Plastic Enclosures and DIY effect building

[mnordbye]

Hi

I'm relatively new here, and to effect building. And it's already getting hard to stop building.. 

A few questions though..

When using plastic enclosures for building effects, what do i need to do different from building with aluminium?

Also, any good or bad experiences on this subject?

Regards,
Magnus Nordbye

[smnm]

You need to insulate the box if you use plastic - with foil tape or conductive paint. I did one one box with aluminum foil tape when I was starting out a few years ago, but it was messy and annoying.
Plastic generally won't be strong enough if you are actually going to STOMP that stompswitch.
A cheaper alternative to the cast boxes is folded alumunium - these go for only a little more than the plastic ones and I actually like them. They're not indestructible, maybe they'll buckle and bend a bit in time, but they are ok, and cheap.

This is one from Craplins in the UK, not elegant, but with a certain utilitarian charm, and easy to drill:


image for illustrative purposes only - lots of places sell similar boxes cheaper

[Mark Hammer]

Some people go to great lengths to shield them, and quite frankly it is not nearly as critical as you might think for a great many pedals.  If it is a high gain pedal, then obviously you don't want to amplify hum from fluorescent lights by a factor of 500, so some shielding is recommended in such a case. A simple piece of small gauge shielded cable between jacks and switch is often enough to do much of the hard work, and even when you have a perfect shield in the form of metal box, you still have to worry about layout inside the box and "rat's nest" leads (i.e., a metal box does not guarantee freedom from stray signal and noise).  It's always good practice to keep lead length short, but perhaps a little wiser to do so when the box is plastic and the gain on the high side.

I build most of my pedals these days in plastic boxes.  Here (all the non-1590B stuff) are some examples:

Where better shielding is useful, I stick a piece of copper shim along the underside of the chassis top, since most of your EMI sources will be above the pedal, and because I get it cheap and can use the pots to secure the shim-shielding to the box.  Many commercial pedals and even high-end audio will use a shield layer along the bottom of the chassis, underneath the copper side of the PCB.  Obviously you'll want some insulating layer between those two.

Although obviously cast aluminum is built to withstand great force, a great many industrial plastics are stronger than you'd think.  Obviously you can't do fancy packaging stuff like etched patterns/legending on the chassis, but on the positive side, they often come in colours and there is nothing to chip off the surface of the box.

[mnordbye]

Thanks for the replies..

I've already built a Rat clone in a "sheet metal" box, sol by Banzai, i guess that's the cheap alternative to diecast alu boxes. Doesn't take much to be bent when top and bottom is separate, but when mounted together (as they should be in the end) they can take a STOMP or ten.. Mine also came with a shiny blue top! Combined with green knobs, it's the most funny looking, Rat i've ever seen. 

[oldrocker]

Most of the builds I've done are in plastic enclosures.  I really haven't had any problems at this point.  I haven't done much shielding but then again I haven't taken many of the pedals out of my house much either.  Different environments could create problems I'm sure but so far so good.