# Here's a thread for those new to threading :)



## precisionworks (Dec 22, 2009)

http://www.metalartspress.com/PDFs/60_degree_threads.pdf


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## wquiles (Dec 22, 2009)

Very good reading material - thanks!

Will
(still not following step 4 for Al as it regards to the 30 or 29.5 deg :devil


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## darkzero (Dec 22, 2009)

wquiles said:


> (still not following step 4 for Al as it regards to the 30 or 29.5 deg :devil


 
Why? :thinking:


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## wquiles (Dec 22, 2009)

darkzero said:


> Why? :thinking:



Short answer: because it works great.


Long answer:
I understand the science/reason behind the need of the 29.5 deg angle, which has to do with various factors including the stress on the metal being cut/sheared, the finish after each pass, and also on the cutting edge. Given that I like to experiment I actually have tried cutting threads both ways, but for these soft Al hosts, I did not see an advantage. 

The other reason is that it seems to work better than good enough: I have had experienced machinists evaluate and comment that my threads are great - they don't even know I cut them straight. I now have close to 100 customers (many repeat buyers) of my 1xD's telling me my threads look/work great; so if my customers are happy, I must be doing something right.

That being said, I have a very nice threading tool with coated inserts that works great and stays sharp time after time (probably have about 40 thread jobs on the same edge right now):












Since I have done so many of these thread jobs, I have developed and fine-tuned my own method/pace while cutting threads, I use a kerosene-based cutting fluid, and I typically cut no more than 5-6 mills on each of the initial passes, and even less as I go further. At the end, I am doing a 1 mill pass, and then a 0 mill pass (meaning like a spring cut; I cut again at the same value as last time - easy to do with the DRO), and this seems to clean up and polish the threads quite a bit as well. 

It took me many, many tries and experimentation to get a "system" or methodology that works for me, my lathe, cutting tool, and these Mag Al hosts, but after a light pass of a scotch pad, and I end up with this:











Try it. You might be very surprised how well they look/work 

Will


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## precisionworks (Dec 22, 2009)

> 30 or 29.5 deg


Actually, the preferred angle can be any angle from 15° to 29.5°. Most people use 28 or 29 degrees, as it is difficult (on smaller machines) to split one degree.

By not using 30+30 (say 28+32) there is more metal removed on the leading edge of the tool, but still some metal removed from the trailing edge. Since the chip is uneven in thickness, it tends to break nicely. See "modified flank" below.

If you set 30+30, the threading tool is being pushed into the cut just as if it were a form tool. As the thread form is being finished, there is full contact on both side of the tool, which increases the tendency to chatter - especially when doing internal threads where the tool point may be some distance out from the tool post. Since chip thickness is equal on both sides of the cut, the chip may not want to break. See "radial" below.

The machine can also be set up for a flank cut (middle drawing) although it is not often used.






On edit: Will is using a radial cut (30+30), or "straight in". Most people use the modified flank, so the tool feeds more toward the front as it is being fed into the work. I'm not surprised that Will is getting nice results on aluminum, but wouldn't expect to see the same smooth finish on harder steels or Ti.


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## darkzero (Dec 23, 2009)

precisionworks said:


> but wouldn't expect to see the same smooth finish on harder steels or Ti.


 
Thanks for those pics Barry! Gives a whole new perspective & understanding seeing what's actually going on in pics rather than from reading or being told.

Although brass is easy to cut it's much denser than alumn I can actually see the difference when cutting at 29 deg & 29.5 deg especially when cutting internal threads like you mentioned. I was also taught to thread at 29.5 deg but I like threading mostly at 29.




wquiles said:


> Try it. You might be very surprised how well they look/work
> 
> Will


 

Thanks Will, I've always wondered. I have tried it on alumn & brass. I agree that on alumn I can't tell any difference. I still prefer 29 deg & I've been threading a lot of other metals other than alumn so I just leave my compound there. Plus it's just easier/quicker for me to use my reference numbers for DOC at 29 or 29.5 deg for reference for whatever pitch I'm cutting. I'm all in for any time saved having to calculate for the threads that I don't cut on a regular basis. I've been using Tap Magic Alumn for alumn & brass & Boelube for steel, SS, & Ti & I've been very happy. As you said, whatever works & what one is comfortable is all that matters. :twothumbs

To add & not that it matters I use Carmex threading tools. Although I was not taught this way in shop class (learned from someone else), for internal threads, I still leave my compound angled to the right as if I was cutting external threads. I mount my internal threader "upside down" & cut on the opposing internal surface. This also helps chips not to build up at the tip inside the work for smaller diameters close to the size of my threader. Also allows you to get a better view of the work in progress.














While I'm at it, some other pics of another build....


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## bluwolf (Dec 23, 2009)

Don't know what to say. Thanks again Barry.:twothumbs

Mike


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## wquiles (Dec 23, 2009)

darkzero said:


> Plus it's just easier/quicker for me to use my reference numbers for DOC at 29 or 29.5 deg for reference for whatever pitch I'm cutting. I'm all in for any time saved having to calculate for the threads that I don't cut on a regular basis.


I will be the first one to admit that the way I am cutting threads should not be used on anything other than Al. One of these days when I have fewer projects pending I will spend the time to learn the reference numbers/DOC for the 29.5 and like you just leave the compound at that angle, but for now like you said, it just works well. I also have a full profile 20 TPI internal threading insert for my threading tool that would be perfect for these 1xD's, but again I have not had the time to play with it since I bought the insert over a year ago!




darkzero said:


> To add & not that it matters I use Carmex threading tools. Although I was not taught this way in shop class (learned from someone else), for internal threads, I still leave my compound angled to the right as if I was cutting external threads. I mount my internal threader "upside down" & cut on the opposing internal surface. This also helps chips not to build up at the tip inside the work for smaller diameters close to the size of my threader. Also allows you to get a better view of the work in progress.


Awesome photos dude - very nice finish on those brass parts :twothumbs


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## PhotonFanatic (Dec 23, 2009)

darkzero said:


> {deleted content}
> 
> 
> While I'm at it, some other pics of another build....



Hi Will,

Nice pics and nice work, but I have to ask: Why are you using brass for your light engines, other than for its looks?

The thermal conductivity of brass is far worse than that of aluminum, or of copper.

*Thermal Conductivity Btu / (hr - ft -°F)*


Copper -- 231
Aluminum -- 136
Brass -- 69
Admittedly, brass may be fine for many drive current/LED combos, but why not use the superior metal all the time?

Of course, if money were no object, sterling silver would be even better. :devil:


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## cmacclel (Dec 23, 2009)

PhotonFanatic said:


> Hi Will,
> 
> Nice pics and nice work, but I have to ask: Why are you using brass for your light engines, other than for its looks?
> 
> :devil:




Probably because you can solder to it 

Mac


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## PhotonFanatic (Dec 23, 2009)

True, but that won't help the thermal transfer issue.


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## jhanko (Dec 23, 2009)

Thanks for the link. Lots of good information there.
I am also guilty of sticking with the straight infeed method. It works for me just fine, and this is on 6AL-4V Ti. I've cut over 100 thread joints so far in titanium and they all turned out great. I tried the angle infeed method and the results were no better or no worse and I'm still using the first points of my laydown inserts. so tool wear is no issue. The required slow cutting speeds on manual lathes makes the advantages of angled infeed a moot point. The key is proper setup & taking your time. I realise that taking you time isn't an option when running as a business, but I'm at a hobbyist level.


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## niner (Dec 23, 2009)

JHanko said:


> Thanks for the link. Lots of good information there.
> I am also guilty of sticking with the straight infeed method. It works for me just fine, and this is on 6AL-4V Ti. I've cut over 100 thread joints so far in titanium and they all turned out great. I tried the angle infeed method and the results were no better or no worse and I'm still using the first points of my laydown inserts. so tool wear is no issue. The required slow cutting speeds on manual lathes makes the advantages of angled infeed a moot point. The key is proper setup & taking your time. I realise that taking you time isn't an option when running as a business, but I'm at a hobbyist level.


 
I don't know anything about threading. But Jeff, I have to agree with you. I have your light in my pocket everyday. I just took it out and turn the body. YES, it is butterly smooth:twothumbs


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## precisionworks (Dec 23, 2009)

> The required slow cutting speeds on manual lathes makes the advantages of angled infeed a moot point.


I've got to disagree on that point ... especially in tougher materials (Ti) or harder steels (4140 prehard, tool steels, etc.)

If you've ever used a form tool, you know that the deeper the tool gets into the cut the worse the tendency for chatter becomes. Sure, you can work around this by taking very light finishing cuts as the thread approaches full form, although it takes much longer to produce the same surface finish generated by the modified flank infeed. Longer times may not matter, and some people take great pride in how much time it takes to make something, but it is a less efficient way to get the same result.

Modified flank threading is not a new idea. Sandvik has a good, one page tech guide on threading:
http://www.coromant.sandvik.com/san...us01154.nsf/LookupAdm/BannerForm?OpenDocument

Changing the angle of the compound from 30° to 29° does not sound like it can make that big a difference, but the devil is in the details. You won't find any production shop that uses a 30° compound setting, because of the problems with the equal thickness chip, chatter, and surface finish. Even if your "production shop" is a lathe & a mill in the garage, that's not a sound reason to use a method that has proven to be less than optimum for many thread pitches and materials.

Straight in feeding (radial infeed) is the method of choice _for some situations._ If the thread pitch is very fine, meaning a pitch less than .059", it is the method most used. For these tiny threads, I've ground a couple of HSS thread profile tools.


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## precisionworks (Dec 23, 2009)

> I mount my internal threader "upside down" & cut on the opposing internal surface.


+1

Also a great way to bore a small diameter part.


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## Tekno_Cowboy (Dec 23, 2009)

I've got a 4-in-1 tool from Mesa-Tools that I've been contemplating using for internal threading in reverse. This would completely eliminate the chances of running my compound into what I'm working on.


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## darkzero (Dec 23, 2009)

cmacclel said:


> Probably because you can solder to it
> 
> Mac


 
Exactly the reason.  The Aleph LEs (with the exeption of the e-screw part) are also made of brass, they're just nickel plated. I know brass doesn't conduct heat well but making a can like this in alumn would pose an issue with grounding the driver as there's no room for a threaded hole for ground. I could have made the LE like TnCs alumn cans but that probably wouldn't have been as easy for me right now.

The LE is for an A2 style head. Since the emitter won't be positioned in place by resting against the reflector, since I'm using a XP-G, I made an extended can to sit where I need it to in the head. I could have made a spacer like I did here to position the LE where I needed it but the owner of this particular light wanted two LEs that he could swap back & forth. I wanted to make it so he wouldn't have to remove a spacer everytime he wanted to swap to the other LE.

The LE will be running 1A & the host is an "exotic" Ti host. Yes 1A, brass, & Ti is not a good combo but it's shouldn't be an issue & I doubt the owner will be using this light in critial situations. It still will be very usable light. 

EDIT: Is there another way I could have made the can like this in alumn & attach ground without having to use electrical conductive epoxy?


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## darkzero (Dec 24, 2009)

Thanks for the compliments, hope to be just like you guys someday. 




wquiles said:


> One of these days when I have fewer projects pending I will spend the time to learn the reference numbers/DOC for the 29.5


 
No worries Will, I'll make it easy for you (but don't tell anybody this).   

Here's my contribution to this thread (pun intended)......








This is what helps me to do threading so easily & quickly. Again I use this just for reference as every machine will differ on how accurate the compound's leadscrew & dials are. So for 20 tpi at 29.5 deg, DOC should be 0.0373".

Also good to know (I have not actually tried it to verify yet though): With the compound set to 30 deg, side movement of the tool is half the amount of the compund feed. So at 30 deg, feeding the compound in 0.010" will cut 0.005" from the end of the workpiece.

EDIT: There's got to be a calculator for this, anyone know where to find one?  (Nevermind, found an easy solution)


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## darkzero (Dec 24, 2009)

Thanks to the help of my little brother, we've made a spreadsheet that makes it even easier. All you need to do is enter in thread pitch & compound angle. Also added for metric thread to automatically convert to inches. Can't get more easier than this.

Here are two screenshots showing no values entered & with values entered. I can't host the file so if anyone is interested please email or PM me you email if you would like a copy. If someone would like to host it, that would be even better.








Hope you guys might find it useful cause I think it sure is.


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## PhotonFanatic (Dec 24, 2009)

Will, 

You can put it up for public access at GoogleDoc.com

BTW, you really need two DOC's for any particular pitch--one for internal threads, as well as external threads.


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## precisionworks (Dec 24, 2009)

> every machine will differ on how accurate the compound's leadscrew & dials are.


A more accurate way to hit the target diameter is to not rely on the dials at all, but to use two mag back dial indicators instead. One is needed to return the compound to the last position before it was withdrawn at the end of the thread. The second one is used to advance the compound into the thread for DOC. Together, they eliminate the problem caused by a loose screw-nut fit.

Thread wires or thread triangles then verify that the root diameter is correct before removing the part from the lathe. Wires are a pain to use, triangles less so. Thread mics are the nicest solution, but pricey as each one covers a limited pitch range. Some makers offer a universal mic with interchangeable anvils, like this VIS (made in Poland):

http://www.amazon.com/dp/B0007CXJAY/?tag=cpf0b6-20

http://translate.google.com/transla...annel=s&rls=org.mozilla:en-US:official&hs=cdU

Before acquiring a dozen (used) Mitu's, the VIS mics were what I used. Not as nice as Mitu or Starrett, but 10X better than any Asian mic I've seen. Good value for the money.


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## wquiles (Dec 24, 2009)

precisionworks said:


> A more accurate way to hit the target diameter is to not rely on the dials at all, but to use two mag back dial indicators instead. One is needed to return the compound to the last position before it was withdrawn at the end of the thread. The second one is used to advance the compound into the thread for DOC. Together, they eliminate the problem caused by a loose screw-nut fit.


For me an even better method has been to use the DRO for the infeed (remember I am going at a straight 0 deg) "and" a dial on the ways, to start and finish the threads exactly in the same point pass after pass.

Either way I could not agree more with you in that for any decent accuracy one should not rely on the built-in dials on the lathe. To be honest I don't even remember the last time I used either one of the two dials in my carriage


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## darkzero (Dec 24, 2009)

PhotonFanatic said:


> Will,
> 
> You can put it up for public access at GoogleDoc.com
> 
> BTW, you really need two DOC's for any particular pitch--one for internal threads, as well as external threads.



I did/tried but googledocs doesn't fully support all options of excel so there were some minor variances, the formulas still worked though. Doesn't matter, my brother is turning it into a program right now.

I don't understand. Why would you need two DOCs for internal & external threads? Shouldn't DOC be the same for a particluar thread pitch, it's only the starting diameter for internal & external that are different?





precisionworks said:


> Some makers offer a universal mic with interchangeable anvils



I have a Mitu thread mic with various sets of interchangeable anvils. Sure beats having to have various individual pitch mics. I don't use it that much but it has come in handy lots of times & it's one of my favorite measurement tools that I have, one of the few that always gets cleaned & put back into it's case after use. You are right, they sure are expensive but I snagged mine on ebay for a very good price, practically brand new with 6 sets of anvils for unified & metric threads. Can't believe these originally cost over $400! 








But this is only good for external threads. Not that I really need one but what is used for internal threads, only plug gages?


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## precisionworks (Dec 24, 2009)

> what is used for internal threads, only plug gages?


Plug gages are pretty common, but a full set for every thread form would cost a fortune. Thread balls (don't laugh if your threads have none) are the same diameter as thread wires, and made by quite a few companies:

http://www.precisionballs.com/Ball_Gage8.html

http://www.mtggage.com/i_inspect.html

There are any number of internal thread mics, like these:
















(Source: Handbook of Dimensional Measurement, ISBN 0831130539) One of the best (and easiest to read) metrology books available. About $35 from AbeBooks or Alibris.


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## darkzero (Dec 24, 2009)

darkzero said:


> Doesn't matter, my brother is turning it into a program right now.


 

Well here it is after some additions & tweaks. He made it so it doesn't round the value up. I think it's an awesome little app.


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## gadget_lover (Dec 25, 2009)

darkzero said:


> I don't understand. Why would you need two DOCs for internal & external threads? Shouldn't DOC be the same for a particluar thread pitch, it's only the starting diameter for internal & external that are different?



The difference between the internal and external thread is the dimension of crest / root. The crest of the screw thread (external) is 1/8 the pitch. The root is 1/4 of the pitch. 

The crest of the nut (internal) is 1/4 and the root is 1/8. 

In both cases the height (from root to crest) of the thread are 5/8 of the pitch.

If you use a full profile tool, the DOC is the same since the internal tool has a different shape (narrower nose) than the external tool. The DOC is 5/8 of the pitch.

BUT..
When using a sharp pointed tool, you still want the correct ratio of crest to pitch the same so you have to change the DOC to account for the different crests. Assuming that you have turned the screw to the major diameter, the sharp pointed tool will have a DOC of 7/8 pitch and the nut (it bored to the minor diameter) will have a DOC of 6/8 inch.

Yes, I know 6/8 is 3/4 but I was trying to show the relationship. 

Daniel


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## PhotonFanatic (Dec 25, 2009)

Hi Daniel,

Hey, thanks for saving me all that writing. 

Fortunately, a lot of us are already using full form inserts, so Will's single DOC will most likely work just fine.

But it doesn't hurt to understand the geometry of threads, so when you are faced with an unusual situation, or limited choice of tooling, you will know what to do.

From my notebook I have this really simple set of numbers:

Internal threads: D = pitch x .5418
External threads: D = pitch x .6134

Those would need to be adjusted further, depending on your compound slide angle, if other than zero, of course.


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## PhotonFanatic (Dec 25, 2009)

darkzero said:


> Well here it is after some additions & tweaks. He made it so it doesn't round the value up. I think it's an awesome little app.



Is that a downloadable .exe file, or just an image?

BTW, Stellram has a downloadable Thread Calculator on its website--good for a variety of thread forms. It will even show the major and minor diameters to use. No need for that heavy _Machinery's Handbook_. :devil:


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## precisionworks (Dec 25, 2009)

> No need for that heavy _Machinery's Handbook_. :devil:


To say such a terrible thing on Christmas Day


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## darkzero (Dec 26, 2009)

gadget_lover said:


> The difference between the internal and external thread is the dimension of crest / root. The crest of the screw thread (external) is 1/8 the pitch. The root is 1/4 of the pitch.
> 
> The crest of the nut (internal) is 1/4 and the root is 1/8.
> 
> ...


 


PhotonFanatic said:


> Hi Daniel,
> 
> Hey, thanks for saving me all that writing.
> 
> ...


 
Thanks Daniel & Fred. I went back & did some reviewing....

I understand where crest is smaller than the root & with a sharp pointed tip DOC for internal threads would have to be smaller than external threads. I thought this was the case for ISO metric threads only. 

For American National Thread crest & root are the same as they are both 1/8 of the pitch so DOC should be the same for internal & external threads regardless of the type or cutter tip. However I doubt I'll ever be cutting NPT threads on the lathe & I really should practice cutting unified threads but for small flashlight parts it's not that critical. 

I now know that unified threads is a combination of BSW & American National & root & crest is similar to ISO metric in size except they are rounded (or flat for crest). I know I'll probably still use partial profile inserts for the capability of covering a wider range of threads (will get a couple of full profile for flashlights) so I now know to keep in mind to take into account for internal threads.

My partial profile inserts have sharp points. So for full profile inserts, aside from them also cutting the crest, do the external inserts really have a broader tip than the internal inserts as in .250p/.125p & are they rounded too?

Of course it's not that critical for me as I'm not trying to make space shuttle parts but I really want to learn.


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## darkzero (Dec 26, 2009)

PhotonFanatic said:


> Is that a downloadable .exe file, or just an image?
> 
> BTW, Stellram has a downloadable Thread Calculator on its website--good for a variety of thread forms. It will even show the major and minor diameters to use. No need for that heavy _Machinery's Handbook_. :devil:


 
Downloaded it thanks, great program. What I posted is only a screenshot, I no longer have a host to put it up. Any suggestions?

Another question, what exactly is National Form threads? The app was used with the pitch depth for American National which is consistent to the DOC chart I posted for National Form threads.

According to info online, American National Standard has been replaced by Unified National Standard. Unified National thread is similar to ISO metric except only the thread pitch is different.

If I use the pitch depth for Unified National the DOC numbers will differ from the chart. When I cut threads & in class we used DOC according to the chart & never had any issues with various threads.

According to the diagrams in my book, for external threads:

ISO Metric:
External Threads Crest: .125 x P
External Threads Root: .250 x P

Unified:
External Threads Crest: .125 x P
External Threads Root: .1666... x P


What should I be using, pitch depth for Americal National that matches the DOC chart or pitch depth for Unified National?


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## darkzero (Dec 27, 2009)

darkzero said:


> Another question, what exactly is National Form threads? .....
> What should I be using, pitch depth for Americal National that matches the DOC chart or pitch depth for Unified National?


 
Nevermind, found everything I needed to know. 





darkzero said:


> Well here it is after some additions & tweaks. He made it so it doesn't round the value up. I think it's an awesome little app.


 
Download Here (removed for now)

Please let me know if there are any issues.


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## wquiles (Dec 27, 2009)

darkzero said:


> Nevermind, found everything I needed to know.
> 
> 
> 
> ...



Cool little program - thanks much. And by the way, it runs perfectly fine under Ubuntu 9.10 using WINE 

Will


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## wquiles (Dec 27, 2009)

Will, question: When we calculate DOC we don't address the major and minor diameters which of course are important for the resulting thread, specially if one is making threaded parts to fit an unavailable part. Even more so if we are trying to achieve a particular thread engagement percentage - my taps have two columns, one for 60% engagement and another one for 75% (which seems to be the rule of thumb most often quoted). Wouldn't it be nice if your program can be "enhanced" with a function to specify for a given TPI:

- minor diameter and percent engagement - program calculates major diameter

- major diameter and percent engagement - program calculates minor diameter

Something similar that calculates the minor/major diameters based on the TPI is here:
http://www.tanj.com/cgi-bin/tpi.cgi

If you enter 20 TPI and the major diameter of 1.0", you get this as output (although I don't remember what is the percentage of thread engagement used):
Looking for 20 threads per inch
The major diameter is 1.0
The minor diameter is .94588

Calculations for the proper cutting depth using a sharp V tool, AKA partial profile.
This will provide a flat crest and sharp V groove.

For a thread of: 20.00 TPI
The pitch is: 0.0500 inch per thread
The thread height is: 0.0433 inch ( pitch * .86603 for UN and UNR)
External thread depth 0.0379 inch (H * .875) (for a screw)
Internal thread depth 0.0325 inch (H * .750) (for a nut)

Calculations for the proper cutting depth using a full form tool.
This will provide a flat crest and flat root in the groove.
The same depth is used for both nuts and screws
Full form thread depth 0.0271 inch (H * .625)

I guess what I am asking is: can you (your brother) combine this minor/major diameter calculation in the same application? It would be great to have both functions in a single application 

Will
(the other Will)


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## darkzero (Dec 27, 2009)

wquiles said:


> Cool little program - thanks much. And by the way, it runs perfectly fine under Ubuntu 9.10 using WINE
> 
> Will


 
Thanks for the feedback Will! :twothumbs

More tweaks might follow. Might add other threads like Acme & BSW along with DOCs if using partial profile inserts for all the specific threads. Will repost if he can pull it off.


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## darkzero (Dec 27, 2009)

wquiles said:


> Will, question: When we calculate DOC we don't address the major and minor diameters which of course are important for the resulting thread, specially if one is making threaded parts to fit an unavailable part. Even more so if we are trying to achieve a particular thread engagement percentage - my taps have two columns, one for 60% engagement and another one for 75% (which seems to be the rule of thumb most often quoted). Wouldn't it be nice if your program can be "enhanced" with a function to specify for a given TPI:
> 
> - minor diameter and percent engagement - program calculates major diameter
> 
> ...


 
We were actually talking about some of this. He's going to try working on adding the DOC for a standard V point tool for specific threads & maybe with the addition of American National Acme & British Standard Whitworth (55deg). Right now the app only applies to DOC for full form tools & not for unified.

My main reason for this app was simply to calculate DOC at a given angle (although it's simple to do with a scientific calculator). There's already apps/spreadsheets that calculate thread depth for common threads like the one from Sherline but not with compound angle. So now we will try to add into account for standard V point tools.

Problem is my book only shows basic diagrams for threads other than American National & Unified. It doesn't cover all the formulas. He's already found an error/typo in the formulas given for American National (go figure) as he showed my why & also showed me that the numbers given aren't consistent with the table given. I'm going to finally pick up a hard copy of Machinery's Handbook or Engineer's Blackbook so he can review & be sure. I need one anyway.

Although a simple app it's time consuming, hopefully he can pull it off before getting fed up with me. 

EDIT: Removed the app for now.....


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## PhotonFanatic (Dec 27, 2009)

Will,

Perhaps this will help--it shows some profiles for the common thread forms. I believe it is accurate.

Threading Profiles

BTW, I believe that most of us would cut either a metric 60° or UN 60° thread for 99% of all the threads that we might cut in our lifetimes, so why bother with the others? That's what Machinery's Handbook is for. :devil:


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## darkzero (Dec 27, 2009)

PhotonFanatic said:


> Will,
> 
> Perhaps this will help--it shows some profiles for the common thread forms. I believe it is accurate.
> 
> ...


 
Thanks Fred, that's perfect & I will pass it along to my brother.

You are correct, in conclusion, if we are even going to bother with making another app, all it's going to be is a combination of pretty much what's on Daniel's site & Sherline's spreadsheet calculator plus DOC for given angles for unified & ISO metric only. Even with Sherline's spreadsheet there appears to be an error that doesn't match what's on Daniel's site which makes more sense.

One of the problems was the book made no mention of American National being replaced by Unified & nor did our instructor tell us that as he taught us by the chart. Guess they're just both old. :laughing: Thanks for putting up with a noobie who trys to figure out too much information that's not even necessary.


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## darkzero (Apr 12, 2010)

Another threading question & Sat is too far away to ask my instructor. 

I needed to thread some ferro rod today with 24 tpi. On my threading chart there are no numbers given for 24 tpi. Just to be safe I just used the number 1 & finished the part.

Just want to make sure I'm understanding this correctly. For even number of threads, you must engage at any main division or half divison on the dial. For odd threads you must engage only using any main division on the dial. For fractional threads you must only use any opposing main division & must use that same division every time. So since there are no numbers listed for 24 tpi on my lathe, I'm assuming it's a multiple of the TPI of my leadscrew so I can enagage at any time & would not need to use the threading dial?


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## darkzero (Apr 13, 2010)

Anyone? :candle:

Well I suppose I could just try it & see what happens. :thinking:


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## PhotonFanatic (Apr 13, 2010)

Hi Will,

I don't have a threading dial on my lathe, so I can't speak from experience here. But this summary might help, or not? 



> Using the Threading Dial
> Some folks are confused by which marks to use on the threading dial on their
> (assumed Imperial) lathe. Of course, you're always safe restarting on the
> same dial mark on which you started but that means you'll spend a lot of time
> ...



The author is a very bright guy, btw.

Source.


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## Anglepoise (Apr 14, 2010)

darkzero said:


> Anyone? :candle:
> 
> Well I suppose I could just try it & see what happens. :thinking:



Quick tip to remember. If you have an Imperial Machine with an 8 TPI lead screw and you are threading any multiple of the lead screw ( 8,16,24,32 TPI) 
you can engage the half nuts anywhere without needing to look at the dial. Just engage and all will be fine.


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## darkzero (Apr 14, 2010)

Anglepoise said:


> Quick tip to remember. If you have an Imperial Machine with an 8 TPI lead screw and you are threading any multiple of the lead screw ( 8,16,24,32 TPI)
> you can engage the half nuts anywhere without needing to look at the dial. Just engage and all will be fine.



Thank you David! That's exactly what I needed to know. Those are the exact numbers on my chart that have lines through them. 

:thumbsup:


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## gt40 (May 19, 2010)

I am still trying to figure out threading and I came accross this "tip": 
Cutting Threads on the Lathe - 

Tim Walnoha - [email protected] 

A two part tip for making your threading life easier


Here is a method for threading I have been using for 30 years. I call it the infeed for 30 degrees. After you have set your top compound over to 30 degrees for threading zero its dial and get your touch with the cross slide. Now divide .750 by the number of threads you are cutting. Lets say we are threading a 1/4 inch 20 thread .750 divided by 20 equals .0375,(.750 divided by the number of threads equals Infeed at 30 degrees.) This is the depth you must cut to with the top compound for the finished thread. No need to even check for a fit until you are within .002 or .003 of this number. This works regardless of the size part you are doing a 1 inch 20 thread bolt would still have an infeed of .0375. If you do not want to remember this formula you could make of a chart of the most used thread pitches.

Now that we know exactly how deep we are going for any number of threads we may be doing, lets try to do it a little quicker. Using the 1/4 20 thread example, lets germ the bulk of the job done in the first 3 or 4 cuts. As long as you have a good sharp tool, on center, and good cutting fluid, things can go very quickly. On this thread with its .0375 depth I will take cuts of .015 first pass, .010 second pass, .005 third pass, .0025 fourth pass, and you can see how quickly we have closed in on finishing the thread. Of course if you are threading a bolt this small of any length you should have it center drilled and supported with the tailstock. When I worked for a large Steel Mill in a Maintenance Shop, and they wanted everything yesterday, we did many bolts in the 6 and 8 inch diameter size with 4 threads to the inch. This requires an infeed of .187. I would start this thread with a cut of .050 or .060 in depth. This may sound scary but it worked, besides these are the kind of things you do when someone is standing there looking over your shoulder waiting for a part.

Here is a link to the site: http://www.floridaame.org/HowTo3.htm

I wonder if it really works!


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