A little more dive gear

[Captain Starfish]

My HUD (heads up display) for my rebreather controller died, as did the replacement they sent me out. Electrically it's only one or two LEDs hanging off the end of a cable.

Now, with the depths we're going to, the ambient water pressure is up to 12 bar (180psi) and it seems no-one's gotten close to 3D printing something that will hold water or air out with that kind of pressure difference. But it turns out that, printing at 0.1mm layer height, you can make a pretty functional one-shot (maybe more) mould. Couple of thin coats of PVA woodworking glue as a release agent, fill it with a mix of Araldite (epoxy glue that comes in a handy twin syringe if you don't need much), glass powder and black dye, et voila!

Didn't bother finishing it with sandpaper etc, either the part or the mould. It'll do just fine as is.

[img]http://www.simonlockwood.net/linky/3dp/newhudmould.jpg[/img]

[img]http://www.simonlockwood.net/linky/3dp/newhud.jpg[/img]

Just poured the goop in from the top, a bit hit and miss and an 8 hour wait to see if I'd caught bubbles in it this way. Next time around I think I'll buy a syringe to pump it in, and incorporate a runner and gates into the mould - a little more reliable and a little more confidence when I see goop come up the sprue that way.

[McSlappy]

This is looking cool! I need to try some 3d printed moulds.

Have you tried other filaments such as PETG or carbon/PLA for diving gear? I know you're pushing the limits of filament, so I was curious.

[Captain Starfish]

I was surprised.

Turns out if you get the model right (think about how a viscous fluid is going to move through the cavity, how air is going to vent, how you get the @)#$@#()* part out at the end and so on) then the actual moulding process is pretty simple. Even better - it's really easy to make a new mould if things go wrong. I tried some old Axson isocyanate two pack that's been sitting on the shelf for ten years and it foamed up like crazy, because it's old and dead. No hours spent cleaning the mould to try again, just chucked the lot and printed a new one. Phew!

After some initial experiments I abandoned (for now) trying any kind of pressure-holding printing.

Structurally, though, I've used ABS and Nylon. Very quickly discovered that Nylon has great application in its flexibility when saturated but is useless for anything structural that requires stiffness. Haven't played with any other filament types yet - most of the time I just print with whatever happens to be loaded in the printer unless I need a specific material.

[Jimustanguitar]

I printed the molds for my own vibration isolators on the quadcopter project. It worked pretty well. Definitely worth trying, if you're curious.

[img]http://i.imgur.com/hnKpUu3.png[/img]

[img]http://i.imgur.com/IJn6PSp.png[/img]

[img]http://i.imgur.com/4Og2iiT.png[/img]

[Captain Starfish]

Nice.

Agreed - fun times, anyone interested can cast with bathroom silicone out of a caulking gun to play around, makes it cheap and easy.

[precisionpete]

You guys are great to post up this stuff, keeps the mind juices flowing!
I have always been printing my molds with pla and putting them into plaster of paris mixed 50/50 with play ground sand.
Then casting brass.
Never thought to use plain old silicone and "other" stuff instead of using the high temperature metals.
Fun stuff.

[Captain Starfish]

Not sure I posted one I did very early on in my career. We needed a "shot", pretty much a torpedo that can be thrown off the boat at a wreck which will tow a guide line straight to the bottom underneath without being dragged away by current. So it's gotta go fast and straight.

I ended up making a male plug in PLA, making a female mould in plaster and newspaper around that, removing the core, reassembling the mould around an eye bolt and a few washers in the ground to keep it together and stable, then filling it with 30kg of molten lead heated up pot by pot in the back yard.

Thing goes like a rocket, hits the mark every time, and a pretty good little experience. Lead is bloody easy to work with for casting, it'll melt easy on a camping stove, and very low particulate emissions in the fumes at the lower temperatures so it's not insanely bad for you unless you're working with it all day every day.

[McSlappy]

Those quadcopter dampers are sweet, I saw the original post and was impressed. Nicely done.

Well I've no idea what need I have for casting anything - but I'm keen to try it.

We really have no idea how many applications 3d printing can be used for yet

[Jimustanguitar]

Just poured the goop in from the top, a bit hit and miss and an 8 hour wait to see if I'd caught bubbles in it this way. Next time around I think I'll buy a syringe to pump it in, and incorporate a runner and gates into the mould - a little more reliable and a little more confidence when I see goop come up the sprue that way.

A vacuum chamber would help as well. Everything I've done has been big enough to fit in a pickle jar, and when you apply a vacuum (with a hand pumped automotive brake bleeder) the bubbles are much more likely to float out of the nooks in the mold and out the top.

I've been scheming about building a bigger chamber and buying a "real" electric vacuum pump. I could use that for filament too, so I'm doubly inclined to do it.

[Captain Starfish]

Never thought of the brake bleeder - brilliant idea. Does it pull things down low enough to make a difference? My brother has a proper vane pump somewhere that he uses to degas resin and bag down windsurfers and fins that he used to make, but that seems like overkill for very occasional use.

He did say one thing: air exposure is the death of resins, both polyurethane and epoxy. The moisture gets sucked into the goop over time then, when you mix it, it creates heaps of bubbles. Sounds kinda familiar

[bot]

I tried to mold a silicone ear but gave up and just printed a PLA ear. Nice work on ll these molds in this thread. I'm super jealous.

[Jimustanguitar]

Never thought of the brake bleeder - brilliant idea. Does it pull things down low enough to make a difference? My brother has a proper vane pump somewhere that he uses to degas resin and bag down windsurfers and fins that he used to make, but that seems like overkill for very occasional use.

He did say one thing: air exposure is the death of resins, both polyurethane and epoxy. The moisture gets sucked into the goop over time then, when you mix it, it creates heaps of bubbles. Sounds kinda familiar

I'm able to pull between 20 and 30 in/hg which will make the bubbles expand enough to float out of the material, but it's not like a real vacuum chamber that will degass things completely. In my experience, most of the bubbles come from you mixing the 2 parts of the epoxy together. I used Smooth-On DragonSkin for my molds. I want to try some of the air curing materials next.