Torx sizes

Can't help with why a T40 is a T40, but the following web page lists all the point to point measurements with their corresponding T number:

I don't know what the numbers mean, but there are some plastic gauges on a key ring, that are available for checking Torx socket sizes.

From my experience, the size of the Torx bit relates to the thread size as follows:-

Thread size (M) = Torx number / 5

Example: T30/5 = M6 T40/5 = M8

HTH

Anthony Remove stars and a sky to reply.

Thanks Graham,

I had a good Google around, but I didn't find that one.

Steve

Thanks,

Not much use when you have to find a tool to remove them, its a bit tricky to measure the thread first !

So is this some new international measure - a fifth of a millimetre ! Another reason to consign every Torx I ever see to the bin. I have now found the blasted things in bolt-head form on my Calibra - they are springing up everywhere. I have BSF, BSW, AF, Metric, BA sockets, spanners, allen keys, 3 different types of cross-head screws and god knows what else - do we really need whole new sets of head types ?

But, ta anyway. Steve

Cheshire Steve wrote: I have BSF, BSW, AF, Metric, BA sockets,

Well, they are less likely to round off than say an Allen key, but point taken!

American invention! They live on an island.

Nick

Yeah - I already read the Wikipedia entry before I posted my question

- it says the size is given by a 'T' followed by the point to point dimension - it doesn't mention the units. I assumed this was either a) wrong, or b) in some units never heard of before (even in America). I am still not sure which one it is.

Anyway I sussed out I need a T45 - so thats on my shopping list.

I think they have been invented as they are good for machine assembly

- but I don't like 'em. I wouldn't like to try and make either the male tool, or the female socket (or in some cases vice versa), plus they are in silly sizes. I saw someone advertising metric Torx (Please don't let there be imperial and metric ones!!!!)

Steve

Read the external link at the bottom of the article...

Heat part up to a good orange heat. Place in bolster. Heave on fly-press handle. Remove part from bolster. Lather, rinse and repeat. Use a cut off Torx bit or male Torx headed screw as the tool.

There are no metric/imperial Torx bits it's a non-dimensional standard.

Mark Rand RTFM

You'll like them when you have to drive hundreds of screw into wood. Good invention.

Nick

I guess. :-) But comparing the contact-area of the bit, the sequence is Robertson, Hex and then Torx. Torx also avoids the non-perpendicular contact by the wings, thus reduces the forces even more.

Clear that I won't try to mill my own Torx-bits.

Nick

Seems to be the same for Canada. You won't get a single Robertson here (Germany), even if you beg. Pozidriv are common for wood screws with the Torx catching up. For obvious reasons.

Nick

Surely that's what Robertson bits were invented for?

Tom

Fortunately wood screws around here have yet to come with torx drive. Robertson have been around 100 years by next year and do the job admirably.

Tom

Not that I am never going to need to screw hundreds into wood, but what was wrong with 'allen' screws for that ? Why invent something more complicated.

So far I have only discovered them on cars, have never seen a wood screw with a Torx.

What worries me is that I might have to unscrew hundreds of rusted, seized, and generally bunged up Torx from under cars. Discovering them on a differential cover and driveshafts was a bit of a surprise. I have now discovered male torx bolts in a few locations too. I can see some tool shopping coming up for new male and female Torx sockets.

Steve

It maybe true for the bits, but I see its not true for the bolts/ screws - looks like they come in metric and unified - I see UNC and UNF at this site

Steve

On or around Tue, 02 Oct 2007 08:34:50 +0200, Nick Mueller enlightened us thusly:

Torx (and the reversed-torx which has a socket in the tool) are pretty good, in fact - the only problems you get are the same as the ones you get with every kind of fastener, viz. crap quality materials in the fastener or the tool. As a design for a tool to transmit torque, it's pretty good.

Wood screws here are nearly all parallel with Phillips heads. It's becoming increasinglt difficult to find proper tapered screws with slotted heads, particularly if you want real brass rather than yellow plated steel, or round head rather than countersunk.

Cliff Coggin Kent UK

I think you mean posidrive heads not Phillips. Screwfix have loads of slotted countersunk, raised and round head brass screws. They call them "traditional solid brass" screws. See