What Makes It Work #25 JACOBS DRILL CHUCK tubalcain w/cutaway

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  • Опубліковано 27 вер 2024
  • CLICK HERE---to see the playlist with ALL of my WHAT MAKES IT WORK VIDEOS.
    • WHAT MAKES IT WORK?
    Thanks for watching.

КОМЕНТАРІ • 180

  • @ianpendlebury3704
    @ianpendlebury3704 7 років тому +28

    Excellent demonstration - you old favourite 'the cut-away' really helps to show how it works. Thanks for all of your wonderful videos - they have taught me so much over the years. Keep 'em coming.

  • @dadlaponizil3687
    @dadlaponizil3687 Рік тому +1

    Brilliant. Thank you. I’ve always wondered about these chucks which I use almost every day. So satisfying to know their workings. You are a true craftsman.

    • @mrpete222
      @mrpete222  Рік тому

      😀😀

    • @dadlaponizil3687
      @dadlaponizil3687 Рік тому +1

      Now that I have tried to dis-assemble my Jacobs 33AB 1/2" chuck, there are two important points missed here. 1) the jaws should not be at the base of the chuck (all the way open). That's what I did and as the sleeve came off, it damaged all three jaws near their bases. Setting them about half way would be ideal. 2) There is a center holding screw keeping the chuck from unscrewing if the drill is operated CCW. I did not know about this LEFT handed screw. Ouch!!! Wound up stripping it out.

  • @samdavis5079
    @samdavis5079 7 років тому +13

    been using Jacobs chucks 30 years , never knew how they worked. Thank you

    • @jaxxbrat2634
      @jaxxbrat2634 7 років тому +3

      Sam Davis
      same here..interesting​ and good to know

  • @johnkinnane547
    @johnkinnane547 7 років тому +1

    Thanks mrpete for sacrificing one of your chucks so you could show how they work, very interesting and how precision made they are, thank you John

  • @bcbloc02
    @bcbloc02 7 років тому +18

    I have rebuilt many Jacobs superchucks and they are a fine piece that will last for years and stay true provided you don't let a bunch of bits slip and spin in them. It was nice meeting you at the NYCCNC event. Feel free to check out my Old Barn/Shop channel for a dose of heavy iron.

    • @wither8
      @wither8 7 років тому

      DANG! I was thinking about going just to see Keith Fenner and Adam's show down but Mr Pete would have sealed the deal!!!! Keep at it, someone said your "what makes it work" is "ave without the swearing" and it's so true. Great stuff!!

  • @Mekratrig
    @Mekratrig 7 років тому +1

    Thanks for sacrificing the old chuck to make a much clearer instructional video than it would have been otherwise.

  • @dougankrum3328
    @dougankrum3328 7 років тому

    ....No matter how much we know, always a pleasure to hear you explain it....again....Thank You...! And.....amazing the amount of 'grip' you can attain with this simple design...no beating or hammering, except for these demonstrations.....!!!

  • @garygerard4290
    @garygerard4290 3 роки тому

    I've watched some 6 videos on pulling apart chucks
    'what a piece on ingenuity - thank you for your explanation
    and time spent editing.
    I've recently heard the saying when an old man dies a library burns down
    Most younger people nowadays don't know which end of the screwdriver to hit with the hammer
    again Thank you for this

  • @MrGoosePit
    @MrGoosePit 7 років тому +2

    I love all the "What Makes It Work" videos. This was no exception. Thanks for taking the time to make the cutaway Mr. Pete!

  • @jayhahn346
    @jayhahn346 7 років тому

    Thank You Sir. I have used Jacobs chucks for about 60 years and now I understand how they work..............Jay

  • @sandralewis1689
    @sandralewis1689 7 років тому +2

    Thank you for EXCELLENT tutorial. I love the cutaway and the old instructions.

    • @maverickgraysen2537
      @maverickgraysen2537 3 роки тому

      I guess it's kinda off topic but does anybody know a good site to stream newly released series online?

    • @yousefjeremiah8918
      @yousefjeremiah8918 3 роки тому

      @Maverick Graysen I use Flixzone. You can find it by googling =)

  • @billlee5307
    @billlee5307 7 років тому +18

    If I had been able to watch your videos sixty years ago the world would have been saved a whole lot of grief! I was one of those little boys who wanted to know how things worked. Back in those days the blue haired library ladies were very reluctant to let a ten year old kid take "adult" books on machinery home and so began my career of taking everything I could get his hands on apart. Of course, at first I had no ability to put any of those objects back together. Out came the hairbrush applied to my backside on many occasions. It took many years of dismantling before I could cover my educational activities by successful reassembling what I was looking into. You have no idea how much respect I have not only for what you are now doing but for all those years teaching young boys. Very nice video, many thanks!

  • @aserta
    @aserta 7 років тому

    Excellent video Mr. Pete, as usual, i should say.
    These chucks are some of the best ever made. I have a small collection of them that's been passed down from grandpa to me and outside cleanup and a jaw set replacement they've never failed me or their previous owners. Some tools are done just right.

  • @roylucas1027
    @roylucas1027 7 років тому

    Thanks Mr. Pete. A well thought out video explaining what we all should know, but just take for granted.

  • @melvinschmecklebak3766
    @melvinschmecklebak3766 7 років тому

    Excellent demonstration. Beautiful description of how that chuck works. Thanks

  • @edweenier
    @edweenier 7 років тому +1

    Great video as always , love the working cutaway . A must for us folks who NEED to know how things work .

  • @kevCarrico
    @kevCarrico 7 років тому

    WOW! never had a reason to wonder how it worked -- but impressed indeed!! THANK YOU!!!

  • @shanek6582
    @shanek6582 7 років тому

    I bought a big Jacobs chuck at an estate sale last month for $15 that had a 1 1/2- 8 thread on the back, it made my day when it fit perfectly on my atlas lathe.

  • @billbussler3332
    @billbussler3332 7 років тому +1

    Thanks MrPete! I am really glad I'm not going to go to my grave not knowing things like this, I feel bad for everyone that lived before UA-cam haha....they had to cut it up themselves or just not know. My dad was really smart and knew all these things....I bet he spent a lot of time cutting things up....also he learned about a lot of stuff when I took something apart and he had to put it back together!

  • @RRINTHESHOP
    @RRINTHESHOP 7 років тому +6

    Great demo.

  • @mikeyp2277
    @mikeyp2277 7 років тому

    This is great. It was just like watching the coaster brake video, they both have been part of my life forever but I had no clue what made them tick.

  • @Zrambo49
    @Zrambo49 7 років тому +1

    The wisdom you have. Really enjoy your videos.

  • @paulaleksinko9039
    @paulaleksinko9039 7 років тому +1

    Great job Lyle, Thanks for the experience, time , money and detailed information that you put in all the videos.
    There is one thing that baffles me and it is why there always are about 10 people that dislike your work... I guess jealousy or just foolishness is the motivation.

  • @thomaslevy2119
    @thomaslevy2119 7 років тому

    Now I know why the hand-tightened chuck on my cordless drill is so hard to get tight enough on a bit so it does not slip. The mechanism needs a little lube in the right places! Thanks for the demo and info.

  • @mrmatt2525able
    @mrmatt2525able 2 місяці тому

    Wow that’s awesome! Nice cutaway!

  • @TravisTerrell
    @TravisTerrell 6 років тому

    "Ehh, about twenty other guys have done that already."
    Just kidding, only repeating your own words for fun. Honestly, yours is the best explanation I've seen so far. Thank you!
    (Edit: After watching 3 other videos, I'm a subscriber. Great stuff!)

  • @Erik_Swiger
    @Erik_Swiger 6 років тому

    I just want to let you know, I joined a community on Facebook that deals with machining, and on post after post, you are mentioned as a source for good information about machines and machining. I don't know if this reflects in your numbers, but you are definitely noticed. Best wishes, Tubalcain.

    • @mrpete222
      @mrpete222  6 років тому +1

      Thank you very much, I was unaware of that

  • @nickdusek5104
    @nickdusek5104 Рік тому

    Thanks for the info, very well presented!

  • @1martyjr
    @1martyjr 7 років тому

    never thought it was like my 3 jaw chuck but now that you've shown it I see how else would it work. thanks tubal

  • @ScottandTera
    @ScottandTera 7 років тому

    wished I had this video about a year ago. messed up a Chuck cause I skipped a step. 150 dollar mistake.. but I now know. thanks Mr pete

  • @TheAyrCaveShop
    @TheAyrCaveShop 7 років тому +1

    Best Educational Videos on UA-cam! Keep up the good work!
    -Dean

  • @keithkemper
    @keithkemper 7 років тому

    Excellent Mrpete

  • @elsdp-4560
    @elsdp-4560 7 років тому

    THANK YOU...for sharing.

  • @TM15R
    @TM15R 7 років тому +1

    I can only guess how much fun it was to machine one of these before CNC came along.

  • @michaelmurray3422
    @michaelmurray3422 7 років тому

    That was quite interesting. I didn't know how to get the sleeve off. I have one that has some metal shavings in it, and doesn't turn very well when locking a bit in it. Now I do.
    Thank You!!!

  • @darrenmartin2195
    @darrenmartin2195 7 років тому

    Excellent as ever. Thanks for taking the time to this, it's appreciated.

  • @newton9837
    @newton9837 7 років тому

    Why am I just finding out you have a "what makes it work" series after 25 entries! I NEED to watch these. well so much for doing anything productive tomorrow :-)

    • @mrpete222
      @mrpete222  7 років тому +7

      Stay home from work and WATCH those videos.

  • @1musicsearcher
    @1musicsearcher 7 років тому +1

    Thanks for another great educational video.

  • @roserecruitments6762
    @roserecruitments6762 7 років тому

    Thank you very much teacher. I like your lessons.

  • @DochNiemals
    @DochNiemals 7 років тому

    Fabulous video! It answers questions I've had since childhood.

  • @MrUbiquitousTech
    @MrUbiquitousTech 7 років тому

    Excellent video Mr. Pete! I've never had one apart before; learned something new! And with a great Tubalcain Cutaway!

  • @kevinwillis9126
    @kevinwillis9126 7 років тому

    i learn something new every time i watch... Thanks for sharing sir..

  • @Tamazonch
    @Tamazonch 4 роки тому

    GREAT VIDEO thank you very much!

  • @kevinhamling4675
    @kevinhamling4675 7 років тому +2

    very informative.
    Thanks.

  • @pepsiatlas5452
    @pepsiatlas5452 5 років тому

    what a cool mechanism

  • @skycarl
    @skycarl 7 років тому

    Yeah there was this guy who was showing this at Radio City with the Rockettes kicking their lags on a rotating turnstile while Bing was singing " some times you feel like a split nut.",,,,, but that guy didn't show any patent drawings to us.

  • @grizzlydan8
    @grizzlydan8 7 років тому

    First time I have seen the inside of a geared chuck. interesting.

  • @ecrusch
    @ecrusch 7 років тому

    Thank you Mr. Pete.
    That was very interesting.

  • @bossecarlberg
    @bossecarlberg 7 років тому

    Thanks for the very interesting video now I know how its work.

  • @MikesToolShed
    @MikesToolShed 7 років тому +1

    this is awesome. I always wondered what exactly was inside ofnthose

  • @Badgermatt-nc5nr
    @Badgermatt-nc5nr 7 років тому

    Always learn something, I wish you were a teacher when I was in school!

  • @charlescompton4495
    @charlescompton4495 7 років тому

    I learned something new today; thank you very much, Greg.

  • @redoorn
    @redoorn 7 років тому

    nicely done.
    thank's Teacher.

  • @thegreatga
    @thegreatga 7 років тому

    I seen you at NYCCNC Zanesville the other day, holding a camera in the background. Unfortunately I didn't recognize you until I got home. Would have loved to personally thanked for all your videos you create. Perhaps next year I will get the opportunity.

  • @1jtolvey
    @1jtolvey 7 років тому

    GREAT VIDEO !!!

  • @EngineerNick
    @EngineerNick 7 років тому

    Wow thanks for this video. A lot of effort and a chuck sacrificed to the youtube gods for this one :)

  • @piecetoyou8285
    @piecetoyou8285 4 роки тому

    Brilliant,
    I Wreckon once the jaws have been replaced,place in the freezer,using elastic band to hold the two halfs,
    Warm the outer cover slightly ,then pull the inner out of the freezer and slip the outer cover on,would this work or would the outer sleeve shatter once toutching the frozen inner section,
    I would be intresred watching if you would try with a none functiong one,

  • @randomdude1786
    @randomdude1786 7 років тому

    ya number 1 and 2 3 will be obvious and some will bind if the jaws are not in the position in the instructions scoring the shell got mine at boeing surplus years ago all their tools are marked with a capital B with a circle round it written with a engraver pen that's why you hear the term lazy B its like a cattle brand

  • @JimmiePorterAtStuartArts
    @JimmiePorterAtStuartArts 7 років тому

    Really interesting. Thanks!

  • @genial6589
    @genial6589 7 років тому

    Great!

  • @AlRoderick
    @AlRoderick 7 років тому

    So I suppose the question is in the premium chucks, where do they introduce the ball bearings? I figure it must be between the split nut and the body since that's the only frictional surface but I could also see them between the body and the jaws.

  • @jamesburns0657
    @jamesburns0657 7 років тому

    So, that was cool! Learn something with each video, thank you!

  • @cosimomarotta9552
    @cosimomarotta9552 7 років тому

    One of the best things ever seen. Mr Pete, according to your knowledge, what makes a chuck accurate?

  • @fsj197811
    @fsj197811 7 років тому

    Very cool, thanks for the video and your time to make it. :-)

  • @mahocnc
    @mahocnc 6 років тому

    My three chucks, 0-1/2" ball bearing Jakobs are about 35 years old...and I'm like some other machinist...don't let the drills spin in the chuck!
    Never had problems with worn jaws...just the key had worn out 5/16" diam. stub which goes inside the chuck...I find that stub was made too short, [new] and over time the key is rocking too much in the hole which then can skip teeth on the beveled gear, today I fixed all 3 keys by cutting the 5/16 diam. stub off and drilled with carbide and reamed 5/16" hole then pressed a dowel pin into, cut to length, [longer then original] fits nice and snug again...should be good for a long time again.
    I also have some keyless, [ok for small holes].... for heavy duty large drilling nothing beats the Jakobs.

  • @ip161314
    @ip161314 7 років тому +2

    AWESOME!!!

  • @djberg3483
    @djberg3483 7 років тому

    thanks, just got a new chuck that needs some gunk removal, and now i know!

  • @johnstrange6799
    @johnstrange6799 7 років тому

    Interesting.

  • @Segphalt
    @Segphalt 3 роки тому

    How in the hell have I been watching TOT for years and only discovered this now?
    Should have looked at the blueprint...

  • @petek210
    @petek210 7 років тому

    I wonder if the Stoner in the patent drawing was related to Eugene Stoner, of AR15 fame?

  • @tomhare3190
    @tomhare3190 7 років тому

    That Stoner patent must have been for an improvement. I found a patent granted to A. I. Jacobs in 1902 for the chuck. It is patent number 709014. You can easily find it by going to google patents and searching by either "Jacobs drill chuck", or the patent number. I like the style of the patent drawings and have discovered a lot of them granted to Laroy Starrett, including the RPM indicator that you did a video on.

  • @jaxxbrat2634
    @jaxxbrat2634 7 років тому

    Needed to weld our big Jacobs chucks ..tapers too short for the MT 4 adapter

  • @yanwo2359
    @yanwo2359 7 років тому

    I've heard sometimes that a drill chuck should be tightened from all three positions. What does my favorite shop teacher advise?

  • @lumspond
    @lumspond 7 років тому

    Loved it!

  • @cylosgarage
    @cylosgarage 7 років тому +4

    I can see clearly nowww

  • @robroysyd
    @robroysyd 7 років тому +6

    Does the shell drive only drive the the nut through friction?

    • @kevCarrico
      @kevCarrico 7 років тому +2

      Robert Grant -- it's more than "friction"... it's an "interference fit"... hence the need for a press to disassemble/reassemble (but the cutaway still has a tight-enough fit to make it work as shown here).

    • @robroysyd
      @robroysyd 7 років тому

      Kev - An interference fit relies on friction, a lot of it but it's still just static friction. My question was more about there being no key or spline, hence the shell could be pressed on with any alignment.

    • @kevCarrico
      @kevCarrico 7 років тому

      Robert Grant -- of course interference is a form of friction... but you didn't mention keys or splines in any way.

    • @kevCarrico
      @kevCarrico 7 років тому

      Robert Grant -- of course interference is a form of friction... but you didn't mention keys or splines in any way.

    • @robroysyd
      @robroysyd 7 років тому +2

      Kev - I had intended to but decided to keep it brief.
      Long version: I'd like to have seen more about how the shell engages the nut and how the nut is made. The shell moves the nut through friction from an interference fit but it's not that simple. The nuts is machined and then split. Doing that and maintaining the tight tolerance seems quite something to me. I thought whatever mojo goes into the manufacture of these chucks deserves more coverage.

  • @veganadventure5282
    @veganadventure5282 7 років тому

    cant wait for the next one!

  • @isbcornbinder
    @isbcornbinder 7 років тому

    This is what I read in the Cummins history book, The engine that could. Google it and buy it for a really good read.

  • @howardgolden5536
    @howardgolden5536 7 років тому

    Is the chuck on a cheap hand power drill constructed the same way?

  • @cmonster6
    @cmonster6 7 років тому +2

    Wish I was your next door neighbor.

  • @MrShobar
    @MrShobar 7 років тому

    I'm not too sure you can even buy a drill motor with a cord anymore, let alone one without a keyless chuck. The keyless chuck was a real unfortunate development (unless you're talking the expensive Albrecht chuck). They never hold, and have given rise to those drill bits having the three flats ground into the shank as a remedial fix.

    • @John_Ridley
      @John_Ridley 7 років тому +1

      Of course you can still buy AC powered drill motors, and many still come with proper keyed chucks. Just typing "corded drill" into my favorite home improvement store's website shows that there are many of them available and half of them have keyed chucks. If I had to have only one drill motor, it would be corded, but I have to admit that 90% of the time I use a cordless.

  • @hishammosa6977
    @hishammosa6977 7 років тому

    thanks for your sharing
    can you make video in whats makes work a keyless drill chuck?
    thanks

  • @jameshohimer2542
    @jameshohimer2542 7 років тому

    What turns the split nut? Is there a spline or notch in it?
    Please explain the relationship between the Shell and the split nut.
    If the Shell is a press fit on the body...how does it turn?
    Can you tell us how the split nut is manufactured?
    Is the body one piece?

    • @Volcker1929
      @Volcker1929 7 років тому

      James Hohimer from what I can make out in the video, the shell is pressed on to the split-nut. Once pressed in they move in unison. The body of the chuck holds the jaws loosely so they can slide in and out. Once the chuck is assembled, the jaw teeth engage with the split-nut. When the body is kept still and the shell/split-nut combination is rotated the jaws slide in and out of the body.

  • @markkoons7488
    @markkoons7488 3 роки тому

    Got a #19 Super Chuck that has one jaw that will not extend with the other two and is jammed in so the chuck will only retract - open? - half way. The chuck isn't rusted or been beaten on. Any suggestions how to get the thing apart so I can assess the damage, clean and lube the thing? I tried pressing it apart as usual but there was clearly something jammed by the out-of-position jaw.

  • @wgm-en2gx
    @wgm-en2gx 7 років тому

    Hey Mr Pete. I'm a pretty regular watcher and never saw #385 and can't find it on your channel. Was it released?

    • @mrpete222
      @mrpete222  7 років тому

      its still not released

  • @МиколаМирославенко

    Я хочу виготовити такий патрон. Але не розумію, як це робиться.

  • @umajunkcollector
    @umajunkcollector 7 років тому

    Jacob's Charles in the UK

  • @michaellitzkow8123
    @michaellitzkow8123 7 років тому

    Mr. Pete - I love your "What makes it work?" series. Many thanks for your clear explanations. I want to suggest one that I don't think you have done yet. I recently got one of the Noga dial indicator holders and it's really nice. However, I keep wondering how a single tension knob manages to tension three articulated joints at once?

    • @mrpete222
      @mrpete222  7 років тому

      Thanks. If I did get a noga--I sure wouldn't take it apart

  • @MyGrowthRings
    @MyGrowthRings 2 роки тому

    What are your thoughts on the effect on a drill chuck of using a Wagner Safe-T-Planer, or similar rotary planer? They require the jaws to be almost fully opened. I also love studying patents! Scott

    • @mrpete222
      @mrpete222  2 роки тому +1

      No problem I have use one hundreds of times

    • @MyGrowthRings
      @MyGrowthRings 2 роки тому

      @@mrpete222 Excellent. Me too, but always on a Shopsmith with a 1/2" router chuck.

    • @MyGrowthRings
      @MyGrowthRings 2 роки тому

      @@mrpete222 I did a video on the rotary planer last week and already expressed my unfounded concerns about using it with a drill chuck. I owe my subscribers a follow-up and intend to mention your insights. Any chance you'd be open to recording a statement about this that I could include? I have a small but loyal audience of Shopsmith users, so it's not like I can make a compelling offer for a collaboration, but even so, it would be a thrill if you'd be interested. I could arrange a Zoom meeting. Scott

  • @RookieLock
    @RookieLock 7 років тому

    I love cutaways aswell! Im trying to find some Lock Cutaways at the moment :P

  • @rupert5390
    @rupert5390 7 років тому

    Is it true these are no longer manufactured in the USA. I can't believe it.

    • @MrShobar
      @MrShobar 7 років тому

      Some are presently manufactured in Spain, I think.

  • @genkidama7385
    @genkidama7385 3 роки тому

    thats what school is supposed to teach you. insted you have to memorize who the heck is ramses and whatever mummies that were never found in pyramids.

  • @68sweetnovember
    @68sweetnovember 7 років тому

    I for the life of me cannot find #385.....
    Kindest

  • @shotgunreloader4964
    @shotgunreloader4964 7 років тому

    Why not check the runout I have bought 16-18 (and returned them all) the runout is the worst in the industry, the smallest jacobs chuck had runout greater than the diameter of the intended small drill bit. The cheap Chinese ones are precision boring heads compare to jacobs brand. brings shame on the USA brand. Jacobs if you are hearing you owe me alot of return postage.

  • @michaelmarks8954
    @michaelmarks8954 7 років тому +8

    Mr. Pete,
    I disassembled my chuck and did not realize the jaws had to be in a specific order and never could get it to close all the way after the tear down. Tomorrow will be fix it day.

    • @aserta
      @aserta 7 років тому

      Everyone's first-time-disassembling-a-chuck mistake. :) Pickled my brain for weeks how a crunchy but otherwise very precise J'sC wouldn't close right when it struck me that they must grind them just like they do with lathe chucks.

  • @junglejammer1
    @junglejammer1 7 років тому +5

    Never knew how they worked until now. Thanks for sharing.

  • @jamesdenney9653
    @jamesdenney9653 7 років тому +2

    Then first time I ever played with one of these I was 4. I was convinced it was mysterious magic. I've never had to take one apart and, of course, never discovered the inner workings. What a marvelous piece of engineering. Mystery solved! Thanks!

  • @bobbyw9046
    @bobbyw9046 7 років тому +1

    Mr. Pete, as always I enjoyed your Jacobs Chuck video. I recently replaced my (1990's vintage Taiwanese but descent) Drill Press Chuck for a brand new old stock made in the USA Jacobs 14N. I also have a Jacobs 18N and a tiny 0 also made in USA - I got from my Dad. Believe it or not you can still find a NOS on Fleabay if you look hard enough and have the time and patience. They also still have NOS re-build kits for the old Chucks too. The new production Jacobs are not terrible but certainly not as good as the original USA models.
    I've got an older MSC 1HP floor model Industrial rated Drill press ( early 90's production) that is a really descent machine. You might not believe this but the Run Out is only .0015" measured with Federal and Starrett gauges. I got this DP new and have taken good care of it throughout the years. What makes it more special is that my Dad bought it for my 40th Birthday!

  • @Bushradical
    @Bushradical 6 років тому

    great video. Thanks!!

    • @mrpete222
      @mrpete222  6 років тому

      Thank you for watching

  • @mwganson
    @mwganson 7 років тому +1

    Great job, Mr. Pete. I'll bet there were a lot of unhappy customers finding those broken nuts in those boxes. So, do they break them at the factory or do they cut them? I would think cutting, but then that would result in at least some small loss of material, which in this case might be an immaterial loss of material, if you'll pardon the pun. If they do indeed break them they must have some method of ensuring they just end up with 2 (and not 3 or 4) pieces and also they would need a way of preventing bending or warping the part.

    • @experiencingtechnicaldiffi5184
      @experiencingtechnicaldiffi5184 7 років тому +4

      Matching broken pieces like this are machined and then hardened. While still full hard a notch is ground on each side and they are impact broken so they don't distort or shatter. They are then tempered in an oxygen free furnace to avoid scale, assembled, clamped together and the threads ground to size.
      If you take a HSS tool-bit and notch it then bend it, it will break but the ends will distort so it won't go together evenly. But if you smack it with the correct force and speed while holding one side at the notch they break cleanly and fit together nicely.
      I have seen 2 chucks that had 2 piece nuts and they would occasionally bind as the machined split passed a jaw. Irritating because each had certain sizes of drill that wouldn't tighten properly and would spin. They eventually went to the scrap bin. If you have a chuck that spins some drills this may be why.
      Mike (o\!/o)