On 2016-05-27 10:26, Fred Lunnon wrote:

I expect RWG can come up with something which will explode on command. But it might take a fortnight to reassemble ... WFL

On 5/27/16, Henry Baker <hbaker1@pipeline.com> wrote:

...

People are using 3D printers more & more for prototyping.

I received a small electronic gizmo which plugs into a USB port whose plastic case was 3D printed.

The problem is, the plastic case keeps falling apart, due to the relatively poor tolerances of current gen consumer 3D printers.

So...

The challenge is to come up with a way to print a little rectangular plastic box -- probably in 2 pieces -- that can be put together in such a way that it won't fall apart under normal handling (e.g., carrying it in your pocket banging up against your house keys), but can still be easily disassembled w/o any special tools, screws, etc.

Note that current 3D printers have the following characteristics:

* the plastic isn't very strong and isn't very flexible, so "fingers" that interlace may be too weak and may easily break off.

* the plastic deforms slightly during printing, so registration isn't terribly good.

* the resolution in different dimensions is different, so the tolerances have to be quite wide.

If printing the box in 2 pieces won't produce a satisfactory answer, how about 3 pieces?

I expect Fred refers to https://www.youtube.com/watch?v=pvT5ySMnO8U which NeilB printed in ABS several years ago on his homebuilt (which you can hear running in the background.). Note adequate mechanical strength and accuracy. Henry, you've been cr@pped on. 3D printing is way better than that. Shapeways (et al) will make stuff out of almost anything, to almost any desired tolerance. (For a price.) These next two(?) are sintered nylon: gosper.org/IMG_0204.JPG gosper.org/tubecube1.jpg ("strong and flexible plastic") How about a steel-copper mix? https://www.bathsheba.com/math/klein/klein_Abeer.jpg Or bronze: https://www.youtube.com/watch?v=LGUfgplJRSc --rwg