I’m looking for a little help here. I’m getting ready to start cutting some 1/4" Plexiglas on my CNC router and wanted to know if anyone had any tips or suggestions on type of cutting tool, with feeds and speeds. I’ve only cut wood up to this point so this is something new.
I’ve designed the general shape of a barn that my wife wants for the layout and I’m going to cut it out on my machine. This will be the structural part of the barn, then we will cover it with wood.
I’d be very careful cutting that stuff. I’ve had it shatter while cutting it on a table saw, and it developed a small bead of melted plastic on the cut edge, that was easy enough to break off. I almost wished I had a flak jacket when I cut it…(http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)
One of my associates at work has a large vacuum table CNC router. We cut acrylic sheet with it quite often. Leave all the masking in place while cutting. I will ask him for advice on bits and speeds.
Chuck
I’ve cut/rabbeted/milled quite a bit of acrylic/plexi on my router table but nothing that thick. I actually use just straight shank wood bits however being that you have a CNC I would recommend getting a set of plastic/acrylic cutting bits. The bits that I’m familiar with are called O-flute and the sign guy I know has yelled at me several times for not using those bits.
As Ken stated with a table saw if it vibrates or lifts just a little it will crack especially at the edges so it must be very secure. You want it to shave the plastic not melt it. However when working with 1/4 pcv material I actually like to melt it just a little as it’s not as messy and then you can break off the melted wasted (balls) with your fingers.
Here is a PDF from TAP plastics https://www.tapplastics.com/uploads/pdf/Tech%20Data-Routing.pdf I’m not the read and follow instructions type of guy I’m more of the hold my beer while I try this type of guy.
I’ve been cutting clear lexan with a 3 flute soft media bit from precise bits, MM3I8-0370-017F. I’m doing about 10 ipm and 10K rpm. I’ve been experimenting with styrene too, same speeds.
X
Hey thanks guys for the responses. Now you’ve brought up a couple more questions. What’s clear Lexan vs Acrylic? Is this all the same or different types of material? Do they machine different?
David@ I guess I’m the same way but I also respect the power of my CNC. I will be investing in some special bits after reading more.
Martin@ Thanks for the speed and feed info. I should of thought of Precise bits they’re on my vendor list of where I buy bits. BTW nice picture of your cat. Looks like he/she has an attitude just like mine, “Leave me alone”.
Here’s something - I don’t have machine tools but do know the plastics are different, my late grandfather worked with them.
Found these via Google, think they will be useful at least as something to start with.
http://www.coloradoplastics.com/blog-0/bid/42625/Polycarbonate-Lexan-vs-Acrylic-Lucite
Each of the two have benefits and drawbacks. Acrylic is shinier and polycarb is stronger. Acrylic is less expensive but easier to crack. Polycarb is more impact resisant but easier to scratch. They are both stronger and lighter than untempered glass; acrylic is 4x to 8x stronger than glass, while polycarb is about 200x stronger.
A video produced by the motorcycle windshield company National Cycle illustrates some of these differences by showing the effect of various projectiles and weapons on both acrylic and polycarb windshields.
A page with some technical numbers, http://www.hydrosight.com/acrylic-vs-polycarbonate-a-quantitative-and-qualitative-comparison/
It looks like you got your answer before I got back here with my friends advice which was to use specialized bits for acrylic and spin them ant 10-20K RPM.
Lexan and Plexiglass are both trade names of Acrylic sheet. There is also Polycarbonate sheet that is made from different materials and has different properties. Acrylic breaks more easily, but will stay true to it’s color over time. Polycarbonate is much more flexible and break resistant but will yellow over time. The home centers will recommend a ploycarb sheet for storm door glass replacement because it’s safer - will bend and pop out if struck hard rather than shatter.
