Hon30 25’ boxcar

[timwatson]

I have just designed my first full fledged boxcar in Hon30 this will be the place I put the progress and learnings. I’ll post the failed prints as well (unless they’re too embarrassing). This is based off a shorty boxcar @Chris333 made (based on a Bachmann On30)  that I redrew and reconfigured.

I am trying some “new to me” techniques.

• Printing the roof closest to the build plate. Upside down build
• Having the car “friction fit together”
• Having a more detailed floor
• Detailed interior floor - with the hopes of having doors that open

The designs.

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To be continued when I get back home and check the print.

[peteski]

Interesting.  Make sure not to make the board gaps as wide and deep as on N scale Rapido meat reefers!!   
I'll go and stand in the corner now.   

On a serious note, there was a discussion (and experiments) here in the past about this subject in 3D printed shells.

The discussion is spread around in this thread.  Here is a good starting point.

[timwatson]

Thanks Pete I will peruse some of those.

[Chris333]

Well if he has my 3D model to look at he can lift my board gaps from that. 

And the OR&W had a bunch of 25' boxcars if you wanted to go off a prototype. There are many plans in the Gazette.

[timwatson]

True to my word here is the first fail. I think this method of putting a car together is going to actually work. I’m trying a print now to reduce the suction forces from the floor being printed all at once. The interior wasn’t supported well enough and pretty much pulled apart.

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[timwatson]

Well if he has my 3D model to look at he can lift my board gaps from that. 

And the OR&W had a bunch of 25' boxcars if you wanted to go off a prototype. There are many plans in the Gazette.

You are correct sir, but you knew that already! I do have a good floorboard gap when I get this done I can send it your way.

[timwatson]

I’m trying to get to a point where you can 3d print a hollow car and have the doors open.

[Chris333]

That FEP suction has to be the next thing they figure out about this way of printing.

And it is why I print things the way I do. Not because it is the best way to make a model, but because it is the best way to print a model. With the roof on top it is angled so the FEP reaction is minimal. And I make the inside of the roof tapered as well and an even greater angle.

Now what you could try is printing the boxcar standing straight up on end and print the ends separately like Bryan did here:  https://www.therailwire.net/forum/index.php?topic=53269.msg729609#msg729609

[Chris333]

I’m trying to get to a point where you can 3d print a hollow car and have the doors open.

You will probably need to print the door hole filled in, but leave a lip so it can be cut away easy. This way you don't get a big ripple where the door opening is.

[peteski]

You will probably need to print the door hole filled in, but leave a lip so it can be cut away easy. This way you don't get a big ripple where the door opening is.

I wonder if you could print the filler in the door opening slightly smaller than the opening, then use bunch of "supports" which connect the filler piece to the edges of the door opening?  Removing that filler piece should be easier than cutting it out at the lip.

[Chris333]

I wonder if you could print the filler in the door opening slightly smaller than the opening, then use bunch of "supports" which connect the filler piece to the edges of the door opening?  Removing that filler piece should be easier than cutting it out at the lip.

Yeah that would (or should) work. Insetting the perimeter and making it very thin while the bulk of the door is still as thick as the boxcar walls. It might just be able to be pressed out with a thin flash around the edge to clean.

[timwatson]

The issue so far is the warping but I pulled a bad print so I was at a deficit to start with.

[timwatson]

That FEP suction has to be the next thing they figure out about this way of printing.

And it is why I print things the way I do. Not because it is the best way to make a model, but because it is the best way to print a model. With the roof on top it is angled so the FEP reaction is minimal. And I make the inside of the roof tapered as well and an even greater angle.

Now what you could try is printing the boxcar standing straight up on end and print the ends separately like Bryan did here:  https://www.therailwire.net/forum/index.php?topic=53269.msg729609#msg729609

I agree on the FEP suction if the resin is more pliable and soft when pulled from the FEP how easily that deforms is part of the equation. I'm intentionally printing a more flexible soft resin for testing.

I consider you the G.O.A.T. on printing for model railroading. You've pretty much been light years ahead of everyone on this stuff. That's why I keep bugging you!
I am just trying to see what other options there might be. I may end up going back to how you're doing things. I loved the interior of the On30 boxcar redo with the center frames (where the screws connect). That was really clever.


Car number 2 is out of the printer ... I printed it at a 10% angle. For the SM4k you SHOULD print at a 40.6% angle at .03mm. I didn't do that, just to see what moire effect might come through. I was pretty surprised it wasn't as bad as I expected. In fact I think it's probably acceptable.

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Moire/banding was very minimal.

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Still suction at the edge of the floor.

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Overall side view

[Erock482]

You might try building a support lattice in the body of the car to help hold the sides from bowing. if you make it thin enough it should be easy to rip out after curing.

[timwatson]

You might try building a support lattice in the body of the car to help hold the sides from bowing. if you make it thin enough it should be easy to rip out after curing.

That's an awesome suggestion - that's my next plan. Thanks for coming along.