PCBs and the chassis

progress0r

Member
2010-12-10 7:14 am
Hi all,

I am handy, but new to the world of DIY audio. I'm trying to figure out how to properly mount PCBs in an aluminum chassis. I hope you can help me learn the ropes and the terminology.

How do I raise the PCB to the exact height I need? What are these posts called, properly?

Also, can anyone tell me how to correctly make the right screw holes for these PCB riser posts?

Thank you for any tips you can share.
 

progress0r

Member
2010-12-10 7:14 am
Ok, after some searching I figured out that these mounting posts are called "PCB standoffs."
I also figured out that they use M3 screws, familiar from computer chassis.

The question that remains, however, is how to make threaded holes in the chassis that would allow secure attachment of the the PCB standoffs.
 

progress0r

Member
2010-12-10 7:14 am
Okay, I've learned something here and maybe this thread can help other newbies like me.

The tool that makes holes threaded is called a "tap," and it is usually propelled by a "tap driver." There are variations of such tools that make it easier to start a hole, deepen it, or terminate it properly if it does not go all the way through the chassis.

For the regular M3 size hole, common for PCB standoffs, one needs to make an "under hole" 2.5mms in size, and then create the thread with a tap.
 
The simplest way is using standoffs which are threaded, say 10mm tall. A simple clearance hole in the chassis and a 3mm screw holding it in place from underneath. Do up very tight. There are nylon standoffs available which remove all risk of shorts.

Then a 3mm screw holding the PCB from above. Simple!

In non-mm land I'm sure you can get "funny(!)" sizes locally. In fact I'm sure most PC chassis use them.
 
Hey does anybody know how to secure the potentiometer against the case?

First of all, the shaft is too damn long (almost 2in). I guess I can saw some of it off. Second, the potentiometer is soldered to the PCB, so I wonder if it can really support the huge, heavy aluminum knob I've got for it.