Edge Lit LED Lexan Sign.

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backyard_cnc
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Edge Lit LED Lexan Sign.

Post by backyard_cnc »

Hi All,

I haven't been too active on here of late but after spending a little time playing in the shop today on a new non revenue project, I thought I would post. For some time now I have been wanting to try a V carved edge lit design in lexan and a few small pieces donated by a customer (abandoned actually) seemed perfect for a test. I v-carved my ham radio callsign with a 2" 120 degree V bit into this 1/4" lexan and mounted it into a simple base from a piece of particle board. The base is recessed to take an inset piece of 1/4" PVC to attach the LED to and the Lexan is just a snug press fit into the base. I did flame polish the edge and the carved letters to a certain extend with a propane torch but this skill will require some practise as I got a little carried away on the first try and raised a few bubbles. I recut the lexan and was more cautious the second time :roll:

Overall a cool little project and a new technique tried. Gonna get a bunch of this LED strip from China on Ebay and try my hand at something larger.

Gerald
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highpockets
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Re: Edge Lit LED Lexan Sign.

Post by highpockets »

Nice job. I have a ham radio friend I may have to make one for.
You're right about flame polishing, I've messed up my share of plastic with a torch. :oops:
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glenninvb
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Re: Edge Lit LED Lexan Sign.

Post by glenninvb »

I've read polycarbonate/lexan should not be flame polished?.... I always do it with cast acrylic using a propane or mapp torch and its not difficult, saw cut edges should be cleaned up and smoothed with router (CNC or table) for best results, just keep torch moving at a fairly slow but steady pace depending on thickness. I find several passes until clear works best with thicker material. Overheating will cause bubbles in acrylic. There are good youtube videos showing the process and a little practice on scrap is recommend. Also lexan/polycarbonate is prone to stress and solvent crack. I believe the plastic fabricators use a process called vapor polishing for polycarbanate? but am not familiar with the process.

http://plasticsmachining.com/magazine/1 ... onate.html

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Re: Edge Lit LED Lexan Sign.

Post by glenninvb »

Nice sign!

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Xxray
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Re: Edge Lit LED Lexan Sign.

Post by Xxray »

I do enough plexi that I long ago made an investment in an industrial grade buffer and got away from flame polishing all together, one of the best investments I ever made.

I sand cut edges with 120 grit with an orbital sander, blow off then sand with a mouse sander using 220. Buff, finish is superior to flame. For edge lit, I'd sand whether flaming or buffing, flame will soften but not get rid of nics and saw scratches, and these are very apparent when lit. Also, after sanding sometimes I leave it unpolished for the smooth, glazed look.

It is true, flame polishing lexan is risky due to its low flash point, by the time it is hot enough for an acceptable polish it is ready to burn and it goes up quick. It can be done with care, but mechanical polishing will yield better, more predictable and repeatable results.
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Re: Edge Lit LED Lexan Sign.

Post by GJ87 »

Xxray wrote:I do enough plexi that I long ago made an investment in an industrial grade buffer and got away from flame polishing all together, one of the best investments I ever made.
Which industrial grade buffer did you buy?

Gerald

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Xxray
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Re: Edge Lit LED Lexan Sign.

Post by Xxray »

Baldor 332B 3/4-Horsepower 1800 RPM Heavy Duty Industrial Buffer



[I got mine direct from ACME and it was a bit cheaper, couple years ago though price may have gone up]

I tried another much cheaper similar buffer first, was pure junk that almost shook itself apart in a week. Returned it, got this and never looked back. So smooth and well balanced it is a joy to use and should easily outlast me. Baldor has been making quality tools for a century, still made in the USA, well worth the investment if you think you can use a tool like this.
Comes in handy for any number of things besides plexi of course, I would be handicapped without this thing.
Doug

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Re: Edge Lit LED Lexan Sign.

Post by backyard_cnc »

Thanks for the comments guys, wish I hadn't sold my jewellery polishing set-up last year due to basic non use and running out of space......... will likely stick with flame for the few projects I will do. Just priced out some sheet Acrylic today and at prices like this I can't afford to just play but would need some revenue projects for the bulk and use the scraps and off cuts for lesser shop projects!

Gerald

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Re: Edge Lit LED Lexan Sign.

Post by glenninvb »

Gerald,
I buy from these guys.... have not done any LED stuff in a while though, ideally you want "cast" acrylic for rotary engraving
http://www.estreetplastics.com/Clear_Ac ... k_s/42.htm

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