Mega STE case screws

[Jens]

Hi,

I have gotten my old Mega STE out of storage and noticed that I had not properly assembled it the last time I did touch it (some 20-30 odd years ago). Given the amount passed I did of course every single last case screw (except for the bdd cover one which by coincidence seems to be the only one that isn’t just screwed into plastic stands).
I searched around and there are suggestions that M30 20mm self tapping screws are the right size. I could not find any official documentation regarding the size (I went through the service manual but the 91 version I found is lacking some diagrams which I think cover the case).
So my question would be is M30 20mm the right size, is there some official documentation?

Thank you
Jens

[darkxavier]

They are M3x10mm self tapping screws

[frank.lukas]

The original Atari case screws have a special thread pitch for the plastic bolts. I bought regular 3x10 wood/plastic screws, and while they work, they are difficult to screw in.

[Jens]

I found the answer in the Atari tt service manual. There is a drawing in there detailing all the parts. Assuming that the tt and ste case are identical the screws are M3-12. It does make a lot of sense to me though that a variant that is meant to be used in plastic was actually used.

[frank.lukas]

1 - Atari original screw
2 - sheet metal screw
3 - sheet metal screw

gehaeuseschrauben.jpg (202.76 KiB) Viewed 1083 times

[Jens]

I will order some Würth screws. I will post details one I receive them. If I get adventurous I might try torx screws too.

[aadhoc38802]

I'm looking for Mega STE case screws too.

The M3x10mm is SIMILAR and NOT compatible.
The STE screws are same width (3mm) as the M3 screws.
The Mega STE screws have steeper threads, because there are two thread spirals (twin-lead / double-start).
So they sink farther with each screw turn.

Putting an M3 screw into a Mega STE will definitely cross-thread the existing hole.
That will weaken the grip and may eventually strip the hole completely.

I don't yet have a source for the Mega STE screws.
Hopefully someone can find a source.

NOTE: These findings are based on my US Atari MSTE. I don't know if they are all the same. I used a motherboard anchor screw to verify the specs for the case screws. That screw fit perfectly (tho short), and the M3 screws didn't. I examined them both under magnification.