Cutting a 20in Diameter Circle out of Plexiglass

[Mike McCarthy]

What's up guys? I'm new here and just started really building things and doing projects, so I really don't have a clue what I am doing yet. I have built a circular ottoman where there is a hole in the middle to put a circular 20in diameter piece of plexiglass for a coffee table top. I'm planning on using two pieces and sandwiching one of those vinyl stained glass designs to make it look nice in between them. I went down to HD and the guy I spoke to there said I could cut the circle using my Jigsaw, but that did not work so well when I started with cutting the piece in half as it started cracking. So what can I do to cut the plexiglass into two 20in diameter circles? I have a jigsaw, miter saw and a table saw and I don't really have the money to buy something else right now, so should I just get the plastic cutter that I saw right next to the plexiglass and just score it until I can pop it out or what? Like I said, I'm new to all of this, but I love it so far, so any help would be greatly appreciated.

I'll post some pics when it is all done. Thanks guys.

[Derek Noel]

I think the jigsaw is the best tool you listed. You could use the table saw to cut your blank into an octagon so it is easier to work with. What blade did you have in the saw when you made your first attempt? too fine of a blade would gum up and start to melt the plastic causing it to bind up , too course would leave a rough cut. ??? I think the most important thing would to support the sheet very well so it docent tend to vibrate.

If you had a router I think that would be you best tool for getting a clean edge.

[Lex Boegen]

I had to cut a piece of acrylic recently, and it was a bear to keep from chipping. I think the best way is to sandwich it tightly between two pieces of hardboard or plywood and cut slowly with a fine-tooth blade. Any vibration in the plastic will cause cracks and chips. Good luck.

[Kevin Groenke]

I jigsaw will not do a very good job on this, it's going to be a rough cut and it's not going to be a perfect circle. Perhaps you can cut close with the jigsaw and sand down to a line but it's going to be labor intensive.

The best way (other than a laser or CNC) may be a laminate trimmer or hand held router on a trammel beam with a 1/4" spiral cutter.

You can use double-sided tape or 3M Command adhesive to attach the pivot point to the acrylic.

http://images.meredith.com/wood/images/165issuepreview/routertrammel_bg.jpg

-g'luck
-kg

[Lee Schierer]

Acrylic is going to be tough to cut without chipping or cracking. Switch to a piece of polycarbonate (Lexan). It cuts easier than acrylic and is much harder to crack. It will also hold up better in your application.

For cutting, I would rough cut the piece with a band saw, free hand, then make a plywood template and use double sided tape to stick the plastic to the template and do the final trimming with a router. A small hand plane can be used to eliminate the sharp corner edge.

[Scott Gibbons]

I have cut acrylic for large aquariums and what I would do is.....
Cut a template out of mdf and use a router with a template bit to cut the circle. You want to make sure you get a good carbide bit so it stays share and cuts the material instead of melting it. Once you are done you can take a torch with mapp gas and flame polish the cut edges. Practice the flame polishing on some scrap so you can find the ideal heat/distance for the thickness of the material.

[Jamie Oren]

I work in a shop here on base and we use a laser ingraver to cut odd shapes in plexi. my best advise pay the few dollors to get it done.