# Acrylic mounting for bus bar



## major (Apr 4, 2008)

sabahtom said:


> 5mm acrylic seems a good choice for mounting bus bar, dc-dc fuse etc. has anyone got photos of how they did it with this or other materials? I'm thinking of an Aluminium anglebar frame with an acrylic box.


I think polycarbonate is a much better choice.


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## sabahtom (Mar 1, 2011)

*Polycarb vs acrylic*



major said:


> I think polycarbonate is a much better choice.


Looks like polycarb is better. I didn't consider it because I haven't seen it thicker than 1-2mm (common for roofing).

How thick would you go for a span of 1 foot between aluminium angles? It seems stronger than acrylic so 5mm should be plenty.

*Impact Resistance:*
Two frequently used methods to evaluate strength of these materials are the notched Izod test and falling dart impact. Results are measured in footpounds. The notched Izod test evaluates shear stress while the falling dart measures resistance to direct, penetrative impact. Comparison of polycarbonate and two types of acrylic shows: 
*Notched Izod*
*Falling Dart* 
Polycarbonate (3)
16
125 
High Impact Acrylic (4)
1.2
8.0


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## Siwastaja (Aug 1, 2012)

Yeah, don't use acrylic. It can crack very easily when stressed to constant forces. It can even develop internal stresses and crack with very little external stress. For decoration and optical systems it's a must because it has almost perfect light transmission; nice and clear.

Polycarbonate doesn't look so good, it's a bit violet-grayish in color in thick layers, but it can literally stop a bullet without breaking. Other good choices are ABS or even PVC. Find a shop that supplies typical plastics cut for the measurements.


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## Woodsmith (Jun 5, 2008)

I have some white faced phenolic panels, about 6mm thick, that came from some old uPVC doors, before they were all insulated.

Very stiff and tough.


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## major (Apr 4, 2008)

*Re: Polycarb vs acrylic*



sabahtom said:


> How thick would you go for a span of 1 foot between aluminium angles? It seems stronger than acrylic so 5mm should be plenty.


Some places I use 1/8" thick and it is pretty stiff. It machines well (drills, saws, etc) and also can tolerate sheet metal equipment (shears, brakes, etc). Where I don't need the stiffness or want gradual bends (large radii), I use 1/16th.


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## Siwastaja (Aug 1, 2012)

Polycarbonate is _stronger_ than acrylic only in the sense that it doesn't break, but it actually flexes more. I'd use at least 5mm thickness in anything except very small parts or places where the flexibility is ok.

If you want a really stiff structure, you need to form a 90 degree angle to the plastic, as it would be unrealistically expensive and heavy to use thick enough material (>20mm). You can use hot air gun to make the bends.


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## sabahtom (Mar 1, 2011)

Siwastaja said:


> Polycarbonate is _stronger_ than acrylic only in the sense that it doesn't break, but it actually flexes more. I'd use at least 5mm thickness in anything except very small parts or places where the flexibility is ok.
> 
> If you want a really stiff structure, you need to form a 90 degree angle to the plastic, as it would be unrealistically expensive and heavy to use thick enough material (>20mm). You can use hot air gun to make the bends.


The only polycarb I can get here is 3mm roof sheeting. Good enough if I glue two of those in a sandwich and put a 90 degree bend in them? They'd be bolted together along the edges where they sit on the frame.

Size would be 1ft x 1.5ft.


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## Siwastaja (Aug 1, 2012)

Gluing is always a bit difficult, at least you'll need a special glue (if you can get it, you should be able to get the proper size of polycarbonate sheet too). 3mm may be just fine if you can make proper bends that support the structure.


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## sabahtom (Mar 1, 2011)

Siwastaja said:


> Gluing is always a bit difficult, at least you'll need a special glue (if you can get it, you should be able to get the proper size of polycarbonate sheet too). 3mm may be just fine if you can make proper bends that support the structure.


Maybe no need to glue it, since all the components will be bolted to the polycarb so the sheets will be bolted in many places on sides and in the middle, will act as one piece.


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## Nabla_Operator (Aug 5, 2011)

(from my UL experience: )

and... polycarbonate (PC) is much better fire resistant where as Acrylic (PMMA) can catch fire and maintains burning by itself. PMMA is not UL approved.

Choose PC.

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