Am I just being stupid? (Nut/Bolt Sizes)

[HD]

Basically I have bought a set of nuts for the bike. I ordered m12 nuts and they arrived. I tried to fit them and wondered why they didn't fit. Measured the inside and they are 10mm.

Now I'm not 100% and the seller is a business seller so surely they know their stuff but they said that I need nuts the size of the bolt. So I measured it and sure as shit the bolt was 12mm. Now they are saying that I need a nut that is 10mm smaller to fit.

Now I know that it needs to be a bit smaller otherwise it will slide over but I am talking a fraction of a millimetre, not two full mil?

Can someone confirm this before I do return then buy some more nuts please.

Just to clear up, the nut I had measured 12mm internally, the bolt measures 12mm externally. I ordered m12 nuts and they are 10mm internally.

Cheers
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Rusty '02 Vito Camper + CBR600F3

[WannaBeDude]

M 12 bolts need ..........................................................................................................................








M 12 Nuts.
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Jogging on, destination living.

[HD]

My bolts are 12mm so surely they need 12mm nuts? Isn't M12 the same as 12mm? I thought it was metric classification?
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Rusty '02 Vito Camper + CBR600F3

[Nexus Icon]

12mm could mean 12mm AF, which would mean that a 12mm spanner would fit. I think that'd make it a 5mm thread though. M12 is the correct nomenclature for a bolt with a nominal thread diameter of 12mm.
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Greetings from Shitsville!

[DrDonnyBrago]

The M12 bolt is almost 12mm wide at the tips of the thread (see pic below, major diameter) , the hole in the M12 nut will be smaller because some of it will sit inside the thread of the bolt (if that makes sense, i.e. the minor diameter of the bolt). If the hole was also 12mm the bolt would just slide in and out without screwing in.

If they don't fit, you are sure the bolts are M12 and sure the nuts are M12 then i would suspect that it is the thread pitch that isn't right.

If the pitch is out then you might get it to thread on a tiny amount then get stuck.

Thread pitch is the distance between the threads:

https://www.jjjtrain.com/vms/Media/glossary_m/minor_diameter.gif

To measure the bolt pitch, measure the distance across 10 threads with a ruler, divide by 10 and that will be your pitch ( I say 10 because measuring one is tricky without a vernier caliper).

Then you would get nuts in M12 x pitch in mm - i.e. M12 x 1.5, M12 x 1.75 etc.

If it is rear sprocket bolts you are after then IME they tend to be M12 fine (M12 x 1.25).

[HD]

No, its a nut to go on the back of my peg hanger.

If anything, it measures slightly under 12mm with my verniers. They were only cheap though so not sure of the accuracy. The old nut has stripped threads inside thats why I need a new one.

What shall I do?
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Rusty '02 Vito Camper + CBR600F3

[DrDonnyBrago]

[HD]

Think I may just do that then as I only need one and atm I am getting 5

I have to get lifts everywhere atm though :/

Verniers and the peg hanger are both down the garage so I'll have a look tomorrow.

Cheers
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Rusty '02 Vito Camper + CBR600F3

[Raffles]

[HD]

On a side note, will these be okay for my sprocket? https://www.ebay.co.uk/itm/10mm-Flange-Track-Nuts-/270795082587?pt=LH_DefaultDomain_3&var=&hash=item84b843593a#ht_500wt_969
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Rusty '02 Vito Camper + CBR600F3

[Rob W]

[DrDonnyBrago]

[Polarbear]

Remember that there are up to 3 different pitches for each size metric bolt. There is the standard, then the fine and in some cases ultra fine. Quite a lot of bike stuff is fine pitch, off the top of my head sprocket nuts and caliper bolts are usually fine pitch.

As DonnyBrago says, if you are going to order on line a pitch gauge and vernier/mic is essential, but to be honest, if you have a decent hardware store that sells individual bolts, you are better off going there. My local one is superb, they can sort you out anything. If they sell them pre packed, forget it, you will get a spotty yoof who's only idea of screw is what hes read in Mayfair.
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Triumph Trophy Launch Edition

[Rob W]

[HD]

Well I know where I'm going one day this week then!
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Rusty '02 Vito Camper + CBR600F3

[wilz1234]

Bear in mind that a 12mm bolt is 12mm wide but a 12mm nut will only be about 10mm wide (inside) because of the nut thread sticks into the shaft of the 12mm bolt

[wilz1234]

Just realised thats what donny brago meant