PRR K7a Stock Car build

[peteski]

There is a board at the top, but the groove is minuscule at 0.1mm and so disappears under paint. There is also a groove at the floor height outside.

This to me looks like a perfect example of where the model's designer would make the grove a touch deeper/wider to compensate for the paint thickness (which he knows will be applied). Like you said, compromises have to be made when designing a small model. Just don't make the gaps grossly too wide/deep (like the infamous meat reefer).   

[Lemosteam]

@peteski, No it just means that I am not a good painter, lol.

I really should have used the air eraser on this model. It’s just such a pain to set it up and use for one project.

I’d feel differently if I had built this for someone, but it’s for me and compared to any other K7a out there, it’s much better, IMHO.

[Chris333]

Robbman used to say if you made rivets in N scale no one could see them. So he drew them oversized...

[Lemosteam]

Well of course! I never can draw things at scale in N when I do an HO or S Scale model for a customer and I decide I want the design in N, I scale it down, and things get so small they’d never print. N Scale is fudge factor city.

[wm3798]

So this is for transporting dogs?

[peteski]

So this is for transporting dogs?

Maybe giraffes?   

[bbussey]

Hi Bryan, love your confidence! I'll send some stl files to you.  I'll reimburse you for your print, if you are willing.

I don't care for the SW tan, the clear is much better now than that and the old FXD. The two materials are just new Projet material iterations.

Have you done any accuracy studies to verify against CAD?

The print volume is not there yet for me and the things I want to print and I want to be convinced of its accuracy, and I still don't like the resin mess.

I’ll do the print test, send me the STLs.

I haven’t checked every print coming off the DLP printer, but a checked the first few and they were within acceptable tolerance. As long as the factory settings are followed for the various resins on slice times and delays and raise times then parts print perfectly. I’m very pleased with the DLP. The SLA printer is relegated to printing items such as car payloads and scenery detail parts.

The DLP is faster than the SLA. Yes, the plate volume isn’t there yet. But I can still print on one plate: at least three car bodies; a complete 85’ passenger car body, floor and interior; 200 coupler pocket adapters; at least two motive power bodies and test frames; dozens of detail parts; and much more. It’s also possible to stack parts and take advantage of the volume if needed. That doesn’t save on print time, but it would save on labor time. Although given the low print and labor cost on a loaded plate of parts, it’s not worth saving that setup time.

And regarding Shapeways printing vs DLP printing - it’s not even close cost wise. I have an Excel sheet with formulas that calculates unit cost based on raw material cost, FEP cost, isopropyl cost, resin volume, electrical use, setup/breakdown labor, print time and part cleanup time. It costs pennies on the dollar to DLP-print vs SW contracting. It’s a no-brainer on product development. How many submissions did you make to SW until you got the final design?  I also printed an EF4 Virginian Electric engine frame last week to confirm the design actually works from an operational standpoint. It can’t pull a feather because there is no weight. But it will pull itself, so I was able to confirm the frame design is viable before sending the digital model off for machining.

[Chris333]

Where do you find settings for specific resins?

All I've ever found were a list posted that is made up from other users. Never any info from a resin maker.

[dem34]

  I also printed an EF4 Virginian Electric engine frame last week to confirm the design actually works from an operational standpoint. It can’t pull a feather because there is no weight. But it will pull itself, so I was able to confirm the frame design is viable before sending the digital model off for machining.

 

So your saying I might not need to stumble upon a rare Graham Farish model to have something to put under that Shapeways shell in the far future?
Also makes me wonder if there is enough strength there for a stripped down, bare essentials chassis to have accommodations for more standard Tungsten cubes etc.

[rodsup9000]

Where do you find settings for specific resins?

Anycubic has setting for their resins

  https://store.anycubic.com/blogs/news/resin-settings-for-anycubic-3d-printers?tm=tt&ap=gads&aaid=adaSU7wmdvATJ&gad_source=1&gclid=CjwKCAiAi6uvBhADEiwAWiyRdkSxFE-fCiy9655AKTkzIH-qczFw1xB51tlDT6KSNs9rEip_RI2a7hoC620QAvD_BwE

[Chris333]

Ah thanks. But they seem to only list settings for their printers. I just got some Anycubic Craftsman resin in to try.

[rodsup9000]

I just got some Anycubic Craftsman resin in to try.

Craftsman resin on a DLP printer is unbelievable. Very sharp edges and round where it'd supposed to be. Details really pop.

 Haven't tried any on a mono screen yet.

[Cajonpassfan]

Great model, great prototype!
Too bad it don't moo😜
Nice work, John!
Otto

[bbussey]

@Lemosteam John, I printed your test today.  All the detail rendered and the slats are see-through.  I used the auto-generate option for the supports and didn't fine-tune them much.   While the supports on the A-end could use some manual adjustment and reduction, the goal was to prove that a DLP could render the model better than Shapeways as opposed to rendering a perfect print.  The model was printed at .50mm slices on .51mm XY pixel resolution and a 44.43° angle with the A-end of the body facing the plate.  The model printed in under 4 hours.





I assembled the body/roof and applied a coat of Mr Surfacer red oxide primer.  I drilled the grab iron holes through with a #80 bit (I missed the rib grab holes and vertical grab holes on the ends) and enlarged the roof-mount holes in the body with a drill bit that matched the diameter of the roof mounting pins.  All fine detail including the rivets rendered.  As I mentioned, the build supports could be adjusted on the A-end so the yoke sill fully renders.  I did not carefully remove the supports on the A-end, so that resulted in minor damage.  Normally, I use minimal supports on the end that are strategically located.  Given the presence of the extended yoke and the rib bracing, there really is no need for any supports on the wood slats.  However, the following photos still show the quality of the AnyCubic DLP printer and craftsman resin.

[Lemosteam]

@bbussey Impressive, and thank you for proving your point.  The end wall on the unsupported side is incredible, supported end not so much, and on the roof too.  Support tweaking would be a thoughtful process.

I do have a version of it with your cutaway ribbon wall support technique, both for the roof and the shell, which I bet would render perfectly at 0.03 steps

I'm sold, but it will be a while before I buy a DLP.  Ladders even printed nicely (the kit doesn't have them, it uses an etch).

As a debt fulfilled, I will mail you an etched fret to finish it off.

Thanks again!