What is the typical screw size for most pre threaded rails to mount the equipment?

Not talking about the rails with the "cage" nuts.

I prefer the truss head screws that have the tips unthreaded and slightly tapered, which makes it easier to get started without cross threading (beneficial when you're trying to install a heavy amp by yourself)

Are most threaded rail holes 10/32? 12/24? or metric (M6?)

I'm in office this morning and all my rack screws are on a job site, so I can't measure them. Need to order more and didn't realize there were so many choices. Pretty sure I need 10/32.... but maybe 12/24???

[Link: middleatlantic.com]

All the ones I use..FWIW

If you install a rack shelf upside-down in the space under the amp, you don't need to hold it up to put the screws in.

I thought they were 12-32, but I'll have to go to my drill set to be sure- I keep a tap for rack screw holes in the case.

10/32 is most common

If you do a lot of racks, this is a fine accessory.

[Link: atlasied.com]

Middle Atlantic is always 10-32 (I think). Server racks are usually 12-24 but it depends on the vendor. Ortronics can be ordered with either threaded 12-24 or cage nuts. APC cage nut racks come with a bag of 10-32, 12-24, M5 and M6 and you can use any or all of them. So the answer is, it depends.

pretty sure the one's I'm looking for are 10/32

Fred, I like that rack tool from Atlas.

Steel racks are usually 10-32 and aluminum racks are usually 12-24.

these!!!!

all i use

[Link: middleatlantic.com]

only 3/8" long?

I recently searched for this and the partly helpful answer to your multiple choice question with a "yes.":

Threaded rail holes are 10/32, 12/24 or metric (M6x1)
One manufacturer says metric 6mmx0.1, meaning one thread per centimeter. It's 6mmx1.

The comments made by others here should help you decide. In my experience, equipment derived from 19 inch rack cabinets uses 10-32, equipment derived from telephone or data equipment use 12-24, and metric is rarely found in the US.

Buy a hundred each of 10-32 and 12-24 screws. Then you'll be ready, no matter which thread you run into in the US.

Everyone probably should carry some rack nuts, too. "Custom" should mean "we can do whatever" and not "we'll go to the store whenever we run across something new."

By the way, a 10-32 screw will appear to hold in a 12-24 hole until you put too much weight on it. At that point the screws will pop out and the shelf will fall.

yes they are absolutely perfect for all but the thickest faceplates.

+1

Thanks all. As John suggested, the normal size are 10/32. Cage nuts (Which I hate) appear to be 12/24.

Occasionally....one runs into M6.

I was looking for the normal size which is 10/32.

What he said.

Fred, that thing looks cool.