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About 10thumbs

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    MCM Ohana
  • Birthday 02/26/1951

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  • Scale I Build 1:25

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  • Location East of here..
  • Full Name Michael Gray

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10thumbs's Activity

  1. 10thumbs added a post in a topic Peterbilt 359 Day Cab...Metal Parts!!   

    Today is Fathers Day in Germany, a good day to build.  The plan is to make gaskets so the differentials can be attached.  The front unit gets a gasket with 10 holes for bolts.  The rear unit has nice ones molded in, it's good enough as it is.  The gaskets will just have "wings" that stretch out over the slits that were cut out, or I'll make a separate gasket, might even look better as separate parts.
    The patina has changed a little, for now the housings were sandblasted, only the domes are polished;

    Time to get at it.
  2. 10thumbs added a post in a topic Peterbilt 359 Day Cab...Metal Parts!!   

    Some info here;
    When you see the slit in the front of each axle, these were cut in to make sure the investment material was getting in to where it needed to go.  Otherwise, the axle shaft had too long of a blind run, I couldn't control if material flowed in or not.  This would mean in a worst case, the tunnel would be solid metal.  Catastrophe!  Since the differentials are attached anyway, I'll just add a brass flange to fit the differential as well as to cover the gouged out area on the axle housings.  One piece of metal, two uses.
    Here the slits that were gouged out in front of each axle housing;

  3. 10thumbs added a post in a topic 41 Willys - 1/25 Scale   

    Ron, with your talent....send me some plastic wheels and I'll cast them in metal.
    Maybe this way, I could offer a way for some new incentive. We'd love to see this project moving along.
  4. 10thumbs added a post in a topic Ognibs other deuce   

    Hi Ray!
    Man I'm happy about reading this news.  I like the way your thinking goes about progression, and the execution.   Save, then play.  A really satisfying way to go .
    Looks like you have a good and solid corner built up, and the controls are at hand.  Good stuff.
    Good luck with your further endeavors, I'm in.
    Take care and good you're back to your new bench.
  5. 10thumbs added a post in a topic Peterbilt 359 Day Cab...Metal Parts!!   

    Hi Tom, man I'm speechless with your enthusiasm, this really thrills me because you say you've been building for 50 years, we must be of similar age.  I had my 1st taste of this kind of casting stuff 50 years ago.  I was 15 and had a summer vacation with relatives up north in The Great Lakes region.  With a dentist in the family,  I could go and look around his place, I was building or lets say crash-building kits back then too.  He said then , boy come over and lets look around.  I did, and this stuff has been with me ever since.  Well, the teeth thing too.  I have access to the material, and knowledge of the products, and a love of the hobby.  Just this truck stuff is new, but I love it!
    Thanks Tom, real kind of you sir.
  6. 10thumbs added a post in a topic Peterbilt 359 Day Cab...Metal Parts!!   

    Further on now....
    This is the way to separate the parts from the sprues.  Big strong disc, hand piece, 25K rpm.  Goes through the metal like it was butter;

    Here's my hand piece.  I bought it 25 yrs. ago as a used machine for $1000.  Lots of money, but there's not a better one to be bought.  Made in Germany.  I had it once for re-fitting.  Invincible.  It has, and will still run for hours on end, goes to 50K rpm.

    The rest of the casting goes back into the box.  I'll reuse it for the next casting procedure, the metal is that good!

    Finally, the parts,

    Oh yeah!

    This is a HotRod 359, we want shiny rear ends.
  7. 10thumbs added a post in a topic Peterbilt 359 Day Cab...Metal Parts!!   

    more of the process;
    Breaking out the mold.  The investment is now soft and easily removed.  Wear a mask, the material contains quartz and it's of course very dry and dusty now;

    More of the same....I'm dying to know if it worked;

    OK, the vents are there....that's real good news!  I know now the metal reached out everywhere;

    Just to have a look at what's going on inside the casting procedure, the axle was partially finely sandblasted to show more;

    Here's the casting.  It looks very good, has fine positive bubbles. These were during the pouring process small air pockets left in.  What was air, becomes metal after the casting procedure.

    The other axle;

    Light at the end of the axle tunnel!  Hurrah!

  8. 10thumbs added a post in a topic Peterbilt 359 Day Cab...Metal Parts!!   

    The casting session was a complete success!
    Here the beginning.  The oven with 2 molds and crucible in place;

    Here the electric motor casting machine, Germany, vintage 70's,  a great piece.  Broken Arm Casting Machine,

    Here the "broken arm in cocked position";

    The torch, using oxygen/propane gas.  It can really cook!

    Here the crucible filled with metal, ready for casting;

    The mold is placed firmly in the cradle and the heat is on!

    The go button pressed when the metal melts.  After the arm stops swinging around (2500rpm) it stops after 15 seconds, then this view.  Hot metal thrown into the form;

    Whew!  This is always exciting!  Here the mold waiting to cool down.  I like to wait an hour. The mold had a temperature of 1300°F;

  9. 10thumbs added a post in a topic Peterbilt 359 Day Cab...Metal Parts!!   

    Thanks Dennis, very kind remarks and greatly appreciated.  Sometimes it does seem like a lot of extra work, but knowing how these "metal jobs" look when finished, I just can't see getting skimpy because of my own lack of truck model knowledge.  So, the rear end is set up and ready to go, well now I can cast it and not worry about construction surprises.
    Here we go.  This is a big one, 25 pics, not much text.  I'll be finished in a few minutes.
  10. 10thumbs added a post in a topic Peterbilt 359 Day Cab...Metal Parts!!   

    Thanks Gator,  Your support is really helpful and very greatly appreciated.  About the tarnished frame,  I just haven't found a way to keep the soldered parts clean and shiny over a longer period of time.  Last week I dug out from under the kitchen sink some wicked kind of "super spray cleaner"  I remember seeing in a TV commercial.   The lady sprays the liquid on a dirty penny and the coin comes out shiny and new.  Well, it works for brass too!!  Just not for the lead based solder, it turns really dark.I hit these spots with a small bristle brush and polish, this helped.  Lots of work, but the frame is not as filthy looking.  I'm good with it.  Every few weeks I'll spray it, but the solder remains dark, at least it's clean.
    Rob, I can understand your confusion.  If the casting turns out well, I plan on taking pics that show better the transformation.
    Dan, the investment is a gypsum based, high heat resistant powder that mixed with a special liquid.  Everything is measured exactly so as to have constant results.  The powder is in small bags, not bulk, so the size is just right for the job at hand.  When mixed, it's a thin, as you suggest, grainy and watery mix.  The base of the form is placed on a small electric appliance that has vibrating surface (about 1/3 the size of a small shoe box).  So when the mix is just poured into the mold, the vibration lets it sneak into every corner, through every hole and all around the whole deal.  in the meantime the oven is already at operating temperature needed.  After exactly 20 minutes, the mold goes into the pre-heated oven.
    Wax is immediately staring to melt and burn out, the room smells like an old coal burning steam locomotive.  Wax takes about 1o minutes to burn out, the styrene takes 25.  The mold is left in the oven for 45 to 75 minutes, depending on the mold size.  After I took the pics yesterday, the mold went into the oven, it was in there long enough to melt everything out, then I turned the oven off and let it be until this morning.  I'll turn the oven on in an hour or so, let it heat back up and cast the metal.  I'll  take pics of this casting process this time around, I think it will clear things up fairly well.
    Tonight we'll see more.
    Thanks guys for your interest!
  11. 10thumbs added a post in a topic Peterbilt 359 Day Cab...Metal Parts!!   

    Today the parts were prepped for casting.  3.5mm wax sprue leads have been attached to each part, the thinner 1mm profiles act as an exhaust.  When the mold is heated up, the styrene and wax melts and burns away, leaving a void.  When the mass of molten metal is slung in there forcefully, the displacement helps to make a better casting, plus it's a sort of an assurance that the metal gets to the most remote parts of the mold.  A perfect casting should show these vents to be almost completely filled with metal.  Here's a look at what's done so far;

    Here's the mold former placed onto the base;

    From above, a look inside;

    After the investment is poured and set, the plastic ring is removed and here's the block;

    The bottom, this is where the molten metal goes in;

    After calculating how much metal is needed, here the Alpaka pellets weighed and ready to go into the crucible for melting, when the mold is heated and ready to cast;

    The way the amount needed is calculated by weight of the object that's to be cast.  When the funnel is attached to the base, the base is then weighed, at best in metric grams.
    After all wax and styrene objects are attached, all sprue leads and vents finished, then the base with the objects is weighed again.  This time around the wax and styrene objects weighed 4.5 grams.  The specific gravity, or weight factor of Alpaka is about 9.  Wax and styrene have a 1 factor.  So, 4.5 multiplied by 9 is 40,5 grams.  This is the amount of metal needed to fill the entire void with metal.  Since this metal starts to pop and spark a little bit just before it's molten, I like to add 10% material.  So this is 45 grams of Alpaka.  This metal is really nice to work with, allowing the 100% re-use of old metal, meaning the remaining sprue leads can be re-used.
    Tomorrow morning the block goes into the oven and then cast, tomorrow at this time we'll the result.
  12. 10thumbs added a post in a topic B.R.B.O. - Brockway 758   

    This is looking very good Dan and the wheels are really fine.  I think Brockway trucks are interesting, I don't know much about them though.  I like this one.
  13. 10thumbs added a post in a topic B.R.B.O. 1955 H-63 Mack   

    Looking great Brian, I've seen pics of truck floors like this on my internet travels and thought that would be cool on a model.  There you go, really innovative and adds to the overall work your putting into this fine build.
  14. 10thumbs added a post in a topic A different take on a Freightliner COE, update 5/1   

    This is really turning out sharp and clean looking.  I like the colors, the wheels look excellent.
  15. 10thumbs added a post in a topic Johan 1962 Dodge Dart 330 Max Wedge   

    Jason, this model is outstanding.  You've really captured the simplicity of this nasty and simple car.  Beautiful and correct detailing, it looks like it should look.  I like!