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Acrylic plinth for small card modules

Introduction

One seems to acquire a collection of small PCB modules for experiment and research. Most of these low cost modules are bare PCB modules without a housing, and are at risk of damage when conductive material finds its way under the boards when being used.

Replacement a SOT-23 voltage regulator on one of these modules triggered consideration of some form of protection, and the solutions are offered here as ideas for others.

The plinth and feed also offer furniture some protection from scratches from the underside of PCBs with through hole components.

Examples

Fig 1:
 

Fig 1 shows an Arduino Mega2560 board mounted on a small rectangle of 3mm clear cast acrylic sheet. The board is attached to the plinth using ordinary zip ties with a small spacer between board and plinth.

A lot of these type of boards do not have space for screw heads or nuts, and so the zip tie often offers a workable method of attachment.

Holes should not be drilled too close to the edge of the acryllic, the plinth needs to be cut large enough to allow a small gap to any holes (3mm is adequate for a 3mm hole in 3mm cast sheet). 

Fig 2:

Fig 2 shows the underside detail. The end of the tie is positioned under the holes, the tie tensioned and cut flush and used as nylon feet for the module. The spacers are pieces cut wit secateurs off a length 4mm rigid irrigation riser, but M4 nylon nuts are a good solution if they are at hand.

Fig 3:
 

Fig 3 shows another example, this time the PAB has 2.5mm mounting holes and the plinth has been drilled for 2.5mm nylon screws. The philips screw head is under the plinth, a nylon nut threaded on above the plinth, the PCB fitted and another nut to top of each screw. Stocks of nylon screws and nuts are fairly inexpensive on eBay.

Materials

The acrylic sheet is readily obtained on eBay in small quantities. A pack of 3xA4 size sheets cost about A$13 including post.

The example in Fig 1 was cut with an ordinary slide compound mitre saw with a tunsgten carbide blade for wood. This is a tiny bit of chipping that can mostly be cleaned up with a filed chamfer.

The example in Fig 3 was cut using a Bosch Multimaterial blade. It has a smoother cut and no chipping visible to the naked eye.

Fig 4:
 

Fig 4 shows the tooth shape for the Bosch Multimaterial saw blade. The chamfered tooth takes most of the material out of the cut and leaves a small triangular section on each side. The other tooth cleans up the remaining part of the cut for a clean almost chip free finish in materials like acrylic sheet.

Acrylic can be cut using the score and snap method, but it becomes challenging on 4.5mm sheet, difficult on 6mm sheet.

Don't remove the protective paper until absolutely necessary to permit assembly.

Links

Changes

Version Date Description
1.01 02/05/2013 Initial.
1.02    
1.03    

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