Mystery Material

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JamesW
Posts: 93
Joined: Sun Apr 07, 2013 12:23 pm
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Mystery Material

Post by JamesW »

Hi All,

In my workshop I seem to have scrounged up some ~3.8mm clear plastic material that appears, at first glance, to be perspex. It has clear(ish) protective film on both sides.

It appears to be very like perspex until you try to laser it.

At that stage, and with similar settings that I'd use for perspex, it gives off a fair amount of white smoke, becomes a bit melty, and the edge becomes very slightly orangey brown. Parts don't fall out like with perspex - they tend to re-melt onto the cut edges, and need to be popped out.

I assumed it was a different brand of acrylic, until I started snapping some offcuts that are about 10mm wide.

And they didn't snap. They bent. If you bend it fast, it snaps. If you bend it slowly (at room temperature) it just bends. You can even bend it back again, though the end looks fatigued. This is not how perspex behaves.

What is this mystery material? Polycarbonate? (It generally appears to be somewhat unsatisfactory - but I'd like to know!)

Cheers,

James
izzysdaddy
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Joined: Mon Apr 23, 2012 12:18 am
Location: essex/herts border
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Re: Mystery Material

Post by izzysdaddy »

Morning James

The material is clear extruded acrylic. The thickness of the material is mainly produced for large display companies. It is produced to save costs as saving 0.2mm over tens or hundreds of sheets amounts to a lot. The end customer is none the wiser they have a display manufactured in 3.8mm acrylic instead of 4.0mm acrylic.
I myself purchase either 2.8mm, 3.8mm,4.8mm & 5.8mm clear extruded acrylic on certain jobs but only machined by panel saw or router.

Regards

Stuart
owner of a LS1290
JamesW
Posts: 93
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Re: Mystery Material

Post by JamesW »

Thanks Stuart!

That's really helpful. I'm surprised that it has such different lasering characteristics from cast acrylic. The meltyness (?!) I understand - but the smoke is most disconcerting. At least it won't be damaging if it's acrylic.

Can you recommend approaches to lasering it? High speed or low speed? A single pass or two passes? For regular cast acrylic I tend to use a low(ish) speed and a reasonably high power - so that the edge quality is nice and shiny. But this stuff goes annoyingly brown and has this remelting characteristic that's really annoying.

Cheers,

James
izzysdaddy
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Joined: Mon Apr 23, 2012 12:18 am
Location: essex/herts border
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Re: Mystery Material

Post by izzysdaddy »

Hi James

Best ask Daven for advice (I do). I would probably stick to cast acrylic as you know you should not have any problems. The extruded acrylic is ideal for routering as I do then I flame polish for a nice finish.

Regards

Stuart
owner of a LS1290
Daven
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Re: Mystery Material

Post by Daven »

Sorry guys - can't help on this one, I may have tried extruded when I had the 3020 but not used it since.

I would try it without the covering (replace with masking paper) and increase the air assist if possible.

Cheers
Dave
Using two LS3060's and an ex 3020 user
Please note I am not employed by HPC, any advice or recomendations I give are based on my own experience and are not necessarily the same as HPC's. First point of contact on any hardware issues should be with HPC
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