So if I cut a wheel or a gear with a central axle/hub as part of my cut, can I just fix that hub to a substrate and be confident that it with be smooth enough for the wheel/gear/whatever to rotate on? Or do I have to cut out another piece? Also, if I do that, am I likely to have it wear too fast to be useful?
Something like that. (And don’t worry about the fact that it’s not constrained in out-of-plane movement; I have ideas about that.)
Depends. You have to be meticulous with your kerf settings. There might be a small witness mark where the laser starts its cut.
Sometimes I cut the holes slightly small and drill or ream out to size. It is pretty easy.
As far as wearing out. It depends on your material, rotation speed and life expectancy. Maple would be a good choice as it is pretty hard.
It will depend very much upon the material(s) you use.
You are depending upon the surface around center hole to be the bearing.
If the material is a good material then that is fine, but some are not.
Soft wood? Not a good bearing material.
Corrugated cardboard? Nope.
Acrylic? Not if the axle is also acrylic, but acrylic on a hard wood can work OK.
Hard wood (Maple in particular) can be a good bearing surface especially if you burnish it.
You best bet will be Acetal, or a High Molecular Weight plastic.
Delrin and other acetal brands are excellent for bearings, and are cuttable with relative safety.
I would suggest you consider using that!
Edit: Should not ever laser teflon if you are venting inside. Probably wouldn’t even with the filter unit. Teflon does give off toxins and laser makerspaces have banned it. So can’t recommend it. I also suggest you don’t smoke or eat bacon.
Yeah probably shouldn’t cut teflon. Definitely shouldn’t cut if you are venting inside. And the filter unit may not capture the bad stuff. PFTE is somewhat toxic to people and definitely toxic to pet birds. It will kill them. Same with teflon coated pans if you get them too hot. Easily kills parrots and other pet birds. Human lungs are different and not as susceptible but there could be effects. I am venting to the outside and the space is not connected to a living space. If I needed a small part I might, but can’t recommend it to others.
You can cut out a crude bearing and all, for say, a knuckle hinge, but if you’re thinking a moving wheel, you not only want a precision cut bearing, and axl, but also that interaction to be as frictionless as possible.
I like a little stiffness in my hinges. /Wink. You would really need to base the cutting on the material, but like they said, Delrin might be as frictionless as you could get.