dsbrantjr

Those square drive fasteners are called Robertson or Scrulox: https://en.wikipedia.org/wiki/List_o...ives#Robertson

Clyde1820

On a bike's brake rotor? Wouldn't surprise me those screws were grossly undersized given the torque they were to require. (Which wouldn't be a leap, on an application where weight means everything.) I'd bet that if those screws had been specified 50% larger than they were, there never would have been a problem. I've had the same issue with screw head types of all sorts, over the years ... mostly on lighter-weight type applications (ie, bicycles, electronics devices, etc). Invariably, on screws clearly "big" for handling the torque loads, there's not an issue.

I'm all for weight savings, generally speaking. But not at the expense of appropriateness to the application. Not when serviceability is part of the utility.

JMO

TGT1

Don't know about the modern ones since my time working on them was in the 70's but the R-50 to R69S series required a torch and temperature crayons to get the shrink fit case parts apart and back together.

But then, they never leaked oil either.

fietsbob

Yea but Roberson screw head type never went anywhere as far as common use, outside of Canada..

T25 Torx head 5x0.8 mm machine screws are what the bike industry has chosen to affix brake discs.
Options Shimano Centerloc hubs & discs ... Rohloff uses 4 chainring bolts to fit discs on those hubs on the rear..
Or, buy hex head bolts for your bike , if that pleases you... 8mm wrench used on heads of 5mm bolts..





...

fietsbob

So it's actually a case of a mechanic making mistakes , then blaming his tools , Classic

woodcraft

Oh yeah, there's also a ******g T27.

Darth Lefty 

maybe so, but I only ever get one of those when I buy a set, whereas I have at least half a dozen T25 Bits because that’s what comes in a box of screws

Amt0571

It surely would be better if everything was Torx. Specially on the smaller bolts. Not sure why allen enjoyed more popularity, but it's not surprising considering Phillips screws are so popular and are a piece of crap.

RGMN

Allen, or internal hex head fasteners, simply has had more time on the market. It has been in use since the early 1900. Torx wasn't invented until the late 1960s

I've quit buying kits and now buy the individual bits that I need. It may cost a little more this way but it makes it much easier to get the right sizes and lengths for different applications (a 3 1/2" T25 is perfect for Campagnolo Ergopower levers.) Plus you can get some oddball bits, like Torx ball ends, which are great for loosening disc rotor bolts.

Iride01 

I've had allen set screws and counter sunk allen socket head cap screws crack in the corner of the socket. Makes them pretty near impossible to remove without a lot of cussing. Any torque applied with the allen wrench to remove them will spread the crack open and the sharp edge is amazingly effective at biting into the steel or aluminum hole it's in and preventing it from turning.

Never had it happen with a torx, but certainly we didn't have a lot of torx set screws used in the same application. Torx at the time was and probably still is rare for a headless set screw.

robertorolfo

Not sure if I can agree that the result is better, but that's down to personal taste. On the other end of the spectrum, I loved that, until recently, Ducati took the exact opposite approach (despite being viewed by many as an "exotic" brand). I remember reading about all the effort they put into their 999 and 1098 series designs to make them easier to service, and really appreciating it. Indeed, my 749 was an absolute joy to work on (aside from looking amazing and riding beautifully). But hey, those boxers (eye roll)...

Correct me if I'm wrong, but aren't those lever band bolts notorious for stripping easily? And yes, I know they are hard to get to from the proper angle, but don't many people prefer the earlier ones that are allen/hex?

fietsbob

Eklind tool company makes folding tools... I have 2 for allen* & 2 for Torx..

*1 fractional ,1 metric set.

https://www.eklindtool.com/

Dan Burkhart 

Only because Peter Robertson refused to give Henry Ford exclusive rights to the design.

WizardOfBoz

Try working in a shop assembling Schwinn (SAE/UNC imperial whaterver) and Raleigh (Whitworth) bolts. The Whitworth heads, for the same nominal thread major diameter, were larger. End up reaching for the wrong wrench 40 times a day. Grrrrrr.

fietsbob

Capitalist expropriation really prefers a monopoly as the final goal..

RGMN

I don't know if they are easy to strip but with a conventional "L" wrench tightening them is at a slight angle, making it more likely they can cam out and damage the head. Having the longer Torx bit allows a straight in access to the bolt. I'm sure a piece of long hex stock would do the same on the allen.

woodcraft

My worst is servicing plumbing trim with set screws of unknown size that are facing down and cannot be seen, recessed up to an inch, and 1/4" from the wall. Even after finding the correct size from among 6 or more SAE, metric, (or even slotted) by feel, the key has to be refitted for every 1/8 turn of the screw.

Camilo

It's a little aggravating when a bike is mostly hex, but has some torx (aka star) because you might need more tools and your multitool might not have the right fittine. But if I could snap my fingers, I'd have everything be Torx rather than hex. They can be smaller without stripping - imho.

TiHabanero

Not sure of the mistake the mechanic made, so help me and others understand and explain the mistake. Thanks.

Trevtassie

Then just to confuse the issue are JIS screws, which look just like philips (but are hopefully marked with a punch mark near the cross) but are mauled by a philips screwdriver. A JIS screwdriver in a JIS screw is firm as you can turn by hand. I use all Vessel brand JIS screwdrivers now. They work better than a philips driver in philips anyway!

RGMN

Chapman Mfg:

Much more convenient than standard "L" wrenches.

HeHateMe2976

Torx is fine, but when you encounter a "security torx" and realize your torx bit isn't the security type, then you've been screwed. (pun intended / Dad joke).

TGT1

Had a Mazda truck in the 70's with a Perkins (licensed built in Japan) diesel engine. Whitworth bolts with metric heads.

Glad I never misplaced a bolt!

WizardOfBoz

Morris and MG engines from the middle 50 years of the 20th century were the reverse: Metric pitch (but Whitworth thread form) and British Standard Whitworth heads!

From a strength and fatigue standpoint, Whitworth was a superior thread - much superior to the National Standard thread from (NS had sharp thread roots, Whitworth is rounded).