Fully functional Z scale Ohio MOW crane

Discussion in 'My Work In Progress' started by PopeDesign, May 9, 2012.

  1. PopeDesign
    PopeDesign Well-Known Member
    Here's my first try at a Ohio MOW crane. only part that does not have to be reworked is the car body. Lots of mistakes on this one. Hand tool pugs into side door window to make boom go up and down. Side tank on crane upper slides out so hand tool can plug into hoist drum. This makes the crane hook go up and down.

    I have gotten some really good advice from other members on cleaning FUD parts. But no one seems to know how to get rid of the surface "frost" (see the white texture on the first image). Seems the only thing I know that works is scraping it off. Not easy on really small parts (boom on this took forever to clean...). Does anyone have any good ideas on cleaning FUD?

    Ohio-crane05-09-12.jpg
     
  2. arklan
    arklan Member
    i have no advice of use - but just wanted to say how REALLY cool that is.
     
  3. stonysmith
    stonysmith Well-Known Member Moderator
    Jon.. it's mentioned in many other forum threads here.. the white area you are looking at is caused where the "support material" touches underside of the FUD as it's being printed. It is actually a distortion of the surface of the FUD. There's nothing really to "clean" here, what is necessary is a good amount of sanding, but unfortunately that can be very difficult on parts that aren't flat.

    There's a lot of talk about "print orientation" to try to move the rough parts around to an unseen area, but as yet, that's an option for the future.

    If any of the model is "waxy" and/or if you have any wax trapped inside the model, that can be disolved easily with a product found at craft stores called "Bestine" (heptane). It turns the entire surface of FUD opaque white, but it may actually contribute to making it hold paint better.
     
  4. CharGyse
    CharGyse Member
    I wonder if there are any woodworking tools that can be used or adapted, say by sticking on some abrasive paper, to help smooth nooks and other parts that are frosted?
     
  5. GWMT
    GWMT Active Member
    Fantastic work, PopeDesign!!

    The only way to get rid of the 'fuzz' is to sand or scrape it off. I'm partial to Flex-I-File/Alpha Precision products like the #0101 assorted Mini Sanding Sticks: ( https://www.alphaabrasives.com/alpha/sanding-files.php ) and Sanding Needles ( https://www.alphaabrasives.com/alpha/plastic-sanding-needles. php ) as well as mini Jeweler's Files.

    You could try printing it in Polyjet HD Blue from someone like ZoomRP ( https://www.zoomrp.com/polyjet-printer.aspx ). I hope Jeff posts some pictures of what he receives from them here:

    https://www.shapeways.com/forum/index.php?t=msg&th=9172&a mp;start=0&

     
  6. PopeDesign
    PopeDesign Well-Known Member
    Thanks for the info Stony, you have confirmed many of my theories. If I were doing these parts in SLA, I'd want my A surfaces facing up. Side surfaces will show more stepping in the finish. Seems the same here and the bottom surfaces are the scorched ones. That being said, I've tried to force the orientation to my favor. But I think they pack the printer as much as they can, making orientation choice a random act of violence... I'd be willing to pay extra for orientation choice.

    So far I have used dawn and isopropyl in my ultrasonic cleaner. Both work well but also seem to leave a lot of frost behind. Both also really heat up in the ultrasonic cleaner. You would think heat would be good (remove oil and wax) but I'm beginning to think its bad.... I have a feeling the acrylic sub-straight is very sensitive to heat. I think the frosting might be a product of heat and the "cleaner" reacting on the surface.

    I tried baby shampoo and after 24 minutes in the ultrasonic cleaner, it stayed cool. Its a degreaser but its very genital compared to isopropyl or the chemicals in dish washing soap. It also left very little frost behind. I also have some Bestine I use to clean up drawings and models. It also works well but like you said, it turns the model white. I don't know what it does to it's structural integrity but I do know isopropyl and Dawn dry the part out making it very brittle.

    So I'm running a test right now. I cleaned and primed 3 of the exact same trucks printed the exact same way. One cleaned with Bestine, one with isopropyl and one with baby shampoo. I got to say, the baby shampoo seems to be taking the primer the best so far. I have to let it dry overnight to make sure the primer drys and adheres to all 3 treated surfaces. I'll post the results and images tomorrow.
     
  7. PopeDesign
    PopeDesign Well-Known Member
    Glad you like it GWMT. I checked out the ZoomRP. a bit more expensive then FUD. But a lot cheaper then a good SLA. I'm really curious about the quality and if you can paint it and how much finishing work needs to be done. Unfortunately the website it very vague. Have you seen any results from this process?
     
  8. PopeDesign
    PopeDesign Well-Known Member
    For acrylics, ABS and bondo (polyester) I find scraping works the best. I'm using a exacto chisel blade. Its harder to knock off the rounds on your edges. Then a 400 and 600 wet sand at the end.
     
  9. Pope-

    The problem that you're running into during your cleaning process isn't that you're leaving behind support material. The problem is that during the printing process at the interface of the support/model materials microscopic mixing occurs of the different fluids before they are solidified. This means that when you remove the support material, the final surface will have microscopic roughness in and around any locations where support material was located. The frosted look you are seeing is caused by this microscopic roughness. The only solution is aggressive sanding which automatically leaves an undesirable artistic finish.

    For this reason I do not use inkjet processes for any of the structures I produce. I recommend that you use an SLA process (many vendors, 1000+ dpi x-y, 4 mil layer thickness) or DLP based sla process (envisiontec, 1 mil layer thickness, up to 600 dpi in x-y). Such processes will produce models without the surface finish problems you are encountering.
     
  10. GWMT
    GWMT Active Member
    I haven't yet (just paid my taxes; won't order more for a few weeks) - I hope Jeff will post some pictures of what he received from them here:

    https://www.shapeways.com/forum/index.php?t=msg&th=9172&a mp;start=0&