Question Hex Nut Size

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Lifer
Nov 11, 2004
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There seem to be three common hex screw heads used in PC cases, one of which is 1/4 inch (largest), a smaller hex head for drive screws (what head size), and what hex head size are the brass standoffs?

The 1/4 inch, i have a few nut drivers for. The others I am looking to purchase.
 
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ch33zw1z

Lifer
Nov 4, 2004
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You should probably just buy a small kit. The hard drive are probably torx, like T8 or something, I think the standoffs are 5mm

maybe this is more your speed


note: the torx bits in that kit are NOT security bits, so while they may fit the hard drive screws, the bit may not nest into the screw snugly. This one below has security torx bits.


Either way, you're better off just buying a kit, you'll spend just as much on individual drivers and only have those drivers later, whereas a kit is more robust
 
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Googer

Lifer
Nov 11, 2004
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You should probably just buy a small kit. The hard drive are probably torx, like T8 or something, I think the standoffs are 5mm

maybe this is more your speed


note: the torx bits in that kit are NOT security bits, so while they may fit the hard drive screws, the bit may not nest into the screw snugly. This one below has security torx bits.


Either way, you're better off just buying a kit, you'll spend just as much on individual drivers and only have those drivers later, whereas a kit is more robust
I have a 5mm Nut driver, but it was a bit loose when placed over a brass stand off. I suspect the head is of an Imperial Measurement (aka fractions of an inch). My guess is 3/16?
I already have plenty of tools in my house and just want to either minimize my purchase, tool count, or find something I already own; in the end I am looking to purchase (or find in my garage mess) just two dedicated nut drivers and not a set that has 100 loose parts.
And the hard drive MOUNTING screws are slightly smaller than 1/4" with their own thread patter that is different than the ones used in the stand off holes. Torx are for if you want to open the drives cover (i dont need to do that).
Thanks.
 

Googer

Lifer
Nov 11, 2004
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They are two different styles of screw with two different thread pitches, thread types, hex head sizes, and locking interfaces. One fits the quarter inch driver, the other screw (i see them often, does not).

(Edit: 1/4 and 5mm are the smallest I own)
 

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Muadib

Lifer
May 30, 2000
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That's more than I need and more than I need to spend. All I am looking for are 3 nut drivers. It also does not answer the original question. What are the nut hex sizes?
They make smaller sets. Sadly my bits are loose in the bottom of a toolbox. It sounds like yours are too, or you could have answered your own question.
 
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ch33zw1z

Lifer
Nov 4, 2004
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Ok, if your hell bent on getting the exact right size without buying a PC kit, then you bring the screws or standoffs to the hardware store and find the right one!

I don't spend tons of time figuring out or remembering these things, I have tools, I get it done, I almost always have the right size but I carry around a tool bag 😉

One of my colleagues got a kit and fixes all sorts of stuff with it, PC's, laptops, printers, servers, some of them are pretty nice, all inclusive, and you are hard pressed to not have the right one when needed
 

mindless1

Diamond Member
Aug 11, 2001
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I've never found a PC screw or standoff that was too tight to just use a Phillips screwdriver on, or pliers for initial loosening/final-tightening of the standoffs.

I grab a #1 or #2 phillips screwdriver anyway because some don't have hex heads, nor do most fan screws. #000 and #00 high quality phillips are also very handy, for getting off some tiny heatsink screws self-tapped into aluminum heatsink, or laptops/etc where they are threadlocked in. Really, just high quality for every size phillips so they aren't camming out of the screws as easily.

A set of SAE or metric nutdrivers is about $8 ea. on Harbor Freight, but it looks like their smallest metric is 5mm. A couple of their SAE do have a 3/16". IMO you need a caliper to measure things in general, more than nutdrivers for PC work. Some digital calipers even convert into inch fractions,. making them very handy for determining fastener sizes.

Anyway the left screw looks like an M3 with 5mm head, but PC screws tend to be low quality and tolerances are often off a bit. Standoffs, if 4-40, probably 3/16". If M3, probably 4.5mm. Here's an inexpensive set with a 4.5mm, though I'm sure there are others.

 
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Muadib

Lifer
May 30, 2000
17,340
600
126
Ok, if your hell bent on getting the exact right size without buying a PC kit, then you bring the screws or standoffs to the hardware store and find the right one!

I don't spend tons of time figuring out or remembering these things, I have tools, I get it done, I almost always have the right size but I carry around a tool bag 😉

One of my colleagues got a kit and fixes all sorts of stuff with it, PC's, laptops, printers, servers, some of them are pretty nice, all inclusive, and you are hard pressed to not have the right one when needed
That's why I posted the kit he said no to. It just works!!!
 
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Googer

Lifer
Nov 11, 2004
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Phillips screwdriver is what I use on those.
Sometimes I do too. But a magnetic nut driver keeps me from dropping loose screws inside my chassis and hex heads wont slip like a phillips will.. The hex head is also better for removing stubborn screws or screws that have a stripped out head.
 

mindless1

Diamond Member
Aug 11, 2001
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^ You forgot to mention the magnetic, requirement. It's your tools and your call but in most of my toolboxes, I have some rare earth magnets that I can put on any tool to magnetize it as needed... got a 10 pack of the magnets on ebay for about $2, or maybe it was Fasttech.com.

I also have a Magnet-On-A-Stick™ to fish metallic objects out of tight spaces.

Stripped out heads... I just don't see that very often with computer screws because they aren't very high torque, and as mentioned previously, I use high quality screwdrivers. Before I got high quality screwdrivers, I would touch up worn screwdrivers with a file to ensure that the tip had maximum purchase on the screw heads, though eventually that results in them being the next larger, phillips size.

I do have magnetic nut driver bits, acquired 30 years ago when I did HVAC work, but I never use them for computer work, just not worth the bother to get up and walk to the tool box they're in. I can literally do the most common build/upgrade/repair tasks, with just needle nose pliers and a #1 pilliips, or forcepts in a really cramped case, for something like swapping a battery or moving a jumper... which is seldom these days besides the clear CMOS jumper.
 

OlyAR15

Senior member
Oct 23, 2014
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I can literally do the most common build/upgrade/repair tasks, with just needle nose pliers and a #1 pilliips,
Same here. A phillips screwdriver is basically the only tool I use to build computers. The only time I needed a hex nut driver was to loosen/tighten mb standoffs. And even then, a set of needlenose pliers can work on those.
 

Googer

Lifer
Nov 11, 2004
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Pliers can round off a stuck or corroded stand off. What size nut driver do you use for stand offs?
 

OlyAR15

Senior member
Oct 23, 2014
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Pliers can round off a stuck or corroded stand off. What size nut driver do you use for stand offs?
Can't remember. I just grab a bunch of my small ones and find out what fits.

You are doing something seriously wrong if you have stuck or corroded standoffs, though. There is no need for them to be so tight.
 

mindless1

Diamond Member
Aug 11, 2001
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Pliers can round off a stuck or corroded stand off. What size nut driver do you use for stand offs?
I tend to disagree. If the stand off is that corroded, the system had to be sitting in salt water and is a complete loss.

I have never in my life, used a nut driver for standoffs. I have built many systems, once upon a time ago, for profit.

This whole topic makes no sense, as if you are trying to pretend attributes/difficulties of other, larger fasteners used for other things, are somehow also applicable to computer work.

It just doesn't make sense. I have an extensive amount of experience working with older hardware, where the issues would be most prevalent, and it just isn't a problem to use a mere screwdriver and pliers. Not at all.

On the other hand I understand disabilities, if you are extremely frail and/or severe arthritis, okay then, as already suggested, a caliper to measure things is a good tool to have, then buy appropriate to your needs.
 

Googer

Lifer
Nov 11, 2004
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Can't remember. I just grab a bunch of my small ones and find out what fits.

You are doing something seriously wrong if you have stuck or corroded standoffs, though. There is no need for them to be so tight.
Thats the problem I dont have anything small enough, smaller than 1/4
 

Googer

Lifer
Nov 11, 2004
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I tend to disagree. If the stand off is that corroded, the system had to be sitting in salt water and is a complete loss.
I live near salt water, the air is enough to make anything rust. I have encountered a few in the past that would not bust loose. It's just my personal preference to use a Nut Driver when I can, no need to get fussy about it. My nearest hardware store is about an hours drive, their inventory stinks, so ordering this online is going to be the best option. Ordered one already, got the wrong size. Hence this thread.
 
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Googer

Lifer
Nov 11, 2004
12,569
4
81
I tend to disagree. If the stand off is that corroded, the system had to be sitting in salt water and is a complete loss.
I live near salt water, the air is enough to make anything rust. I have encountered a few in the past that would not bust loose. It's just my personal preference to use a Nut Driver when I can, no need to get fussy about it. My nearest hardware store is about an hours drive, their inventory stinks, so ordering this online is going to be the best option. Ordered one already, got the wrong size. Ordering a set would solve the problem but at an unnecessary expense. Hence this thread.
 

Googer

Lifer
Nov 11, 2004
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Found out the stand off is the same thread as the 1/4 screw but uses a 3/8" nut driver or socket. 2 Down, 1 to go.
 

Sick Willie

Senior member
Apr 8, 2010
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Found out the stand off is the same thread as the 1/4 screw but uses a 3/8" nut driver or socket. 2 Down, 1 to go.
Although I have never seen a removable motherboard standoff that was 3/8" nut size, I won't say they don't exist. But certainly aren't common. I just did a random sample on six standoffs and they were all 5 mm. Don't know what the approximate SAE size would be but it would it would be a little larger than 3/16"

The inside thread can either be coarse or fine, depending upon the manufacturer. It's little things like this that tend to irritate me. :) Just like the fact that there are coarse threaded and fine threaded screws, and standoffs of varying height.
 

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