Cinelli 1R bar clamp bolt

[Mick F]

M7 14mm fine thread.
That's the issue. Not sure if they are generally available.
If Express Fixings in Plymouth can't help ............ and they are wonderful ........... I doubt anyone has them.
Longer than 14mm is fine, coz I can cut it down of course.


As for the difference between a bolt and a screw (engineering, and not wood etc) .......... bolts on the left, and screws on the right.

[jb]

I was always taught that a screw had threads all the way up, a bolt has an unthreaded shank. This takes the load between two plates with out having the thread as a stress crack starter.
Engineering terms are often corrupted by the 'Jack of all Trades' boys though.

[SimonCelsa]

Are you sure it is M7 fine (does this exist) and not something like 1/4" - 20 UNC ??

I'm no bolt expert but have worked on many old ships with so many different thread standards, and wasted loads of time once looking for an 11mm allen key when it was actually 7/16 or somesuch.......

[jb]

I'm fairly sure my Shimano Mountain Exage brakes from the nineties had M7 threads on the brake blocks.

[SimonCelsa]

But Cinelli is Italian and I can't see them using a simple thread

[Mick F]

6mm Allen key fits, and none of the Imperial ones do.
The thread measures a tiny bit less than 7mm.
Difficult to measure the pitch, but normal metric has a 1mm pitch, and this one is less than that.
I understand that Metric Fine is 0.75mm pitch.

Any road up, tomorrow morning I'm riding up to the station and getting the 09:15 train to Plymouth with Moulton on board, and then after calling in at Express Fixings, riding home.

[philvantwo]

Let us know how you get on please Mick F.
Hope you have time to call in at the Wetherspoons!!

[freiston]

The way I've understood it is that a bolt fastens with a nut - if it fastens into a captive threaded hole or by tapping a thread, then it's a screw. Typically a bolt will go through a non-threaded hole hence it typically only needs a thread at the end - and so is more likely not to be fully threaded.

My screw and bolt provider of choice (Accu) consider a bolt to be driven via the outside of its head and a screw to be driven via the inside of the head (so if it needs a key or a screwdriver, it's a screw and if it needs a spanner, it's a bolt). They also have quite a lot of information on the subject including a legal and taxation differentiation between bolt and screw in the USA (the USA definitions are more or less the same as my understanding of the difference):
https://www.accu.co.uk/en/p/131-differe ... -and-bolts

[Jdsk]

The way I've understood it is that a bolt fastens with a nut - if it fastens into a captive threaded hole or by tapping a thread, then it's a screw.

Yes, there's a range of similar "definitions" along those lines. I think that it's a much more useful approach than "threaded to the head or not". But there are still exceptions,

They also have quite a lot of information on the subject including a legal and taxation differentiation between bolt and screw in the USA (the USA definitions are more or less the same as my understanding of the difference):

The Wikipedia article linked above describes the changes in the SAE "definitions" over time.

Jonathan

[Jdsk]

My screw and bolt provider of choice (Accu) consider a bolt to be driven via the outside of its head and a screw to be driven via the inside of the head (so if it needs a key or a screwdriver, it's a screw and if it needs a spanner, it's a bolt).

interesting, isn't it? And totally different from "threaded to the head or not" or "goes into nut or goes into material".

"There is no universally accepted distinction between a screw and a bolt."

Jonathan

[freiston]

My screw and bolt provider of choice (Accu) consider a bolt to be driven via the outside of its head and a screw to be driven via the inside of the head (so if it needs a key or a screwdriver, it's a screw and if it needs a spanner, it's a bolt).

interesting, isn't it? And totally different from "threaded to the head or not" or "goes into nut or goes into material".

"There is no universally accepted distinction between a screw and a bolt."

Jonathan

Yes, it is interesting. I do like their closing sentence:
"The best way to avoid confusion is to avoid guesswork, and refer to product specifications. Many components are manufactured according to strict manufacturing standards, which clearly define specific component dimensions such as head type, thread type, and thread length"

I couldn't find any M7 socket cap head screws on their pages - they will custom manufacture but I don't think they'd do a one-off

I do hope Mick gets what he needs.

When I had a little project involving camera tripod fittings, to make life easy, I ended up buying a 1/4" x 20 UNC tap. I don't think I would like to tap a new thread into a quill stem clamp though.

[peetee]

My son, who worked in a hardware shop, learned the hard way that when it comes to fixtures and fittings there are as many ways of naming each item as there were items in the shop!
The whole topic is about as standardised as the use of the word ‘engineer’ which once upon a time was a term applied to someone with extensive technical knowledge. These days it seems acceptable to add it to the job title of a toilet cleaner.

[rogerzilla]

Cinelli expander bolts also use a finer 8mm thread than the usual M8 x 1.25 thread on Far Eastern stems.

[rjb]

You can check the thread pitch by holding your bolt/screw against a standard M5 threaded screw. These are usually M5 X 0.75 or 0.8, if the threads align then it confirms the pitch.

[Jdsk]

Yes, it is interesting. I do like their closing sentence:
"The best way to avoid confusion is to avoid guesswork, and refer to product specifications. Many components are manufactured according to strict manufacturing standards, which clearly define specific component dimensions such as head type, thread type, and thread length"

My son, who worked in a hardware shop, learned the hard way that when it comes to fixtures and fittings there are as many ways of naming each item as there were items in the shop!

Yes, definitions can cause problems when the two parties aren't using the same one.

That doesn't happen with "fully threaded" or "hex socket head".

Jonathan