Torx®, Hexalobe, Star Drive System

A Most Confusing And Irrational Drive System

or; One Man’s Descent Into Absolute Hysteria

The events in this blog are true. Only some of the language has been changed to protect the innocent (but, only a little). What follows is my fall in to the madness that is; the Torx®, Hexalobe, Star Drive System.

Fair Warning: The content of this blog post may trigger some who have OCD and/or Autistic tendencies (as do I), or those that have a high intolerance to the chaos that is the stupidity of others (as also do I). The reading of which may cause outbursts of incredulity, anger, and the utterance of foul language (as is plainly illustrated in the following text). For those who wish to avoid such behaviour (or, indeed, read about it), then please feel free to click to any of my other blog posts, which are far more logical, intuitive and pleasing to read.

 

Ramblings

As an upcycler/recycler of old wooden furniture (not to mention I completely renovated a late 1940s house from scratch, almost single-handedly, back in 2005), I have encountered more than my fair share of slot-head screws. Most of which were covered in layer upon layer of paint and/or varnish. This then involved having to scratch out the slots to have any chance of getting a screwdriver in there to remove the screws. Having to remove slot-head screws is an entirely different issue. Slot-heads have a tendency to cam out if the screwdriver blade isn’t exactly centred, and/or if the blade is half a second of a degree out of being perpendicular (in any direction) to the screw head..!

In short; I hate slot-head screws, with a passion.

 

What’s In A Name..?

There are numerous head types for screws, machine screws and bolts, out there today. Each with their own quirks, idiosyncrasies and/or specialised uses. But, the one that currently inflames my ire (over and above all of the others), is Torx®. Or should I say; the hexalobular drive system. As Torx® is a brand name and registered trademark of Textron Inc. (formerly, Camcar Textron). The Torx® name is so synonymous with this drive system, that it’s fallen in to common usage to describe the system itself (like when people say; Allen® keys for the hex head wrenches, Hoover® instead of vacuum, Tannoy® instead of public address [P.A.] system, or Velcro® instead of hook and loop fastener).

But, why does the Torx®, Hexalobe, Star Drive system irk me so..? Well, it all started when (out of pure curiosity) I decided to look into, and try to understand, how this system’s alpha-numeric drive head designation related to the size of the drive heads.

Here’s what I found.

 

Designations

Hexalobe drivers go from T1 to T100. No problem with that (I naively thought). Should be simple enough, but I did notice that there didn’t appear to be one hundred different sized drivers. There are individual drivers for T1 through to T10, which is fair enough. Then, it jumps to T15, and T20, followed by T25. Ah (I thought to myself), I see where they’re going with this. So, the next one in sequence is… T27!

I’m sorry, what.!? T27..? But why..? What’s so critically important that there needs to be a T27, thrown in there, completely buggering up the nice, clean “multiple of five” sequence..?

Next in sequence is T30 (Phew..! Back to some logic), then T40. *Vinyl record scratch sound* Woah, woah, woah..! (sweet child o’ mine) Back it up there, cowboy..! Where’s the T35 driver, please..? (At which point, my logical inner voice chimed in to say; “Chill, dude. This is just the point where the system jumps into multiple of tens. Now, go make yourself a huge mug of Earl Grey and everything will be alright”). Which, is exactly what I did. I then came back to my laptop to continue my research.

We have a T40 (but, no T35), which means next up is T50, right..? Wrong! Next in sequence is T45. I spat a mouthful of Earl Grey clear across the room, then carefully placed the mug down on a coaster and wiped my chin. Surely, this can’t be correct (unfortunately, it IS correct, and don’t call my Shirley). *Mild confusion and annoyance set in* (Coincidentally, the exact moment my left, upper eyelid started to twitch).

So, let me get this straight. It appears that it’s imperative to the survival of Homo Sapiens Sapiens (as a species) for there to be a T27 driver in existence, yet no-one will ever need a T35, so it can just piss right off.!? Seriously..?

The sequence continues to proceed in multiples of five, until it reaches T60. Then the last four drivers are T70, T80, T90 and finally T100.

 

Size Isn’t Everything (Apparently)

Okay. *Calming breaths* This was all well and good, but I still couldn’t find out how the actual T-numbers actually relate to the actual size of the actual drive head..? After reading a couple of blog posts on other sites about the Torx®, Hexalobe, Star Drive System, they mentioned that it’s the “point-to-point” dimension that’s of relevance, here. But, these sites’ pages neglected to state this dimensional relationship to the T-number designation.

A bit more searching and it turned out that there’s an International Standard (ISO 10664:2014) for the hexalobular drive system. Maybe I could find what I needed there. Nope. Well, not without forking out ₣61.00 CHF (Swiss Francs. Approximately £56 GBP or $71 USD, as of writing this blog) to get my mitts on it, anyway. And no amount of Googling turned up an *cough* ‘unofficial’ version, just so that I could have a quick peek. Which meant I, ultimately, landed on the “ever-so-reliable, bastion of all knowledge” site (sarcasm, by the way) that is; Wikipedia.

On the Wikipedia page for Torx®, there’s a table that lists the point-to-point dimension for each of the T-number designations, in both the metric and imperial measurement systems, which I have lovingly and fastidiously recreated for you, below.

Looking at the measurements, both the metric and the imperial, it was evidently clear to me, that there was absolutely no discernable logic or correlation between the T-number designation and its associated point-to-point size. Or, for that matter, in the difference in size with the next T-number up..! *vein on left temple started to throb* (which was also the exact moment my now fragile psyche showed the first signs of a new hairline crack).

As I worked my way down the table, was when I noticed the glaring inclusion that surprised, saddened, pained me and brought tears to my eyes (more than a swift kick in the nadges from behind, in a darkened alley). And to this date, no three characters have grated the most against my OCD and Autistic tendencies more than; T47!

T47.!? GM®-style..? *sight blurred into tunnel vision* (additionally, the exact point that I couldn’t contain my anger and keep it together enough to restrain from articulating verbally). In my rage-borne delirium, the words from the recording Capstick Comes Home – Dingle’s Records (1981), performed by the late, great Tony Capstick, sprung to mind (if you’re too young to remember Tony Capstick, or indeed, have never even heard of him, just imagine Sean Bean in a rage, saying it); “…yer gret, useless, spawny-eyed, parrot-faced wazzock..!”

If I could’ve “…reached out and gently pulled…” the individual at General Motors, who thought it’d be a great idea to make a T47 hexalobular drive bit (and thus f*ck with the heads of all sane, rational individuals everywhere), towards me “…by t’throat…”, then threw them “…on t’fire…”, I would have. Gladly..!

 

In Conclusion

Even though I’ve calmed down a bit (on the advisement of both my doctor and therapist), I still can’t bring myself to delve any further and find out exactly what the originators of the Torx®, Hexalobe, Star Drive system based their T-number designation on. Nor can I (to this day) force myself to investigate the external (inverted) version of this drive system, with their E-number designations. As I fear it would be more than detrimental to the state of my mental wellbeing.

If anyone out there does know the reasoning behind it all, then please, please do let me know.

Cheers,

C…