Taking the Mystery out of the Threading Dial

A practical demonstration of the "why" behind the threading dial.

[@operculum]

perfect length , content and clear illustration for me on what has been mysterious. keep doing these Tom , they are great.

[@rjmars1]

Well done this is about the best job of explaining a thread dial I've seen.

[@TheStuartYork]

A nice tutorial, very well demonstrated. More on threads and cutting threads both imp. and metric would gratefully received. Thank you Stuart

[@TomsTechniques]

+Stuart York Thanks Stewart. I have several videos on imperial internal and external threads. I probably won't be doing anything on metric because my lathe is not set up to cut them. Tom

[@volcom7114]

Great video Tom I'm a big fan of a few great machinist and I happen to run across your videos from a forum and I must say I love watching you make things simple and very understandable! Keep em coming!! :)

[@TomsTechniques]

Thanks, I'm glad you like them because I have a lot more of them up my sleeve. Tom

[@572334]

Great series on threads Tom. watched other guys videos as well, and every time something more is learned. but the one that put you ahead is when you mentioned the thread angle. I took notice. shall practice that, to-date had no need to cut threads on a lathe but learning is very important. I am not a machinist watched a video a year ago and started doing a small hit and miss engine. have learned a lot since. like the challenge of making a tool or jig so I can complete a job. I am 70 retired.

[@Self_Evident]

Thank you! The simplest, clearest, & most basic explanation! In short, the threading dial is actually a scale, where each number represents 1" of travel of the carriage. I've not seen another explanation that pointed that out. (Not that I'm claiming to have seen them all. :) While it seems rather obvious now, before watching this video it always seemd so mysterious... In any case, thanks again!

[@DmitriIvanov]

Great explaination - easy to understand how this thing works! Thanks a lot for the video!

[@RaysGarage]

Great demo, and explanation of the threading dial Tom, Thanks!

[@TomofAllTrades]

Thanks for sharing! I have an old Monarch Model B with a threading dial, and now I know how it works.

[@Hutch5321]

Wow, best explanation I've seen. You've convinced me, Tom. Thumbs up and subbed!

[@TomsTechniques]

Thanks.

[@kenzpenz]

What a great video. I have just begun my threading on a mini lathe. Sure glad I watched this video. I sure makes sense now. Thanks very much for all you talent and time.

[@TomsTechniques]

Thanks for watching Kenneth, I'm glad you enjoyed it. Tom

[@TomsTechniques]

Thanks, I'm glad you enjoyed it. Tom

[@RyanWeishalla]

Wish I would have found this video before watching a lot of other videos on threading where it was never clear whether one had to go back to the exact same starting spot when returning the carriage. What I didn't realize is that the thread dial remains engaged (the aha moment) and so takes care of that and your video shows that well. You have well made videos that are very informative. Thanks, Ryan.

[@TomsTechniques]

Thanks Ryan, I'm glad you are enjoying them. Be sure to check out the project tutorials as well on tomstechniques.com. Tom

[@domenicaloisio5136]

Thank you for clearing things up, great video.

[@frinxasestronca3399]

One of the best explanations :)

[@davidrice9995]

Thank you, Tom! I liked that you showed what would have happened on the side rather than actually ruining the thread. I'm going to practice that way after I have the thread started, to make sure that I'm in the right spot for practice.

[@TomsTechniques]

Thanks for watching, David

[@Festivejelly]

Great video. Thanks for the explanation and visual demo. Thats really helped me understand how that works.

[@michaell4793]

Thanks for the great video. I didn’t get a thread dial with my atlas so I just purchased one. Now I feel comfortable to cut threads.

[@FredMiller]

Brilliant! I agree with your logic on understanding how it works! Really nice video!

[@TomsTechniques]

Thanks. "How" is a good word, but "why" is even better. A basic understanding of a procedure gives that procedure more meaning and makes it much easier to apply. Tom

[@darylcarlton407]

Thank You the simplest explanation and easiest to understand

[@colinwarner7762]

Tom, I must say that I enjoyed that, while learning also. thank you, very much indeed. Colin UK.

[@TomsTechniques]

Thanks for watching, Colin.

[@hondathinktank]

Great theory to visual demonstration, in the past I've had some frustrating attempts with cutting those 11 1/2 pipe threads. Now I just leave the half nuts engaged, it seems quicker than waiting for that thread dial to come around. Less chance for errors.

[@kennethpersson5619]

I´m new in learning about how too use a lahte.I just want too say that you explain in a good way.Thank`s from Sweden.

[@TomsTechniques]

Thanks Kenneth, that's good to hear. Tom

[@calevel]

Thanks! Kept simple yet very instructional. Thumbs way up!

[@girliedog]

Thank you very much for this video you encapsulated this process in a simple and clear way that even this novice can understand.

[@TomsTechniques]

That's good to hear. Thanks for watching.

[@Hans_Strandberg]

Best explanation ever on this topic! Perfect!

[@TomsTechniques]

Thanks It was a fun video to make.

[@hdoug5]

cool thanks for explaining that and the demonstration I've been wondering how and why the dial is set up like that. great videos thanks !

[@paulschoen4901]

Tom, thanks for the informative video. I had a heck of a time trying to cut 3/4"-8 threads on my HF 9x20 lathe, and I did not know that there were positions between the tick marks where it would cause it to cut between threads. At least your lathe has a reasonable size dial. Mine is tiny, with 8 tick marks, and I have a 16 TPI leadscrew and a 64 tooth gear on the dial. So I would have to engage the half-nut with extreme accuracy. On my second try I got it right three times in a row and then I blinked or flinched and wound up cutting a nice two-start thread. My thread cutting tool is only 0.035" wide so it's actually a good-looking thread. Maybe I can fit a 32 tooth gear on the dial, and/or use a back gear or spindle crank.

[@TomsTechniques]

Hey Paul. If you have trouble hitting the mark, do it with the spindle stopped. Just move the carriage until the marks line up, engage the half nuts and start the spindle. Tom

[@bigbattenberg]

Very good video! Thanks. This has given me some ideas.

[@shawndangerfield2451]

Excellent video Tom COMMON SENSE MACHINING THANKS

[@jamestkirk1864]

Tom That was very informative. Thanks so much Keep up the great work

[@TomsTechniques]

+Michael Pfleegor Good to hear it was useful to you. Thanks for watching. Tom

[@RayyyjH]

Thanks for responding to my question. I wanted to mention that Saturday morning I watched your threading videos and then went out to the garage and ground two sixty degree bits, one for internal threads and one for external. I carefully mapped everything out, figured out what to turn the blanks down to and cut both the internal and external thread almost perfect. Not to mention it was 1-1/4 X 12 from a piece of stainless bar stock on a 1930 something southbend. It made my whole day, I've been showing it off ever since. Your videos really was the key to my success. Do you take cash or credit? lol thanks again Tom!

[@TomsTechniques]

Ray Hill CongratulationsRay! I always enjoy hearing success stories. Don't forget to check out my website (tomstechniques.com) as well. There is a lot of additional info over there. Tom

[@alirezazare243]

با تشکر واضح ترین توضیح و ساده و قابل درک ❤

[@marrasm1965]

thank you very much for your teaching, greetings from mexico

[@TomsTechniques]

You are very welcome.

[@boutellejb]

Nice, simple, and clear! Thanks!

[@stewartmackay539]

Great demo. Thank you

[@outsidescrewball]

Best explanation I have ever seen...thanks...

[@GlennNowOnYouTube]

Great Demo Tom. I purchased a threading dial for my 1953 Logan lathe. When I got it there were no lines on it, numbered or otherwise. It's brand new from the Logan lathe Company. Yes they still make parts for all of their old lathes. Ever run across anything like that before?

[@tonypike5785]

I got tired of waiting on the #1 to come around and i was looking on the tube and saw this video, Tom you are the Man. Always like your videos but i had just forgotten this bit of info, please make more videos any kind you like will be great i like the way you are able to teach !

[@TomsTechniques]

Thanks Tony. Been thinking pretty hard about it lately. It's amazing how busy you get after retirement, but it's going on three years now and I'm starting to catch up. :)

[@tonypike5785]

Toms Techniques i was able to make a 1-3/8 X24 nut for my tree mill on the lathe today .Thanks again

[@ronhubbard4663]

Again another great video. Ron

[@KevinToppenberg]

Very helpful. Thanks!

[@mikehanks2725]

Love the no nonsense approach, really helps me see it clearly. Keep it up Tom. Thanks

[@TomsTechniques]

Thanks for watching Mike. Tom

[@plainwornout3564]

Thanks Tom. Well done sir. I actually learn from you.

[@TomsTechniques]

Good to hear

[@whyturtleracer]

very clear explanations and easy to follow the logic. congratulations nice channel

[@TomsTechniques]

Thanks. Hearing that means I'm doing something right. Tom

[@davidpetersonharvey]

Thanks for explaining this. I've been wondering about that.

[@peterk.4385]

Awesome exactly what I was looking for !

[@DM-rp7ps]

Thank you for this great vid. It really helps as I'm one of those people who also likes to know the WHY of something before just doing it by rote. Good judgment comes from experience - and a lot of that comes from bad judgment Will Rogers

[@bikerides]

Excellent. Really helpful video.

[@TomsTechniques]

+John Mellor Thanks for watching, John.

[@Barleyspoog]

Perfect! Now I understand how to ((properly)) use that dial!

[@TomsTechniques]

It's probably a toss up between leaving the half nuts engaged and having to wait for the tool to return to the start vs. waiting for the two inch mark to come around. Whatever works for you is the way you should do it. Thanks for taking the time to comment. Tom

[@newstart49]

Well well, that's what I was doing wrong. Thank you so much! You are a great teacher!

[@TomsTechniques]

I'm glad it helped you out. Thanks for watching.

[@RTOHIO]

You have the best training videos out there. I am devouring them. Just curious, how do you thread on your Hardinge with no thread dial. Beautiful machine, would get one if I ever hit the lottery (unlikely since I don' buy tickets, ha)

[@anthonyhowardsmusic]

To me the best explanation ever ! In Advance Thanks :)

[@fredcarnes9763]

Great tactile explanation, love your vifeos

[@TomsTechniques]

Thanks Fred

[@TomsTechniques]

Thanks Ray.

[@johnnym1320]

yes you are correct, just meassured it.

[@DIYTinkerer]

Thanks you made that so easy to understand 😀

[@firstmoonboots]

It appears your dad has an 8TPI leadscrew with 16 teeth on the chase dial (an outlaw). If so then there would be 8 places in registration but your dial only shows quarters. As you said, even threads all resolve to 1/2" length registration but if the lead (like 8TPI) is the same or a multiple of your leadscrew it resolves to 1/8" length (16 places on dial) or if the TPI is half your leadscrew TPI then any multiple (like 4,8,12etc.) will resolve to 1/4" length (1/8 revolution of dial = 8 places). Every little bit helps sometimes! Thanks for the vid! q:)

[@12345NoNamesLeft]

Really good demo.

[@TomsTechniques]

One of my favorite adages. To cut a metric thread, you need to add a 100/127 gear cluster to convert the feed from threads per inch to turns per 2 cm. Then you leave the half nuts engaged and cut the thread, reversing the feed to return the tool to the start. I've never done it, but that's the theory. Tom

[@mick1gallagher]

Cutting metric on imperial lathe or vica versa you always leave the half nut engaged

[@tommyharbofriis]

Thx, i just got a cs18a mini lathe, there is a 16T indicator on it, how do i react/work to 16 numbers :-)

[@TomsTechniques]

I'll see if I can fit some more in. It's tough to do because I have to wait until they are out or I'll never get anything done. :) Tom

[@rahumada5051]

Thanks man, very well!

[@jurgcor1]

Greaat info thanx a lot I have a question though, I'm cutting a left hand 8 thread why do I keep cutting the thread off every 3 pass? Using the exact same mark on my thread dial, I'm using the num 1 just so I can assured to not mess it up, and every 3rd pass it wipes the existing thread out. Just curious what I'm doing wrong

[@TFB82]

This is very handy info. Sometimes seeing things on a line is easier to understand than thinking about it on the rotation. Since you're doing so much on threading, can you do a video on reacquiring a thread once the piece has been removed from the lathe?

[@TomsTechniques]

Thanks. When cutting metric threads on an imperial lathe, the half nuts are left engaged until the thread is finished. Tom

[@RollingEasy]

You can disengage the half nuts on every pass when doing a metric thread as long as you have set your very own synchronization markers on the carriage and on the spindle.. The carriage can be zeroed with a dial gauge and the spindle engaged in its zero position via the engagement lever engaging the mesh of the lead screw driver/driven gears. With the carriage on zero, your margin of error in setting the spindle to be in its correct starting position once again, is 15 deg. (One cog error either side of where the cog was at the beginning). This is easy to see and so with a little practice, you can reset every pass on a metric thread if you choose to. otherwise its an emergency reset if you've accidentally disengaged the half nuts. Get some plastic electrical conduit 3/4" and play around and you'll soon see that you can always return to synch after opening the half nuts.

[@souhailsaihi1492]

Thanks for all clarification s

[@bobs74xlch]

Tom, thanks for taken the time to make this video. What about metric threads, does the thread dial need to always stay engaged?

[@priyamtiwari491]

thanks tom...very helpful for production engineers.....

[@TomsTechniques]

Thanks. It's always good to have a little "why" behind the "how". Tom

[@priyamtiwari491]

Toms Techniques u have any video for swivelling of compound rest for taper....please let me know..

[@bbtjd001]

Please do more old school videos on your Dad's lathe. Great video.

[@fayvinplace]

Just starting out myself also - great video, plain and simple explanation - however, I have a thread dial that has marks 1 > 7 - how does that work? I can forward photos if necessary. Thanks

[@TomsTechniques]

fayvinplace It's pretty much the same as I described in the video. The numbered lines on your dial are odd and the un-numbered lines even. Put a piece of tape on your ways and mark it like I did and it will makes more sense. Here is a pretty good description of the threading dial on a mini lathe: www.mini-lathe.com/Mini_lathe/Features/features_2.htm Tom

[@MrToolsinbox]

great vids Tom. A great help. I have a question and wonder why there is no difference when using the angled compound vs cross slide? If using the angled comp wouldn't you be "pushing" the threads? Making them farther left down the piece? If you are just using cross slide that doesn't happn. As you explain using both, on the same work is where I really get lost. Much thanks.

[@Travisfromoregon]

Great video Tom, to sum up your theory: Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime. The visual masking tape explained it for me. thanks. I always just tried to memorize it, and if I forgot, I just used the same line. Don't understand the cutting metric threads on an imperial lathe though?

[@crookedriver2079]

I simplify memorizing of the rules by using: 1) Even number of threads: chose any mark you like, numbered or otherwise 2) Odd number and fractional number of threads: choose the same NUMBER every time (it doesn't take that long to wait for your number - not a production shop)OR A SIMPLER RULE:If the thread IS NOT EVEN WHOLE NUMBER, use any mark.Otherwise, only use the same number every time.

[@TomsTechniques]

I learned my trade in a vocational program that stressed hands on experience over theory and that's the approach I take teaching it. The chance someone will remember a procedure is much better if they do it themselves than if they listen to someone talk about it. Of course some theory is required, but it's the act of applying it that counts. The average viewing time of my videos is 4.3359 minutes, so the average YT viewer prefers shorter videos. Sorry if you disagree, but it's a fact. Tom

[@johnnym1320]

Hi Tom, great video, my lathe only has 3 marks, what do you make of that?

[@MrToolsinbox]

Done. Thanks

[@TomsTechniques]

I've never seen one with three marks. They are likely in one inch increments, but to be sure, just put a piece of tape on the ways like in the video and measure it. Thanks, Tom

[@denisl2406]

nice stuff Tom good food for thought. Denis

[@stuarth43]

Well Tom I am new to screw cutting I have a big Precision lathe made in France but very old it's a beautiful machine so what I do on whatever thread I want to cut I just get to where the end of the thread is stop machine run it backwards dial in a bit more cut and run it forwards that way you can't go wrong it may take longer but it doesn't matter I do not have a half nut I have a big dial I wish I could send you some pictures because I do need a lot of help and you seem like the sort of guy that would listen intelligent like me haha

[@TomsTechniques]

The best way to contact me should be through my website, tomstechniques.com, but the contact page is acting up and I'm a machinist, not a webmaster. Until that gets fixed, there is nothing wrong with asking questions here. I get notice whenever a new comment pops up.

[@mannyfilmsinc]

Great video Tom, what is the noise like loose gears, is that coming from the Hardinge lathe? Is that normal ( I am in the market for one) Thanks

[@TomsTechniques]

This lathe is my Dad's old worn out Atlas. Hardinge lathes don't make noise.

[@mannyfilmsinc]

@@TomsTechniques Yes, you mentioned that in the video, I got lost in the class...

[@RayyyjH]

In this video I take it that you originally put the part in the chuck then lined up the thread dial with a number or tick then finally lined up the tool to fit into the grooves. Is this correct? I'm just watching thinking that at any point if you use the compound rest you can line up the tool in the groove of the thread when its off. Sorry if that was a little confusing, I was just a little confused myself. Thanks by the way for taking the time to make these videos. -Ray

[@TomsTechniques]

Ray Hill To tell the truth Ray, it's been so long since I made that video that I really don't remember. I may have lined it up to an existing thread, or I may have just cut the thread in place, it doesn't really matter. Either way the lines and numbers will still line up. At some point I'll be doing a video on picking up a thread that has been disturbed, but you are right, a combination of the compound and cross slide will do it. Tom

[@mogulsmoke2428]

I am new at this... Dumb question: does the thread dial turn only when the half nut is not engaged. On my old 6X18 Crafts man that is what happens. Logic says to me, the dial must turn both when the half nut is not engaged or when the half nut is engaged.... What is the correct answer? Thanks for the videos...good explanations.

[@TomsTechniques]

The threading dial only turns when the half nuts are disengaged. It's purpose is to tell you when to engage the half nuts and once that happens it no longer needs to rotate.

[@borislavantonov9831]

Tom I have a brand new Harris lathe CE 6241 L x 1000 /chinese sorry but the price was very good for me/ any way I watched the video, but couldn't understand if I want to make threads is it necessary to use thread dial indicator everytime. Thanks

[@TomsTechniques]

The thead dial must be use for most threads to get the tool back into the same groove. The only time it is not necessay is when you are cutting a thread where the pitch is a multiple of the pitch on the leadscrew.

[@borislavantonov9831]

@@TomsTechniques Hello Tom I'm Bobby with my question for thread dial indicator...Ok thanks for your explanation maybe I wasn't clear but if I use half nut /I dont know how to say in english - half nut/, if lead screw is working all the time, when cutting tthread, have I use a thread dial indicator. Tnaks again .

[@das250250]

This is a good video .. I assume if you wanted to cut metric you would have to change the lead screw ?

[@TomsTechniques]

You wouldn't need to change the lead screw, but there are change gears for most lathes that will allow you to cut metric gears. I think you need a 127 and a 100 tooth gear. Do a search for "metric threads on an imperial lathe". Tom

[@das250250]

Thanks for you reply and videos Tom .

[@TomsTechniques]

Thanks, I'll take a look if I decide to shoot any more videos on it. At 88, Dad really doesn't use the lathe much any more. :( Tom

[@ta8807]

Just watched your file safety video, where you mentioned long sleeves are bad.

[@DrewLSsix]

question... i have a 1920z machine with no dial attachment and while I am looking to retrofit one or fabricate one as I have seen elsewhere. your video made me think that if one had no gauge and no time or interest to get one couldnt your masking tape demonstration be used in a pinch to get the job done? a strip of tape as you did with a refference mark relating to the corner of the carriage or an improvised pointer then carefully measure out a few hash marks. as long as you engage on one of those marks you should be good right?

[@TomsTechniques]

I never thought about it that way, but I suppose it would work in a pinch. Thanks for pointing that out. Tom

[@mr1enrollment]

No wrong. The tape mark indicator does not move with the saddle until the half nut is engaged. What is needed for threading is a measure of the angular position of the spindle AND the position of the saddle. Using a dial on a lathe which is driven by gear ratio of the change gears - is a measure of the position of the spindle relative to the saddle and the saddle to the drive screw.

[@TomsTechniques]

Yeah, I must have been wasted when I responded to this one. :) The best way to cut a thread on a lathe that doesn't have a thread dial is to simply leave the half nuts engaged throughout the threading process. Just turn off the spindle at the end of the cut, back the tool out and reverse the spindle to move it back to the start. Tom

[@mr1enrollment]

wasted can be good

[@brentconner5461]

Toms Techniques yes that would do the trick

[@rfnoise]

Hey Tom, you could spend 15min on your dad's lathe and get it to run much quieter, Oil the inside of the drive pulley and it will be much quieter in back gear, try greasing some of the easy to get to gears for the lead screw and that will help also. The quieter the lathe the happier the machinist!

[@bobjimenez4464]

thanks, double start even pitch threads are between the lines.....I forgot that method.

[@davidjames1007]

Does the same apply if one has a metric leadscrew and you are cutting imperial threads?

[@TomsTechniques]

I have limited experience with metric threads, but that should be true, since the ratio of the lead screw to spindle rotation has been changed to generate those imperial threads.

[@TomsTechniques]

Why don't you post this same question under the video "Thread Cutting on the Lathe, Part Four" and I'll see if I can explain it better. Thanks, Tom

[@mythril4]

That jingling sounds like broken trying to happen. Good video though, I appreciate the info.

[@TomsTechniques]

Thanks. That's pretty typical sound from an Atlas lathe with pot metal gears.

[@TomsTechniques]

Yes, long sleeves are very bad around rotating machinery, along with rings and long hair. I've been meaning to do a little demonstration on how any one of them can ruin your day and your life. Tom

[@byatse3013]

thank you for undestanding from mongolia

[@TomsTechniques]

Thanks for watching

[@chapiit08]

That was very clarifying, but does it work for standard (inch) threads only? What about metric threads? Or there is a dedicated dial for metric? Thanks!

[@TomsTechniques]

The thread dial on a metric lathe works the same as on an imperial lathe. The only difference is the pitch of the lead screw. Simply put, the distance the tool moves per revolution of the dial is a metric dimension instead of an imperial dimension.

[@chapiit08]

@@TomsTechniques Thanks for the reply. The reason I'm asking is because in my neck of the woods both metric and inch threads are commonly used with practically every lathe having metric dials (not referring to the threading dial here) and change gears for the type of threads one's about to cut although modern lathes do not require such a maneuver but have quick change levers or knobs to do so. But if the lead screw pitch is the sole factor that actuates the threading dial then I guess it's set for metric on a mainly metric lathe. Am I right?

[@vanguardcycle]

man, Tom... i wish you would start doing videos again :(

[@TomsTechniques]

It's in the works Ron. Just bought new house and am in the process of building a new shop. Maybe something this winter.

[@rolandsmith2141]

So helpfull from a non theory bloke,thanks