[hackpgh-discuss] Re: watertight 3d printing
- From: Steven Owens <stevenjowens@xxxxxxxxx>
- To: hackpgh-discuss@xxxxxxxxxxxxx
- Date: Thu, 26 Jan 2017 18:31:54 -0500
I'm back at a real computer now, so...
On Thu, Jan 26, 2017 at 2:13 PM, Andrew C. <soshumasamune@xxxxxxxxx> wrote:
Reminder- it takes a lot more time to cnc machine a case even with a program
than laser cutting does.
I'm curious what you mean by this. If you're referring to the router
CNC at HackPgh, I find that confusing, I would have thought the CNC
did a faster job at cutting through thick materials than the laser.
If you're referring to some other CNC technique, I'm curious as to
what you mean.
What I was suggesting before, in (the likely) case I wasn't clearly
expressing myself, was cutting out a folding box outline, i.e. some
design sorta like this (this design is probably too cubical, but it
gets the idea across):
http://printables.atozteacherstuff.com/435/cube-pattern/
This could include doing half-depth cuts where the folds would go, and
then using some approach to fold them. With thin plywood, use steam
bending. With plastic sheet material, maybe infrared heat lamps or
something?
If you need a weatherproof enclosure, milling out of a block of plastic
would be best way to go in our shop
That was my thought for the "best" way (for some value of best) but
not necessarily the most feasible way. I don't know what the
implications are for material use or time for that approach. I was
thinking in terms of making a 3D negative blank and either casting or
vacuum forming*. The blank could be made with the router CNC, or
possibly 3D printed, or milled by hand.
Then perhaps the laser cutter or router CNC could be used on the
formed case to cut various apertures.
For the sealed boxes, that's another topic but still, I think, worth
looking into. Note that I'm mostly talking about weathertight cases.
Truly airtight/watertight cases gets into problems where you have to
think about heat dissipation. It's doable and might be worth sorting
out. These kinds of projects seem to come up often and it'd be good
to have a well-thought-out approach ready to use for them.
For truly sealed cases, from what I've been able to learn, the best
approach seems to be either to seal it permaently with caulk of some
sort, as discussed, or to cut a groove and embed some sort of rubber
grommet in it, and a matching groove on the lid.
You can waterproof a wooden object to a large degree by coating it in molten
beeswax aftee gluing up is done, and let it soak into pores of the wood
Beeswax was used a lot historically, to seal leather or wood or even
canvas. For example leather flagons. It does the job reasonably
well, but isn't good for hot liquids, like coffee or tea. For that
sort of thing, food grade polyurethane or rubber works well, I've been
told. Not historically accurate, but you can drink coffee and liquor
out of it (another technique besides beeswax was to seal the drinking
vessel with pitch, which breaks down when you get above about 20%
alcohol).
Steve
On Thu, Jan 26, 2017 at 5:56 PM, j. eric townsend <jet@xxxxxxxxxxxx> wrote:
On 1/26/17 16:14, Keith Elliott wrote:
I've found it really difficult to 3D print something watertight directly
off the printer. No inter-layer adhesion is perfect and so there will
always be gaps. However, I managed to seal a print using some XTC-3D
The problem I'm facing is that my manifold/watertight containers need to
be made of PEEK or something with PEEK's properties. I'm moving to a
Dyze head and going to try something that worked with other plastics --
heat well past the temperature needed for printing and see if I can get
a weld-like bond between layers.
--
J. Eric Townsend
<http://www.flatline.net>
HF: KC3HSO
PGP: 0x335E5548 / 75DB 5C22 FD5D F33E B1FA D5BA B429 EA93 335E 5548
--
Steven J. Owens
stevenjowens@xxxxxxxxx
puff@xxxxxxxxxxxxx
412-401-8060
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