So far what is your favorite resin for detail?

[mahcr450]

The Siraya build grey looks similar to the Sunlu resin. 

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[GaryHinshaw]

Those look great.  What can you say about the strength and/or flexibility of the cured product? Any issues with warping?

[mahcr450]

This resin is brittle compared to Siraya tech after curing.  But to me it compares to the flexibility of a cast shell.

This is an HO scale replacement for an Atlas RS3 to convert to a MoPac GP12.  I print at 23.5 degrees and drew internal supports.  The internal supports print at 90 degrees to the build plate and help with reducing layer lines and warping of the shell sides.  There is still some warping where the cab is attached on this shell.  I think I can reduce that with another support.  I haven't seen additional warping once the supports are cut away.

The only thing still bugging me are the support attachments around the shell perimeter.  Particularly on the battery boxes.  I'm thinking of trying a membrane section that will transition from the supports. 

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[Lemosteam]

Experimenting some more. I really like the concept of the membrane, but I took it a few steps further. I created a file with various types of supports that I can copy in and manipulate to another shape, by altering height, width and length.

Yesterday’s attempt yielded a complete model with som design, and print file improvements on the way.

If successful, the final kit will be made of five parts; a shell, roof, chassis and two end sills that will mount the couplers.

[Chris333]

Those supports are groovy baby. 

[Lemosteam]

Those supports are groovy baby. 

The wave started after removal. They are perfectly straight in CAD.

[Lemosteam]

Soooo close on the board gaps! About 50 percent are see through an were printed horizontally.

[Erock482]

@Lemosteam

What was your exposure time on that one? and what do the board gaps measure out to in the model?

[Lemosteam]

Well, your advice has paid off, resulting in some great prints of late.

Roof was printed at 30 degrees with the Z height set at 0.03mm. Terrible pic but you can see the rivet detail. The
PRR K7 had layered pitched, and riveted panel seams that taper down at a very slight angle. Printing it horizontal left some really bad striations that the angle eliminated.





I can tell you that the snap of the roof into the shell was quite satisfying, and the fitment is near perfect now that I moved the membrane under the shell.



Reprinting the shell and roof is almost to the point of how I need it, and the detents and alignment lugs aligned really well.





Reprinting the chassis was equally satisfying with a snug but non interference fit into the shell. The four jack pads provide the vertical location for the chassis.





Adding a brass strip provides a decent weight, and fits well once the puddling and support puckers are shaved away.



So results are much better with everyone’s help and so a huge “THANK YOU” to everyone!

[Lemosteam]

@Lemosteam

What was your exposure time on that one? and what do the board gaps measure out to in the model?

@Erock482 , the gaps measure 0.3mm on the model and I think the exposure was 3 seconds, with the Z height set to 0.03.

[Erock482]

I feel like the exposure it still too high and causing bloom, Using anycubic gray or elegoo gray and .05 layer height I'm running 1.3 for my layers

[GaryHinshaw]

That's looking way better John!  Isn't it great when parts fit perfectly?   

I would tend to agree that the exposure per layer is still too high, especially for such a thin z layer.  (How did you arrive at a layer thickness of .03 mm?)  For comparison, the grating on this tank car frame has a gap size of .25 mm and the grating slats are .15 mm thick.  This was printed with a 2.0 sec exposure, a layer thickness of .051 mm (equal to the x,y pixel size), and printed at 45 degrees with Anycubic Basic:



The grating dimensions are oversize compared to the proto, but the print itself is as crisp as I could ever hope for.

[Lemosteam]

That's looking way better John!  Isn't it great when parts fit perfectly?   

I would tend to agree that the exposure per layer is still too high, especially for such a thin z layer.  (How did you arrive at a layer thickness of .03 mm?)  For comparison, the grating on this tank car frame has a gap size of .25 mm and the grating slats are .15 mm thick.  This was printed with a 2.0 sec exposure, a layer thickness of .051 mm (equal to the x,y pixel size), and printed at 45 degrees with Anycubic Basic:



The grating dimensions are oversize compared to the proto, but the print itself is as crisp as I could ever hope for.

@GaryHinshaw , since the screw controls the Z, the layer height can be controlled. This is what let me set the roof at 30 degrees.

Now that the design is proven (still need to work out some fits on the end sills) I will be able to print the kit and refine the exposure time until I am satisfied. Still not sold on the Siraya resin either, even though I have seen improvement.

The reason I have been using 3 seconds is because I am using some 0.3mm wire supports and barely touching supports.

[Chris333]

John, I'd try at least once printing with less time. I don't have the same printer so can't really give you a good starting point.

[AlwaysSolutions]

I tend to agree that 3 seconds seems like it could be trimmed a bit, but - if the exposure time isn't getting you anywhere (sometimes it won't) - add a chamfer to the bottom edge, inner side of your slats.  Inner side so it's hidden, bottom because of the orientation of your model to the build plate.  Basically you're setting up as little surface area as you can get away with so resin isn't hanging out in the gap areas.  Or, a low effort alternative for you to try is to actually increase the layer height, try .05.  Super thin layers allow light to pass thru them, exposing resin sitting on top of the cured layer to UV which can gunk up your details.  Thicker layers do a better job of blocking that effect.

Good luck! -Mike