Screw Sizes - Page 1
Forum section: electronics / general

author: Sparky49
author_rank: Regular Contributor
timestamp: November 28, 2018, 12:36:13 pm
content: I've recently bought a heatsink for an LED project, listed here:http://store3.sure-electronics.com/dc-hs11138And noticed that it described the project as having 10xM2 screws. I misread this as saying it would have ten M2 screws. However, when I received the heatsink the screws were obviously not M2. I emailed the manufacturer and they simply said"The Screw size:10xM2 mounting holesM2 is Screw type"Googling 10xM2 doesn't return anything.Has the company made a mistake in their spec, or am I (likely) missing something?Thanks in advance.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: November 28, 2018, 01:02:21 pm
content: Probably a typo. Obviously ten screws - maybe M2.5 or M3?

author: SMTech
author_rank: Frequent Contributor
timestamp: November 28, 2018, 01:14:26 pm
content: I would have expected 10 to refer to the length in mm, but there we go. Std pitches for M2 are 0.25 and 0.4 so presumably not that either...

author: Berni
author_rank: Super Contributor
timestamp: November 28, 2018, 01:14:38 pm
content: Yeah typical chinese specs.M2 just means the screw is 2mm in diameter. The smaller sizes tend to be pretty standard on thread pitch so its unlikely you have a M2 with the wrong pitch. Its the large screws like M5 and up that are found in course and fine thread versions.M2x10 is often used to tell you its a M2 screw that is 10mm long. So if you just measure the screw in the fat flat part of your calipers it should be somewhere close to 2mm.Worst case if you only need to put one of these together and you can find similar diameter screws of the wrong thread you can simply force them in using a bit of lubrication. Aluminum is softer than steel so the screw will make its thread. Don't tighten them too much since these threads may be weak but they will hold a LED. Its a bit of a cringe solution but it works in a pinch.

author: SMTech
author_rank: Frequent Contributor
timestamp: November 28, 2018, 01:18:22 pm
content: And if you're anything like me and have a collection of small screws from hard drives, motherboards, laptops etc, they are typically right in this ballpark.

author: Sparky49
author_rank: Regular Contributor
timestamp: November 28, 2018, 11:32:39 pm
content: Thanks all, as I suspected. It's just strange they would email back to confirm the size is 10xM2. I suppose this might be just a case of copying from an incorrect document. Unfortunately I don't have many spare screws, and none which fit, but I'll sending another email asking for them to properly clarify.Cheers again.

author: thm_w
author_rank: Super Contributor
timestamp: November 29, 2018, 12:51:10 am
content: So you received screws which fit or not? The page says you should receive 4 screws with the heatsink. If you have some calipers you can try measuring them.Quote

author: Andy Watson
author_rank: Super Contributor
timestamp: November 29, 2018, 01:30:06 am
content: Looking at the picture of the heatsink I think what they are saying is there are ten holes threaded M2. Further down the page it says that you should receive four M2 screws.

author: Sparky49
author_rank: Regular Contributor
timestamp: November 29, 2018, 08:53:58 pm
content: I did receive screws which fit. Measuring the major diameter gave a result of 2.8mm. Is this close enough to M3? I'm afraid I have no idea around the tolerances for these parts.I can't use the screws which came with it as I need longer screws as part of a mounting mechanism.

author: sokoloff
author_rank: Super Contributor
timestamp: November 29, 2018, 09:07:28 pm
content: Most likely M3.http://almetal.nl/techinfo/gti/scthmc.htm

author: TassiloH
author_rank: Regular Contributor
timestamp: November 30, 2018, 11:20:32 am
content: 2.8mm would be quite spot on for ANSI #4 screws. This could be tested with a locking screw from a D-Sub computer cable...

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 30, 2018, 12:48:05 pm
content: Repeatedly asking them about the hardware is likely to get you nowhere except frustrated. IME, it is unrealistic to actually find someone who knows what they are talking about AND speaks English, AND is willing to communicate with you. Part of the experience of buying dirt-cheap parts from Asia is that you are essentially on your own with zero (or perhaps NEGATIVE) help or customer-service.Spend a couple of $ and buy a metric screw kit. Then you will have a variety of diameters and lengths for this and future projects. Or go down to the hardware store (if available to you?) and try the different diameters and threads to identify what your heat sink has, and then just buy some longer screws. The cost of a few screws is pennies and not worth the frustration of trying to find someone on the other side of the planet with the proper information.Since you have concealed your location, we don't know where you are? If you were in the USA, you could go to an Ace hardware store or even Home Depot big box store and find metric hardware.

author: 1276-2449-1-ND
author_rank: Regular Contributor
timestamp: November 30, 2018, 02:14:52 pm
content: Heatsinks normally use M3 screws. M2 isn't used very often, but M2.5 is very common.

author: fsr
author_rank: Regular Contributor
timestamp: December 01, 2018, 04:08:06 pm
content: Why not go to a store that sells screws with the heatsink + screws and ask them for the same size, in the length you need?