Polishing acrylic edges

[Welderpaul]

Don't do much of it in my game, but we need to polish up the edges of some 10mm clear acrylic. Been looking at the videos on here, and noticed the one about flame polishing. Obviously care needs to be taken to avoid melting the edges, but how sucessful is it - does it need any further work once you've been over it with the flame, or does the flame produced the finished job?
Beats rubbing away with wet and dry

[Welderpaul]

Good timing

I only uploaded this a couple of days back http://www.youtube.com/watch?v=GE7UIRhh-jM , then today I spent three hours sanding, rubbing with wet and dry and then polishing a table. I still have two more left to polish which equals about another 5 hours of sanding/polishing.

Clear Acrylic is the best to flame polish as long as it is standard acrylic and it is not one of the new types with a non gloss finish, such as Perspex frost etc.

You have to get the edge clean to begin with, so any saw marks need either scraping to remove them or you can router the edge, then flame polish using a small blowtorch.

You can get a special blowtorch for this purpose, but I have no idea where they sell them.

I'm sure one of the technicians at our place has flame polished with oxy acetylene, but you would have to be extremely careful as it will soon set on fire.

Do you have any scrap pieces to practice on?

[Welderpaul]

Yeah, its clear extruded acrylic - job is some machine guards; i was planning to cut the sheets with a circular saw - with as fine tpi as i can find.
So i need to give it a going over with a sander first before flame polishing? I'm glad you said oxyacetylene - that's what we have to hand
Sure there will be some offcuts to have a go on first.

[ultimatehandyman]

You just need to remove the saw marks, so a router will do the job much better than sanding it, or you can scrape the edge with a scraper ( the ones that hold a stanley knife blade ) held at 90 degrees to the cut edge.

scraper.jpg (6.36 KiB) Viewed 10747 times

Here is a guy flame polishing with butane http://www.youtube.com/watch?v=Vx7MHdWXQvc

You'll have to be really careful with oxy!

[Welderpaul]

Oxy acetylene looks a bit ott for flame polishing - i'll get hold of a blowtorch to do it.

[ultimatehandyman]

Oxy acetylene looks a bit ott for flame polishing - i'll get hold of a blowtorch to do it.

Yeah, I think it would be much better.

Oxy gets too damn hot, and it's a dirty gas until you get the right mix of oxygen with it.

[amarg]

Make sure you remove the protective covering first as it melts and catches fire

[bredred]

Extruded acrylic is a treat to flame polish - unlike cast acrylic which will tend to dull and "sizzle". You can actually make quite poorly prepared surfaces look pretty good with a spot of flame polishing, but i agree with UHM about using a router - it will provide a good finish that will look great after polishing. Acrylic can be worked in the same way as wood.

I use a butane blowtorch (£15 - £20 b&q etc). Whatever you use, practice on off-cuts......keep the flame moving and don't apply too much heat at once. If you have missed a bit, you can go back to it - overheat it and it will bubble / melt. Its actually quite a quick process to flame polish. It takes literly 5 or 10 minutes to polish an 18" diameter 6mm thick disc