop guys. And once he realized I didn't really care if he thought I was doing this the hard way his final suggestion was this. Buy a professionally made tap and die and then use that to make one tap and die out of drill rod. harden those and then use them as the tap and die to make all the rest out of drill rod. when the original two tools wear out you still have your "Master" professionally made Tap and Die to make a new set. So say Hardened O-1 tap was good for making 25 dies. and the Pro Die was good for making 100 taps. you would be able to get 2500 dies from one High priced Die.
> By the way he thought the price we are getting for a triple lead Tap and Die in the group buy was a pretty fair price. He would expect to pay 40 - 50 dollars for a single lead.


Daniel - I wouldn't be surprised if e-taps was doing something similar to make their dies.  Original invoice had a $65 charge to make a tool to make the dies (which are cheaper than the taps by the piece) and then a per piece price.  No tool was quoted for the taps, so they be a bit harder to machine or require another process.


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## pipecrafter (Nov 24, 2008)

Paul in OKC said:


> This is a no-no. You will break off the tip of your threading tool, if for no other reason than unless you have zero backlash in your lead screw the slack will make the tool not line up on the 'return'.



Yeah, this was in the back of my head, too.  I don't have much lash, but there is some there.  Enough to make me think twice about that particular step - the machinist I spoke to about it works all day on CNC mills, so he may be slightly out of touch with using a late '40s South Bend in your basement.  

For nothing but a brainstorming session, I'm surprised nobody jumped in and told me I was about to open a wormhole straight to the seventh level of Hell.  :biggrin:


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## Daniel (Nov 24, 2008)

I wonder what MSC would say if I ordered 100 pieces of 1" drill rod 1/2" long?


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## Paul in OKC (Nov 25, 2008)

I would be a little leary of making taps or dies from 'home made' ones, even with heat treating the O-1. I might be tempted to make them from the real ones, and use those for pens, keeping the good ones just to remake the user ones when they dull beyond resharping.


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## Daniel (Nov 25, 2008)

Probably right about the homemade taps and dies. I can pretty well snap a store bought one in half just by looking at it. I always have to try that little bit more of a twist.


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## bitshird (Dec 4, 2008)

pipecrafter said:


> I was discussing making a multi-start tap with a machinist friend the other day and, given my tools and equipment, he suggest the following:
> - use hardened O1 drill rod stock turned to the appropriate diameter (because I have experience working with O1 and heat treating it)
> - make sure you relieve an area behind where the threads will be so that it is a reduced diameter - not strictly necessary, but helps you go deeper into the hole than the tap's thread depth if needed
> - using a collet chuck, secure the workpiece on the lathe
> ...



Kurt; O1 isn't that hard until you harden it, we taught all our students to lathe cut threads on  O1 and a lot of stainless with HSS 3/8 lathe bits they used a fishtail to grind their 60 degree point, off the top of my head I'm thinking unhardened, as delivered O1 drill rod Rockwells somewhere around 18-23,with a cutting speed of 50 to 60 sfpm. material  like 12L14 is around 13 or 15,Rockwell with a cutting speed of about 70-80 sfpm.  I've hardened 01 to 66 and drew it back to 58 ,some back to mid 40s, The only problems are to harden it you need to wrap the part in Stainless foil with the actual part wrapped in a heavy layers of paper, this is so as the paper burns off it consumes the oxygen and stops oxidation and seal the foil by bending it over and hammering it closed, otherwise you wind up with a nice coating of Oxidized carbon, which makes you tap and die nearly useless, Used motor oil works great for quenching it's already rich in carbon. the nastier the better. May haps your friend has a gas or electric oven that will get it to 1600 and hold it for one hour per inch of cross section, He might even have some Stainless foil, or I think you can get heat treating foil envelopes from knife making supply dealers, I know it's possible to make a tap and die for a machine screw of .015 Dia by 110 pitch and it has tapped quite a few holes in various mild steels and brass, I think it gummed up on Alu. though,
 I could possibly find time to harden and draw it back for you, I'd have to reimburse the school for the foil,  probably a buck in the coffee kitty would work. I can cook it in my electric casting oven, it's pretty accurate.
I really wish I hadn't gotten into this thread, I won't get a darned thing done now because this will be going round and round in my functionally challenged brain.
The math is around for set up of the tipple lead screws, I think Bryan Gray or Dan Fulano posted the Trig, just cant remember if it was here or http://www.pencraftsman.com/ thing to remember hardening may not be that necessary, you going to be threadinf stuff tha has a cutting speed of 250 to 400 sfpm, lots of good stuff on Dan's site for OAK work, which I'm supposed to be doing right now. (but it's raining.)


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