Research: stiffest and hardest materials?

For reasons of general foolishness, I’m planning to use the GF to cut parts for a small machine, so I’m wondering two things:

  1. what is the stiffest material that can be cut with a 40w laser?

  2. what is the hardest (most wear-resistant) material that can be cut?

In my particular case, a full-size machine would be made primarily of steel, cast iron, and some bits of stainless. I’m looking at making a small very light-duty version out of laserable materials, partly as an experiment and partly because I don’t presently have access to a milling machine large enough to handle this full-sized in metal.

Some parts need to be quite stiff, while other parts need to be as wear (abrasion) resistant as I can manage. So, to be clear, I don’t particularly need to find a single material for both purposes, they’re separate components.

Also, I regard the entire assembly as being fundamentally sacrificial, because if I can manage this in the first place then I don’t mind just cutting replacement parts as the need arises (I’m trying to make a die filer for small nonferrous parts because, again, I’m being foolish).

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Sounds like, other than support, spacers, or risers, you are looking for a Plastic Something.

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Good question. For toughness and wear resistance in a laserable material, Delrin is hard to beat. For rigidity acrylic comes to mind.

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Consider laminating for stiffness. You may be able to lay up a thicker part from thin parts that are laserable.

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^^^ This.

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And if those materials are insufficient, laser a template in draftboard and use a router with flush cutting bit or template guide to make the part out of aluminum or UHMW sheet.

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A registered friction fit on 1/8 Baltic birch is very rigid and would likely be moreso if you glued it too. You could try cutting 1/4, but 1/8 cuts much more reliably. It’d be interesting to rigorously strength test a 1/8 assembly versus 1/4, but who has time?

Also, apparent rigidity is a function of size of your piece. 1/2” square of acrylic feels like a rock. A full sheet bends like a banana.

Stress, strain, physics, etc.

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Well, in a perfect world I’d be able to find a laserable material that’s about twice as stiff as acrylic (so, say circa 6GPa or better both elastic & flexural modulus). If I can get that high I can probably avoid wholesale redesigning of components (just shrinking them instead). Which is the lazy way out, but laziness and foolishness go well together…

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Looks like Delrin isn’t going to get you to 6.

http://www2.dupont.com/Plastics/en_US/assets/downloads/design/DELDGe.pdf