[s1artibartfast]

I get the manufacturing Tradeoffs. What I was responding to was not an issue with part complexity, but part material.

They said "I can work with metal. I can't work with plastic."

Sure, nobody is going to machine a plastic replacement complex injection molded housing. You probably werent going to re-create a complex press-formed metal part either.

IT seems like it is more of a design complaint than a material issue.

[ElevenLathe]

How often do you encounter mass-produced consumer goods that include parts made of machined engineering plastics?

[s1artibartfast]

That's not what Im saying. Machined plastics are rarely encountered, but many molded plastic products can be trivially machined.

Im saying that the fabrication difficult is driven by design, not material.

almost nobody is going to home fabricate a spline gear at home, and it doesnt matter if it is metal or plastic. If something is like a plate or flange, it is trivial to fabricate and doesnt matter if it is metal or plastic.

For any given design, I think refabrication is the same or easier for plastic.

[ElevenLathe]

Not sure why we're arguing, but I think we are on the same side. We would prefer that products have parts which are easily replaced by, in order of preference:

1) easily-sourced commodity products like standard screws, washers, bolts, etc. 2) barring that, parts that could easily be fabricated by realistic home production methods (hand tools, FDM printing, possibly simple machining) 3) barring that, parts that the consumer can have easily fabricated by a third party (maybe it requires a 5-axis CNC but all the CAD/CAM files are available to upload somewhere like Shapeways) 4) barring that, easily-ordered at-cost OEM parts

...and in all cases the user manual should require all relevant drawings with dimensions.

The problem is that if you tell an industrial designer to keep costs down, and that they can use injection-molded plastic parts, they will almost certainly NOT design parts that are conducive to 1-3. They could, but all the incentives run the other way, so they probably won't.

[s1artibartfast]

I was mostly just curious about the person who said they absolutely cant work with plastic, but can work with metal.

I like some things that are repairable, but don't think everything needs to be. My product choices rarely are willing to compromise cost, function, or aesthetics for repairability.

[ElevenLathe]

That's the idea (I assume, not the same guy): you're right that is mostly the form of the part that makes it easy/hard to work, not the material, but nobody designs machinable plastic parts. they design injection-moldable ones. So in practice "plastic part" is synonymous with "impossible to recreate in small quantities". Yes, in theory plastic parts can be of the same shape (and therefore ease of boutique manufacturing) as metal ones, but they aren't, not in the real world.

[MeImCounting]

I have a pocket knife in my pocket (perhaps not quite as mass produced as what you were imagining) whose handles are made of G10 which is a composite material made partly of epoxy. It has been 3d machined into its current shape.