Oddball SK socket set - Why???

[Davefr]

I picked up this 1/4 drive SK metric socket set at an estate sale. The sizes are in 1mm increments down to 7mm but below that there's a 6.3mm and a 5.5mm socket. My other SK sets don't have these oddball sizes.

Did SK want these sockets to also fit 1/4" and 3/16" SAE?? Seems odd???

 

[lbhsbz]

I have a 5.5mm socket that I bought for something when I was working at either Toyota or GM dealerships...can't remember what. I want to see it was to remove studs with a little hex on top, but not sure.

 

[Jaysreal]

I wanna say 5.5 is pretty common but I'm sure 6.3 directly converts to 1/4" when I was doing research about Urrea tools I discovered that they have both metric and fractional sizes marked on their sae sets. That is because it is law(in Mexico) that all sized tools must feature metric markings. So this is just a shot in the dark, but maybe your set was intended for sale in Mexico?

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[Wamsutta]

5.5 is common for hex head interior screws. I've never heard of 6.3mm.

 

[Rileysan]

I picked up this 1/4 drive SK metric socket set at an estate sale. The sizes are in 1mm increments down to 7mm but below that there's a 6.3mm and a 5.5mm socket. My other SK sets don't have these oddball sizes.

Did SK want these sockets to also fit 1/4" and 3/16" SAE?? Seems odd???

5.5mm is pretty common but I've never seen 6.3mm. I have also seen 4.5mm.

My guess is that S-K made that socket during the rush to convert everything to the metric system back in the 70s. Obviously, it was short-lived. Personally, I would consider that a rare find. Just my opinion ...

Brian

Edit: Dave, where in Oregon are you?

 

[Stevenn1]

5.5mm is for Ford ignition modules that were located on the side of distributors back in the 1980s.

 

[T45]

Agree with the above 5.5 is standard DIN size, and the 6,3 is metric equivalent for 1/4 inch. I'd say its only oddball sizing if the socket set is 3/8 drive.

For 1/4 drive, today....i'd say its common for all sets to have 5.5mm and many also have either standard or as optiona...a 1/4 (6.3xmm) as a hex bit holder.

 

[ocloc24]

The weirdest one I've seen is a 6.5mm that comes in hf sets..

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[bimmer630]

I have that same 6.3 sk socket. My theory is they included them in metric sets to deal with the generic hose clamps that would show up on cars that are mostly metric but the crappy hose clamps have a 1/4" hex on them. Also in a pinch you can use them to drive 1/4" bits

 

[dwasifar]

It's a little outside the normal topics of discussion here, but it's common for keyboard enthusiasts in Europe to buy 5.5mm thinwall drivers to disassemble old-school IBM Model M keyboards for restoration. (Yes, I am one of those weirdos who uses a 25-year-old keyboard with modern computers.) The M is held together with deeply recessed 7/32" hex head screws, and 7/32" drivers are hard to come by outside the USA.

 

[JohnDeere1]

I have an so 5.5 and 4.5 and my focus uses 4.5mm under the hood.

 

[Fedwrench]

The 5.5 mm is pretty common on Ford & GM vehicles. As others have mentioned trim components, AC Actuators, etc. I would not want to be without 5.5mm.on the other hand I've never used 4.5 or 6.3mm

That looks like a pretty old set given the green/white spinner handle, no knurling on the extension, and the classic hammertone green metal storage box. I surprised it has the odd metric sizes. Hey, are there cut outs on the square drive ends of the sockets for the retention ball on the drive tools?

 

[californiaHank]

A 5.5 mm socket fits both M3 hex head bolts and hex nuts.
I've never understood why some small sets include a 5 mm but no 5.5 mm
(A 5mm socket fits M2.5 nuts, which aren't as common.)

6.5 is the closest metric equivalent to 1/4".
It fits #6 and #8 American machine screws. The weird thing is that I don't think it fits any metric standard hardware. (At least it doesn't fit hardware made to modern metric standards.)

 

[kb1982]

I used a 7mm for the first time not to long ago. Of course, it was the last one I picked up through the 4.5 - 8 mm shuffle

 

[StillTooManyHobbies]

As to the original question, I am guessing that they might not have been original to the set, but perhaps added to the box later. The box looks crowded. Anybody know?

 

[monkeyspanners]

5.5mm is quite a common nut size used to hold circuit boards in enclosures here.

 

[Stevenn1]

Interesting that out of the 4.5/5.5/6.3mm that only the 5.5 is now showing up in their new catalog. I do have all 3 but only in deep, i personally only used the 5.5mm tho. Specialty Ignition mini-wrench sets come with 4.5 & 5.5mm. Technically 1/4" is 6.35mm, but maybe they rounded it down.

 

[desertdog256]

The 6.3 is definitely a Mexican thing. I have a Urrea combination wrench that says 5/16 on the front and 7.9mm on the back.

View media item 71803

 

[drtyler]

Does the 91860 1/4" drive set still show up in the catalog?

It is their most complete 1/4 set, and 4.5mm standard and deep sockets are included.

Interesting that out of the 4.5/5.5/6.3mm that only the 5.5 is now showing up in their new catalog. I do have all 3 but only in deep, i personally only used the 5.5mm tho. Specialty Ignition mini-wrench sets come with 4.5 & 5.5mm. Technically 1/4" is 6.35mm, but maybe they rounded it down.

 

[disston]

First time I saw 5.5 was about 1972. I was told it was something on a Porsche. I didn't own a Porsche but that was what I was told it was for. Since those days it has turned up a few times. Used in many places of my 2009 Ford.

 

[Biomed]

Here is a link to an old Garage Journal thread about 5.5mm sockets: http://www.garagejournal.com/forum/archive/index.php/t-91741.html

Please understand that there are many applications for sockets outside the automotive world including electronics, medical and industrial applications.