Re: Acrylic or Polycarbonate substitutes for Glass Tops

[Bill Wichers <billw at waveform_net>]

> two pieces together.  [Cement this stuff requires, gloves
> (preferably nitrile), very good ventilation or a carbon
> filter mask -- the cement gives of some goshawful dangerous
> fumes.  Maybe working with acrylic is why I made those
> mistakes in the Horsepower=Btu discussion :-0  ]

Best to just use it outdoors. The fumes are also very flammable. The cement 
is Methylethylketone usually -- nasty stuff.

> You can cut acrylic and polycarbonate with saws.  But if
> the saw blade gets too hot, the sheet will melt around it.
> In fact, the cut can close up right behind the blade.  And
> if you stop mid cut, you might find it hard to retrieve
> your blade from the material.  A circular saw, therefore,
> works better than a "sabre" saw because the large blade,
> and the air stream it produces over itself reduces heat
> build up.  Tuffak brand polycarbonate, for example, melts
> at 270F.

The best blades to use are a fine pitch carbide-tipped circular saw blade 
that does NOT have canted teeth (they should all be in a straight line, 
that is not be bent to opposite sides of the blade with every other tooth 
like most wood blades are). Best to finish each cut since trying to back 
out will often make the blade stick and sometimes will fracture the plastic 
sheet. Been there, done that :-)

> jigs and templates.  Polycaronbates are susceptible to
> yellowing with exposure to ultraviolet -- but many types
> are coated one side to prevent or reduce this.

GE makes one now that is specifically intended for glass replacement in 
outdoor windows. It's called MarGuard <sp?> and also has a fairly effective 
scratch resistant coating. It's UV resistant too. It's significantly more 
expensive than generic polycarbonate sheet though.

Note that it is important to remember that both acrylic and polycarboonate 
both scratch MUCH more easily than glass.

> All the versatility comes at a premium; generally, the
> plastic sheets are much more expensive than plain glass.
> And polycarbonate is even more costly than acrylic.  If you
> can find a dealer that sells scraps, you can work
> inexpensively.  I think Erik Olson built an entire sump out
> of such scraps -- and very nice job he did:
>
> <http://www.thekrib.com/Plants/People/Darn/darn4.html>http://www.thekrib.com/Plants/People/Darn/darn4.html
>
> I wish I could have found affordable material to build my
> sump :-\
>
> Scott H.

It's usually the wholesalers and particularly the wholesalers that do 
in-house custom fabrication that will have scraps on hand. I've found some 
that will give away pieces that are less than maybe 1-2 feet wide in 
various lengths. The sizes they'll have as scrap depend what they make 
commercially, and the larger their products are the larger their "useless" 
scraps will be.

        -Bill


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