Metric vs. English Screw sizes...

[fleabag]

The only information that I know about the screws I need is that I believe they're metric and they're very close in size to 2-56 screws. I have 2.5mm written down but I'm starting to wonder if that's just the length of the screw. I've found that while the 2-56 screw fits in the hole, it just isn't thick enough and therefore it doesn't screw in properly because it's an english screw and the hole I'm dealing with is clearly metric. I don't know what 2-56 means and I don't know much about the whole 2M 3M 10M metric system and I'm hoping someone can help me figure this all out.

Oh and btw, the type of screw is a machine screw.

Edit: Ok well I just figured out that a 2-56 screw =.086inches = 2.1844 millimeters by following the formula on this page:http://en.wikipedia.org/wiki/S...nified_Thread_Standard

Ok, so this make sense as to why the 2-56 screw kind of fits but doesn't quite fit..

 

[Newbian]

You kids and your newfangled measurements.

My car gets forty rods to the hogshead and that's the way I likes it and I refuse to change.

 

[FallenHero]

k

 

[zerocool84]

Go to a home depot/lowe's and they have little boards you can put your screws in to make it easy for people like you.

 

[gw186]

2-56 would be a #2 size and 56 threads per inch. A #2 thread is .0860inch or 2.1844mm. Lots more info here - http://en.wikipedia.org/wiki/Unified_Thread_Standard

 

[zinfamous]

Originally posted by: zerocool84
Go to a home depot/lowe's and they have little boards you can put your screws in to make it easy for people like you.

hell, this is what I do.



EDIT: actually, I just go to OSH, where they have no boards, and just hold my screw or nail up to the screws in the individual plastic packages, assuming they're close enough to what I need...


It works 94% of the time

 

[fleabag]

bump for day crew

 

[jlee]

Originally posted by: fleabag
bump for day crew

Uhm, it's nighttime.

Are you from Australia?

 

[xSauronx]

Originally posted by: zinfamous

Originally posted by: zerocool84
Go to a home depot/lowe's and they have little boards you can put your screws in to make it easy for people like you.

hell, this is what I do.



EDIT: actually, I just go to OSH, where they have no boards, and just hold my screw or nail up to the screws in the individual plastic packages, assuming they're close enough to what I need...


It works 94% of the time

bingo

this or a Fastenal should be able to get you sorted out, OP

 

[waffleironhead]

Cliffs for your incoherent babbling?

 

[Triumph]

OP, what exactly do you want to know? Are you looking to replace a missing screw? You need a metric screw, namely a M2.5 x 0.45, it very very rarely works putting a SAE screw into a metric hole. The only time this works is when you have sloppy threads or weak material, such as plastic or nylon. It sounds like you understand this, but you haven't posed an actual question for us to answer.

Just go to mcmaster.com and look around until you find one that looks like what you want.

Originally posted by: zerocool84
Go to a home depot/lowe's and they have little boards you can put your screws in to make it easy for people like you.

Sears or Ace Hardware usually have a much better selection of screws and bolts than Lowes or Home Depot.

 

[Ballatician]

Wow I was going to post almost the same exact thing as Triumph. First, I'm unclear on what you want to know. Second, go to mcmaster.com. I found their 2-56 machine screws in one second but then again I don't think that's what you're looking for.

 

[fleabag]

My question was, is M2.5 the sized screw that I'm looking for or not? I gave an example of a screw that most closely resembled the screw that I needed. I know I need a metric sized screw, but I just wasn't sure what size but did know that the 2-56 screw was a close fit so then I needed a metric screw that was a similar equivalent. I used the 2-56 screw as a guide as to the size in metric that I needed but emphasized that it was too small for the hole in order to make sure that nobody got me a metric sized screw that was exactly the same.

 

[Triumph]

Yes. M2.5 x 0.45

0.45 means there is 0.45mm between each peak of the thread (the thread pitch)

 

[Paperdoc]

By the way, to avoid further confusion, you used the term, "English Screw". There are metric screws, and the common type in the USA and many places is SAE. But there is at least one OTHER system of "standard" screws used - in England! For now I'll assume you meant SAE vs. Metric.

Both systems use two numbers to identify a machine screw. The first is the diameter of the screw, the second is the thread pitch. Metric ones ALWAYS use a whole number or a decimal number for the diameter part, like M8 or M2.5 (sometimes they skip the M). The second number in Metric bolts is thread pitch, expressed as mm spacing between successive thread high spots. So you'll see sizes like 2.5 x 0.45, or 8 x 1.0, or 10 x 1.25.

SAE screws may use an integer number for diameter, especially for smaller ones, but they switch to fractions for larger bolt diameters. For the second number they use thread pitch in threads per inch (opposite from Metric that uses mm per thread). So you'll see numbers like 2 x 36 and 6 x 24 and 6 x 32 (last two same diameter, but different pitch), and 1/4 x 16.

As a general rule you can never make a Metric bolt fit into an SAE nut just right. On rare occasions you can force it in and risk destroying the threads, but you're better finding the right screw. If you can't, one solution is to abandon the "right thread" and use some self-tapping screw that can be forced in. Or, you can drill a new hole there and get out your handy tap set to cut a new set of threads to fit the slightly larger screw you do have.

 

[zerocool84]

Originally posted by: Triumph
OP, what exactly do you want to know? Are you looking to replace a missing screw? You need a metric screw, namely a M2.5 x 0.45, it very very rarely works putting a SAE screw into a metric hole. The only time this works is when you have sloppy threads or weak material, such as plastic or nylon. It sounds like you understand this, but you haven't posed an actual question for us to answer.

Just go to mcmaster.com and look around until you find one that looks like what you want.

Originally posted by: zerocool84
Go to a home depot/lowe's and they have little boards you can put your screws in to make it easy for people like you.

Sears or Ace Hardware usually have a much better selection of screws and bolts than Lowes or Home Depot.

But there's more likely to be a Depot or Lowe's near someone than either of those