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Reply to "Building a PRR/PC/CR G39 Ore Jennie - Scratch building with a laser, Part 2"

This car has been trickier to model than it appeared.   The body itself wasn’t hard, once I had a good set of drawings.  It’s basically a bathtub with ribs, no drop bottoms or hopper doors to worry about.   As they say, the devil is in the details.  The corner ladders/pusher bumpers/steps have been the hardest to resolve, and not totally there yet.   There are two different types of assemblies overall, mounted to angled car sides and each other.  Because I will be mass producing these (for myself), I need the parts to be fairly idiot proof.  Right now they involve gluing up super thin pieces of .020 polybacker at right angles with ACC.  Giant hands, super glue, and small parts aren’t a good combination.  I can do it, but it’s tedious, and I’m experimenting with another method.  I’m on V5.0 of this car right now - see below photo - and it will likely enter service, but V6.0 will be a slightly improved version, from an assembly standpoint.

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My other rivet counting OCD issue, was the ribs.  If you have been following along, the initial versions of the ribs were made from 1/8” acrylic, after an attempt to cut .080 styrene on the laser cutter resulted in too much distortion and curling with the thick styrene.  The acrylic cuts nicely, but the .125 thick ribs just looked slightly too thick, compared to the prototype.  There was some research needed to determine the actual size of these ribs, and since they were slightly tapered from the outer edge back to the hopper side, my best estimate was anything in the .080-.100 range would look better.  I couldn’t find acrylic in either of those sizes, well cast acrylic, that is.  You can get .080 extruded acrylic, and it will cut on the laser, but there is some sort of thermal issue and it crazes or cracks when you use the solvent glue on it.   The solution that I came up with was to use .100 styrene and cut it on the CNC machine.  I used to use the CNC for most things, but after obtaining the laser, I sort of forgot about it.   The next picture is sort of an over-kill situation - .100 styrene being cut by a 13 horsepower spindle.  

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You can see by this side by side photo, the difference in the ribs is noticeable, even though we are only talking about .025” .  V1.0 on the left has the thicker .125” ribs and V5.0 on the right, the .100”.    Styrene ribs are also much easier to glue onto the acrylic sides than acrylic to acrylic.  

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I hope to have a completed V5.0 in the next week.  V6.0 is started.  

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  • A0A09532-7490-47A3-8510-8D8BB3DCE3AA
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  • 79DF7483-9015-403E-BC01-C9E96C28BE2F
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