PCB Discs..

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PCB Discs..

Postby Steve Anderson » Thu Apr 26, 2007 8:05 pm

Gents,

Has this been done before?

PCBs can be made with great accuracy, to within 0.02mm and hole sizes down to well under 1mm.

A single sided PCB (in this case unetched) can be shaped and drilled to great tolerances, including circular. Using a fibreglass based board would ensure that it's flat and rigid.

In a one-off application this is expensive, but with a dozen or so (remember no etching required) it should become feasable in terms of cost.

Anyone had ideas in this direction?

Steve A.
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Postby DrZarkov » Thu Apr 26, 2007 11:48 pm

Isn't PCB too thick? But it would be an interesting material, easy to work with.
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PCB Discs.

Postby Steve Anderson » Fri Apr 27, 2007 1:01 pm

For a single-sided fibreglass PCB the 'standard' thickness is 1.6mm. But others are available, down to less than 1mm.

How thick is the Darvic sheet as stocked by the NBTVA?

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Re: PCB Discs.

Postby gary » Fri Apr 27, 2007 1:28 pm

Steve Anderson wrote:For a single-sided fibreglass PCB the 'standard' thickness is 1.6mm. But others are available, down to less than 1mm.

How thick is the Darvic sheet as stocked by the NBTVA?

Steve A.


Using a micrometer mine measures .6 mm.

Preliminary investigations here in Sydney indicates the cost would be
similar to having them CNC or Laser cut from thin aluminium, although I concede that I have yet to source aluminium sheet less than 1mm (Peter Yanczer, I think, mentioned 'engraving stock', does anybody know where this is normally obtained?) but the holes can be countersunk.
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Aluminium discs.

Postby Steve Anderson » Fri Apr 27, 2007 2:18 pm

The problem with thin aluminium is that it's a malleable material it's very easy to bend or warp a disc, either during construction or transportation. Trying to 'flatten' it out again is unlikely to be successful.

Whereas a fibreglass disc is brittle and takes a lot to bring it to breaking point. Similar to the difference between cast iron and steel.

I don't know the properties of Darvic, I'll do a bit of Googling...

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Re: PCB Discs.

Postby Viewmaster » Fri Apr 27, 2007 6:24 pm

gary wrote:Preliminary investigations here in Sydney indicates the cost would be
similar to having them CNC or Laser cut from thin aluminium, although I concede that I have yet to source aluminium sheet less than 1mm .


The 'Aluminium Shop' here in the UK does .7mm in various grades and sizes. You could ask them if they ship to Australia for you.

http://www.thealuminiumshop.co.uk/acata ... et_30.html

I recently bought ali sheet on eBay .8 mm so worth looking there too.


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Re: Aluminium discs.

Postby ac7zl » Sat Apr 28, 2007 6:29 pm

I think fiberglass PCB material would make an excellent wheel.

I would expect that the principle loading a nipkow disk sees is radial and tensile in nature. Glass fibers have excellent tensile properties, and can exceed the performance of steel, at reduced weight to boot.

The one problem I can envision is that fiberglass may not be sufficiently opaque. You'd probably have to paint it. If it has copper cladding, of course, you're all set.

Pete


Steve Anderson wrote:The problem with thin aluminium is that it's a malleable material it's very easy to bend or warp a disc, either during construction or transportation. Trying to 'flatten' it out again is unlikely to be successful.

Whereas a fibreglass disc is brittle and takes a lot to bring it to breaking point. Similar to the difference between cast iron and steel.

I don't know the properties of Darvic, I'll do a bit of Googling...

Steve A.
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PCB discs.

Postby Steve Anderson » Mon Apr 30, 2007 12:26 pm

The one problem I can envision is that fiberglass may not be sufficiently opaque. You'd probably have to paint it. If it has copper cladding, of course, you're all set.


I was thinking of unetched single sided PCB, with the copper layer it should be opaque enough I would have thought.

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