best way to bevel/chamfer plexiglass

[jholman76]

Ok, hopefully a simple question..

I have a plexiglass overlay for my CP, but it sticks up just a little bit over the t-molding, so the corners poke out. They are still on top of the CP wood, but they are just shap corners.

What is an easy way to trim that down uniformly? would a router/chamfer or round-off bit be gentle enough or would I best be hand-sanding it?

I have seen some examples of chamfering thicker plexi then using a plastic sanding/smoothing kit which I cant remember the name of and some high grit sand paper.

I dont want to buy anything because I hope I dont have to do this again. I'm just looking for a simple solution.

thanks.


joe

[The Lumberjackass]

ive never worked with plexi , but if you have any left over from the project , i'd try and experiment with different router cutters to see if a bevel or roundover
bit would cut it nice and smooth. as for the sanding of plastic , it must be a high grit , eg - 240 wet paper and higher. anything lower would scratch the hell out of it,
and also , the sand paper would get gummed up because of the friction ( melting plastic ) . so use plenty of water.

but i doubt you'll have to use sandpaper. the router bit should cut nice and clean , provided you dont force feed it to the plexi hehe
but as i said, find some leftover plexi and experiment on that.

[EightBySix]

I would use some wet wet&dry sandpaper, wrapping it around a block to keep it flat and uniform. Curl your fingers under the block so your knuckles ride on the plexi, to keep the angle constant.

[Franco B]

Normal router bits + emery/wet and dry work a treat

1/2" round over bit used on 5mm acrylic:
 


6mm chamfer on 8mm acrylic using large 45 degree chamfer cutter.



3.2mm roundover bit used on 3mm acrylic:



Acrylic cuts fine with regular router bits.

For polishing I start with 180 or 320 grit to remove the machining marks depending on the quality of the finish. Once the machining marks have been removed I normally move up the grades 600 > 800 > 1000/1200 and then use Novus 3, Novus 2 and finally Novus 1.

You can flame polish plastics but I'm not too keen on it. You need to get the machining marks out before you flame polish and by that time you may as well finish it off by hand. Its a little more work hand polishing but its so worth it.

If I'm polishing something flat like that large chamfer above I use a sanding block.

If you are polishing something on a drill arbour/lathe etc you need to keep the revs down to stop the plastic from burning. Somewhere around 300rpm works well for something around 40mm diameter. You can go faster if you can keep the component cool with coolant, airblast etc

[Beley]

If you just want to knock a bit off of the edge i would sugest using an acrylic/plexi cutting knife,  specificly the inside corner of the blade i designed for this exact purpose.  Of course its not gonna be mirror smoth, but it works quite well.

http://www.tapplastics.com/shop/product.php?pid=10

you can get these at homedepot