Measuring Screw Thread Diameter and Pitch Using a Vernier Caliper | Accu Tutorials

In this Accu Tutorial, Matt shows us how to measure screw thread pitch & diameter using a vernier caliper.
This is the second of four videos showing how to measure components:
Watch the full playlist here:
• Measuring Components
Need a vernier caliper for your workshop?
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[@40beretta1]

I know this is three years old, 'but'. My daughters always interested in whatever I'm working on, Diesel or petrol engines, wood working... one day I had rounded out machine screw. After extracting the screw, I got out my gages and calipers. She wanted to know why I was doing what I was doing. As it goes...Dad'xplaining made her eyes role back in her head... The blessing that day was, I needed a conversion for my (leaf) thread gauge; imperial to Metric (couldn't find my Metric gauge). I stumbled across your tutorial. In less that four minutes, she got it. Thought there's still a debate. I say, I explained it just as easy as you did....she says: "you sure did, after 30 mins"

[@AccuComponents]

Thanks so much Jeff and that's fantastic news! We're always happy to hear about inspiring young people to take an interest in engineering 😄

[@djuroradulovic1371]

One of the best tutorials ever made generally speaking

[@Tdotttttt]

wow very thoroughly explained. The guy is also a great presenter.

[@AccuComponents]

Thanks so much for the great feedback, we're happy we could help 🙌 - Matt (the guy in the video!)

[@richardmiddleton7770]

You forgot to mention that all bolts are measured from under the head when determining the length, a lot of people get this wrong and measure the overall length of the bolt including the head.

[@AccuComponents]

Great point Richard! We actually cover that in our companion tutorial 'How to measure screw length using vernier calipers' here: kzbin.info/www/bejne/nKK5qGV7hcSng6M Will add a card/link to this video so that it doesn't get missed!

[@joelstolarski2244]

Arrgh. Me too. Should know better ,thanks.

[@littlefrank90]

Oh he forgot a lot of stuff, not just that.

[@JJC1138]

Thank you for the great concise explanations. Accu is such a great to company to deal with. I only wish I'd discovered you years ago!

[@AccuComponents]

Thanks so much, we love to hear that kind of feedback! Look forward to helping again soon!

[@nikolailu]

brilliant, now i just hope my diy shop has these

[@AccuComponents]

Thanks, we're glad you liked the video 😀 Our full range of precision components (including the metrology tools featured in the tutorial) can all be found on our website - and we have global express delivery too! www.accu.co.uk/

[@jcolan715]

This is a really helpful video. Thanks!

[@AccuComponents]

You're welcome!

[@ram.64]

Thank you for your useful guide.

[@AccuComponents]

You're very welcome! If you need any components or tools, be sure to check out our online store here: accu-components.com/

[@KL-bi2un]

This is really helpful

[@AccuComponents]

Cheers KL - anything we can improve? We also have more videos around this topic - this one about measuring a screw thread with a ring gauge offers the most precision: kzbin.info/www/bejne/nl61iXduYsedaM0

[@liornir2993]

Thank you!!!

[@AccuComponents]

You're very welcome, thanks for watching 😁

[@joelstolarski2244]

I'm lost . So Bentopal cat toy has stick on top for cat toy, like feather, or fluffy. Cat scared of sound. I will make a longer stick. Thread on toy, not regular. Metric I find 5.81 dia, and peak to peak, 1.20. Imperial is .235 dia and estimate 20.83 thread per inch. Does this sound like they made custom size so people can not make a threaded stick of longer length? Or do I make mistake measuring ?

[@sweillerYT]

Thanks ! Magnifier with LED

[@sweillerYT]

needs 0.1mm precision on graduation

[@sweillerYT]

see sweillerxfreexfrxATMxPitchSizeMeasurexjpg replace x1 x2 by dots, x3 x4 by slash and x5 with dot

[@nissan300bhp]

hi. can you supply an m10 bolt with a thread pitch of 0.75mm and about 40-45mm long

[@AccuComponents]

Thanks for getting in touch. This search should help get you started: www.accu.co.uk/en/search?query=m10+40mm+bolt If our standard range does not meet your requirements please get in touch via our custom manufacture form: www.accu.co.uk/en/p/27-custom-manufacture

[@theonlyrick]

Very handy, thanks.

[@edhagerty]

Thank you!

[@JohnLo]

Excellent video, cheers

[@cockpitcock7450]

Can u plz tell me why the screw doesn't have exact dimensions example ( 2mm dia )when it measured it is around 1.8or 1.85 why

[@AccuComponents]

Sorry for the delay in replying to this question. This would be because the screw has a nominal diameter of 2mm (M2). As mentioned from 1:48, this is because screws are slightly undersized to allow a Nut (which is slightly oversized) to pair with it. Hopefully this helps!

[@idhatemet00]

Did we watch the same video? He explained that…

[@glennfrancisco5525]

I would like to see how to use the Vernier Caliper to measure thread pitch. I was hoping your video would show that.

[@AccuComponents]

Hi Glenn, we covered this here: kzbin.info/www/bejne/f3SmiKl7gJuSqsk&lc=Ugz77QbYtYa3y08bUFJ4AaABAg&t=155s Although, for very fine threads it would be sensible to measure across say 5(n) thread peaks then divide by 4 (n-1) to give the pitch. This would minimize any measurement errors.

[@davidk6271]

If you don’t have the screw or bolt but only the threaded hole that the screw or bolt went into, how do you work it out from there?

[@AccuComponents]

Here's an old school trick that may help in this situation. Take a dowel or kebab skewer slightly larger than the hole and screw it into the threaded hole, then unscrew the dowel again and the peaks of the threaded hole should cut marks into the dowel. You can then measure those marks. Depending on how tight the dowel fits and how hard the dowel wood is you may need some pliers to get a little more force. Let us know how it goes David!

[@energyenergy2199]

Thank you very much. But what it is square thread

[@AccuComponents]

Hi there 👋 Square threads are a type of thread profile more commonly seen on threaded components used for high load capacity applications, for example jackscrews and leadscrews. As they afford low friction they are ideal where high power transmission is needed. Hope this is helpful, should you need any further information, you can speak to our engineers here: www.accu.co.uk/contact

[@SpottedEagleOwls]

Thank you so if I measure 9.85 it is M10 what will 21.2mm be

[@AccuComponents]

Hi Manie, would this be the thread diameter of a screw or bolt that you're measuring?

[@SpottedEagleOwls]

@@AccuComponents a bolt

[@davidhanes6861]

You are not using a vernier caliper; you are using a digital caliper.

[@AccuComponents]

Hi David, you are quite right! We chose to use a Digital Caliper over a regular Vernier Caliper for the video, mainly for the ease of reading the measurements via the LCD display (much easier to read quickly on video!) However the same measuring principles would apply even for dial or vernier calipers, so hopefully the video is helpful regardless of which type of caliper is chosen! 😊

[@freemanfreed1581]

how do you know whether it is metric or UN standard ?

[@AccuComponents]

Hi Freeman, great question! The short answer is with just a vernier caliper it can be hard/almost impossible to be sure the type of screw with absolute certainty. A leaf gauge or a no go gauge are the precision metrology devices that will do this - but outside the machine shop these devices are not so common. We are working on a new article to help explain the best you can do with a vernier - you can see the process in this spreadsheet: docs.google.com/spreadsheets/d/1P2z88sRuZmTclNa13Vetq1ow3JCRVMA-30dv5dnjL30/

[@richardmiddleton7770]

UN or Unified is American and is imperial (Inches). There is UNF which is fine thread and UNC which is course thread. Diameters will be 3/16", 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 3/4", 7/8", 1"...etc.

[@l.cicero9194]

Useful video, I would turn down the music. It was distracting and repetitive to my ear.

[@AccuComponents]

Thanks for the great feedback, glad you found the info helpful! If you're in the market for components and tools, be sure to check out our online store at accu-components.com/

[@barrysutton5092]

Why do you keep referring to "screw" when everything you talk about is a bolt?

[@AccuComponents]

Great question Barry! It can lead to quite a heated debate which we've seen before on our social channels. We tried to write an authoritative article on this a few years ago: www.accu.co.uk/p/131-difference-between-screws-and-bolts Hopefully that helps you understand why we call them screws!