Holier than Thou: Precision Holes by Drilling, Boring, and Reaming

It's imperative that design engineers understand the full journey of the parts they design, from the drawing definition, through manufacturing, and inspection. One of the most common features in machine design is a hole. Whether it accepts a bolt or holds a precision bearing, it has to be the right size and in the right location for the machine to function properly. In this video, we'll outline the considerations for designing holes and precision bores, give you some tips for machining them reliably and cost-effectively, and compare the different ways they may be inspected.
00:00 - Introduction
00:47 - Precision Bores in Machine Design
02:36 - Limits of Size of Holes
03:03 - GD&T Location Controls
03:55 - GD&T Form Controls
04:43 - GD&T Orientation Controls
05:31 - Surface Finish
06:26 - Drilled Holes
07:33 - Tips for Using Drills
08:23 - Spot Drills
09:44 - Reamers
11:26 - Boring
12:27 - Circular Milling
13:07 - In-Control Compensation (G41/G42)
14:28 - Accuracy of Machining Processes
16:21 - Inspection of Precision Holes
17:03 - Plug Gauges (Go/No-Go Pins)
17:54 - Calipers for ID Measurements
18:26 - Telescoping Bore Gauges
19:00 - Tubular ID Micrometer
19:36 - Dial Bore Gauge
20:19 - Tri-Point Micrometer
21:45 - How to Confirm a Bore is In-Spec
23:10 - Rule 1, The Envelope Principle
24:01 - ISO vs. ASME for Features of Size
25:31 - Conclusion
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Companion Blog Post: tarkka.co/2021/02/07/holier-t...
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[@mjones2431]

I've been a machinist and builder for 20 years and am now moving to engineering. This is some of the best content on youtube

[@CorndogBrownie]

Oh my goodness. as a machinist this is fantastic. Impossible holes, or ridiculous call outs kill shop time, and cost tons of money. More engineers need to watch this kind of stuff

[@iizvullok]

Oh yes. Especially if the part has very thin walls. Sometimes i have to do parts which have tight tolerances (something like 0.02mm) on the inside and outside diameter while having a wall thickness of only 1 or 2mm and a 50mm diameter on the inside. The part deflects a lot and that deflection has to be compensated for in the program. Micrometers are basically useless since they deform the part by up to 0.02mm while measuring. The ring gauge fits just fine by itself, the plug gauge also fits just fine, but they do not fit both at the same time. The quality control also has a hard time getting meaningful measurements because the part is not perfectly round after its finished. Then funny thing about this all: There are a bunch of similar parts which serve the exact same purpose but have 0.1mm tolerances which makes them much easier and cheaper to produce.

[@TheMetalButcher]

Engineer (and machinist) here. Watching it! Great stuff.

[@herrkulor3771]

Thankfully there are also parts that can help hold bearings in plastic and aluminium as those materials expand way more than the steel of the bearing. I don't know their englisch name, "Toleranzhülse" can be useful if you have no precision. Edit: so you don't need utter precision.

[@navyf4s]

Everyone in our shop needs to watch and learn from this video! Every engineer who what's something made needs to watch this.

[@stochasticsignal1951]

It's been a while! I'm so glad to see some more from you guys. Your older videos are some of the best GD&T explanations I've ever seen.

[@scottw1808]

Couldn't agree more

[@juraterfan]

It's crazy how I learn more things on this channel than anywhere else, this is heaven for people who are interested in machining and engineering in general! Please make more videos!

[@gamingbros400]

Recently found your content on advice and got disappointed that the last upload was a year ago. But then I saw this and really happy. Great work guys, helping every trainee/university students to learn the details and less taught things. Cheers guys.

[@humbermg]

This is amazing! Detailed, to the point and a great reference for anyone learning the basics. I love it! Congratulations!

[@reyyannajeeb1067]

As a mech E, these videos are always fun to watch. Thank you for making them

[@twistytriangle]

Thank you for this video. The SI unit mentioned while narration were especially helpful. Without it I would have no concept of the the dimension.

[@bluescrat]

Love your video and audio quality, up close camera shots and thorough detailed explanations. Thank you!!

[@sarvjotsingh]

You guys are awesome. You explained these GD&T principles so much better than my book. Bravo 👏

[@austindiodene972]

This is probably the best put together video on manufacturing information I've ever seen. Definitely subbed

[@HopelessCT]

I am very glad you guys still upload, such good quality ya’ll deserve so much support

[@georgescott6967]

I watched your fits and tolerances video before this one. The narration on this one is _much_ better; I understood everything being said. Great job, thank you.

[@rc8rsracer1]

I’ve been machining 10 years and I agree with all of this! Well done!!

[@TheMetalButcher]

Same. Rare that I agree with everything in a machining video since it's so dependent on one's own style.

[@JeffandJake]

Excellent presentation with great real-life examples. Thanks for sharing this for free.

[@MrShkolololo]

Wow! I'd never thought that technical details video on precise machining can be THAT interesting!

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Knocked it out of the park as always!! Nice and clear descriptions of high-level concepts, along with good video clips showing practical applications of the discussed topics!

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This channel is such a gem. Easiest subscription I've ever made.

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The! best channel on youtube right now. Just amazing! Thank you sooo so so much

[@dziggy3004]

THANK YOU! This is an awesome BOOTSTRAP VIDEO! Even for OLD DOGS continuing life's ventures into new learning territories! Despite cursory awareness of these metrology/machining techniques -- as I enter into the VASTLY CREATIVE "hobby world of reinventing the wheel" -- having now more than wet my feet with vast opportunities of solving problematic issues, wondering WHY someone hasn't ALREADY solved certain BASIC PROBLEMS -- this is so applicable at my stage to be introduced to, and to leverage this otherwise DARK KNOWLEDGE that was hidden from us novices! With the well-done visual aids, this breaks down and connects the controlling variables, and is definitely THE TEASER and POINTER for further exploration! I feel blessed by your HOLINESS! Again, thanks! Dave

[@ethanmye-rs]

Thank you! Would love more videos about GD&T

[@ILIKECHEESECAKE100]

Always glad to see more from this channel! Really quality work

[@jmannUSMC]

Kinda bummed I just now found this channel. Thank you for creating such great content that really tickles the brain. Hope the team is well and we get some new videos in the future!

[@CN-cv7kq]

Seriously these videos are amazing. Helps me out so much. The terminology you use makes it easy to understand and explain to other people. I just wish you had more videos to watch. I just found this channel and watched everything you had. Thank you for taking the time to make these. By the way I subscribed within 1 minute of the first video I watched.

[@brettcoles6462]

You're back! I thought you weren't going to post anymore and I was very disappointed. Your videos have been more helpful than my manufacturing class in undergrad!

[@davidewing9088]

EXCELLENT Information and presentation of this material. Thank you.

[@sharkbaitsurfer]

It takes true expertise and talent to explain such a potentially complex subject with such clarity - that was simply brilliant, brilliant work!

[@maplesyrup2944]

Great figures and animations. Glad to see you actually machined some pieces to demonstrate.

[@milaanpatel4997]

I accidentally came on to this video. This is kind of information I was looking for since years.

[@AlphaSierra375]

This was exceptional! I no longer can look at the most experience engineers like they're infalible. It almost broke my brain and heart at the point where you mentioned & demonstrated with CMM how a hole (& shaft) can never be perfect. Maybe that is what draws me to the world of CAD. A hypothetical realm of perfect dimensions.

[@jamesmanoni]

I'm a draftsman and I learnt so much useful information I never knew before from this video, consider me subscribed!

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I love this channel. It has some of the best quality videos and educational content

[@Cheticus]

Been hoping for a new video for awhile! Without exception, they continue to be exceptional. Hope you're doing well :). Thank you!!!

[@asheshshrestha]

Really glad to see you guys after a long time

[@Alorand]

The KZbin algorithm has recomended me a 'Boring' video, but I didn't mind...

[@jacobwild278]

Please do more like this! So good! Start a patreon, so many people will support!

[@Maeili]

Thanks for the very helpful and well explained video! Metric conversions also much appreciated.

[@PPAATTful]

I'm a manufacturing engineer for the last 40 years, absolutely loved your show very well done. One thing it's not called a ruler it's called a scale, I'll buy one.

[@user-tw9io9nz2m]

Amazing, you guys actually went through the effort to machine a part the wrong way to show what happens if the holes don't line up. Love it!

[@robertsomerville5377]

They assembled incorrectly . Start all bolts before tightening .

[@lohikarhu734]

@@robertsomerville5377 funny, something that one would normally do, but they did not? OTOH, with countersunk screw heads, you could end up generating significant distortion forces on a part of the clearance holes allow more tolerance during assembly. Tricky stuff. Thx for comment.

[@sergiourquijo4000]

This channel is just awesome. I haven`t studied any of this but it is really interesting to get a sneak peak of what it is all about.

[@brucewilliams6292]

I love learning so much about machining. This is a great video.

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This channel is gold!!!

[@gaffney92]

Wow! Extremely insightful and concise!

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Great stuff. Consolidated a ton of stuff that took years to pick up as a practicing engineer.

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Thank you very much guys!, Please keep posting!

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Those videos rock. Lovely and accurate content.

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Thank you! These videos are amazing.

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Nice, after so many time, I was waiting for another one of your very pleasent with that Golf commentator voice videos.

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Awesome as always!

[@wallinkevin]

Machinist here. Great videos! Really looking forward to your GD&T videos! Subscribed!

[@nickp4793]

Great content and no fluff! Thanks for making it.

[@3073Sean]

Deep dive into GDT please!! You guys are awesome educators, keep it coming!

[@superpilun]

Excellent videos! I always learn something new.

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Please never stop making these videos.

[@e2jw]

Great Job with this! Thanks for sharing it!

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I really like the way you've done this video it's perfect you should do more!

[@PacoOtis]

Excellently presented and very informative! Thanks for sharing and the best of luck!

[@rustinwebster]

Incredible and spot on once again!

[@CNCMachinistEducationNetwork]

excellent video - such a basic thing but how to explain why is great

[@k1ngofthosewhoknow]

Excellent video. Thank you.

[@greybeard9x44]

A very good video. Thanks. I have used all these methods. Setting telescopic gauges as Go and Nogo gauges using a micrometer and then trying them in the work can be helpful. There are also wedge gauges which in some situations, e.g. measuring slightly worn or rough holes before making a new part to fit the hole, can give useful and repeatable results. As these are used directly with a micrometer, they are quick to use too. Getting a feel for the kit you are using really is important, so lots of test runs, and comparison of results from different equipment being used, do build up confidence and opinions of what's best.

[@100x35.Design]

I LOVE YOUR VIDEOS AND I LIKE HOW EXPLANATORY THEY ARE. PLEASE DO MORE VIDEOS! PLEASE!!!

[@OriginalJetForMe]

This video was great! I really learned a lot. Thank you!

[@Wyllie38]

Stumbled across your channel. Easily earned my subscription. Great stuff. Even if I am an ISO guy

[@ayushmahato4481]

Amazing content with an all round scope

[@ka9dgx]

That was really informative, thanks! Glad to see you've got a decimal inch scale on your ruler in your shop, you've avoided my pet peeve. 8)

[@AshLeeeeee]

This is amazing! Thank the youtube gods you showed up so I could sub and watch more content

[@Lichalisen]

Thank you so much. Very informative.

[@Jadfitree]

you guys are awesome!! Thank you so much for this kind of video very professional

[@devurandom2019]

Excellent Video - Thank You!!! ❤

[@lockbuilder]

That is a really great video guys! Thank you. Subbed and look forward to more!

[@reyspec]

Nice Quality content you show us! My student should watch this!

[@lohikarhu734]

Just went over to your website... Kiva juttu! Now, I need to spend some hours looking at previous videos ;-)

[@kylechrystal4532]

Excellent video. Regarding the telescoping bore gauge - you can lightly tighten the thumb screw with the handle at an angle in the hole and the piston over extended, then by rocking the tool over past center (like the dial bore gauge motion) the hole wall will push the piston in and it will stay there, at the proper size.

[@Saki630]

this one video has more information than all the 'trending bullshit' for the past 10 years on KZbin. This answers many questions, but then leaves more to be answered like how to fit things into the bores/holes and makes sure everything is in the right position.

[@JinKee]

Check out their older video on "tolerances: how to make parts that fit together"

[@lamtran2993]

Wish to see more from you guys.

[@spcp001]

Great Video! One more trick for measureing tight tolerance holes is to check your workpiece temperature before you measure it, especially on larger bore and people are trying to hit lower tolerance boundaries. I've seen numerous housing sent back to the machine shop because they are slightly too tight. And it turns out the machining shop just is cooking hot.

[@youcandoit786]

Awesome work, please keep that coming

[@thedillestpickle]

Really great video thank you!

[@grant-is]

I really would love to see more :)

[@obak15]

best video ever. Made with love

[@maximf.5537]

excellent video, thank you

[@andrewfortus2629]

Please post more thank you in advance :)

[@sashab5656]

You know what, I never leave comments. However I am compelled to leave you guys one: Great job, I've subscribed and please keep these vids coming.

[@rockzbassist]

Hi, I really love your series of mechanical engineering basics! If you don't mind, please make videos about bearings (journal bearing included!) Thank you.

[@abhijeetmane8]

What a great video keep it up, upload videos about GD & T. Thanks

[@sky173]

Where have you been? Glad to see more content from you. I hope to see more soon.

[@Vikingman2024]

Excellent!

[@helicopterdriver]

Roller Burnishing. Perfect fit, slick finish and perfectly round. No reaming. Very repeatable even with interpolated bores in steel. Micron tolerances. Did that 25 years ago.

[@lohikarhu734]

Thanks for the comment on this...Have you seen any videos, or web discussions on this subject? I wondered, too, of roller burnishing would also give any advantages in grain formation, or surface "integrity"?

[@helicopterdriver]

@@lohikarhu734 The fit of the bore is very repeatable. The surface finish usually looks like chrome finish on steel or aluminum. Roundness is very good as well. Can't beat it on a production setup. I made parts for tobacco harvesters and the tolerances were very tight. Saved a lot of time.

[@lsorgule]

Fantastic resource!

[@berlin93666]

New sub, pretty good job with yur videos, love the simplicity of it.

[@pauls5745]

this has some good info. I liked the charts.

[@bluebull1985]

awesome video!

[@ImolaS3]

Hoping to see more content coming our way soon

[@ReubenSchoots]

Great video! Thanks!

[@lohikarhu734]

I'm not sure how I came across this video, but it was certainly "a good use of time" :-) And, hey, Metric AND ISO discussion ;-) !

[@3073Sean]

Love the video, keep them coming! Where do you I find your older GD&T vids?

[@vishnooramdin2915]

Enjoyed your vidio from Canada.Miss working for the DANA corporation making disc brake Rotors as a CNC machine operator on a CNC turning center lathe and drilling machines Wish I had your vidio while being employed.Now retired(lol)