Material Selection

[thepieman]

Hi, i am looking for some help with selecting a material. The design is for an experimental chamber which will hopefully machined out of a single lump of the selected material. This material needs to be clear so what is occuring inside can be seen.

So basically i need a material which:

Comes in a large enough single block (30cm X 12 X 4 approx)
Is clear or very close to in appearance
Can be machined
Does not cost an arm and a leg

Pretty simple but i thought i would ask you guys as you will know far more about it then i would

 

[CoryPad]

What are the conditions of the chamber? Temperature, pressure, fluids?

 

[patprimmer]

Any clear plastic sheet will be available in the size you want, however like Cory says, there is a lot more to be considered.

Regards
Pat
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[prdave00]

Without knowing your application and just considering machinability and clarity, the first thing that comes to mind is polycarbonate (same material they make some bell jar lids out of). To achieve / improve clarity from there you might consider vapor polishing after machining.

If this is just a rectangular box, have you considered solvent bonding polycarbonate or acrylic sheet together?

However as CoryPad noted, more information is needed to make an educated recommendation.

 

[patprimmer]

Acrylic is actually easier to work and is clearer and cheaper than PC if it is ambient only.

Regards
Pat
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[btrueblood]

A film of silicone grease works to cover machining scratches and provide some degree of transparency, usually just enough for the purpose.

 

[ornerynorsk]

Pieman, you'll need to give a few more details to narrow down your choices. Is there some purpose in having this machined out of a single piece? That's a very expensive way to make something, given your dimensions. Is it OK if it costs just an arm or just a leg, but not both? )))))) Sorry, couldn't resist.

 

[Pud]

If you could actually get a block of polymer with suitable properties, how are you going to polish it to make it optically clear after machining? PC is virtually impossible to polish, PMMA is ok but time-consuming after machining.

imho, PMMA sheets bonded, or best would be glass bonded with silicone (think aquaria)

Cheers

H

http://www.tynevalleyplastics.co.uk

 

[thepieman]

Thanks for the suggestions. It will just have water like liquid at ambient temperature and low pressure. Can't use several sheets stuck together due to the geometry of the chamber and the fact that the glue or bonding agent means its not clear. It needs to be clear so we can see an item immersed in the liquid.
The hard geometry is to try and reduce turbulance through the chamber.

Would prefer it didn't cost me either an arm or leg, ornerynorsk

 

[patprimmer]

It can be glued and remain clear.

Is it a solvent.

Is it high or low pH.

How many teeth do we have to pull to get enough information to give valid advice.

Probably acrylio. It can be flame polished in some circumstances.

Regards
Pat
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