building a robot - looking for ideas for good flat materials?
matt venn wrote 06/10/2016 at 19:13 • 2 pointsI'm looking for something thats:
easier to machine than aluminium,
dimensionally stable,
strong and stiff
available in different colours
available to order in tolerenced sheets,
I liked the article on baltic ply http://hackaday.com/2016/04/26/materials-to-know-baltic-birch/.
but not sure if it would shrink and grow with heat from the motors.
I like tufnol but I've not seen it in different colours.
Any ideas?
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I've ended up using delrin, which machines beautifully. Check out the results here, about half way through the photos is where we start using it:
https://photos.google.com/share/AF1QipNaz9tMceRi-mXtJv4RdqrP6kD47sogOVb3A29a2S-6pEGMRwSNoXlWVGmveeD9vQ?key=Z3RDbTI1aXN2SzdUbkpqMFZ2Zi1PVWliaW1qYmd3
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We use a sheet of "Polymer" on the bottom of our "Airboats" here in South Florida . I'm sure you can get it in varying thicknesses. Most Airboat suppliers sell it , or maybe "Plastics" suppliers. It can be shipped.
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do you know what the polymer is? It's quite a broad term!
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Plastic cutting boards!
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My body on my K9 robot is going to be all High Density Foam over an aluminium frame/skeleton. But I do use perspex which I have bent with a heat gun for a few places. Not sure if these are all helpful but that's what Ive used.
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We usually use pcb panels. You can check out in our project. It's easy to work with. Maybe it's good for your project too.
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I suggest acrylic too. I have a CNC router that use a wood router with wood cutting bit. That is ok, does not melt the plastic at all. if you use a bit for metal it will. have a look at my projects made in acrylic. there is also a walking robot. acrylic is quite strong much more than any wood.
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what thickness do you use? I've found that even a small drop is enough to break 5mm acrylic unless it's reinforced.
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nice projects, do you mostly use 6mm?
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yes all is made of 6 mm
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acrylic
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In my experience, too brittle. And I've found it's often hard to machine without it melting around the bit.
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Machining with slower RPMs usually removes the problem of the stuff melting.
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Michal from awesome CNC and casting guide http://lcamtuf.coredump.cx/gcnc/ says:
- If it's supposed to be cheap and doesn't have to be *very* rigid or
tough, or if you can make up in thickness - sheet HDPE or
polypropylene,
- If it's supposed to be even cheaper but can be a bit vulnerable to
moisture and you can paint it - plywood, MDF, soft wood,
- If you want a tough, easily machinable plastic, but don't mind the
elevated cost - Delrin sheet,
- If it has to be even more stiff, then yeah, reinforced / laminated
phenolics or something like that.
- If it has to be very pretty, acrylic =)
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Evil Mad Scientist say via twitter: The acetals (delrin, acetal homopolymer) are our go-to materials meeting that set of criteria.
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You can buy flat sheets of various plastics. I haven't done much with it yet, but HDPE has pretty cool properties provided you're not trying to glue things to it. Plus, it's cheap if you can find chopping boards made of it :P
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I asked over on reddit /r/cnc for you: https://www.reddit.com/r/CNC/comments/4ni02z/building_a_robot_looking_for_ideas_for_good_flat/
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thanks bro! Meant to big up https://kitnic.it/ when I saw it here - will do it now
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