Please look up ISO1173.

https://cdn.standards.iteh.ai/samples/23588/ab32510c11f74bfbb198fcd63d2b9a04/ISO-1173-2001.pdf

I would have thought those were intended for woodworking use in handheld pistol drills, so unlikely to be of the levels of precision we are more used to in precision metalworking kit?

Likely made undersize so they go in and out of the typical carpenter;s quick change 1/4″ hex holder quickly and easily?  A bit of slop never slowed a carpenter down. As long as they don’t fall out, he will be happy.

And if they are cheap ones, quite likely all over the place in line with low cost manufacturing standards.

For more precision suited to use on steel etc in milling machines for model engineering etc, I think I would be looking at the more expensive countersinks with the ground round shanks.

Looks like you picked up a bit of a Lemon, measured an assortment of mine for comparrison. If you are putting them into a cordless with built in hex recess holder then there is more risk of wear to the holder, if you are just using a separate hex recess holder or even a drill chuck not such an issue.

From The Top

Trend 5mm TCT drill/csk

Trend 4mm TCT drill Csk

Kreg Pocket Hole drill

Bosch Lip and spur drill

haffle sprung jig drill

Screwfix drill bit

Toolstation Drill bit

Tec Driver

Wera #2Pz

All except plain shank jig drill quite close to 6.35 and withing the upper and lower limits of DC’s table 5 which is the recessed one

On 8 October 2024 at 16:08 Bill Phinn Said:

[…]  Do either the 1/4” or 3/8” come within a recognised standard?

 

“Easily Detachable” perhaps

MichaelG.

I have been lucky with the 1/4″ hex shank toolbits which are intended to fit in screwdrivers and small impact drivers. I have just bought one of the 12V Lidl drills with the 10mm chuck which comes off to reveal the 1/4″ hex drive. It comes with a good set of drills and screwdriver bits and the drill box for £13.99, they were £ 16.99 before. You have to already have the charger and battery, though.

A loose fitting square or hex connection reduces the effective contact area under load (torque). This increases the stress and thus increased wear and probability of failure.
That’s apart from location issues and perfomance of the tool combination.

Robert.

Is this an expectation management problem?

Bill hasn’t said where his set came from or how much it cost.   The evidence suggests these are low-end countersinks of the type bought by DIY woodworkers.  Cheap, with a high-risk they will too cheap for serious metal-work.  No tears please if a set of 3-bits costing under £4 bought randomly off the internet turns out to be nasty!   The purchaser took a risk, and the product failed to meet his expectations.

The expectation that hex-ended tools must be sized to a standard is also false.   As far as I know, there is no legal requirement for these tools to be made to an ISO, BS, JIS or any other standard.   These standards only apply if the seller claims the product is made to meet them.  Did the supplier claim that: I bet not.

Trading Standards are fairly clear on who is responsible when purchasing goes wrong.    Organisations are expected to have a competent person in charge of purchases:  in a case like this it would be his fault if he bought an item without checking it met the standards required by his firm.   Consumers are better protected by law in that they aren’t expected to be competent.  Refund or replace if the product doesn’t meet their ‘reasonable’ requirements.   If the buyer or seller don’t agree on what’s meant by reasonable, off to arbitration or the courts.   In practice, at least in the UK, most sellers replace or refund without making a fuss.    Though it mostly works reasonably well, the system is imperfect.  Model Engineers are a case in point:  we’re a customer group with some competences who buy as consumers.  Having a few competences is a good start, but there’s more to competent purchasing than knowing a few reliable brand-names and assuming stuff.   For example, a pro-buyer has to know when it’s necessary for him to insist on a specification like ISO1173.   A Model engineer might assume incorrectly that was part of the deal: nope!

I notice Bill has done bought a tool-set with a specification!  His Gühring Set has a DIN number on it, in the blur bottom left:

None of this confusion is new, certainly not a sign of the times. My memory of youthful tool buying is there was a lot of dreadful tat about.  The Romans advised Caveat Emptor, and we Brits know not to buy a pig in a poke, because that might let the cat out of the bag!

Although honest trading is clearly most effective, there’s always a percentage of shady buyers and sellers who fink sharp practice is clever.   One clue we might be dealing with an opportunist is him offering items that are unreasonably cheap or, just as alarming, with a very high asking price.   Plenty of folk are fooled by ‘reassuringly expensive’!  It’s not easy, and we are lucky to have a Nanny State looking after us.

Professional engineers do their best to dodge buying uncertainty by setting standards because specifications can be tested objectively.   Purchases based on cost, brand-name, or previous experience can all be a con!    Unfortunately purchasing to specification isn’t easy, and it tends to be pricey.   I don’t have a big budget, and Model Engineers famously have very deep pockets and extraordinarily short arms.

What do I do myself?   Mostly I buy mid-range tooling from reputable UK hobby suppliers, relying on their expertise to avoid too cheap, and protected financially by UK consumer law.   ArcEuro do particularly well in this space, but I don’t expect top industrial tooling at rock bottom prices from them.   Ditto Tracy Tools, for taps, dies, and drills.  Others too.   They provide good value for money in my lightly loaded workshop, but sometimes a job makes it necessary for me to go upmarket.  I occasionally take a punt on ebay, so far without being sent rubbish.   The worst tools I’ve ever bought all came from street markets and exhibitions.   Consumer protection drops when the buyer actually sees the item:  then we are held much more responsible for our decisions.   If you buy in person, take extra care.   Distance buying is safer.

My buying strategy turns out to have been excellent for bad reasons.   Two years ago my mother’s failing health dropped my time for workshop fun by about 75%.   Over the last 7 months I’ve been too ill myself to use the workshop at all, and the problem is ongoing.   A tiny consolation is that I didn’t spend a fortune on the best tooling.  Even better, I’ve told my children not to worry about the value of the workshop when I die.  If it suits them to dump the whole lot in a skip, they can.  Had I invested in an expensively tooled-up workshop, it suffering that fate would be heartbreaking.

Do loose fitting hex shafts matter?  Not much in a basic DIY toolbox, perhaps only used once in a blue moon by a youngster to put up wooden shelves.   Same tools much less satisfactory when lots of countersinking needs to be done, and especially so in metal.   Robert points out that loose fitting hex shafts tend to chew up the driver, a quick way of wearing a good tool out.   Curiously all of my metal-working countersink cutters have round shafts and I don’t care what diameter their shafts are!

Dave

Just to point out the ARC ones don’t have a Hex shank so as that is the one failing aspect that you mention of your set then ARC customers won’t be complaining about that. Also ARC set almost double the price though still a lot less than a similar Guhring set.