Flaming

[George Elston]

Would someone explain IN DETAIL, how to flame polish plexi? I have tried acetaline and butane and can't seem to get it. With acetaline I get smoke all over the plexi and with butane I seem to go right to the bubbly stage and never get the polish. Do I direct the flame at the plexi or play it over (parallell) to the piece? What part of the flame should I be using? What should the flame look like (white, blue, orange)?

HELP and thanks

[Belinda Barfield]

George,

Try this thread, it may have the answers you need.

http://www.sawmillcreek.org/showthread.php?t=73300&highlight=polish+acrylic

[George Elston]

Thanks Belinda, but that was the post that got me in trouble in the first place, never would have tried it without everyone saying "this is all there is to it". I need the Dummy's guide.

[Scott Shepherd]

George, I might be speaking non-sense, but I don't believe you can expect to take it off the laser, hit it with a torch of any kind, and have it clear and perfect.

I believe the process is more like burn it out, take at least 400 grit sandpaper (maybe higher) and get the edge really smooth. Then you can hit it with the torch and it should clear up.

Not too long ago, I tried taking a piece of 3/8" that I cutout and just flame polish it. Didn't work. The lasered edge is just too rough to flame polish directly, in my opinion.

It is an art, for sure. There's a super fine line. One side, nothing's happening, the other side, it blisters the material. It's not just a "Heat it with a torch" type applications.

Just my opinon.

[Bob Cole]

Frank has several posts with his work on here that is very imformative. I only found this one:

http://www.sawmillcreek.org/showthread.php?t=56768&highlight=torch+laser

I think there are others.

When I first saw flaming in the title, I was expecting an entirely different thread :D

[Frank Corker]

If you have got yourself to the bubbly stage you are waaaaaayyyyy too far from where you should be. The trick is to rub it down as has been mentioned, any rough edges will show if you don't. Various grades of wet and dry do the trick and I end up using 600 grit, the smoother it is, the better the finish - like it is with painting. You should have a milky appearance when you have finished rubbing it down.

Then take your torch and just go over the piece, go fast at first and see what it does, then do another run a little slower if there was no effect. It should become clear (not the milky appearance any longer - transparent) as soon as the heat starts to get at it, if it begins to cloud a little you have gone too much, move on to the next area that needs to be done. By the time you have finished the next stage, the burned part can be re-examined to see if it needs rubbing down again. It's not easy George but just takes practice.

If you are wanting to do very thin acrylic like 4mm or the like, forget it because the heat will kill it in seconds and permanently distort it, unless you have one of those teeny diddly tiny winy blowtorches that they use for jewellery.

I am told that buthane is the best one to use, however I have only ever used mapps, which by all accounts heats up tremendously. If you do a search on my posts I did a couple where I created bases for awards using a router and finishing with flame polishing. The acrylic I used on that occasion was 20mm. The thicker it is the better it will turn out.

From your description of the smoke etc shooting out, too much heat and too slow hands, I'm thinking of what the best speed description would be. I know, you have a two feet piece of wood which needs to painted with a very smooth gloss paint, the same smooth motion that you use (unless you paint like a snail of course) is the speed your hands should pass over the piece. Don't be tempted to cover the area over and over because you will be causing too much heat. One smooth pass should ultimately get it, as it turns transparent move the torch around in small circle about the size of a quarter (see that.....???? Americano) should make it happen.

[Thad Nickoley]

Frank,

What brand name is that??

:Dteeny diddly tiny winy blowtorche

[Frank Corker]

Crumbs Thad, now you're asking, I'm a Brit. This is it.

[Thad Nickoley]

Thanks Frank, I will have to pick one of those up.

[Luke Phillips]

"teeny diddly tiny winy blowtorch" - thanks for the tip Frank, I thought my torch might be a little too big!:rolleyes:

[pete hagan]

I just use the ol welding rig (oxy-acetylene) and use a fine tip. wave it quickly over the areas that are problems and use a lot of light to see the changes. If you get to bubbly stage you have left the heat on too long. Most of my panels are 3/16 to 3/8 thick so they warp quickly. If I get too much warping I must heat the entire panel to a consistant temp and let cool.

Pete

[Bill Cunningham]

For thinner acrylic, I got the perfect little torch in my Christmas stocking this year.. My wife put it in there because she knows I like gadgets.. This torch uses a 'drop in' butane cigarette lighter for it's fuel supply.. It's a little small for thicker stuff, but works great on 1/8" to 1/4" (approx 3-6mm)

[Frank Corker]

Bill I have one of those refillable pen torches and found it to be useful but for the refilling every few minutes. However, it's been a long time since I tried that one, maybe I have got a little better at it.

Luke, that one's a 'tad' big, do you get much singeing on the roof?

What Pete is talking about is what I originally saw being used to demonstrate polishing. It really is extremely fast and his advice is on the nail for how it should be done.

[George Elston]

Thanks Frank,
I think I get the idea now. I usually sand with 100 to 200 and then go to steel wool and then a buffing wheel, usually on 1/4" to 1" material. But sometimes I have odd shapes and would love to use the torch. I have a "itty bitty butane torch" and an oxy-acetylene rig. I thought I saw someone say to not turn on the oxy when polishing and thats where the smoke comes from. Is that correct? Other than that You have given me confidence to try it again on a job later this aft.


Thanks

da geek

[George Elston]

Frank your a genius, or at least a very smart fella. You hit my problem right on the nose. It was the speed, I just polished a piece (Name cut out of 1/4 inch white plexi) and it worked beautifully. I did have a little problem when I got the swoop of an "S" too hot and it slumped, but just held it in place for a moment while it cooled. I hate trying to finish all those little areas inside the letters. I may be ready to try the welding rig on a bigger piece. Do I turn the oxy on or not? I think yes.

Thanks again, your fan

ps and your right IT'S FUN

[Bill Cunningham]

If your using OxyAcet. you 'have' to have the oxy on, or the carbon deposits from the Acet. will turn everything black... you can 'decrease' the O2 a bit until the cone is about 1.5 times longer than normal.. This will soften the flame, and spread the heat a bit.. Your still going to have to watch it, or it will burn.. It's much like welding, you can look all you want, but until you begin to 'see', the results will be poor. The only thing I ever used a rich Acet. mixture to increase the carbon, was for putting Borium Ice gripping corks on horse shoes.. It added enough carbon to the mix to keep the hardness up on the borium, and without the added carbon the corks would break off in no time.. Couldn't get the horse under the laser..ha..

[Frank Corker]

Aha! The old Borium Ice Gripping Corks Trick!

[Rodne Gold]

You do of course realise that flame polishing stresses the acrylic incredibly and that anyone cleaning it with a solvent is almost guaranteed to get stress cracks?
The best way of scraping down the edges is just that , scraping em with a hard steel flat edge, its sometimes far quicker than sanding. You should also put a slight chamfer on the edges, a duburring tool or the hard edge steel will do that.
Heres a very good resource for machining and working with perspex or acrylic
http://www.maizey.co.za/component/option,com_docman/task,cat_view/gid,33/Itemid,235/

[Bill Cunningham]

Aha! The old Borium Ice Gripping Corks Trick!

I wish I could stick a few on 'my' feet this winter.. I fallen on my butt about four times so far... Old Age Clumsy:o