Fits and Tolerances: How to Design Stuff that Fits Together
Fits and tolerances are a foundational mechanical design skill, but they're commonly misunderstood and misused. In this video, we explain how to apply correct and functional fits and tolerances using ASME B4.1 and Machinery's Handbook, so your parts fit together exactly as you intend, the first time, every time. No emergency filing required!
Blog Post: tarkka.co/2019/02/20/fits-and...
If you're looking to pick up a copy of Machinery's Handbook, don't worry about getting the latest edition. Most of the content hasn't changed in a long time. For example, ASME B4.1 hasn't been revised since 1967!
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Ah this is awesome! So many people just say "Yeah these are the fits and tolerances" but you guys actually showed what those fits look like, which is so important for us to connect what we want with what we have to say!
As a machinist who works constantly with engineers to make their parts, taking the time to talk to the people who make the things you design will end up saving you both time, money, and headaches.
If you are reading this, I hope today is much like a clearance fit - easy to get through, with lots of light at the end of the tunnel.
How on earth did i not find this channel earlier, i've been struggling with tolerances for ages now.
This was infinitely more clear than my engineering lectures at school. Great video
Since I first started on Mechanical design this was one of the most challenging things to understand. I remember feeling incapable of imagining how these tolerances would behave beyond my CAD models. And that's why this video is so valuable. Thanks!
This was excellent! Perhaps as a suggestion a video on GD&T, and another on statistical tolerance stacks and Cpk values?
Sounds like there are a few thumbs up, here and on reddit too, for GD&T, so we've added that to the list!
@@tarkka Sincerely looking forward to it. The 20 minute 'e-learning' provided at work for these sorts of things are usually so dry, and involve clicking of the 'next' button a bunch of times.
@@JaySmith91 Check out the GD&T Basics course. It's pretty long and it is a paid course, but it's very easy to understand
Thanks! Our next video will be position tolerance and we will do more GD&T as well. We discuss material selection for fasteners in our “Screw It!” video, and check out the companion blog post for material compatibility and strength charts. For calculating forces etc., we can do another video. I recommend getting Shigley’s Machine Design book, that has the info you need. Good luck with your career plans! We are happy to hear the videos help :)
That RC3 fit was oddly satisfying
Wow, completely blown away by the quality and content of these videos.
Thank you for this. I think just about any machinists, engineer, or just general builder has encountered these and has some familiarity with them, however to see them lined up next to each and visually put together is a huge help with mental approximation!
This is one of the best video I’ve seen with respect to fits and tolerance
Great video! Thank you I have been trying to find resources on how to determine an acceptable level of tolerances but most fall laughably short. Yours was interesting to watch and informative.
Underrated channel. Schools should play these in shop class on days when the teacher is hungover
Thank you for clarifying that! Definitely helps a lot on the design side.
I subscribed immediately. Fantastic explanation: both informative and short.
this is my new favorite channel ever
Love the visual comparison. Seeing numbers and descriptions of "loose" or "tight" doesnt really paint the full picture.
Then you can paint the rest yourself. And you get a shorter video.
I'm so thankful for sharing this video. Gave a great deal of information on connecting the theeory to the practical application!
Thank you for this beautiful demonstration, neat and informative
This is high quality content. How did you guys get so good at explaining?
Good explanation of making a pin fit. I understand your language, been a machinist for over 40 years. Good luck with your channel 👍
THIS IS THE MOST EDUCATIONAL VIDEO I HAVE EVER WATCHED ABOUT METAL PARTS. - EXCELLENT AND THANSK FOR SHARING KNOWLEDGE...!
it feels like christmass thank you fior this in depth and easy to understand video
just found you guys! WOW THANK YOU FROM THE BOTTOM OF MY SCRAP PILE (which is where my heart is)
Thanks to KZhead for suggesting this video and also Thanks to tarkka
Very interesting. I’m subscribed and look forward to watching more videos from you.
This is a really nice video! You just got one new subscriber! Please keep them coming!!!
Thanks!
These videos are gold for the amateur engineer (like moi). Thanks!
What a gem of a video, this was very well done.
Thank you!
I've watched a couple videos that try to explain limits and fits, but this was the one that caused me to have an "Ah ha!" moment. Thanks!
True position would make a good logical next video. Great Job.
Thank you for this great video. It was really helpful.
Good video, very nice job with demonstrating the different fits
Thanks!
Another great video. Excellent background music
Thanks!
Great video. Would have liked to see examples of when to use each fit in real world designs. I had an older engineer help me out with that when I was starting out. The benefits of the loosest fit possible are many.
Great!! Very Helpful thank you so much!
That lc6 looks like so much fun to play with
Nice video guys ! post videos about all types of GD&T symbols & inspection , tolerance stackup analysis in the same way !! Thank you
Excellent visual examples of ANSI Standard Fits. The use of shop-floor tooling examples was great! Thanks for the design and piece-part applications. T J (Tom) Vanderloop, Author, Mechanical Designer, & Consultant; ATEA, AWS & SME-Life Member & Leader
This was very helpful. Thanks
U guys across the atlantic are a miracle
The Machinery's Handbook is a great tolerance-resource. This is a great video. The graphics from "SME" identify the exponential curve that exists with the tighter tolerances. Thanks for the excellent review on tolerancing. T J (Tom) Vanderloop, Author, Technology-Instructor and Design Consultant; ATEA, AWS, & SME-Leader/Memberships
Great info! Subbed! Maybe do a video on shaft seal/bushing/bearing witchcraft?
This was so straight forward and clear - when I studied it at university, they made it seem like building a time machine.
Wasn't everything like that though?
Excellent video!!
Best video I've ever watched .... Plz do a video on injection moulded polymeric parts and FABRICATION PROCESS TOLERANCES too ...eg final part is made up of many machined parts welded together
An extremely helpful video if you're not a mechanical engineer. I am just an enthusiast who is designing a big thrower flashlight and needs to know the tolerance necessary for the aluminium reflector to slide into the aluminium body of the flashlight. Although this uses the US standard I could see that I need RC3 that would means space of 0.08-0.1 mm between the parts.
Excellent! Thx, a lot. BTW, have a EE degree, but find myself doing a lot of mechanical design/CAD/prototyping (at local makerspace; for members, and clients), so have been on a practical, and self-academic path. Really enjoying the endeavor:)...
Excellent work!
This is a great video, very well explained. I'd love to see an ISO version.
tabletop machine shop made one :)
@@x0urce942 that one is why I found this one!
This. I always wonder how they're made. Nice explanation
Thanks for the video!
That was very informative.
amazing contents hope you keep update :)
You can get a running fit with a drill if the feeds and speeds are correct.
Great explanation , could you guys also make one for how to choose GD&T tolerances ( type of tolerances & it's numeric values)
Hi there, thank you for the insightful video! After watching, I'm left wondering how you design the strength of your interference fit. If for instance you want to calculate the press force required for installation, or the torque that can be transmitted by the interaction. I'm also curious when a retaining compound would be used, and how that would affect the calculations.
Great video ! Maybe one on choice of fasteners or bearings!
About to say that, bearings vídeo would be allsome
We'll add bearing and fastener selection to our list. That will be a fun one! Thanks for watching!
@@tarkka Love the channel. Any thought's on a bearing video yet? Love to see more!
My new How it's made channel.
Do you think you guys could do a video on the types of engineers a company would be hiring for and what their job description might be? I am asking as someone who has worked in manufacturing for over 10 years and has been a CNC programmer/ machinist for the past 8. I have been thinking about going back to school but am still not exactly sure what to go back to school for. I just know I am ready to move up in my career. Great videos and thank you!
Another great video. Does anyone know where one can get a set of parts to demonstrate fit classes? I always recommend new engineers keep a set of calipers and feeler gauges at their desk to help visualize specified tolerances. A set of class of fit demonstrators would be another fantastic learning tool to keep handy.
great content, cheers.
The best video!!!
topic idea: machine tool inspection, the different methods used for ways like dovetails, linear rails and the system to actuate like pneumatic, trapezoidal screw, ball screw - and how to check for wear and alignment, backlash and what to do :-) could be a mini series, like the tolerance classes of lead screws and off the shelve parts, preloads etc.
Excellent Job! The Machinery's Handbook is our "Bible of the Trades" and you did well! T J (Tom) Vanderloop, Author, Technology-Instructor & Design Consultant/ AWS & SME Leader & Memberships
Can you guys make a video series on GD&T? Or a example of engineering and designing a component?
We have a part we're working on now with a .003"-.005" interference fit, a bronze bushing going into an aluminum housing. Had to heat the aluminum in an oven and chill the bronze with dry ice because the aluminum already has marking on it which can't withstand more than 200°f. That's definitely a fit that isn't intended to ever come apart.
what a great vid
Hey guys, Thank you for the video, very informative. I have a question to ask: how can I compensate on tolerances when the assembly has 4 parts stacked up that their thickness may vary. thank you
Can you please make vedio on difference between achieving surface finish by grinding and surface finish achieved by itself in the process of maintaining the tolerance.
great vid
That is a really nice video. Its too bad its imperial so I will never use those terms, but you demonstrated the concept really nicely.
Great video! Can you post video about metal cutting?
Sure, is there a specific topic within metal cutting you are interested in?
Hello, the transition fit LT3 could be acceptable for a ball bearing fitting? between LT3 and press fit there are an "intermediate" fit? thank you for your patience
Good video. Is there an equivalent reference for positional accuracy?
This is the only one I have seen (second table on the page): www.engineersedge.com/manufacturing/drill-mechanical-tolerances.htm It appears to relate to drilled holes. As far as true position of machined features, this might be something we can test.
Great video! Hienosti tehty video! Ihmetyttää tuo Tarkka nimi...?
One thing about this video that doesn't quite sit right with me (maybe it's because I'm used to metric and it's different in Imperial Standarts) is the portrayal of the fits. A high tolerance doesn't mean that parts will end up having lots of clearance - it means that those that do don't go into the waste bin. The workshop will still try to match your indicated nominal diameter. They will not install special "worse" tooling to give you a nice wide range of rattly fits, they will simply not remove that many parts in quality control. Of course I am aware of the concept of intersection fits and press fits, which just mean that the parts "share" a hypothetical space, but the choice of a press fit does not influence the machining cost at all. Tolerance is the determining factor and can run any clearance fit, intersection fit and press fit into a high price range. Yes, even the loosy goosey one. You can have a +0,1 mm to +0,105 mm tolerance dimension on a bore, and that will make it quite expensive, even though it clearly is a clearance fit. Why would you need that? Maybe your part needs to keep a constant oil film on its surface that has to have a very precise volume and flow properties. Just keep that in mind. The choice of tolerance is the thing that makes the accountants angry, not the choice of clearance, intersection or press fit.
I'm in love
Please make video on GD & T detailed one.
can you pls let us know when to select what kind of fit??
Amazing video. How do we design for bearing housings and shafts diameters? I want to make my own R8 spindle but I really don't know more than design with nominal sizes. I need some tips and info
I can provide you with a decent information file if you're still interested.
Surface finish plays a huge roll in fit.
This video is great. Its all fun on the computer like you say but I'd pay some money for a set of ANSI pin and hole fitments just to get a real world idea.
Can you please elaborate the same in millimetre (metric system)
Nice
Rc6 can be repeated using a drill just under the finish diameter repeatedly. I’ve cheated 1” reamed holes using a 63/64” bit then finishing with a 1” bit using a .007” feed. Gotta do what ya gotta do
How does interference fit work- like , how does it make it permanent? what's stopping it from coming apart?
I would like to know why Engineers will place tolerances on a print, (example) .500+.005-0.000 ,and/or .250+0.000-.005, as to opposed stating the mean tolerance along with the acceptable tolerances. It does make for a confusing adaptation of which dimension you are measuring and what the tolerances are.
I think some engineers use this convention to more clearly convey the "design intent." To use your example, the engineer is possibly saying "I want a slip fit on a .500 pin." The problem is that some engineers (and possibly machinists) start to think that 0.5005 (very close to the nominal) is "more right" than 0.5025 (right in the middle of the tolerance band) and end up aiming for the nominal dimension. Instead, you really want to keep parts as close to the middle of the tolerance limits as possible.
Could you talk about different machines?
how much clearance is on an rc6 fit?
A good supplement to this one would be to cover circularity and hole location.
Check out our newest video! We cover both topics.
Good
There are so many KZhead channels, Tom Stanton, Lock Picking Lawyer, Adam Savage, to name just three, that improperly use the word tolerance to mean clearance. As a retired machinist, it drives me nuts. I always leave comments trying to inform them, but to no avail.
You mean the software manual does not explain fits and clearances? I am flabergasted that it does not. Always remember that two objects can not occupy the same space at the same time. I like the way they tolerance cylinderical fits with plus plus, minus minus instead of plus a value minus nothing. It insures that you will always have some clearance.
Tolerance is useful in mechanical design
"They'll tolerate it."
Can someone explain to me @2:44 why the shaft is 0.4295+0.000/-0.010 while the limits are -0.008/+0.018.? Why is the shaft automatically reduced by 0.012?
The Shaft is reduced by 0.0080 from the hole dim (as stated in the tolerance limit, which is -0.0080), so the shaft diameter becomes 0.4375-0.0080= 0.4295. Now a shaft of 0.4295 can can surely fit inside the hole of 0.4375. Now with that shaft, you can go more 0.0100 smaller (extra play) as per the tolerance limits, (difference between -0.008 and -0.018 = -0.0100).
@@rahulvadhvania4809 thanks for explaining that. Makes sense now
Please explain how CNC machining gives different tolerance as per requirement
Hi there, I'm not sure I understand what you're asking. Can you clarify your question?
What changes in machining parameters are done to get different tolerance. Or how different tolerance values are achieved in same machine. Suppose I want one part having surface tolerance of 0.02 and other with 0.01 a machine is used for two of them.
For CNC machines an effective way to achieve tight tolerances is in-control compensation. We can do a video on this and other ways to achieve tight tolerances.
Summary 1. Clearance Fit - Shaft Max OD less than Bore Min ID 2. Transition Fit - Shaft max od greater than bore min id but shaft min od is less than bore min id. Bore max id is more than shafts max od. 3. Interference Fit - shafts min od is greater than bore max id
Hopefully this applies to 3D printing.
Form stack up