Vapour Smoothing System (HP)

Spotted this on the HP website - (Down at the bottom of this page) - http://www.3dprinting.co.uk/htm/coffeeBreak.htm - Nice picture of two gears Beore and After.

The process works by immersing the part in a cloud of vapour, produced by heating a suitable solvent under carefully controlled conditions. The solvent condenses on the part dissolving the surface. The part is then moved to a freeboard area where the solvent evaporates leaving a smooth sealed surface. The system is completely self-contained so there are no environmental issues.

This re-crystallised surface can then be burnished by blasting with cracked walnut shell producing a finish that would have taken many hours to produce using traditional methods.

Has anyone looked at doing a similar thing as a DIY project to make parts smooth / stronger?

I could see a few posts that look quite a lot of manual work to post-process parts (Acetone / ABS solvent / sanding / primer etc.)

I quite like walnuts, but I'm not sure about a DIY Burnishing machine, maybe you can skip this step?

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[richrap.blogspot.com]

It's a cool idea, but personally I'd be wary about vaporizing solvents. Lot's of opportunity for danger when you do things like that. They use the words "carefully controlled conditions" but don't say how carefully controlled.

... i made some surface smoothing of plastic surfaces with a micro-torch - here i used a Weller soldering hot-air gun which could be controlled until 400 centigrades and adapted a steel-tube with 0.6mm inner diameter to the blowing tip, so i received a small hot air stream to front and a bigger sideways, so the temp. controller could work properly.

With the small hot air stream i could burn small spots of maybe 1mm diameter, so carefully moving the hot spot along a plastic surface resulted in molted and resolidified tracks or bigger areas, when moving the hot spot around ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

I saw vapour blasters some time ago, its like bead blasting but vapour as well as air and using very fine media, the SLS parts
in the demonstration looked really smooth.

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Random Precision

walnut media (hulls) is available at the pet shops around here for bedding.

Here is some of the same stuff used to clean brass. [www.midwayusa.com]


Here is a $60 "tumbler" from the same online vendor. [www.midwayusa.com] I think it uses a motor with an offset weight (think pager/cellphone vibrator) to shake the media and parts together.

I like Victor's method - it would be interesting if you could make this into a head for Mendel so it could help 'weld' the layers during build or even as a second process after the build?

I guess it could only do one side at a time unless it could rotate around the object- would be neat.

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[richrap.blogspot.com]

Sounds like they are using a vapor degreaser setup. A stainless steel tank with a thin layer of liquid on the bottom, heating coils on the bottom and possibly part way up the sides, then cooling coils all around the top walls. As long as the solvent vapor is significantly heavier than air, it remains inside the tank, with a visible demarcation where the cold section makes a lid of cold air over the solvent vapor, and also causes any solvent vapor that tries to float upward past that barrier to condense and rain back down. It is doable, but requires lots of stainless steel and probably a freon heat pump to cool the top and warm the bottom.

A poor mans version can probably be put together quickly by taking a small fish tank, checking to see that the solvent (acetone?) does not dissolve the silicone caulking in the corners, then pouring some in and placing two or three tank heaters (glass covered) on the bottom to heat the solvent, and then build a wooden box around the top with the bottom of the box halfway down the sides and fill it with ice. This would become expensive in ice if used frequently, but it would be a cheap way to test the theory. I don't yet have a working repstrap or reprap, so I do not have a fresh supply of parts to experiment on. The good wade geared extruder I got in trade from wade I do not want to experiment on until I can build a replacement!

Mike

... you can vaporize any fluid without heat with the common 'fog-lamps' - i have one with a small piezo-vaporizer in a block of stainless steel.

But i think the powerline won't survive acetone for very long ... it's meant for use with distilled water only

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

rocket_scientist Wrote:
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> Sounds like they are using a vapor degreaser
> setup. A stainless steel tank with a thin layer of
> liquid on the bottom, heating coils on the bottom
> and possibly part....

Way back in the old days, there was a degreaser like this at my dad's work. Of course, it used freon-11 as a solvent. Some got loose, but freon was cheap.


> A poor mans version can probably be put
> together quickly by taking a small fish tank,
> checking to see that the solvent (acetone?) does
> not dissolve the silicone caulking in the corners,
> then pouring...

How about taking the part outside, dunking it in a tank of acetone, letting it soak for a few seconds, and then pulling it out to sit in the sunshine (or maybe a bit of heat gun?)

After that, you tumble for an hour in the walnut shells. Too much VOC's for the EPA to be entirely happy though.

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My blog's Reprap feed: [blog.markbova.com]
I'm currently working on a stock Mendel build with a Seeeduino Mega and four Pololu A4983 stepper controllers.

I used to build plastic construction model kits, which often require sanding, at the joint seam of aircraft fuselages, for example. I used to load a soft brush with lacquer thinners and just flow it along the sanded area, matt in comparison to the mold cavity finish. The thinners will reflow the surface. Dipping your ABS component or putting it on a rack and pouring the solvent over it is pretty much the same deal. Don't touch the surface for a day or so.