Machine screw M6 length Q.

[Sea Chief]

Hi if I want an M6 machine screw does the length its sold as (IE 25mm) -include- the countersunk head (or whatever type of head it has), or is the lenght relevant solely to the thread part?

thx

SC

[pdf64]

I think that countersunk types tend to include the head in the length; other types don't.
The only way to be sure is to ask the vendor.

[Sea Chief]

Are you kidding me.. thing is Ive ordered some c'sunk 30mm M5, asked for a rtn as I actually needed M6 and 25mm ("fine/ keep those theyre worth p's only" so I leave huage A++ etc). These were 35mm long total.. & what i expected

Then I rcv my M6 25mm, but the total is 25/ the thread 20mm.. not what I expected. So I say "sorry you made mistake, these are 20mm" but they again send 25mm total/ thread 20mm. Im hopping mad now: demand again > rcv same again.

I still cant get any certain answer on this Q. Ive scoured the www, asked a buddy who think prob thread should denote the overall mm rating.. but you dont agree.. there's no info on any ebay items simply with a visual measurement of the item specs.

Flamin eck Im going mad with this. Anyone know for sure? Im almosty certain Ive always gone with the thread length denoting the mm rating. I know I have Ive bought dozens of machine screws. Im 100% certain I have.

Strewth.

[J M Fahey]

From: https://www.boltdepot.com/fastener-i...re-length.aspx








EDIT: same thing in better detail, including Allen head bolts, sheet metal screws, carriage bolts, L and ring fasteners, the works:
http://www.hintsandthings.co.uk/work...ers_screws.htm

and it's an UK site, so it applies to you

[Sea Chief]

Well thats absurd- why the feck c'sunk should be different. youve no idea how much hassle this has caused! So 1st lot of c'sunk seller sent was wrong, as like the middle eg, but all replacements were correct.. but I assumed mistakes so slung em back!

blimey o reilly.

Terrific post/ help. Thanks JMF.

[Tom Phillips]

Well thats absurd- why the feck c'sunk should be different...

They are not different once you realize that the length is always measured from the equivalent top surface of the plate in which the screw is mounted. You are going to drive yourself nuts ranting about common established principles.

[Sea Chief]

No I'll only rant at folks who sell me them who don't know these basics Tom.

It has driven me nuts but now I know its a bit absurd-but-logic to it, I have no reason to rant at all.

[Enzo]

When dimensions are important, always check the data sheet, yes, even for screws.

[Sea Chief]

Indeed- but no data sheet available or id have been just fine from the off. Generally no spec/ data on any ebay M6 pozi machine screws fwiw.