Cutting Polycarbonate sheet on budget CNC router

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MySolderIsOlder
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Cutting Polycarbonate sheet on budget CNC router

Post by MySolderIsOlder » Mon Dec 02, 2019 11:00 am

Has anyone tried using a 'cheap' (sub £200) CNC 3018 or similar router for cutting out shapes in 1-2mm polycarbonate sheet? I have zero experience of CNCs and would like to learn - but it would be nice to have something that will cut polycarb more accurately than my ham-fisted efforts with aviation-snips. Seen various comments/reviews saying these generic 3018 routers can cut 'plastic' but no indication what sort!
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MarkR
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Re: Cutting Polycarbonate sheet on budget CNC router

Post by MarkR » Mon Dec 02, 2019 11:46 am

We have a cnc machine at the hackspace, but I have never used it because the one person who understands the toolchain, does not often do training.

Personally, for materials which can't be laser cut, I apply some masking tape, then laser-etch the outline and cut it with hand tools or a scroll saw.

I think the scroll saw works ok for PC if done slowly.

The laser makes a right mess of PC - it goes all melty, catches fire sometimes, and it's not easy to clean off the bed. The laser works ok on polystyrene, which is not as tough as PC but much better than acrylic.
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Re: Cutting Polycarbonate sheet on budget CNC router

Post by Kyro » Mon Dec 02, 2019 12:23 pm

if i need precision (lol me and precision)

i cut out the shape slightly larger then file it to the correct shape... takes extra time but great results...

a set of mini files costs less than a cnc machine ;)
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Re: Cutting Polycarbonate sheet on budget CNC router

Post by LimaHotel » Mon Dec 02, 2019 3:53 pm

I'm standing with kyro on this one - hacksaw and file!
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MySolderIsOlder
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Re: Cutting Polycarbonate sheet on budget CNC router

Post by MySolderIsOlder » Mon Dec 02, 2019 5:05 pm

Well, to date I've always used a hacksaw and/or bandsaw for anything 2mm and above, with aviation snips for the thinner stuff. And yes, I cut slightly too big and file down to the line - though I now need to get some new files, having blunted my favourite Bahco's shaping and balancing the titanium teeth for Recycler :(
I normally print off the design and spray-mount onto the polycarb without removing the film, so it all peels off neatly later. In spite of this, still tends to end up a bit messy and imprecise. Ultimately down to my poor workmanship and cack-handedness - not the tools! Hence my interest in CNC (which is a field I want to learn about anyway.)

Would be particularly useful with enclosed cuts, like the wheel slots on Other Way Up, which were a bit fiddly with a fretsaw (though Mark's suggestion of a scroll saw might be useful here):
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EddieJ
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Re: Cutting Polycarbonate sheet on budget CNC router

Post by EddieJ » Mon Dec 02, 2019 9:51 pm

I cut my polycarb on a CNC, use a 1 or 2 flute bit and it cuts well.

Also the dust is harmful to your lungs and so you want good extraction when cutting with powertools.

Worth noting that a CNC can not cut sharp corners on internal cuts. Since the cutter is a cylinder. The best i have managed is 1mm radius internal, then finishing them up with a diamond saw.
Last edited by EddieJ on Wed Dec 04, 2019 11:59 am, edited 1 time in total.
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Re: Cutting Polycarbonate sheet on budget CNC router

Post by T_Y » Mon Dec 02, 2019 11:18 pm

I mostly use 1.5mm PC, the way I cut it is to draw the outline of the shape I want, then score along the line with a Stanley knife and a metal ruler, aup to around halfway through, then bend and snap on a table corner.

For internal slots (for wheels etc.) I use a small pin vice to drill out the corners, as well as along the lines I want to cut. I then use a pair of plastic cutters to connect the drill holes, then the Stanley knife to clean up the edges.
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