Originally Posted by
RussM
You have what appears to be some moderately severe saw blade burn on the black acrylic. I can't tell on the clear pieces. That black is probably extruded acrylic, which is a PITA to cut using without burning it. I see you are using Weld-on 4. You will not get a strong bond using 4 unless those edges are perfect.
I usually do rough cuts on the table saw using a 10" 80-tooth carbide blade then trim to the exact dimensions needed using a 1/2" spiral cut router bit. The end result is super clean edges - and good joints. This has worked out well for me.
For future projects, if you don't have a good router and router table, or don't want to spend the big bucks for a plastics blade, carefully sand the edges with 150 grit then 220 then 400, (and optionally, 600) using a hardwood sanding block, being extremely careful to keep the sanding block square with the stock. Sand the entire length evenly - don't just hit the saw-burned spots. And, you can try using Weld-on 1802 instead of 4. The 1802 has the consistency of thin syrup and is much more forgiving of less-than-perfect edges than the water-thin 3 or 4, but it doesn't make an awful gloppy stringy mess like Weld-On 16.