How should I cut a cutting board?
January 30, 2017 5:47 AM   Subscribe

I'd like to make neat cuts on ~20mm polycarbonate. Is there an easy way?

I made a cheese press, based on a design on It's great. It presses the cheese. It's so good at pressing the cheese that I'm pretty sure that if you can over-press cheese, this'd do it. I'm considering making a pressed-to-silliness cheese to see if that would work and be a thing. The pressyness is not a problem.

I'd like to make another, but I'd prefer to not have the nasty melted edges the first acquired through me cutting up a polycarbonate cutting board with an angle-grinder.

Surely there's a better way to cut this material, without leaving gunky melted edges. I am thinking in terms of cleaning and microbe growth rather than aesthetics (I don't care how it looks, as long as it works and doesn't introduce too much unwanted bacteria to the cheese).

Is there a Mefite out there who knows about cutting this stuff from, like, study or science or something, rather than just hacking at it with the fastest whirling disc at their disposal?
posted by pompomtom to Technology (11 answers total)
A waterjet would be perfect for this, if you can find a Hackerspace/Tech Shop/machine shop that would do it for you.
posted by spikeleemajortomdickandharryconnickjrmints at 5:59 AM on January 30, 2017

A jigsaw with a fine metal-cutting blade usually works well, especially if you cut slowly. The melting thing happens because of friction and the speed of the blade. If you put tape (e.g. masking tape) along both sides of the cutting line, this will help to keep the cut clean and free from debris.

There's always a bit of tidying-up to do after cutting plastics - I usually clean up the edges of the cut with a sharp knife, then sand with a very fine grit along the cut edge if I want a smoother finish.
posted by pipeski at 6:10 AM on January 30, 2017 [2 favorites]

A sharp router bit would be my choice. Router required, obvs.
posted by jon1270 at 6:16 AM on January 30, 2017

An angle grinder is all about cutting through friction, which causes the heat and melting; a clean blade with fine teeth is usually what's recommended for plastics. If you have a table saw or circular saw, find a blade with tiny teeth and you should be able to keep the melty edges to a minimum, maybe even wet/oil the blade a bit to ensure friction is at a minimum.

If you were to go at it with a hand-saw you should end up with a much cleaner, non-melty, edge because there's less chance for the blade to heat up, but getting a straight line and figuring out how long your biceps hold out will be the key.
posted by AzraelBrown at 6:28 AM on January 30, 2017

I would think a band saw or even a jigsaw would cut through it pretty cleanly without melting it. Maybe drag a deburring tool across the edge when you're done or just clean it up with some sandpaper.
posted by bondcliff at 6:47 AM on January 30, 2017 [1 favorite]

I have used a tablesaw with a fine-toothed carbide blade to cut Lexan polycarbonate with no problems.
posted by mr vino at 6:57 AM on January 30, 2017 [2 favorites]

2nding tape, then jigsaw with fine blade for plastic. You will still get some melty edge (probably on the bottom) but it should come off cleanly with a box-cutter, razor blade or X-acto knife. Drilled holes need to be cleaned with an X-acto knife.
posted by sexyrobot at 7:49 AM on January 30, 2017

I mill Starboard brand HDPE (that I buy from my local marine electronics place), which is roughly the same thing plastic cutting boards are made of, with a circular saw and a router. Have to do a little playing with bit speeds and feed rates to keep the chips from getting caught in the cut and melting and then burning the cut, but it's way easier to work with than acrylic.

If you cut with a hand saw, I very highly recommend a Japanese style pull saw. The kerf is usually a little fine for plastics, but it's easier to get a long straight cut (If I'm cutting 3/8" or less plywood, I'll often break out the pull saw rather than set up the power tools just because I can actually cut a sheet of plywood down a chalk line in about the same time as it takes to set up a rail and run the track saw down it.
posted by straw at 8:23 AM on January 30, 2017 [1 favorite]

Not sure if Harbor Freight is a thing where you're at, but I gave 'em 40usd a year or so ago for this, the world's most adorable table saw. I got it for cutting polycarbonate sheeting and it's done me fine.
posted by 7segment at 9:43 AM on January 30, 2017

Any very sharp blade used with a low feed rate will work. Preferably with a pretty fine tooth. A 10" 80 tooth ATB tablesaw blade designed for melamine for example works well. The low feed rate is important to both minimize heat and reduce the bite of the blade. You want to match the blade with a zero clearance insert if you go this route.

A band saw works good too because the length of the blade is effective in carrying the heat away.

If you are cutting by hand a 18 TPI hacksaw works ok. I've used it to cut guards for machinery so used tapping/cutting fluid as a lubricant to keep the teeth clear. Mineral oil or a vegetable oil would probably work just as well.

I'll second that if your design can use it straw's HDPE is much easier to machine than polycarbonate; it is literally designed for machining and is easily cut and drilled with common wood working tools. And being a common cutting board material it is food safe and non porous. You can even plane a chamfer on the edges to ease them without introducing a mass of micro scratches from sanding that can harbour bacteria.
posted by Mitheral at 12:25 PM on January 30, 2017 [1 favorite]

As wel as chamfering it, you could smooth the cut edges with a hand plane, meaning you can cut it as roughly as you like.
posted by bonobothegreat at 7:29 PM on January 30, 2017

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