I see you guys working with plexiglass and other materials, and all your edges and holes are dead straight or round. Whats the trick? I really seem to struggle with getting a straight edge without filing the object down to nothing. I'm positive someone could give me some much overdue insight.
Its all about the tools. What kind of tools are you using? A table saw with a nice blade is the best thing i can think of. Second would be a straight edge and a router table which might actually leave a better edge and you can do curves.
Just as antiH said above. Get a straight piece of wood or metal and the cut with the blade against it. Otherwise, a nice big circular saw would work swimmingly.
I always use a piece of glass. Put some sandingpaper on top of the glass, the glass on table, and start sanding the acrylic piece over the glass piece with sandingpaper on it. Dead straight! I also use this trick with aluminium and wood. like this:
I use 2 boards nailed together at 90 degrees. The guide edge is covered with velvet, and the bottom holds the sandpaper... I would also like to see some examples of the router blades that can be used on plastic. I've never tried this for fear of exploding shards. If i could find bits that could be used safely, that would open up a whole world of options for me!
i use an old steel ruler, and use that as a guide, filing/sanding until it is level with the ruler edge.
I usualy clamp the piece to my workbench (at the edge, which is straight) and use a router with a flush trim bit. the trick is to roughly cut first and use the router to adjust. taking of to much with the router can cause the plexi to melt or crack. Also remember to ALWAYS work against the rotation of the bit. (the way it feels heaviest) . if you work with the rotation the bit is guaranteed to suddenly lock up and run down along the edge of the sheet. this is dangerous, and causes chipping. there is no way you can hold back when this happens. (in this situation plexi is much worse than wood) Also be careful around corners and on thin pieces. After using a router the edge should be nice and even (and not white). should be very easy to sand to a nice finish. (or flame polish)
That's always how I've done it, but I use a fence instead of a flush trim bit. Out of interest, what rotational speed do you use?
Wow, some good responses. I had thought of using a piece of steel or a ruler to get the straightness I need, but I was worried repeated use would wear it down until it is no longer straight! I suppose thats just something I will have to deal with. I don't have a router or a circ saw, which I know is excellent for cutting lumber but not as much for steel without special blades, and really not for cutting case panels. Maybe I can make use of my stepdads bandsaw from time to time. The cutting guide on it would work wonders for me on outer edge cuts. My problem isn't so much outer edge cuts, but inner cuts, where its hard to get a straight line to cut along. Some big C clamps and some pieces of wood should allow me to hold a edge guide in place though. Thanks for the ideas, I'm sure I can figure something out for my situation now.
I set it at the lowest. I don't know what RPM it is. When working with plexi, lower is always better. i tried to cut a piece of plexi yesterday with one of those Japanese style saws. (very thin blade) If i kept the saw as paralell to the sheet as possible i was able to get very clean, straight cuts. Wasn't that much work either. (using the side of the blade with the biggest teeth is ok as long as the angle is small enough.)
I did it on acrylic. Don't know if that makes a difference. Just use the length of the blade and go slow. And be sure that you go straight. if you cut in a slight arch the friction on the blade increases drastically.
