Smooth I am, yes…

You think vanity and Yoda do not go together? The force may be strong in this fella, but he used a very powerful scrubbing lotion to make him look much younger. πŸ™‚

Stratasys sent me these sample parts to show of the impressive surface finish you get from a process they call ReadyPartTM. Over the years I’m involved in RepRap I saw a lot of questions and remarks about polishing parts, in some cases by using acetone. I’ve tried to see if I could make objects more smooth by putting them in a pot of (diluted) acetone for a short while, but I never got a good result. I had this Yoda sample, but didn’t blog about it until I got another question about it from someone at Nophead’s post (the one where Chris shows off his smooth surface finishes!)

Actually a more faithful representation of Yoda's skin.
Before
Yoda, after using scrub lotion!
After

For more pictures, view my Picasa RepRap development gallery.

ReadyPartTM is only available for ABS parts, not PC or their PC/ABS blend. This probably tells us that it’s a specific solvent. It’s probably not acetone since that’s very unsafe and environmentally bad. After digging into it they may be using a vapor degreasing method (since that’s listed as a consumable of their commercial finishing stations).

This is a good explanation of the process that I found through the wikipedia entry:

“Vapor degreasing is a relatively simple process. A heat source raises the liquid solvent to its boiling point. When the solvent boils, it produces hot, heavy vapors that rise to an established vapor line. At this point, the vapors are condensed on cold circumferential condenser coils, and the vapors rise no higher. Because the solvent vapors are heavier than air, they push the air above the vapor line. Parts at ambient temperature are then introduced into the solvent vapor, and the solvent vapor condenses on the partÒ€ℒs surface. The liquid solvent produced as a result of this condensation dissolves the greases and oils on the part and flushes them away. As the parts are cleaned, more vapors are produced in the boiling sump to replace those that were condensed.”

Source: pfonline.com

Vapour degreasing is patented but the patent expired. There are more techniques for which the patent expired. There are probably other patents to consider, so you can probably use it experimentally (thanks to the research clause in patent law) but not for profit. Another option is to buy a Stratasys smoothing station to smooth your RepRapped parts πŸ˜‰

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8 Responses

  1. nophead says:

    Nice write-up, thank Erik.

  2. Filiph says:

    Woah that looks amazing! It’s funny nophead just wrote about this a couple of days ago.

  3. Conseils says:

    You amaze me that there is still a patent on this technology. I used to repair machines (a bit of a grand title for what ammounted to a very large heater with water running coolers) using this technology over 30 years ago. The solvent was Genklene an ICI product (1.1.1 TRICHLOROETHANE). It’s banned now, back then we had absolutely no idea how it was damaging us or the ozone layer. You might try searching for alternates of this product.

    The description is spot on by the way, although it doesn’t tell you that if the operatives don’t clean out the resevoir at the bottom the oils will catch fire and the fire department can’t put it out easily.

  4. Erik says:

    Interesting. Let’s stay in touch if we want to builds something like this πŸ˜‰

    Obviously the chamber for the solvent cannot be printed out of ABS, but perhaps another thermoplastic polymer is still feasible.

    Nowadays there is enough choice among environmentally safe solvents. Or at least, 3M, DuPunt, BaSF, e.a. make it seem like that.

  5. Filiph says:

    Oh, well thanks then πŸ™‚ It looks really great and I think it would be wonderful to be able to produce such smooth objects with a reprap. I hope that something like this can be built within the community. Also thanks for taking the time to post this, much appreciated πŸ™‚

  6. Erik says:

    On this site there are additional experiments with solvents to smooth parts:
    http://haveblue.org/?p=548