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Thread: Plastic molding with Blue Stuff

  1. #21
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    They started new threads. They chose projects that were pretty complicated and detailed. Using the wrong type of material in the mold. With all the fine details they went with putty rather than a liquid. The castings had lots of defects from trapped air and the putty not getting into the fine details.
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    I just ordered some to test it out, I'll post pics when that happens (prob next week).

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    Got the 'stuff' in today.

    Still waiting for the putty stuff you see in the video, so nothing to fill with.

    I test molded a garage door and a pallet load of boxes. The detail looks pretty good, tho forming a flat object like the garage door may be difficult with a stiff filler.

    I'm thinking about buying some resin, making a mold holder, and seeing how it fills with some more liquid. I think it'd work better for flat objects.

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    Hobby Lobby has some liquid resins under the Alumalite name. The quick set version has a tendency to bubble but I've not tried the slower setting stuff yet.
    Daniel Dawson

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    Does the resin get warm when curing?

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    You can also buy Alumalite two-part liquid epoxy at Walmart -- https://www.walmart.com/ip/Amazing-C...16-oz/37725399 (40+% cheaper). I bought some but have not had a chance to try it yet.

    You can get also good details if you only need one side (like for a garage door) with clay / putty two-part epoxy. If you look at the Adventures in Blue Stuff thread I posted my early results. However, my issues were mostly how I was putting the epoxy in the mold and not making sure the mold was clean between tests -- I realized less is more and that with the epoxy putty you can actually apply multiple pieces (seconds apart) and they all seem to fuse into a single molded part. This is key to getting the details right and avoiding air bubbles. I just have not had time to post pics of my better results.

    The putty two-part epoxy gets warm but does not seem to get warm enough to mess up the bluestuff mold (at least in the size and quantity I have been using for smaller mostly flat parts).
    Last edited by Mac; 24th Jun 2017 at 07:55 AM.

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    Quote Originally Posted by McNamee View Post
    (40+% cheaper)
    I'm not sure that's cheaper. With a 40% off Hobby Lobby coupon you can get the pair of bottles for $16, but they are much bigger. Can't remember if they are 16 ounces or larger but they are way more than 8 oz.

    Edit: Yeah they are 32 oz, which is 4x the product for for 50% more money. http://www.hobbylobby.com/Crafts-Hob...sin/p/80647425
    Daniel Dawson

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    Quote Originally Posted by Mobile One View Post
    I'm not sure that's cheaper. With a 40% off Hobby Lobby coupon you can get the pair of bottles for $16, but they are much bigger. Can't remember if they are 16 ounces or larger but they are way more than 8 oz. Edit: Yeah they are 32 oz, which is 4x the product for for 50% more money. http://www.hobbylobby.com/Crafts-Hob...sin/p/80647425
    Not a champion of Walmart or anything but the Walmart link is to a 16oz total volume versions (2x 8oz). So agree with a 40% off coupon for Hobby Lobby (did not realize that these were common place) it is cheaper per oz for the larger size: $17.99 ($29.99 x .6) for 32 fl oz vs. $11.72 for 16 fl oz (if you compare apples to apples the Walmart price is $.20 less than the Hobby Lobby $19.99 price with the 40% coupon for the 16 fl oz version). Guess it depends on if you want more or less as well as whether you can get free shipping or local pickup at either store.

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    *scratch that

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    You do have to be wary about buying the larger bottles of resins.

    Once opened the two chemicals will react with the air over time. Plus you have little idea how long the resin and hardener have been sitting in the store. They do have a limited lifespan.

    So, if you are just experimenting, buy small quantities.

    After getting bad results with casting with Envrotex, I tried Alumilite after seeing it at the big Hobby Show in Chicago. Not only were my results fantastic. Things that were molded in the late 80s are still going great.
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    I almost got Alumilite today but I kept finding reviews saying it got pretty hot, so I passed for now.

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    It never melted the coating on the Dixie cups I would mix the Alumilite in.
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    I have not had time to work with my blue stuff and epoxy -- unfortunately, I do not have a hotplate setup in my train room so cannot boil water etc... which puts me in the kitchen (either while my wife is cooking or while the kids are hanging over me to figure out what I am working on).

    It is definitely easy to make replacement loads -- see a coal load I made this morning (got a set of coal hoppers for a cheap price but two were missing loads). The Blue stuff picks up textures so well that the replacement loads have the same sparkle / sheen as the original loads. I used plumbers epoxy to mold the replacement (partly becaese the dark gray would not be a bad color even if I did not paint it).


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  20. #34
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    Woah looks great, how do they look outside of the cars?

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    Quote Originally Posted by baronjutter View Post
    Woah looks great, how do they look outside of the cars?
    Thanks... Pic of the top and bottom of the next load I made (I needed two) and the Blue Stuff mold.

    This was an easy one -- I simply placed the load upright on a cutting board (not sure why I always do this on a textured cutting board since it is a PITA to pull up the Blue Stuff once it cools/hardens) and forced down the Blue Stuff along the top and around the edges.

    I am getting better at kind of rolling the blue stuff and pushing it down as I go to avoid bubbles. I cut off the excess around the edges because I might leave this mold intact for a bit in case I want to make more loads (I have a few packs of Oyumaru/Blue Stuff now but it is still easy to run out if you leave a few larger molds intact to make multiples).

    I had to do a tiny amount of filing around the outside edge to get rid of some spillover and had to notch 4 tiny slots on the sides to mesh around supports in hopper.

    20180217_190203.jpg 20180217_190153.jpg

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    Next project tonight (more complex and not as successful).

    I bought a lot of ultra tiny European hoppers which included a number of chassis without the top as "parts". Anyway, I am hoping I can make 4 or 5 more of the hopper portions to extend this little train (each of these boxes / hoppers are only a tiny bit over 1/2" across).

    There is a great deal of experience that goes into considering how best to mold something (experience I do not have yet). For example, in this case I first tried to mold it from top to bottom (i.e., bottom would be unfinished). The mold did not come out great but I may move back to that approach. If I molded top to bottom I would likely use liquid epoxy (better detail than putty in complex shapes but less control).

    This version was made by molding bottom to top (so top is unfinished) and I used epoxy putty to fill it in. I packed putty it into bottom and then around sides (basically creating a rough approximation of the original box). The 3rd picture is after I filed the top down a bit to clean up excess. The inside will get a load so it is ugly.

    Anyway, others may also learn from my journey...

    20180217_191752_001.jpg 20180217_191822_001.jpg 20180217_193142.jpg

    EDIT: Second project went a little better -- this is an even smaller dump hopper (like 1/2" in the long direction -- to give you a feeling for scale that is the coal load mold in background of first picture below). For this one I did not bother to try to keep the middle hollow (too small) and this may have allowed me to pack the putty in better. Hard to get a good picture of this that is in focus -- it looks better in person (since my eyes are not as good as my mobile phone's camera). Gonna bite the bullet and break out the liquid epoxy tomorrow to post comparative results.

    20180218_004208.jpg 20180218_004259.jpg
    Last edited by Mac; 18th Feb 2018 at 01:21 AM.

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    Pretty happy with the results of my little mine / hopper cars... I know it is a bit hard to see details without painting them. Obviously will need to add loads to the two full epoxy mine cars (I may dremel them out a bit). I decided to keep one casting of the wooden hoppers that had a bunch of bubbles (3rd in the longer train on the left) -- I need to paint it to see how many of these are on the surface but figure I can weather it a bit and make it look rotten / beat up. Some of these bubbles can also be filled (I have used white glue to do this before).

    20180218_162853.jpg 20180218_162905.jpg

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    Ok so smallest thing I have successfully cast -- some little replacement support arms for a pair of Atlas Front Runner Spine Cars (they are the little white pieces on the car to the right). This is a two-piece part that has little pins on one side and small holes in the other so it snaps through the other part that connects to ground and trailer support bracket. EDIT: I also finished decent quality versions of the stairs (still need to carefully remove a bit more flash and make one more small step for the left unit -- also need to make one replacement breakwheel holder and breakwheel).

    20180219_092018.jpg 20180219_092010.jpg 20180219_092055.jpg

    I did these with a two-part mold (helps keep excess epoxy to a minimum if you can avoid bubbles). The mold for this is the blobby blue stuff in the bottom of this picture:

    20180218_124102.jpg

    Here you can see the part I was copying (orange two-part piece at the bottom and yellow pieces at the top) as well as an earlier failed casting attempt -- I realized when using liquid epoxy it is pretty viscous and so does not go into deep holes very well unless you stick a toothpick in there to get a couple of bubbles out.

    20180218_124530.jpg
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    Last edited by Mac; 19th Feb 2018 at 10:23 AM.

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  29. #39
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    That is tinier than anything I have tried to mold. It's good to see someone tackle it and leave pointers!
    Daniel Dawson

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    Quote Originally Posted by Mobile One View Post
    That is tinier than anything I have tried to mold. It's good to see someone tackle it and leave pointers!
    Thanks Daniel --

    One of the biggest issue I have is the amount of epoxy that you need to mix at once vs. the amount needed for these parts. I need to have lots of parts to do at once to use even a small amount up completely but it sets up so fast that it is difficult to do lots of complex parts all at once -- more time to poke at it each mold with a toothpick than to pour a drip into the mold. Same issue when molding with blue stuff -- it is optimally soft for a short amount of time so hard to mold lots of tiny parts. I guess I need a better work process where I log all the items that need replacing or get them all in the same area so I can do lots of steps all at once for example.

    Also there is a pretty high failure rate (due to bubbles mostly) so if you have more originals to copy I recommend doing a few so you can have more chances to get a near perfect one. I have all the stuff to make a vacuum chamber (should reduce bubbles) but I am not sure how I could get my items in there and get a vacuum created fast enough before they set up.

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