Screw Specification

[gmartinez]

hello everyone

i just have a simple question regarding the callout of a screw.

can someone explain what the 't' in a T3.0x10 screw means? is this torx, tapping or something else?

this is going to kill me if i dont find out!

thanks
gm

 

[KENAT]

I was thinking trapezoid if memory serves - kind of like Acme thread form however wikipedia disagrees since that should be Tr.

http://en.wikipedia.org/wiki/Trapezoidal_thread_forms

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[MintJulep]

Well, there is such a thing as a "Type T" thread cutting screw. But your designation doesn't follow the nomenclature defined by the standard {ASME B18.6.5M).

http://www.eaglefastener.net/technical/screw-point-styles.html

Also, in your designation the 10 is where the thread pitch should be, but the value of 10 seems unlikely assuming that 3.0 is mm. All of course assuming that this is metric.

 

[gmartinez]

gentlemem, thank you for your replies.

 

[europipe]

Mint,
I think the 10 is the lenght of the thread, just as M3x10 in metric thread

 

[Jboggs]

Since that callout does not appear to be in some standard form recognized by a lot of people, then the only one that can tell you for sure what it means is the one who wrote it. Go back to the source of the drawing and ask them. That is the only way you will know for sure what they meant.

 

[Screwman1]

Boogs is right; all of us are just guessing at the right answer. Whoever wrote it had something in mind, only they can tell you exactly what it was. If I had a dime for every messed up fastener description I have seen.......

 

[europipe]

Look at Mints link and take the screw noted T,
the dia is 3mm and the lenght of the thread is 10mm;
Is that so difficult?
Greetings

 

[KENAT]

Well, the trouble is europipe that in some parts of the world - at least officially - you're meant to always state the pitch even for metric threads.

So without reference to a relevant thread standard the situation is ambiguous and so yes, if this is a real life question from the OP rather than 'I saw this in an article and didn't understand it' then Jboggs is correct and the OP needs to ask whoever gave him the spec.

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[europipe]

I'm sorry I have offended somebody,
Thought standard pitch was outside Europe also never mentioned.

 

[KENAT]

No problem europipe, US folk often get accused of being too insular in their answers - now we get to use you as an example of the opposite.;-)

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[europipe]

Is there some kind of reward for that?

 

[gmartinez]

thanks to everyone, your replies are really appreciated.

 

[juergenwt]

Europipe - let me tell you that in the US (and may be Burma and Liberia) they will always look for the pitch. So if they see M3 x 25 they have a hard time - NO PITCH. ANSI screwed up by allowing the pitch to be part of a coarse thread call out. Now every time you see a thread listed as M6 x 1 you have to wonder if there is not a coarser thread available. Would it not be easier if for standard threads (coarsest available) you could just say M6 as done in the rest of the world? If you saw M6 x 0.75 you would instantly know you are dealing with a "Fine Thread". By the way - metric coarse is used 95% of the time and most shops do not even have taps and dies for fine thread in stock.