# How do I cut clean circles



## tmrouter (Mar 18, 2011)

How do I cut clean circles out of plexiglass 1/8 to 1/4 inch thick? I need various sizes. I also need to drill a a small hole dead center. I can drill the hole, it's finding the dead center after it's cut. I can drill the hole first and use it as the pivot point (I did it that way with glass), but what is the best tool and blades to use on plexi?


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## jw2170 (Jan 24, 2008)

G’day 

Welcome to the router forum. 

Thank you for joining us

I would recommend a circle jig. You drill the centre hole first and then use that hole to cut the circle.

What size discs do you want to cut?


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## TrBlu (Feb 12, 2010)

*Here is how I cut plexi.*

Here is how I cut circles from plexi.

With new plexi, keep the non-scratch coating in place. Drill a center hole and use a circle jig.

Set the router speed as slow as you can. Be sure to clean the bit after each pass.

You can polish the edges with a propane torch. Just keep the flame moving over the edge.


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## harrysin (Jan 15, 2007)

tmrouter said:


> How do I cut clean circles out of plexiglass 1/8 to 1/4 inch thick? I need various sizes. I also need to drill a a small hole dead center. I can drill the hole, it's finding the dead center after it's cut. I can drill the hole first and use it as the pivot point (I did it that way with glass), but what is the best tool and blades to use on plexi?


These shots show how a circle jig is used, in the project shown, it was a hole that was required but for the disc the principle is the same, simply adjust the jig for the size that you want. The jig shown is easily made and is infinitely variable.


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## jschaben (Jun 21, 2009)

tmrouter said:


> How do I cut clean circles out of plexiglass 1/8 to 1/4 inch thick? I need various sizes. I also need to drill a a small hole dead center. I can drill the hole, it's finding the dead center after it's cut. I can drill the hole first and use it as the pivot point (I did it that way with glass), but what is the best tool and blades to use on plexi?


Hi TM, I'll second JW on using a circle jig. Also drilling the pivot hole and cutting the circle around it just makes more sense to me. If you have quite a few to do, an O-flute is made for cutting plastic. 
I use one of these
Solid Carbide Spiral Plastic 'O' Flute -ToolsToday.com- Industrial Quality Solid Carbide Bits
I did notice the thing has nearly doubled in price since I got mine. Does a great job and leaves a great finish but there are other cheaper o-flutes on the same site that will probably work for you. For that matter, a regular spiral would work, just depends on the finish you want.


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## TWheels (May 26, 2006)

Welcome to the Router Forums, the best woodworking (and other router cutting) site on the web. There are members with all levels of experience, and all are eager to share their experiences.

When I saw title of your thread, I was all set to give you a detailed answer about circle jigs and O-flute router bits, but the more experienced (and with more expertise) members beat me to it! 

Keep us posted.


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## CharleyL (Feb 28, 2009)

You asked for the best method, so here it is. The absolute best way to cut circles in plexiglass is to use a pulsed laser. It is very fast, accurate, and leaves perfectly clear edges, all in one step, but you likely don't have one available in your shop. 

I use Harry's method or something very similar when I need to do it in my own shop. A laser would be great, but I don't own one either. Careful cutting with the router and a circle jig works well if you move quickly, take slow rpm light cuts, and keep the bit clean. 
Too much friction heats up the surface and causes melting of the plexiglass. It may help to experiment with several router speeds, bits, and movement speed to find what works best for you. Some edge sanding and then a very careful light pass with a torch will improve the appearance of the cut and make it look almost as good as a laser cut.

Charley


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## bobj3 (Jan 17, 2006)

Amazon.com: Jasper Circle Jig 200 & 400 Combo Pack: Home Improvement

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## Pirate (Jul 25, 2008)

I use a simple circle cutting jig I made.


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## derek willis (Jan 21, 2009)

Spiral bits are best for cutting plexiglass and there are special ones for this purpose.
Derek.


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## tmrouter (Mar 18, 2011)

tmrouter said:


> How do I cut clean circles out of plexiglass 1/8 to 1/4 inch thick? I need various sizes. I also need to drill a a small hole dead center. I can drill the hole, it's finding the dead center after it's cut. I can drill the hole first and use it as the pivot point (I did it that way with glass), but what is the best tool and blades to use on plexi?


Thanks for all the help, I am taking the easy way out. I forgot I had a friend with a sign shop and a flatbed laser cutter. I can send him a vector file and precision cut what I need. These circles have to spin and any abnormalities will burn up the motor. Thanks again.


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## jigman (Oct 11, 2009)

I use a Northern tool circle jig. It cost is 5 bucks and it will cut a clean circle. I have several and keep them set for different sizes. One thing for sure. Make sure you watch your hands. I have not hit it with a hand yet but I am sure it would do some damage. I set my hand before starting the drill press. Safety first.


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## AxlMyk (Jun 13, 2006)

I was going to loan you my Star Trek phaser, but the lazer will do ok.


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