Allen bolt sizes? - SV650.org

sniff · 30-06-13, 02:24 PM

Can someone tell me how I get the size of a bolt? I know its 3.5cm long and I think it 6mm wide. So I need to get two of these and a few others and want to make sure I get these right.

30-06-13, 03:27 PM

Im not sure on what bolts are called, i have seen m5 and m6 before, perhaps a m6 is 6mm? But regardless, you can take existing bolts to an ironmongers to compare up and buy them there

30-06-13, 04:30 PM

Then it would be M6 x 35, what's the top look like, is it a bolt or an Allen cap head or dome cap?

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rictus01 · 30-06-13, 04:38 PM

Bolts for Jap bike (and many others) are generally discribed as M (for metric) and a number corresponding to the mm size in diameter of the threaded shaft, so an M4 would be 4mm, then you have the type, for allen bolts it's normally cap or button (square type or domed), the other dimension you'll need is length, for example you'd order am M4 x 50 (the 50 would be 50mm length).

beyond this and normally on bigger bolts; they have different thread pitches (smaller than M8 are standardized), for this you'll need a thread gauge to measure it, but an example would be M10 x 50/1.25; the 1.25 being the thread pitch.

HTH

Cheers Mark.

sniff · 30-06-13, 04:55 PM

Thanks Rictus. Think mine are M6 350 and they are countersunk Allen head.

sniff · 30-06-13, 05:08 PM

ipad 022.jpg

timwilky · 01-07-13, 06:50 AM

Technically those are not bolts. They are machine screws.

Difference? Well google says my understanding was wrong. I had thought the real difference between a screw and and a bolt was that a screw has threads the length of the shaft. But apparently is is simply down to use. A screw fixes into an internal thread whereas a bolt requires an external thread such as a nut into which to fasten.

yorkie_chris · 01-07-13, 11:51 AM

If you ask for allen head you'll probably end up with SHCS

That one you put pic of is socket countersunk head cap screw

30-06-13, 02:24 PM	#1
sniff Member Join Date: Feb 2010 Location: Dagenham Posts: 724	Allen bolt sizes? Can someone tell me how I get the size of a bolt? I know its 3.5cm long and I think it 6mm wide. So I need to get two of these and a few others and want to make sure I get these right.

30-06-13, 03:27 PM	#2
stuR Guest Posts: n/a	Re: Allen bolt sizes Im not sure on what bolts are called, i have seen m5 and m6 before, perhaps a m6 is 6mm? But regardless, you can take existing bolts to an ironmongers to compare up and buy them there

30-06-13, 04:30 PM	#3
Galviniser Guest Posts: n/a	Allen bolt sizes Then it would be M6 x 35, what's the top look like, is it a bolt or an Allen cap head or dome cap? Sent from my iPad using Tapatalk

30-06-13, 04:38 PM	#4
rictus01 Member Mega Poster Join Date: Jul 2003 Location: South London Posts: 9,799	Re: Allen bolt sizes Bolts for Jap bike (and many others) are generally discribed as M (for metric) and a number corresponding to the mm size in diameter of the threaded shaft, so an M4 would be 4mm, then you have the type, for allen bolts it's normally cap or button (square type or domed), the other dimension you'll need is length, for example you'd order am M4 x 50 (the 50 would be 50mm length). beyond this and normally on bigger bolts; they have different thread pitches (smaller than M8 are standardized), for this you'll need a thread gauge to measure it, but an example would be M10 x 50/1.25; the 1.25 being the thread pitch. HTH Cheers Mark. __________________ Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming, 'Wow! What a Ride!

30-06-13, 04:55 PM	#5
sniff Member Join Date: Feb 2010 Location: Dagenham Posts: 724	Re: Allen bolt sizes Thanks Rictus. Think mine are M6 350 and they are countersunk Allen head.

30-06-13, 05:08 PM	#6
sniff Member Join Date: Feb 2010 Location: Dagenham Posts: 724	Re: Allen bolt sizes ipad 022.jpg

01-07-13, 06:50 AM	#7
timwilky Member Mega Poster Join Date: Mar 2004 Location: Not in Yorkshire. (Thank God) Posts: 4,116	Re: Allen bolt sizes? Technically those are not bolts. They are machine screws. Difference? Well google says my understanding was wrong. I had thought the real difference between a screw and and a bolt was that a screw has threads the length of the shaft. But apparently is is simply down to use. A screw fixes into an internal thread whereas a bolt requires an external thread such as a nut into which to fasten. __________________ Not Grumpy, opinionated. Last edited by timwilky; 01-07-13 at 01:12 PM.

01-07-13, 11:51 AM	#8
yorkie_chris Noisy Git Mega Poster Join Date: Apr 2007 Location: Halifax/Leeds Posts: 26,645	Re: Allen bolt sizes? If you ask for allen head you'll probably end up with SHCS That one you put pic of is socket countersunk head cap screw __________________ Currently Ex Biker Now rebuilding a 63' fishing trawler as a dive boat

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