Advice sought on SLS-printed Nylon prototype - what tolerances & how to best finish?

[ship69]

I don't think you'll have much luck trying to add material to your nylon part. Nylon is very difficult to adhere anything to. Sanding is an inherently imprecise process; it's difficult to get an accurate sliding fit once you've attacked your part with sandpaper. You might consider re-doing your part and machining the critical surfaces rather than sanding them. In that case, printing the positive part a bit oversize (and making the bore a little smaller) will give you some material to remove. www.computersculpture.com

Oh - so are you saying that if I don't sand a part at all, then (and only then) there would be a sporting chance that I could paint onto it?

I already have a couple of other parts already on order, so maybe I could try deliberating not sanding them. The trouble is that they definitely wont fit in without at least some sanding. OK but I could possibly add some material (paint / lacquer / dissolved ABS?) and then sand all of that down ??

Do you think I could bond ABS onto Nylon by painting it on in solution?

My initial feeling was that I should re-print the part over-sized and then just sand it down to push-fit dimensions. (One trick I sometime use for sanding is to put pencil black onto one surface and see where the other is touching - a bit like dentist's "articulating paper".)

OK I give up - I have no idea what I'm talking about.


So I guess I could try and "machine" the parts, but how exactly ?
a) Turn the parts on a lathe? I don't have ready access to a lathe - the parts are too complex to fit into a lathe chuck in any case.

OR keeping the part stationary?

b) CNC ?

In my home workshop the only machine that might be useful is a hand drill, optionally on a press mount.
I could possibly drill the female hole out with a drill... but I have no idea how to machine the male part without a lathe.

:^/


EDIT: These guys seem to think that there are various options for painting onto Nylon/ nylon(polyamide 12) "Fine Polyamide PA 2200"
http://www.shapeways.com/tutorials/painting3dprintedsls

Including:
- acrylic paint, water based
- acrylic paint, solvent based
- cellulose spray paint, solvent based
- nail varnish, acetate solvent based or acrylic
- oil paint

It seems that sintered nylon 'sucks' the paint it.

Sanding it may well cause problems though... :^/