Bolt heads sticking out of the chassis, metalwork tips

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Smoke

Well-known member
Joined
Nov 16, 2004
Messages
63
Location
Melbourne
I'm just about to start drilling my rack chassis to mount the PCB, the toroids and the mains caps...

the heads of all the screws and bolts (if thats what they are called) would generally stick out, wont that go in the way when placing the unit into a rack case?

what is the best way to mount a pcb to the chassis?
 
PEM nuts are a nice way

http://www.pennfast.com/fastening_products/prod_desc.php3?cat=Fasteners+for+PC+Boards
 
how thick is the material, you could countersink either by a countersink end mill (expensive), or by just using a larger drill and beveling in the hole, then using a machine screw like this:

http://ACE.imageg.net/graphics/product_images/pACEBW-993223reg.jpg
 
[quote author="cjenrick"]...Use a rubber mallet to pound the finished product into the rack...[/quote]ROTFL! :green:
 
[quote author="asm"]by just using a larger drill and beveling in the hole, then using a machine screw[/quote]

thats what I do and it works well for me with par metal chasis. the real trick is making the original hole large enough, much larger than the shaft of the screw, so the countersink will allow the screw to sit flush.

dave
 
[quote author="soundguy"][quote author="asm"]by just using a larger drill and beveling in the hole, then using a machine screw[/quote]

thats what I do and it works well for me with par metal chasis. the real trick is making the original hole large enough, much larger than the shaft of the screw, so the countersink will allow the screw to sit flush.
[/quote]

A proper countersink bit is handy - just a wide, angled tip at the right angle for countersunk heads. I do it a lot, and while I don't have any problems with the hole being big enough, I have to be careful to go slowly and check periodically. Otherwise you get a bit too much countersink.
 
sounds all simple, but the rack chassis is pretty thin...
what about the toroid bolt head thats pretty big, how do you mount those toroids
 
[quote author="soundguy"]thats what I do and it works well for me with par metal chasis.

dave[/quote]

Which Par-Metal series are you using, Dave? The 12 and 14 series are designed to allow the additional height of a screw head on the top and bottom, thus eliminating the need to countersink.
 
Ive used both the 12 and 14. You dont *need* to countersink to fit it in the rack, but it looks neater if you do and if you dont, you are gonna scratch up the top and bottom panels of whatever its racked between if you ever remove it from the rack. Another valuable lesson learned the hard way...

dave
 
[quote author="soundguy"]Ive used both the 12 and 14. You dont *need* to countersink to fit it in the rack, but it looks neater if you do and if you dont, you are gonna scratch up the top and bottom panels of whatever its racked between if you ever remove it from the rack. Another valuable lesson learned the hard way...

dave[/quote]

So does that mean you also drill out the standard holes in the top & bottom covers and replace the screws with countersinkable ones?
 
no, I leave those. with screw heads sticking out you can scratch the front lip of the piece above or below what you are removing if you arent careful, or if you dont even know in the first place that there are screw heads sticking out (like if you have an assistant or someone pull the unit).

dave
 
thats exactly what i thought would happen and im trying to avoid it. its fairly straight forward with the screws,

but once again, what about the toroid transformer bolts?

How do oyu mount toroid transformers? what do you do with that big bolt
 
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