Google tells me a bit but not a lot, for example that T4 is 0.050inch and T15 is 0.128inch but not why it’s called T4 or T15 or whatever. 15 isn’t just over 2 1/2 times 4 either.

Where does this Tn come from? Allen/hex sizes and spanner sizes make sense but what’s going on here?

cheers

T for torx and the number is just a number corresponding to the size not any kind of measurement as far as I know.

It’s just a reference number. Nothing more.

IN which case it isn’t even logical as there is a T27 while every other one is a 5 or zero

They’re just nominal numbers, mostly in steps of 5 in case anyone wants to be awkward and needs an in between size. T47 I think only appears on American V8’s as an example.

They were developed for robotic production lines, so I presume the wrong (too large) bit is probably sized to be ‘only just’ too big that it won’t even sit on the bit even at an angle, which would mean trigonometry is involved so would explain the randomness.

T27 while every other one is a 5 or zero

Well there’s 1-9…

I’d hazard it’s to do with the area of the key face in some way, the numbers look progressive but i cba to do the maths and [try to] find the pattern, not least as i doubt i have the data to do it [if it exists]

<p>Point-to-point dimension of the screw head (diameter of circle circumscribed on the cross-section of the tip of the screw driver)</p><p>https://www.iso.org/standard/63207.html</p><p>If I could be arsed I would go thorugh OU and see the standard.</p><p>https://patents.google.com/patent/US3584667</p><p>Here’s the patent, go nuts.</p>

You can still probably get the X-34 although they just aren’t in demand since the XP-38 came out

go nuts

well, bolts

<p>Mostly screws tbh, you don’t tend to see torx head bolts.</p>

@wombat

That raised a wry smile.

I thought the number pertains to the number of times you have to whack it with a hammer into a rounded out allen head screw. 🙂

How many times you will swear when it rounds off

Not just me then Epicyclo, they are ideal for that!

Failing to get quirrels links working though and my own searching clearly isn’t as good as his.

No idea what Wombat is on about, obviously a joke I don’t get. Does raise another question though, is there just one type, or are there metric/imperial ones like there are with hex keys and spanners?

Doing my own thinking, if it’s an arbitary number have they left gaps (T25 and T27 exist but can’t find a T26) in case they ever need to make an inbetween size for something?

Just one size, although some have a ‘pin’ in the middle requiring a hollowed out head on the bit.

No idea what Wombat is on about, obviously a joke I don’t get.

I used to bullseye wombats in my T16 back home……

You use the same size torx tools for SAE, Metric bolts threads etc.

You also get torx plus, torx security.

Plus people sometimes try torx bits in pentalobe, polydrive, spline, double square, various fluted bits etc.

You get e torx as well (use a torx socket).

Womprats, not wombats

You use the same size torx tools for SAE, Metric bolts threads etc.

A blessing and a curse, at least when you find a 3/8th hex key doesn’t fit you know the thread is probably 6mm not 1/4″, meanwhile with Torx you’re merrily destroying the thread with an apparently similar new bolt.

And not really a blessing, it;s not one fewer tools in your toolbox, it’s yet another set of keys and sockets alongside the metric and imperial ones!

And despite the name it’s pretty shit at transmitting torque as the points shear off long before a normal hex key/spanner rounds off.

[/rant]

A random factoid, we started shipping microwave radios into China in 2003, which were held together with Torx screws. Only problem was even though most Torx tool sets are made in China, you couldn’t actually buy any in the the country, so none of our customers / support engineers could find any tools to use on them. So we ended up buying Torx sets in the UK, all made in china, and shipping them back to China so they could use them…..

The numbers are because they’re from the future.

They were designed to take apart Terminators that had come back, and so were named after the Terminator model they fitted.

Womprats, not wombats

you missed the joke within a joke 🙂

you missed the joke within a joke

Glad someone spotted it.

Like an onion, I am 😉