Polished edges on acrylic

[amcswain]

Hello,

So, I'm trying to add acrylic to my shop. I'm not trying to cut out signs. I'm just using sheets for signs for now, so I'm not ready to purchase a big CNC router right now. It wouldn't make sense at this point. Now to my question, I have a vendor who provides the acrylic sheets and they will cut them down to the sizes that I need, but they use a saw so the edges are rough. I'm mostly looking at 2x3 and 18x24 cut sheets. My question is, does anyone have any suggestions for the best most efficient and most affordable way to polish the edges on the clear acrylic? Or, do I need to go the old school way by hand sanding and polishing? I remember doing that a good 35 years ago in elementary school. I'm not opposed to buying something, but not a big-ticket item because I'm trying to do one specific thing at the moment. Any suggestions would be appreciated. Thanks.

 

[Pauly]

You can find someone to laser cut them for you. This also costs more.
Or
You can flame the edges with a torch.

 

[jfiscus]

I'm still fighting flame polishing the edges here. We are using map gas, but sometimes it'll burn it before it polishes it and other times it turns out great.

 

[GB2]

Turn the flame sideways along the edge of the acrylic. There are a number of good instructional videos at some of the acrylic manufacturers and suppliers websites.

 

[Johnny Best]

I use an electric motor with a buffing wheel and brick of polishing compound. sand edges with sander and 60 grit before polishing.

 

[Notarealsignguy]

+1 to sand and buff. Only takes a few minutes

 

[Digital Cutting Experts]

The flame-polishing that's been mentioned is the most cost-effective way to go if you are just getting into it but, I see you're in Chicago and I work with quite a few customers in the Chicagoland area who have large laser cutters, which is usually the best way to produce polished-edge acrylic. If you end up producing higher volume, I'd be happy to help get you set up with them!

Also worth noting:
• Do not use alcohol on the acrylic once it's been heat-treated (as mentioned above).
• If you end up laser-cutting acrylic, use Extruded, not Cast acrylic as the finished edge quality is far better (and extruded is cheaper).

Good luck!

 

[Lindsey]

I used to do flame polished edges, but I realized that for most signs, nobody is looking at the edges. The are looking at the message. Nobody cared. Now I keep it simple and offer saw cut or router cut edges. Be careful, as flame polished edges are prone to cracks. If the edge is important, sanding and buffing will result in a nice looking edge.

 

[unclebun]

What are you making from your acrylic? Things like room number signs where the edge is in view? The quickest way of dealing with the edges is a sanding block. And then you don't have the potential fragility that flame polishing causes.

You said you're mostly using 18x24 and 24x36. Signs that big the edge tends to be less important, but a quick sanding will clean up most of the edges.

If the sign is going in a frame, then you don't need to do anything with the edges.

 

[Scotchbrite]

I used to do flame polished edges, but I realized that for most signs, nobody is looking at the edges. The are looking at the message. Nobody cared. Now I keep it simple and offer saw cut or router cut edges. Be careful, as flame polished edges are prone to cracks. If the edge is important, sanding and buffing will result in a nice looking edge.

We had cracking edges problem on a project, also called crazing. Our problem was because of the gas we were using. I don't remember the specifics, but just be mindful the type of gas you're using can cause the crazing issue.

 

[bob]

Flame polishing is the proper way to dress the edges. Most people attempt to use way too hot a flame. A cool flame is what you want. Mapp gas usually is way too hot. I don't know if the still do this but in the armed forces it was SOP for the ground crews to polish airplane canopies with an old fashioned plumbers blow torch.

Here's a fun fact about acrylic/plexi/whatever. If you have a chunk of, say, plexi with properly flame polished edges you can drill a hole in one of the edges, insert a sufficiently powerful LED, plug the hole, turn it on and the entire panel will glow. It turns out that light is loath to pass through a polished surface on these materials. You can add as many edge holes and light sources as you like for whatever effect you're going for. Way back when we were messing around with this, the mid 60's, there wasn't the variety of material that there is today and I can't say that this will work with all of them.

 

[Johnny Best]

Flame polishing is OK for thin 1/8" thickness but when you start getting thicker you want to polish it. You can start off with courser sandpaper and work up to 1000 grit wet and dry sandpaper if you do not want to invest in a polisher

Light passing through glass or plastic strands is "fiber optics" which passes information with pulses of light.

 

[amcswain]

What are you making from your acrylic? Things like room number signs where the edge is in view? The quickest way of dealing with the edges is a sanding block. And then you don't have the potential fragility that flame polishing causes.

You said you're mostly using 18x24 and 24x36. Signs that big the edge tends to be less important, but a quick sanding will clean up most of the edges.

If the sign is going in a frame, then you don't need to do anything with the edges.

I'm making welcome signs for parties. I will mount them with vinyl. They will sit on an easel.

 

[Notarealsignguy]

Flame polishing is the proper way to dress the edges. Most people attempt to use way too hot a flame. A cool flame is what you want. Mapp gas usually is way too hot. I don't know if the still do this but in the armed forces it was SOP for the ground crews to polish airplane canopies with an old fashioned plumbers blow torch.

Here's a fun fact about acrylic/plexi/whatever. If you have a chunk of, say, plexi with properly flame polished edges you can drill a hole in one of the edges, insert a sufficiently powerful LED, plug the hole, turn it on and the entire panel will glow. It turns out that light is loath to pass through a polished surface on these materials. You can add as many edge holes and light sources as you like for whatever effect you're going for. Way back when we were messing around with this, the mid 60's, there wasn't the variety of material that there is today and I can't say that this will work with all of them.

Isn't that edge lit that your talking about? You rough the face, stick an led on the side and the rough parts glow.

 

[Raum Divarco]

The most affordable way to prep for polish or flame is to make sure you have cut it as nice as you can.
If possible larger diameter bits will extract debris the best and reduce striation lines.
If you have to use a smaller diameter bit i would suggest using your finishing pass function on your cutter if you have one.
if you dont have that function you can always create an offset size from the OD and leave a small amount on the overall shape large and barely go all the way thru.
Then on the last cut you can shave it down to shape and generally whatever direction of head movement you were using you can use the opposite.
Example, rough counter-clockwise and shave finished clockwise.
You might want to optimize a start and stop point or a lead out depending on what you are doing.

Then with a more prepared edge for less manual work you can get the most out of physically doing the least.

I always stay away from PCD bits but that i just my preference.

 

[Superior_Adam]

The absolute best way to do it is flame polishing but you have to use the proper gasses. Get an Acetylene torch setup with Hydrogen and Oxygen as the two gasses. We have polished 1/2" thick 3'x4' signs in about 5 minutes a piece. The edge comes out like glass. Wheel polishing would be the next best but with large pieces gets a little tricky.