Screw sizes

[paolo.bertolo]

Hi All,

Didn't want to open yet another thread, but I couldn't find any proper place.

I would like to source some compatible yet high quality screws of the same kind and (of course) size that are originally used for fastening MO drives to the internal chassis.

I'm not used to work with US standards, but according to my measurements it should be something like:

Low Head Socket Cap Screw, Hex Socket Drive, 8-32 Thread Size, 3/8" Length, Fully Threaded, Nickel.

Any correction / additional information / source will be highly appreciated.

Thanks

[Nitro]

The NeXT OD mounting screws are metric. They are strongly magnetic so I suspect that the material is nickle plated steel. I threaded an 8mm long (8.5mm measured) M4 x 0.70mm screw into a NeXT OD and it bottomed out early, so 7.75mm long threads seem to be a good length that will work. The dimensions that I measured are shown in the drawing below, and should suffice for a concours level restoration of a NeXTcube. Unfortunately I don't have a source for this specific screw. It should be noted that some replacement screws utilize a 2.5mm hex opening and therefore won't work with Steve Jobs' coveted 3mm NeXTcube tool.





   

[Rob Blessin Black Hole]

Hello Nitro and Paolo: Interestingly the Screws are actually made of Magnesium I was told by a NeXT Engineer Steve Jobs want as few screws as possible in the NeXT hardware and no more than 1 1/2 Turns which I think was later negotiated. Examples are the hinged Floppy and hard drive mounting brackets in NeXT Stations. The Single Center screw in the back of NeXT Station, then case cover hinges forward was brilliant in its design . This single Case screw initially fooled many including the owners , me lol and was a pretty good theft deterrent but caused more than a few cases to be pryed open in haste to upgrade ram.  I found the easiest way to find matching screws was taking them to my local Ace Hardware store ,they have an incredible selection of 1000's of screws and a few templates platter board with nuts on one and screws on the other of differing diameters and threads , length with matching drawer number and part number and composite makes it kind of fun in a geeky way.  You can make the purchase by the screw or box of screws and has made life easier . I have a box with 24 compartments and in a perfect word matching screws and nuts are sorted for me lol I have a catch all compartment and fish through hundreds of them to find the right ones. I can do it by eye most of the time .    I my have a few loose screws at times but my heart is in the right place.

[Nitro]

Hello Nitro and Paolo: Interestingly the Screws are actually made of Magnesium

That's cool; I'd like to learn more about that. It must be an alloy as magnesium isn't considered magnetic.

[Rob Blessin Black Hole]

Hello Nitro: I recall reading about it in one of the NeXT books maybe a someone has a metal composite tester to verify it Best regards Rob Blessin

[paolo.bertolo]

Hello,
apparently, I totally missed your feedback, which I much appreciate, thanks.
Anyhow, I would also say the MO drive ones are steel nickel plated, whereas the captive ones in the back panel are most likely magnesium.
I also think the MO ones were some special run, as the low head is quite large.
Anyhow, considering they are M4, I guess chances may be higher to source a reasonable, functional match.