I'm new here and just a hobbyist with this, but I spent weeks on this as 95% of what I'm currently working with is Acrylics. I found as someone else said, you need CAST Acrylic and be careful, even some vendors or their employees don't realize the difference or it's not real clear what they are selling. TAP sells only cast, a little pricey, but it will be cast. I'm using 2 flute carbide bits I purchased from Precise Bits and I'm generally using bits 3mm and under. For example, I run a .1181 2 flute end mill at around 8-12 ipm with the router speed around 25k with .04 passes and I get gorgeous chips with a nice clean edge. I'm using no lubrication and having zero issues, sorry I can't help with extruded, I gave up on it as I couldn't come up with the right combination and using cast is so much easier.