Flame polishing when working with acrylic

[joehoble]

This post is mainly intended for Joseph since we have been discussing acrylic fabrication by email but I thought to post it on RC since there may be others in the hobby that may incorporate acrylic fabrication in their hobby as well.

Joseph, I remember on one of the emails, we were talking about edge preperation prior to cementing. When we met again at Rob's Reef yesterday I had that "Working With Acrylic" book. I was sitting in my garage this morning and was reading the section on flame polishing since that was one of the items we talked about. Since I am still "fiddling" with acrylic, I wanted to run by you what it says in the book and get your opinion on it.

This is what it says:

"Flame polishing is a fast, economical method of edge polishing that is prefered by some fabricators, but it cannot be fully recommended for use on acrylic sheet, because of its tendency to cause crazing which is often not apparent until sometime after the article has left the fabricators shop. This technique is never recommended if other fabrication steps such as cementing, forming or painting are planned after the polishing step"

I believe I can agree with this quote because when the edge is being heated, it is only the edge and not the panel as a whole. I think the problem is not on the edge but where the location of the difference in temperature is within the material that will craze. Heating a material will either strengthen of weaken that material depending on the method used. Metal is the same way as I have discovered by watching programs of the Discovery and Science channels.

I think the best method for preparing the edge prior to cementing is by using the table router with a double fluted straight bit and that is only based of my personal limited experience. I inspected the edge of a router cut surface and compared it to the edge of a surface after it has been cut by my table saw and found the the routed edge is by far way superior. I think if you and I do not get together before the next meeting, I will get some scrap together and bring it with me.

Anyway, let me know what you think Joseph, Mike or anyone else that has an opinion and looking forward to seeing you all at the next meeting.

 

[joehoble]

After writing the long post I think it is time to get back to building that canopy for my "I'll never get it finished" reef tank.

 

[joseph]

When flame polishing you want to move very quickly with the torch and just slightly melt the very surface of the edges. The interior of the joint should not really even heat up when flame polishing because of the speed in which you need to move the torch. If the material starts to bubble at all then you will know that you are going too slow. The surface of the edge being polished should be cool to the touch within 5-10 seconds or so.

I don't think that crazing is a big concern because every commercially made sump gets flame polished before going out the factory door. I have flame polished some small stuff that I have built at the house and have not seen any crazing so far. Does the article in your book mention the length of time after manufacture that it is expected before the crazing becomes apparrent? I know that there can be many factors to contribute to crazing but am not sure what they all are.

It is amazing how smooth and perfect a double fluted straight bit can make the edges in preparation for glueing. It would be interesting to have some acrylic demos at a future meeting.

 

[ScubaTC]

<a href=showthread.php?s=&postid=6989648#post6989648 target=_blank>Originally posted</a> by joseph
It would be interesting to have some acrylic demos at a future meeting.

This sounds like a great idea! I would like to learn more about how to work with acrylic. I've done a little in the past, but didn't really have the knowledge and all the right tools and so it made it more difficult.

 

[Ikaria]

I seem to remember about 2 months ago, Mike had said something about doing a sump demo. I think its a great idea.

 

[kentrob11]

Hey guys- glad to see there's a jax club- I grew up there but left when I joined the AF! Anyway, I've worked with acrylic quite a bit, more with skimmers, and tubular filtration equipment tho. One thing that I've learned is that you're better off in the long run to gut 3 grades of wet sandpaper and wet sand the corners and then buff them out with a drill buffer and compound. It takes longer but you get a much better edge that doesn't craze. Just about all larger aquariums are done this way to protect the investment....

 

[robwsup]

Goldstrip (Dan) has some experience in sanding/buffing edges. For any of you guys that saw his sump yesterday, you know it works very well.

 

[ScubaTC]

Dan's sump was high quality!

 

[ScubaTC]

kentrob11,

Did you make that skimmer? I've been wanting to do some mods to my LifeReef VS36, like add another 2' extension to the body and drill holes in the side to add a pump for recirculation. Too scared to attempt this myself! :hammer:

 

[joehoble]

I still want to try it out though. Just have to find some more funds, you know how that is....

 

[kentrob11]

Yeah Scuba I just finished that one- Is your lifereef cast or extruded tubing? I think he always made his with cast but I can't remember for sure...If it's cast it isn't that hard to drill with a good drill press and a hole saw

 

[SSweet1]

Sea life systems flame polishes acrylic- sometimes anyways, I dont know if they always do this or not. Carrie

 

[mpdharley]

<a href=showthread.php?s=&postid=6990026#post6990026 target=_blank>Originally posted</a> by Ikaria
I seem to remember about 2 months ago, Mike had said something about doing a sump demo. I think its a great idea.

I'll be hosting the August meeting, so we can do some acrylic work at the meeting. I should have plenty of scraps for people to dry gluing, etc.

 

[joehoble]

That would be sweet mike...

 

[mpdharley]

With any luck, I'll also have my 125 upgraded to the 180 and the fish room/office area done by then!

 

[joehoble]

Interests: Reefs, other Aquariums, snorkeling, Riding my Harley

Mike, I overheard you telling one of the members yesterday that you sold your Harley. Maybe it's time to change your interests to "Dreaming about riding my Harley that I sold to my neighbor" hehe

 

[ScubaTC]

<a href=showthread.php?s=&postid=6990467#post6990467 target=_blank>Originally posted</a> by kentrob11
Yeah Scuba I just finished that one- Is your lifereef cast or extruded tubing? I think he always made his with cast but I can't remember for sure...If it's cast it isn't that hard to drill with a good drill press and a hole saw

I'm not sure if it's cast or extruded. Is there an easy way to tell? I know Jeff used high quality products in his materials as well as his workmanship and attention to detail!

 

[mpdharley]

Sheezzz, give a guy a break...I just sold it on Friday! More than likely I'll be buying a touring bike in a few years, once I get some other things done :bum:

 

[GoldStripe]

Hey guys, the acrylic demo would be great for everyone who needs / wants to build their own sump. I learned a lot from some older posts by Acrylics, melev, and some others. Also learned from Mike who was gracious enough to help me out. In my first acrylic experience, I would have to say that the toughest thing is getting the seams clear. I progressively got better through my sump project.

I think if I had taken more time sanding the edges to be bonded, it would have come out nearly flawless. As far as flame polishing goes, I didn't even try it. I sanded with 150, 220, then 600 wet/dry and finished up with a $4 buffing wheel from Harbor Freight and some Tripoli buffing compound. After the 600 grit, the edges are nearly clear so it doesn't take long at all to buff the edges. That's why I went ahead and did the hole sump, even though it's just a sump. Might as well make it look as good as possible right?

 

[GoldStripe]

One other thing. A crucial tool, in fact I don't know if I'd even try to build a sump without it, would be a router. I have an old one but yesterday I found a Bosch on sale from Amazon. Will post a link to anyone who likes powertools HUH! HUH! HUH!