Author Topic: Scratch Resistant & Laser Cuttable Plastic  (Read 4333 times)

Offline awemawson

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Scratch Resistant & Laser Cuttable Plastic
« on: July 21, 2015, 04:19:47 PM »
I was about to order a bit of 1.5 mm polycarbonate sheet to laser cut a replacement instrument cluster 'glass' for my JCB 803. Then I realised laser cutting is a no no with polycarbonate - apparently the cut is not very good leaving brown edges, and it gives off toxic fumes  :bang:

Acrylic / Perspex works well but scratches easily (I've just cut one from a 3 mm off cut to prove the size)

PetG is easily available but apparently scratches easily

Pet is much the same

So what scratch resistant plastics are easily available in the 1.5 mm thickness that can be laser cut and are scratch resistant?

(I only need 100 mm square for this job but no doubt the same criteria will crop up in the future so I don't mind buying a reasonable sized bit.)
Andrew Mawson
East Sussex

lordedmond

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #1 on: July 21, 2015, 04:25:52 PM »
Andrew

don't know about laser cutting but have you looked at Lexan  they make bullet resistant shields from it , I used to make the chassis plates for my 1/8 scale RC cars as well as the bodies its tuff suff


Stuart

Offline chipenter

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #2 on: July 21, 2015, 04:31:14 PM »
How about water jet cutting that leaves a good edge .
Jeff

Offline awemawson

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #3 on: July 21, 2015, 04:36:25 PM »
Andrew

don't know about laser cutting but have you looked at Lexan  they make bullet resistant shields from it , I used to make the chassis plates for my 1/8 scale RC cars as well as the bodies its tuff suff


Stuart

Lexan is a trade name for Polycarbonate, which is a no no for laser cutting as I mention above  :(
Andrew Mawson
East Sussex

Offline awemawson

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #4 on: July 21, 2015, 04:37:36 PM »
How about water jet cutting that leaves a good edge .

Jeff, sadly I don't have a water jet cutter, however I do have a laser engraver / cutter  :ddb:
Andrew Mawson
East Sussex

Offline awemawson

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #5 on: July 21, 2015, 04:52:46 PM »
 :ddb: :ddb: Ooooooo ........ look what Google found me  :ddb: :ddb:


http://www.cutplasticsheeting.co.uk/clear-acrylic-sheeting/clear-scratch-resistant-acrylic-perspex

It's an acrylic sheet with a scratch resistant coating available in small quantities .... whoopee   :lol:
Andrew Mawson
East Sussex

lordedmond

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #6 on: July 22, 2015, 03:12:35 AM »
Job sorted then Andrew

Stuart

Offline awemawson

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #7 on: July 22, 2015, 05:09:22 AM »
Almost Stuart. Postage is more than the goods :( I may bulk up an order when I have time to plot and scheme what I may need in the future.
Andrew Mawson
East Sussex

Offline Spurry

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #8 on: July 22, 2015, 12:51:31 PM »
IF you have a bit of the polycarbonate sheet, I'm sure it will cut on a cnc router with a carbide bit. I think I've done 12mm polycarb in the past. Soon cut you one out if you've got some material.
Pete

Online philf

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #9 on: July 22, 2015, 03:32:48 PM »

PetG is easily available but apparently scratches easily


Andrew,

Many years ago a rep showed me a PetG sample and recommended that we could use it in preference to Acrylic or Clear PVC (for Clear PVC read clearish and bluish) for guards on electrical test gears. One really nice feature of PETG was that you could flame polish any scratches out of the surface. He demonstrated it by putting in a few nasty(ish) scratches onto a sample and then went over them with a cigarette lighter and the scratches all but disappeared. Unlike Acrylic it could also be welded with a hot-air gun and filler rod. I believe that we never used Acrylic again.

Phil.
Phil Fern
Location: Marple, Cheshire

Offline awemawson

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #10 on: July 22, 2015, 04:39:08 PM »
Interesting facts there Phil, many thanks.

As usual I'm over thinking this, and trying to solve the general case not just this specific job. This job is merely a 93 mm square of 1.5 mm transparent material with 3 mm radiused corners. I can cut it on my guillotine and file the corners, or if I really want to waste time cut it out on the CNC mill. But I wanted to play with my new toy - a 60 watt Chinese laser engraver / cutter. It cuts acrylic nicely but I wanted something a bit better. I've made and fitted an acrylic window temporarily, cut on the laser, but the bit I had to hand was rather grotty and will need replacing.

I'll get a few Petg samples and have a play  :thumbup:
Andrew Mawson
East Sussex

Offline John Stevenson

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #11 on: August 02, 2015, 02:49:57 PM »
Andrew,
I cut Lexan all the while on my little laser cutter.
OK fumes a bit but the extractor take it outside. If the brown edges are a problem they can be cleaned up with a hot air gun and fine nozzle.
John Stevenson

Offline awemawson

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #12 on: August 02, 2015, 03:11:00 PM »
John that's really useful to know. All the bits I've read on the web say don't as the fumes are acidic and ruin the machine. What sort of thickness's are you cutting? And what sort of speed of cut and power level are you using.

I keep meaning to make up a test file of a grid of squares of increasing speed in X and power in Y to test any new to me material easily. Another round tuit I suppose  :scratch:
Andrew Mawson
East Sussex

Offline millwright

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #13 on: August 02, 2015, 05:09:54 PM »
Andrew, just remember to clean the lenses after every use . Don't let the lens get smoked up or the laser will  actually burn a mark in the centre of it. The stronger the extraction at source the better  to pull the smoke away before it rises up to the lens.  I don't know if you have gone the carbon filter route  with yours?  Unless you got a good deal on replacement filters. I would suggest  junking it for good strong extractor to vent outside  preferably where fumes cant be pulled back inside the building. Also that makes it better for you cutting polycarbonate.

John







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Offline John Stevenson

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #14 on: August 02, 2015, 05:36:34 PM »
John that's really useful to know. All the bits I've read on the web say don't as the fumes are acidic and ruin the machine. What sort of thickness's are you cutting? And what sort of speed of cut and power level are you using.

I keep meaning to make up a test file of a grid of squares of increasing speed in X and power in Y to test any new to me material easily. Another round tuit I suppose  :scratch:

Been cutting 3mm and 5mm. the 5mm is at 100% power and speed was 8 if I remember right, 3mm can go at about 10 or 11. It's basically about 1/2 of perspex.#

Not read about that and know quite a few who do cut it. I thought the no-no material that generated the acidic fumes was PVC ??
John Stevenson

Offline awemawson

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Re: Scratch Resistant & Laser Cuttable Plastic
« Reply #15 on: August 02, 2015, 06:10:23 PM »
..mm.. I suspect I still need to tweak mine a bit more. Cutting 6 mm Perspex I'm using 4 to 5 mm per sec at 90-100 % power.. It's a 60 watt laser theoretically. The bits I've been trialing it on are smoked brown if that makes any difference.
Andrew Mawson
East Sussex