Supplier wanted for M3 x 85mm black hex bolt - Page 1
Forum section: electronics / general

author: Psi
author_rank: Super Contributor
timestamp: February 04, 2018, 05:18:21 am
content: So i'm looking to buy 400 machine screws but my requirements are outside the norm in terms of length.* M3 (M2.5 or M3.5 would probably work too)* 85mm long +/- 2mm* Either hex head or hex cap* Black colorDoes anyone have any recommendations or sellers on aliexpress they have used before to order odd length bolts?I have found one person selling them but they are a custom part for a RC car in a box of 6. They want US 80 cents per bolt for 400 qty, which seems very high to me.I think 10-20cents in 400 qty is more reasonable.Any recommendations?

author: timelessbeing
author_rank: Frequent Contributor
timestamp: February 04, 2018, 05:35:32 am
content: Could you use threaded rod with nuts at both ends?https://www.banggood.com/500mm-M3-to-M12-Stainless-Steel-Threaded-Rod-Screw-Rod-p-1028865.html?cur_warehouse=CN

author: Psi
author_rank: Super Contributor
timestamp: February 04, 2018, 05:37:52 am
content: Sadly a threaded rod is a no.The bolt head is on the front panel of the product, so it need to look clean.

author: rx8pilot
author_rank: Super Contributor
timestamp: February 04, 2018, 07:03:20 am
content: The longest M3 at McMaster Carr seems to be 60mm - which is already crazy lengthy.No chance of using a stand-off as an extension?Short and misplld from my mobile......

author: Psi
author_rank: Super Contributor
timestamp: February 04, 2018, 11:48:30 am
content: Quote from: rx8pilot on February 04, 2018, 07:03:20 amnow that is an interesting question.I don't think it would fit unless it was a super thin extension, but worth looking into.It needs to go through a small gap in an extruded aluminum case to hold on the front and rear panels.The case is not threaded and is supposed to be used with small thread-forming screws. but i really hate this approach. It's time consuming and requires cleaning to remove all the ground metal it creates.Which is why i'm looking into a long bolt that could just go through the entire thing.

author: Brumby
author_rank: Unknown
timestamp: February 04, 2018, 11:58:09 am
content: Quote from: Psi on February 04, 2018, 05:37:52 amDomed nuts?

author: sleemanj
author_rank: Super Contributor
timestamp: February 04, 2018, 01:47:20 pm
content: Here's a taobao vendor with various long sized m3. No reccommendation, have not bought from them, just a quick google from my tablet, looks like they do different styles including black buttonheads in one picture, probably could find other sellers there.https://item.taobao.com/item.htm?id=13385048208You can always cut down longer ones.

author: cleanworkbench
author_rank: Regular Contributor
timestamp: February 06, 2018, 11:30:39 am
content: I know a place in the UK but postage might be prohibitive though , very nice people .When i was visiting there he had a whole stash of blackodized fastners , email and seeHere is a linkhttps://www.barenco.co.uk/Hope this helps out.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 06, 2018, 11:50:12 am
content: I've used M3 tri-lobe screws in the past for ali. extrusions - should be less likely to create swarf.https://uk.rs-online.com/web/p/self-tapping-self-drilling-thread-forming-screws/4831218/

author: Nusa
author_rank: Super Contributor
timestamp: February 06, 2018, 03:29:46 pm
content: If you're willing to enlarge the mounting holes a bit, you could install M3 rivet nuts.

author: Psi
author_rank: Super Contributor
timestamp: February 08, 2018, 06:03:12 am
content: Thanks guys.Threaded rod plus rivit nuts might work.Assuming I can find m3 85mm threaded rod

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 08, 2018, 10:07:50 am
content: Quote from: Psi on February 08, 2018, 06:03:12 amThat's readily available, typically called "studding"e.g.http://uk.farnell.com/duratool/st01030100081fa/studding-zinc-plated-m3x1m/dp/517320?st=m3%20studding

author: Psi
author_rank: Super Contributor
timestamp: February 10, 2018, 07:21:09 am
content: OK, i have this sorted!!3mm plastic tube from aliexpress, It's like $9 for 100x 50cm lengths.This fits snug into the untreaded holes in the aluminum extrusion (its intended for M3.5 thread forming screws)Then self tapper screws ~16mm long (which i can easy get in any color/head type cheap as)They bite into the plastic tube and force it outwards like those concrete plug insert things.Works amazing and very tight.So this issue is now sorted

author: rx8pilot
author_rank: Super Contributor
timestamp: February 10, 2018, 07:27:02 am
content: Excellent solution!No exotic screws, no metal chips falling on your pcb..... nice.Short and misplld from my mobile......

author: woodchips
author_rank: Frequent Contributor
timestamp: February 10, 2018, 10:27:41 am
content: I have often usedhttp://www.gandbprojects.co.uk/product/9/category/9who make just about anything small and threaded.