I would add this to the differences between fine and coarse threads: there is a cylinder-of-shear where the amount of internal thread cross section and the amount of external thread cross section is equal (it's about halfway between the major and minor diameters - clearance makes this slightly inexact ). Because the coarser threads cut deeper into the shaft of the screw, the minor diameter is smaller; this makes the halfway location smaller as well. Because this cylinder-of-shear is smaller it has less area; because it has less area it is weaker. Thus coarser threads (against all intuition - how can tinier threads be stronger?) are actually more likely to strip - which is what happens when that cylinder of shear actually shears. It's because the finer threads have an average larger diameter. I really enjoy your videos. Sometimes the fundamentals are needed, even for folks who have some (or much) experience in the shop. (From a fastener guy whose family was in the fastener business from 1929 to 1998.) Thank you.
Thank you Peter for such a great comment. It is great that people such as yourself can comment and explain and really add to the video. Truly a great comment, Marc (I am going to make this the top comment)
Hi Marc, As I recall, the 55 degree angle of the Whitworth system gives the very best strength available from the metal, which is why it was also commonly used in the dovetails of machine slides. When the Metal alloys were of relatively low strength, it was important to be able to use all of that strength, but as materials improved, the small loss of using 60 degrees was not so important and the 60 degree angle is much easer to construct geometrically. It's also worth mentioning the BA (British Association) threads withan included angle of 47.5 degrees. These are commonly used on older British machinery (machine tools, cars and motorcycles, etc.) where a fastener of less than 1/4" diameter is needed (in a similar way to the numbered series in the US, 10-24, 8-32 etc.). It's actually based on a Metric system (the Swiss Thury thread) with 0BA being 6mm diameter and 1mm pitch, the series then decending geometrically with each pitch being 0.9 times the previous one and the OD being 6 times the pitch. This was then of course mucked up by converting to imperial and rounding. Apparently a 2BA thread is still used in the USA for the stem of Dart flights!
I already learned much of what you present. But you present it in a way that still adds to my knowledge. And as an instructor myself, you add as much to my knowledge on how to present a theme in a clear way that get messages across to those who need the knowledge. Exciting? No. But engaging? YES!
I appreciate all your videos, even the basics review videos, as you have years of experience to frame your topics. As for 'no life,' all of us subscribers would beg to differ! Thank you for all the work you put into your productions, including the teaching aids.
I just want to say Thank You for all the work you have done for us that learn and use what you say and show. There is nothing better in life then sharing your wealth of information to others. Again THANK YOU and may your holidays be blessed.
One thing I noticed a long time ago was that if you take an equivalent sized metric bolt to an imperial; the most common thread used is between a imperial fine and the coarse. With the imperial threads the coarse seems to be to coarse and the fine seems to be to fine for most applications. I always compared a thread to a wedge, with the thinner wedge able to exert more force with the same pressure applied. This is why if you applied the same torque to the head of a fine and a coarse fastener the fine thread clamping load would be much greater, which might be part of the reason they seem to strip out easier. Cheers waiting for part 2 John
I had to replace the rotation bearing bolts in an aerial lift truck (ie a tree trimmer boom truck) and the manufacture called for anti-seize be applied to the bolts and the torque value was reduced. I called the manufacture and an engineer there explained that because of the anti-seize that the bolts would turn much easier and if the torque was not reduced the bolts would be stretched. He also added that as long as there was not more force applied to the fastened than the clamping load achieved at that torque, the fastener would not come loose even with the anti-seize applied.
Thank you. I went to training at the Caterpillar plant and they explained why they only use grade 8 bolts. Simple, so a weaker bolt doesn't get used in a high strength application. Also watched them test the bolts. Tensioned in a machine that progressively put more tension on the bolt but with a wedge under the head to induce another force that real life is likely to do. I think all grade 8 bolts are roll formed, not cut. That should improve the metallurgy/strength. But the holes in the castings would still be cut so would need to have a greater depth to be able to fully utilize the greater bolt strength. There are taps that don't "cut" but rather deform but I'm not sure they would be a good idea in cast iron. Your thoughts on that?
Not boring - cutting my first internal thread for a spindle guard on an Atlas 10F lathe, and once I poked my head into this world, much geometry and trigonometry. Throw the classes/levels of clearance in there and I ->almost
Thank you Marc! Very educational video, I can't wait for the second part. Thread tolerances was always a mystery for me especially for metric, all the classification are in letters something that I can't understand how it works. Merry Christmas and happy New Year Jimmy
Thank you and all those involved in the content, contributions, efforts and production of this channel. Merry Christmas, Happy Holidays and Happy New Year to all. May the new year bring you, your families and friends much health, wealth, happiness, safety, security, appreciation, respect and peace.
Another great video, always take good info. away your videos, and you always have the most informative and in depth details in them!!! Thanks always!!!
Yup, it is purported to be Archimedes, a wise soul that probably hoped someone like you would quote him. You two seem to be in one another's good company, educators deluxe. Interesting video and helpful.
thanks Marc. could you elaborate sometime on the buttress thread. I am able to cut one but really want to know "how they work" and what is the relation between an internal and external buttress. Teun (the Netherlands)
Nice video, and quite informative. I have one question, though, about a statement you make around 13:08. You say a sharp-V thread is impossible to manufacture. But isn't this the resulting thread when you single-point cut an internal thread on a lathe? It seems that I have to knock the sharp-V off with a file, else there is an issue with the crest interfering with the roots on commercial nuts. Or am I misunderstanding something? Thanks again for the great video... I love your presentation style!
Hi Clive! It is not rare to have to file the crest of an external thread after cutting it since the single point tool kicks up a burr that can interfere with the root of the nut. If however you are getting a sharp V crest when cutting an external thread it could be that your major diameter is too large? When cutting an external thread I tend to turn my blank close to the smallest acceptable diameter, this helps with assembly and doesn't affect unduly the strength of the thread. Also I should have been more specific with my explanations! When I mention "sharp V" thread I am talking of a sharp root (which would require a pointy tool) and not a sharp crest (which would mean that the OD for an external thread is too large or that the ID of an internal thread is too small. I hope this helps? Please get back to me if more explanations are required and thanks for watching! Marc
THATLAZYMACHINIST Hi, again... In the midst of a brain fart, I typed "internal" rather than "external"; thanks for clarifying that. I can probably reduce the O.D. of the blank before threading, but won't that cause a poorer flank-to-flank fit between the mating parts? It seems to me it would be more "proper", for lack of a better term, to remove the point/burr from the external thread crest so it meets the thread spec more closely. (Crest of external threads are supposed to be truncated or rounded, I believe.) Anyway, my original comment was related to your comment in the video about true V crests being impossible to form. I thought you meant internal AND external, but you have clarified that you only meant internal. My apologies for any confusion. Best regards, Charlie
Tell me if I have this right. A MT 4 is .62326 taper per foot. So taper per inch is .62326/ 12= .05193 . My sine bar is 5 inches so 5 x .05193= .25968. So jo block stack of .25968 under the one end of my sine bar will give me a MT 4 slope on my part.this could be milled on one side of a plate to be used as a template for setting up my taper attachment. Keith ps thanks again for your time.
Hi Keith! I don't have my handbook close so until I do I will say that taper per foot is total taper (both sides). If you want an angular bloc for setting you taper attachment, you will need half the total taper. Your joe bloc stack of .25968 seems a little high? It may need to be divided by two. I will get back to you later when I can verify your numbers more accurately. Marc
...watching a lake freeze over. We are forecast to get that this Christmas. Someone up there left the door to the arctic open again. I hope Woody had the sense to go south, we don't want him to freeze his pec... er, beak off
No life? Bet when you started teaching you never imagined that 28,000 people would sign up to listen to your lectures... and they weren't even forced to do it! In my book I'd list that as a success that many a professor would sell his soul to Ole' Scratch to have.
Pat Wicker typically your maximum strength is achieved at 1.5xD of thread engagement. So a 1/2-13 thread will achieve max strength at 3/4” of engagement.
Really good video because I am trying to use the Machinery's Handbook (download FREE pdf ebook version 29th Edition at allaboutmetallurgy.com/wp/wp-content/uploads/2016/12/Machinery_s_Handbook_29th_Edition.pdf, while you can) and I find it carries so much historical info that it takes a long time to sort through what the tables are actually saying. I watched a video on cutting a thread protector for a 10" Atlas lathe and am still trying to figure out how they got to the thread measurements they did, which aren't what I would have calculated them to be. Slowly I am correlating the data in the tables to stated thread geometry. Looking forward to your next video because I am not sure where some of the info in the tables comes from - can't match all theoretical geometry to numbers in tables. For example, I have to just take "Allowances" as a given, I haven't found the MH explains it will. One good thing, I have worked thru the geometry to be able to understand why/how the "over the wires" measurement works.
I would add this to the differences between fine and coarse threads: there is a cylinder-of-shear where the amount of internal thread cross section and the amount of external thread cross section is equal (it's about halfway between the major and minor diameters - clearance makes this slightly inexact ). Because the coarser threads cut deeper into the shaft of the screw, the minor diameter is smaller; this makes the halfway location smaller as well. Because this cylinder-of-shear is smaller it has less area; because it has less area it is weaker. Thus coarser threads (against all intuition - how can tinier threads be stronger?) are actually more likely to strip - which is what happens when that cylinder of shear actually shears. It's because the finer threads have an average larger diameter.
I really enjoy your videos. Sometimes the fundamentals are needed, even for folks who have some (or much) experience in the shop. (From a fastener guy whose family was in the fastener business from 1929 to 1998.) Thank you.
Thank you Peter for such a great comment. It is great that people such as yourself can comment and explain and really add to the video. Truly a great comment, Marc (I am going to make this the top comment)
Hi Marc,
As I recall, the 55 degree angle of the Whitworth system gives the very best strength available from the metal, which is why it was also commonly used in the dovetails of machine slides. When the Metal alloys were of relatively low strength, it was important to be able to use all of that strength, but as materials improved, the small loss of using 60 degrees was not so important and the 60 degree angle is much easer to construct geometrically.
It's also worth mentioning the BA (British Association) threads withan included angle of 47.5 degrees. These are commonly used on older British machinery (machine tools, cars and motorcycles, etc.) where a fastener of less than 1/4" diameter is needed (in a similar way to the numbered series in the US, 10-24, 8-32 etc.). It's actually based on a Metric system (the Swiss Thury thread) with 0BA being 6mm diameter and 1mm pitch, the series then decending geometrically with each pitch being 0.9 times the previous one and the OD being 6 times the pitch. This was then of course mucked up by converting to imperial and rounding. Apparently a 2BA thread is still used in the USA for the stem of Dart flights!
Learning so much from your channel and website. Thank you Marc for what you do.
I wish you would have been my shop teacher/instructor in high school 48 years ago. I think I would have learned a lot more.
Master instructor. Very intelligent.
I already learned much of what you present. But you present it in a way that still adds to my knowledge. And as an instructor myself, you add as much to my knowledge on how to present a theme in a clear way that get messages across to those who need the knowledge. Exciting? No. But engaging? YES!
I appreciate all your videos, even the basics review videos, as you have years of experience to frame your topics. As for 'no life,' all of us subscribers would beg to differ! Thank you for all the work you put into your productions, including the teaching aids.
you are a great person
I like howyou teach us
nice themes....
excellent explanation
Great discussion....and looking forward to pt2.....Merry Christmas Marc
thank you.. this helped me understand major or minor on internal threads
Finally, I get an explanation of major and minor diameters - THANKS !
Another well explained video, very informative not at all boring thank you for taking the time to explain Marc
Your videos are very educational and fact filled, yet you inject some humor. That combination makes them great! Thank you.
I just want to say Thank You for all the work you have done for us that learn and use what you say and show. There is nothing better in life then sharing your wealth of information to others. Again THANK YOU and may your holidays be blessed.
Thanks Marc, you are wonderful. Keep up the good work. Stuff like this makes UA-cam so great.
Nice demonstration on threads! I like your visual aid. I clarifies alot. The old saying a picture is worth a thousand words.
One thing I noticed a long time ago was that if you take an equivalent sized metric bolt to an imperial; the most common thread used is between a imperial fine and the coarse. With the imperial threads the coarse seems to be to coarse and the fine seems to be to fine for most applications.
I always compared a thread to a wedge, with the thinner wedge able to exert more force with the same pressure applied. This is why if you applied the same torque to the head of a fine and a coarse fastener the fine thread clamping load would be much greater, which might be part of the reason they seem to strip out easier.
Cheers waiting for part 2
John
I had to replace the rotation bearing bolts in an aerial lift truck (ie a tree trimmer boom truck) and the manufacture called for anti-seize be applied to the bolts and the torque value was reduced. I called the manufacture and an engineer there explained that because of the anti-seize that the bolts would turn much easier and if the torque was not reduced the bolts would be stretched.
He also added that as long as there was not more force applied to the fastened than the clamping load achieved at that torque, the fastener would not come loose even with the anti-seize applied.
Great job, Marc. You held my attention throughout. Please give us more.
Thank you. I went to training at the Caterpillar plant and they explained why they only use grade 8 bolts. Simple, so a weaker bolt doesn't get used in a high strength application. Also watched them test the bolts. Tensioned in a machine that progressively put more tension on the bolt but with a wedge under the head to induce another force that real life is likely to do. I think all grade 8 bolts are roll formed, not cut. That should improve the metallurgy/strength. But the holes in the castings would still be cut so would need to have a greater depth to be able to fully utilize the greater bolt strength. There are taps that don't "cut" but rather deform but I'm not sure they would be a good idea in cast iron. Your thoughts on that?
Really appreciate your clear and succinct explanations and great practical insight! Keep up the good work!
Not boring - cutting my first internal thread for a spindle guard on an Atlas 10F lathe, and once I poked my head into this world, much geometry and trigonometry. Throw the classes/levels of clearance in there and I ->almost
it is always great to have the information reinforced.
thank you.
Thank you Marc, this off subject but I like your digital dro unit on your drill press.
Dear Marc, thank you very much
Lesson: 63
Thank you Marc! Very educational video, I can't wait for the second part. Thread tolerances was always a mystery for me especially for metric, all the classification are in letters something that I can't understand how it works.
Merry Christmas and happy New Year
Jimmy
Thank you for another great video. Looking forward to the next one.
Thank you and all those involved in the content, contributions, efforts and production of this channel.
Merry Christmas, Happy Holidays and Happy New Year to all.
May the new year bring you, your families and friends much health, wealth, happiness, safety, security, appreciation, respect and peace.
excellent Mark, as usual!!!
Another great video, always take good info. away your videos, and you always have the most informative and in depth details in them!!! Thanks always!!!
thanks mark for the good explanation on threads.
Another informative video keep up the good work
Yup, it is purported to be Archimedes, a wise soul that probably hoped someone like you would quote him. You two seem to be in one another's good company, educators deluxe. Interesting video and helpful.
Thank you.
Thanks for a good explanation!
Nice video Marc, and Joyeux Noël!
Thanks again 4 another great video!
Thank you Mark
Acme and Trapezoidal in other parts of the world ;-). We are watching you....Joe Pi sent me here!
This is exciting
thanks Marc. could you elaborate sometime on the buttress thread. I am able to cut one but really want to know "how they work" and what is the relation between an internal and external buttress.
Teun (the Netherlands)
Thank you..
Merry Christmas Marc
Merry Christmas to you Darren! And thanks for watching, Marc
Nice video, and quite informative. I have one question, though, about a statement you make around 13:08. You say a sharp-V thread is impossible to manufacture. But isn't this the resulting thread when you single-point cut an internal thread on a lathe? It seems that I have to knock the sharp-V off with a file, else there is an issue with the crest interfering with the roots on commercial nuts. Or am I misunderstanding something? Thanks again for the great video... I love your presentation style!
Hi Clive! It is not rare to have to file the crest of an external thread after cutting it since the single point tool kicks up a burr that can interfere with the root of the nut. If however you are getting a sharp V crest when cutting an external thread it could be that your major diameter is too large? When cutting an external thread I tend to turn my blank close to the smallest acceptable diameter, this helps with assembly and doesn't affect unduly the strength of the thread. Also I should have been more specific with my explanations! When I mention "sharp V" thread I am talking of a sharp root (which would require a pointy tool) and not a sharp crest (which would mean that the OD for an external thread is too large or that the ID of an internal thread is too small. I hope this helps? Please get back to me if more explanations are required and thanks for watching! Marc
THATLAZYMACHINIST
Hi, again... In the midst of a brain fart, I typed "internal" rather than "external"; thanks for clarifying that. I can probably reduce the O.D. of the blank before threading, but won't that cause a poorer flank-to-flank fit between the mating parts? It seems to me it would be more "proper", for lack of a better term, to remove the point/burr from the external thread crest so it meets the thread spec more closely. (Crest of external threads are supposed to be truncated or rounded, I believe.) Anyway, my original comment was related to your comment in the video about true V crests being impossible to form. I thought you meant internal AND external, but you have clarified that you only meant internal. My apologies for any confusion. Best regards, Charlie
Your videos are fantastic! Thank you for all your work. Most of the machinist videos are not as clear as yours
I am following the playlist for the course and don't see a part 2.
Tell me if I have this right. A MT 4 is .62326 taper per foot. So taper per inch is .62326/ 12= .05193 . My sine bar is 5 inches so 5 x .05193= .25968. So jo block stack of .25968 under the one end of my sine bar will give me a MT 4 slope on my part.this could be milled on one side of a plate to be used as a template for setting up my taper attachment.
Keith ps thanks again for your time.
Hi Keith! I don't have my handbook close so until I do I will say that taper per foot is total taper (both sides). If you want an angular bloc for setting you taper attachment, you will need half the total taper. Your joe bloc stack of .25968 seems a little high? It may need to be divided by two. I will get back to you later when I can verify your numbers more accurately. Marc
What about torque to yield?!
That would be a good subject of why and how.
thanks marc!
learned a lot, once again
No life? I beg to differ. You are making things, using your mind, and teaching others! That my friend, is real life.
❤
...watching a lake freeze over. We are forecast to get that this Christmas. Someone up there left the door to the arctic open again. I hope Woody had the sense to go south, we don't want him to freeze his pec... er, beak off
No life? Bet when you started teaching you never imagined that 28,000 people would sign up to listen to your lectures... and they weren't even forced to do it! In my book I'd list that as a success that many a professor would sell his soul to Ole' Scratch to have.
Marc, you’re a fan of Mrs Browns Boys? :D
Haha. No life. I bet I can out no life you. Always uniquely informative.
My question is, how many threads need to be engaged for a strong fit?
Pat Wicker typically your maximum strength is achieved at 1.5xD of thread engagement. So a 1/2-13 thread will achieve max strength at 3/4” of engagement.
Thank you
Well I guess I have no life to because Iam watching Marc. Lol
Really good video because I am trying to use the Machinery's Handbook (download FREE pdf ebook version 29th Edition at allaboutmetallurgy.com/wp/wp-content/uploads/2016/12/Machinery_s_Handbook_29th_Edition.pdf, while you can) and I find it carries so much historical info that it takes a long time to sort through what the tables are actually saying. I watched a video on cutting a thread protector for a 10" Atlas lathe and am still trying to figure out how they got to the thread measurements they did, which aren't what I would have calculated them to be. Slowly I am correlating the data in the tables to stated thread geometry. Looking forward to your next video because I am not sure where some of the info in the tables comes from - can't match all theoretical geometry to numbers in tables. For example, I have to just take "Allowances" as a given, I haven't found the MH explains it will. One good thing, I have worked thru the geometry to be able to understand why/how the "over the wires" measurement works.
Link Is dead.
metric ftw :D
Hey, some weridos like watching a lake freeze over.. now baseball, THAT I will never understand ;)
Get a life, dude! Lol