ALTEC - Screw size ?

[thomasdf]

Hello

I am using a salvaged Altec 1606 rack enclosure to build a hinged front panel varimu compressor. The problem is I am located in Europe (France) and I cannot figure out what are the four locking screws dimensions. Easier to figure out a male screw than a female tap ...
Looks like it's around 3.9mm but that doesn't match with either a no6 or no8 screw...

Can anybody help me with this ?

I would love to find some thumbscrew for these.

Thanks a lot in advance

Thomas

edit : chatgpt tells me it may be a #7-32 UNC ?

 

[emrr]

It's rare to fined odd numbered imperial screws in the US. I've come across some #5, which is also what's specified by Switchcraft for XLR panels. They are special order pretty much everywhere.

Offhand I think those are #6 or #8, same screw on many other Altec pieces, and I've replaced them with other even numbered imperials....whichever they are!

 

[thomasdf]

Thanks Doug ! #8 seems to be 4.17mm, which def seems too big, as I can manage to screw in a M4 (4mm) a certain amount of turns only.
#6 seems to little (3.51mm) but I should def give it a try !

Another solution might be drilling & tapping for european screw ... but if I screw up (hmm..) the enclosure is shot

 

[OneRoomStudio]

You probably already know this, but just in case - Imperial screws come in different pitches too. #6 comes in “fine,” (6-40, or 40 threads-per-inch), and “course,” (6-32, or 32 threads-per-inch).

Those look like they could be 6-32 screws to me.,

 

[emrr]

You probably already know this, but just in case - Imperial screws come in different pitches too. #6 comes in “fine,” (6-40, or 40 threads-per-inch), and “course,” (6-32, or 32 threads-per-inch).

Yep, though rarer to see the fine pitch versions. Usually!

 

[zzzzz]

Presumably 6-32, only saying that because I just replaced some stripped screws in a 1567a last week

 

[heatwalk]

oh dear. I misplaced those screws on a 1592 and remember thinking it was hard finding the correct match which makes me think a if they are a weird in between 7-32 might make sense? I think 6 felt like there was wiggle room

 

[thomasdf]

Interesting, thanks all ! I am scared because if you had trouble finding the correct screw in the US, it may be next to mission impossible here in France !

I think I'll buy a bunch of diff sizes cheap screws and see which one fits the best, then looks for higher quality thumb screw when I've settled on the best fit.

Could it be that Altec used a custom in between size ? What would be the point ? diameter wise a M4 screws seems almost perfect, but the thread doesn't match as it gets blocked some turns later