Acrylic cut to shape?

[Tim Watts]

I have had a genius idea...

I mentioned I wanted some ceiling-wash tube lighting for the daughter's bedroom... After considering cornice (trough) lighting, I have come up with a better idea:

2 foot twin T8 fitting, HF ballast, fairly cheap, mounted in two key places on ceiling. Hanging by fine chain/wire from ceiling about 15-20cm down, and parallel-plane to ceiling is a flat sheet of white transluscent acrylic (or similar), about 1m x 0.6m, say 5mm thick so it will hang by 4-6 wires/chains at the corners. Has to be easy to unhook and clean because it will become a little bug(ger) trap.

This will act as a part diffuser and part reflector allowing some light through and a lot of sideways wash onto the white ceiling.

This is *secondary* lighting for use in dark days, winter etc - not for getting up to, she will have a regular dimmable lamp for that. T8 (or even T5( tubes give me inexpensive fittings and a massive choice of tube colour- temps with decent efficiency.

So all I need to complete my plan is a way or machining place to get nicely shaped plastic sheet. Simulations with sheets of white paper held under a tube suggest this will be a good method.

Fancy case could be long ovoid. Simpler would be a rectangle with strongly radiused corners.

So I could either jigsaw it, then sand and somehow polish the edges. Not sure how to do that - but it needs to look totally pro and not like it's been hacked out by a jigsaw!

Or find some prototyping type place that can laser/water/CNC [1] cut the stuff in small runs. [1] Whatever leaves a clean edge.

Any ideas?

If this works, I am tempted to deploy in the two hallways too.

Ta

Tim

[geoff]

In message , Tim Watts writes

Here's a clue ...

You are an ex member of UKRM, aren't you

[Tabby]

too close, unless you run it heavily dimmed.

that size flat will leave the tubes visible at the ends and maybe sides

A jigsaw will crack it 20 times before youre done. Acrylic is terrible for cracking, either melt cut it or buy spare and score & snap.

Sand the edges, you can pretrim them by clamping between 2 wood sticks & melting them down with a small grind stone in a die grinder.

A flat square's going to be a bit boring. How about a splat shape. Cut it in sheet wood, attach acrylic to it and use the die grinder grind stone to melt cut it to shape. Then also add low powered coloured LEDs to the acrylic for night time use. Use RGB LEDs and add a simple colour control.

NT

[Slainte]

Speak to your local sign company. They will most likely have everything you are looking for and they will also be able to cut and perhaps even flame polish the cut edges.

Neil

[Andy Dingley]

The trick is to have a _good_ jigsaw, which only vibrates the bit it's meant to. (Bosch 135, the good Makita). Also practice, good, sharp blade, good support underneath and the smallest amount of pendulum action you can (helps avoid melt-sticking). Then it's easy.

If you clamp a guide batten down first, and you've a low-vibration jigsaw, you'll get straight edges. If you're really concerned, lay it on a sheet of disposable MDF and saw both together (this is good for bits too small to hold too).

Wet & dry will give you a decent edge, Micro-mesh will give you transparency (ten quid sample pack from Axminster or Tilgear).

Flame / radiant heat polishing is quicker, but practice on scrap first. Personally I use an electric fire element for this, but not a flame - too easy to scorch it.

[Bill]

In message , Andy Dingley writes

Our boat windows were originally made by me out of Oroglas, whatever that is. When renewing the sex bolts that held them on the outside of the hull, we cracked two. I took one of the sheets of slightly darkened perspex that came off some old printer silencing cabinets that were being thrown out, and jigsawed and sanded. I juggled with blades to get a compromise between melt and cut. Worked fine.

[The Medway Handyman]

Sex bolts? Tell us more :-)

[Jim K]

shhurely you remember Terry Scott as Carry On as tarzan? "12345 sex"

Jim K

[Jim K]

doesn;t "natcheral filosofer" claim to be able to cut acrylic (laser, waterjet, someat?) Spose transport could be a killer in the first instance??

Jim K

[Tim Watts]

General reply:

Thanks for all the suggestions.

UKRM - hadn't thought of that - makes sense.

Sign place - definately worth a shot, in hindsight.

Good jigsaw method - well, I need an excuse to buy that Makita. I've found places on the web that will supply all sorts of weird and interesting plastics in small quantities, including cut to size so that's not a problem.

Jigsawing isn't going to be hard[1] providing the material cuts, so I think that could be a goer. I did buff the edges of a small bit of acrylic once with a dremel + polishing bit/paste - but that would take a while with the meterage here. I've never heard of the "flame" method - I shall look into that. But I do know I should get quite close with abrasive paper so I'll only need to put the final shine on it.

[1] In that I'm working with manageable sizes.

Light transparancy of the edge isn't an issue - it's white anyway, just need it to look "factory neat".

I like the idea of the "splat" shape - also means as long as the cuts are smooth no-one will ever know if there are errors.

Point taken about size: I just wanted to indicate the general ball park I'm thinking of.

For final design, if I'm sure I can pull it off - I would fit the tubes up and do some paper mock ups - paper has similar light properties to the plastic I have in mind.

Not too bothered if at some obscure angle the tubes are visible. The idea is to avoid glare from normal positions. I don;t have the room dimensions for fully hidden wash lighting.

I started out thinking 30W CFL with uplighter shade, but the 30W CFLs are long and I can't find a shade I like and I'm after more lumens anyway.

Today, after mist-coating the walls and 1st coat on the ceiling, I find that

70W of daylight spiral CFLs (Prolight - they're good lamps) held towards the ceiling without shades achieve about 1/2 of what I think the room needs. So 2ft tubes are bound to be a better bet.

It would be a good use of a circular tube, but the choices of tube types are reduced. At least 2ft T5/T8's are so massively ubiquitous that if she complains the light is wrong, I can tweak the colour temps.

If she turns into a goth[2] in 8 years and wants weird colours (or even blacklights) that's possible too.

[2] I'm mentally prepared for everything, just about!

Thanks everyone.

Tim

[Andy Dingley]

I've just spent an hour or so cutting up clear polystyrene sheet. Acrylic is an absolute amateur when it comes to cracking or melt- sticking, compared to polystyrene! Still, the Bosch dealt with it. It was a little awkward sawing the tight curves, as my narrow tight-curve blade does have tiny teeth and those are rather bad for sticking.

[geoff]

tell Cane it's for your bike ...

[Frank Erskine]

Just acrylic, much the same as Perspex.

Oroglas came to 'fame' in 1973 being blamed for the cause of a major fire in the Isle of Man.

[<me9]

Acrylic sheet, same as Perspex (ICI) but a different proprietry name for the same product from a different firm (Rohm & Hass?). Made infamous after a fire in the IOM (summerland?) where it was used well outside the conditions in mainland building regs and the recommendations of the manufacturer.

[dennis]

I would think

work better if the work fits.

[Bill]

or Wikipedia has a description but no picture.

I think it was here I asked what these things were called!

They are brilliant for certain specific uses, but every supplier seems to call them something different, and this was the one name I could remember.

[Donwill]

I think you would be better off with toughened glass, you will have some UV coming off the lamps which may in time degrade the perspex, a sheet of perspex that size if held only on the corners will also probably distort with time. Sorry to be negative but it might be worth checking those 2 points before paying big bucks for perspex. Good Luck Don

[Jim K]

aha! now i know! ;>))

Jim K

[Dave Liquorice]

So do I, used to join kitchen unit cabinets together.

[Tabby]

If you're also installing the wiring, it might be worth adding a couple of extra BC lampholders up there too. Then the thing can be switched to a lower power CFL, or to say a blacklight.

NT