Please Explain Screwdriver Bit Standards

[Joe Piro]

I hate that you have to read all this to help me. I'm just trying to buy screwdriver bits and bit holders that work properly together and also work with my American power tools. Also I'm detail oriented and I want to understand this. All I have to do is figure it out once, then we're good for life.
I remember reading in a GJ post a while back that Japanese (and other Asian) screwdriver bits don't fit American bit holders. I've been trying to figure it out. Are all the short "Insert Bits" with the little notches for detent... are they the same in Asia and the US? For example are all the 1" long (or 25mm long), 1/4" hex bits the same, and measure 8.2mm from the end of the bit to the center of the notches?
(see photo)
And are all the 1" (or 25mm) 5/16" hex bits the same all over the world??? (and measure 10.2mm)(see photo)
If the short "Insert Bits" are the same internationally, then that fixes half my problem.
This is where it gets strange, right? In the Vessel Catalog, the "Power Bits" that have circumferential grooves for ball detents, are in two big sections:
Type A Bits and Type B Bits. I couldn't make sense of it because there were too many exceptions so I called JDV which is an American vendor for Vessel products; and I should add that Larry K. worked really hard to find an answer to my question, providing great customer service, and he emailed me as follows:
"A type bits have a 14mm ball detent, commonly used in Asian markets and on most electric drivers." (He wrote 14, but in the catalog most are actually 13, and some 14's are actually Type B which confused me more!
And he added "B type bits have a 9.5mm ball detent typically found in the US market."
But in the Ko-ken catalog (Japanese for sure) all the 1/4 inch hex "power bits" have the 9.5mm detent (yup... heres a photo).
Did JDV reverse the numbers? or does Ko-ken manufacture for the American market (which I doubt)? ( Also BTW the 9mm and 14mm ball detents vary with different diameter bits. )
Also what is the standard in Europe if I buy Stahlwille or Gedore bits and bit holders? Do they use the 13mm or the 9.5mm standard? I looked in both German catalogs and although they refer to the same DIN 3126 and ISO 1173 specifications are they the same or different than the Japanese bits? (C6 for 1/4" hex), C8 (for 5/16" hex), and E6.3 (for the "power bits" with the grooves for ball detents).
When you buy a bit holder or a ball detent chuck, how do you know which power bits fit ? It may be moot with the magnetic ones but they are less secure.
Mostly this came up because I was about to pull the trigger to buy a Ko-ken Attack Driver. I couldn't decide whether to buy the 3/8" drive or the 1/2" drive. Then I started looking for replacement impact rated bits and here we are !
Thanks for your help.

 

[Tools4Me]

In regards to 1/4" hex and 5/16" hex insert bits, all my insert bits have the same 8.2mm (1/4" hex) and 10.2mm (5/16" hex) from the bottom notches. As far as I know that is a worldwide standard that almost all companies follow. I use mainly Wiha, Wera, Apex, Bosch, and Vessel insert bits and they all have the notches in the same spots. The notches are there solely to help hold the bit in place more firmly for bit holders that use a c-ring as the bit retention mechanism.

9.5mm to the center of the detent (type B) is the style used in the US for 1/4" hex power bits. Try to also skip buying any 1/4" (type B) power bits that have screwdriver tips at both ends of the bit, because they won't fit some US style power bit holders. They will sometimes bottom out in the holder before the ball bearing lock engages. Make sure you have a 9.5mm to the center of the detent power bit, and make sure the end of the bit that fits down into the power bit holder has a flat shaped bottom and you will be fine.

A Japanese style (type A) power bit has a noticeably longer 13mm distance from the end of the bit to the center of the detent, so you can easily tell visually which is which when looking at online listings for bits. Type A bits are also very hard to find anywhere in the US. The Koken catalog I have downloaded is an english catalog made for the US market, so all the listings for bits that I see in that catalog show only the 9.5mm style power bits. I would imagine the Koken tool catalog written in Japanese for the Japan market is full of all the same bits, except they will also have the 13mm Japanese style (type A) detent retention distance bit options. My Vessel english tool catalog shows both types.

I think most people would be better off with the 3/8" drive Koken Attack driver over their 1/2" drive model, but make your decision based on what your own needs are. I for instance, use my impact drivers with bits most of the time, and I attach sockets to them occasionally in order to help break small to medium sized frozen bolts free. 3/8" drive bit holder sockets and 3/8" drive impact sockets are noticeably smaller in size than their 1/2" drive equivalents, so a 3/8" driver can reach into tight areas more easily. It's also much easier to find a 3/8 drive 1/4" hex bit holder socket than it is to find a 1/2" drive 1/4" hex bit holder socket if you ever want to use your manual impact driver with 1/4" hex insert bits in the future. I personally use my 3/8 drive manual impact driver with quality 1/4" hex insert bits most of the time, because they are noticeably cheaper to replace and easier to source.

 

[dnschmidt]

Japanese power bits are longer between the end of the back of the bit and the ball retainer. You can make them fit American tools by using a cut off wheel in a grinder and removing about 1/4" from the rear of the bit. 1" bits are all the same.

 

[lardy1]

More confusing to me are the different grades and associated tags given that grade by various manufacturers. I wish they would explain those better. I've bought Wiha bits that were kick *** and others that seemed much softer and shorter lifespan. I see a need to simplify all this for the ******* consumers like myself.

 

[Jeff]

Me thinks you're over-thinking this. I had a similar dilemma when looking for a one-size fits all bit set.

I use this Vessel set and it fits all my needs. I do have a longer bit holder if needed for longer reach.