Cutting Acrylics

william chan

Hi,

Anybody knows the best way to cut clear 2mm acrylics into circular discs without the jagged edges?
I don't want to spend 100K on a laser cutting machine.

Thanks.

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Franklin

Use a jig or band saw then sand the edges.

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- Stephen

Phil Pilgrim (PhiPi)

Acrylics can be cut cleanly on a CNC milling machine with the right setup. I'd use a two-flute endmill, fairly low RPMs, an aggressive feed rate, and no liquid coolant. Too high an RPM or too slow a feed rate can overheat the plastic, causing it to melt and stick to the bit. You may have to experiment to find the best settings, though.

-Phil

Addendum: Given that your material is so thin, you may need to hold it down with double-stick tape, or else find an endmill with straight flutes. A spiral-flute endmill will have a tendency to pull the plastic upwards as it cuts, risking both an inaccurate or jagged cut and breakage of the plastic.

Post Edited (Phil Pilgrim (PhiPi)) : 6/7/2008 7:24:21 AM GMT

Mike W

We use to get good results by putting masking tape on the area where the blade was going to cut to prevent chipping
and then we would put the blade in backwards on a·table saw and push·the Acrylic sheets thru like we would with wood.

Mike····

Ken Gracey

I usually order the material pre-cut and sanded from the acrylic supplier. We have a great shop in California called Tap Plastics (www.tapplastics.com). They even have videos on how to cut acrylic:

http://www.tapplastics.com/info/video.php (half way down on this page)

Their web site is loaded with fabrication tips, too.

Ken Gracey

StarMan

I buy a lot of acrylic discs from Craftics.· They have many standard sizes available and they custom laser cut also.· Their pricing is very reasonable.· The discs come with a slight bevel.



Chris I.

LoopyByteloose

The real problems are melting and chipping.

Circular pieces are much harder than straight runs. With straight runs, one can actually cut acrylics like glass - scratch a line and snap.

I would use the finest tooth coping saw blade I could find and try to do this by hand. It really doesn't take much speed to have friction build up heat and begin to melt the cut. So, doing this by hand is better than by high speed.

If one can rough cut and then finish to size later; a block plane will clean off the roughness. But one has to set the blade extremely shallow. A self-cleaning aluminum file is also good.

The backwards sawblade is commonly used in production work of straight cuts. But with a curved cut, you may have to set the teeth wider than a normal saw blade [noparse][[/noparse]to avoid clogging and friction, every tooth is bent outward a bit - they alternate left and right].

For small circles, a hole saw may work. But go very, very slow to avoid melt.

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PLEASE CONSIDER the following:

Do you want a quickly operational black box solution or the knowledge included therein?······

···················· Tropically,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan

MarkS

The best way to cut circles out of acrylic is with a CNC mill. Second best is with a router and circle cutting jig. I've cut tons of plastics, acrylic, PVC plate and others into circular flanges for aquarium filters using nothing but a router and circle cutting jig.

And you don't want to use a laser on a clear acrylic anyway. The edge will not be square.

LoopyByteloose

2mm seem very thin and could be cut with a rotating knife blade. Some knives can be purchased with a circular cutter - like a pizza cutter.

I find it interesting that a router at 20,000rpm is better than a much slower cutting head. But I guess that all thermoplastic does have some common fabrication methods.

As you can see, there are usually several ways that work well. The choices are usually divided by hand tools versus power tools.

Since I am making small quatities, I usually turn to hand tools in order to save money. The accuracy and quality can be just as good.

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PLEASE CONSIDER the following:

Do you want a quickly operational black box solution or the knowledge included therein?······

···················· Tropically,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan

MarkS

Kramer said...

I find it interesting that a router at 20,000rpm is better than a much slower cutting head. But I guess that all thermoplastic does have some common fabrication methods.

A faster speed means faster chip ejection and less contact time between the blades and plastic. Slower means melting plastic and binding plastic to the blade. If a power saw is used, it must be designed for plastic, not only for a nice cut, but for safety. The method of turning a saw blade around is common, but frowned upon and is actually dangerous. Don't even bother trying to use a hand saw. It is nearly impossible to get a clean cut cutting a straight edge. I shudder to think what would happen while trying to cut a circle.

Brian_B

William,
I've had good luck cutting them with a ceramic tile saw, the water keeps it cool and cuts really nice.

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Thank's Brian



·"Imagination is more important than knowledge..." ·· Albert Einstein

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www.NorthStarMachining.com

T Chap

You don't say whether it is an ongoing project or a one off. I have a friend in LA with a few laser machines, he cuts acrylic all day long and would be happy to do something for you reasonably. PM for his number if you want.

If it is a long term project, you don't have to spend a 100k, you could get a used laser for 10-20K easily that would do the job. If you are into DIY, you could build a stationary table with X and Y motion from steppers and threaded rod, put a laser on it and have as a precision system for $3 - $5k easily. There are dirt cheap CNC controllers that are fantastic, like Mach3 for example.

If you go on youtube and put in "laser" or diode, you will see numerous home brew lasers people rig up to cut plastic.