So far what is your favorite resin for detail?

[bbussey]

This is the NH County-series currently.  The vestibule end has been removed to both be smooth and to remove curl-up on the fluting over the step cutout.  I'm now contemplating splitting the end face into two pieces and rotating them so that the sloped areas are smooth and any stepping would be underneath the diaphragm frame and unseen.  Again, this prints vertically with the right-side being the base against the build plate.

[bbussey]

This is kind of what makes me mad. In theory, the full cross section of each layer should be perfect, independently than layer from layer where suction comes into play. That last print was a 5 second exposure per layer, and I still get the bloom with this resin.

If you're printing vertically, yes.  But not if you're printing the car horizontally (upright or upside-down is irrelevant).  There's no support when each slat starts to print.  The support at the angled bracing isn't enough. At .051mm thick layers, it will sag.

Since you have the floor and body as one piece with the roof separate already ... I would try printing the body/floor/roof vertically as one tubular part and print the ends as separate parts.  Either vertically, or face-up.

[John]

This is kind of what makes me mad. In theory, the full cross section of each layer should be perfect, independently than layer from layer where suction comes into play. That last print was a 5 second exposure per layer, and I still get the bloom with this resin.

5 seconds is way too long ..

I'd refer you to this -- it helped me a bunch ..  https://3dprinterly.com/how-to-calibrate-resin-3d-prints-testing-for-resin-exposure/

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Finally, make sure your resin is not expired.  Where is your printer located and what temperature is that space?  Mine is in the basement .. normally around 60F in the winter .. I warm my resin bottle up in hot water, also warm up any left over resin in the vat and the build plate .. to do that, I have a piece of glass sitting on top of one of those oil based space heaters .. and just put the resin bottle in hot water on the glass plate - also the build plate and vat

[GaryHinshaw]

I don't really have anything to what Bryan notes above.  My take aways are:

- stick to the basic resins,
- design break-way supports directly into the model,
- avoid orientations where a lot of material suddenly appears on a new slice, and is poorly supported.

[bbussey]

Now that I think of it ... there's no reason why any boxcar/stockcar/reefer can't be printed vertically with the floor/body/roof as one part and the ends printed as separate parts.  There is natural support and the body would print with no distortion.  My Erie model printed nearly perfectly, and that was before I went to the membrane base.  The circus stockcars were flawless, with the membranes.  I think I'm going to try one of the 50' boxcars by creating a floor.  I always can design it to utilize the MTL plastic centersill/underframe to save time, and perhaps also design it so that MTL stirrups can be slid in from the ends before the car ends are epoxied in place.  Weights can be epoxied to the floor also prior to installation of the ends.

[Sokramiketes]

This is kind of what makes me mad. In theory, the full cross section of each layer should be perfect, independently than layer from layer where suction comes into play. That last print was a 5 second exposure per layer, and I still get the bloom with this resin.

The longer the exposure, the more the UV light bounces around, and the more bloom/growth/etc you get on the parts.  This is the elephant foot thing you see on the initial long-exposure first layers.  And it's likely what is making your details soft and your board gaps filling in. 

Decrease that exposure dramatically, after the first few layers for good adhesion, and things should sharpen up. 

[narrowminded]

... by running a 0.02mm membrane around the perimeter for a depth of 1mm, then widening it to .1mm and drafting out to the base at 8%.

Did you really mean a .02mm (.000787") membrane?   Or could it be .2mm (.00787") membrane?  I'm surprised if it's .02 and will certainly try it.  I would never have thought to try something that thin for that length with the whole car hanging on it.  .008" I might have tried if I had thought of the concept but not less than .001".  

I really like the concept and will be trying it if I ever get back to model printing, not just mechanical parts for more machines.

[bbussey]

0.2mm membrane, extends from the edge for 1mm, then thickens to 1mm and drafts out at 8% to the base.

[narrowminded]

0.2mm membrane, extends from the edge for 1mm, then thickens to 1mm and drafts out at 8% to the base.

OK.  That is very plausible!   I read that other post and the .02mm dimension didn't really register.  Then later as I was thinking about it, all of a sudden it hit me.  I still think in inches so it's not reflexive.

While we're here, how high is your membrane piece below the .2mm?  I would guess about 6mm from the picture but...

[bbussey]

Minimum height of 5mm to the base.  Base is 1mm with a 30% inward draft.

I think and work in metric now, other than when dealing with prototypical measurements.  But once scaled down, I switch from Imperial to Metric.  Much easier because it's Base 10, and it allows for a smaller greater precision.

[narrowminded]

And for @Lemosteam:  That bloom you're experiencing is part of what I experienced with Siryatech Fast resin.  And with 5 second cure times it would be completely out of hand and would justify the frustration you've experienced.  For basic outside dimensions I wasn't having much trouble, really liked it, but when fine detail was important I found it not so great even after some valiant efforts.  I like its characteristics as far as toughness/ a little flexible and have been using it for all sorts of functioning parts in building some peripheral machine parts but for modelling with a lot of intricate details it just doesn't render well.  Basic shapes OK and will continue using it, model or not, but for real fine detail it just isn't there. 

An example of a part that printed satisfactorily was the tie beds I developed.  A few adjustments and it printed well and was a little tougher than the standard Anycubic (and others) resin.  Seemed like a winner.  But what surfaced later, which I didn't find in the basic literature but should have been there, was its dislike of acetone.  And one of the key ingredients in the Pliobond glue IS acetone.  Meanwhile, the Anycubic resin that I used for most of the development work withstands acetone well and can even be wetted at any time if some glue has set, needs thinned, or if rework is needed.  That became an important feature to gluing rail to those tie beds.  What I found with the Fast resin was it became very weak if it had been wetted with acetone.  Not so with the Anycubic resin and some have even been washing prints with acetone just for the cleaning ability but also the quick dry.  So any benefit of toughness that was realized, which wasn't really a big deal with the most basic care in handling, and really only mattered when handling before to install, and was NOT an issue once glued to the board, was all for naught.  Had something that worked and then worked hard to create a problem!  I hate when THAT happens but I've done it a few times over the years.  I call them solutions for problems that don't exist.   Good luck!

BTW, I have been printing with the Mono at 1.7 second times +/-  for pretty much any of the resins I've used and never more than 2.5 seconds.  That was just recently on a new higher temp resin that's full of ceramic powder, Siryatech Sculpt Ultra.

[peteski]

I think and work in metric now, other than when dealing with prototypical measurements.  But once scaled down, I switch from Imperial to Metric.  Much easier because it's Base 10, and it allows for a smaller precision.

I suspect you meant "greater", not "smaller" precision.  As in greater accuracy.

[nickelplate759]

This is the NH County-series currently.  The vestibule end has been removed to both be smooth and to remove curl-up on the fluting over the step cutout.  I'm now contemplating splitting the end face into two pieces and rotating them so that the sloped areas are smooth and any stepping would be underneath the diaphragm frame and unseen.  Again, this prints vertically with the right-side being the base against the build plate.

@bbussey  I realize you are doing this for your own (amazing!) modeling, but it if ever were to evolve into some kind of kit I'd sure want one (but to be honest, exactly one).

[mahcr450]

I can add some additional information to the resin discussion.  I've used Siraya fast grey with my Epax E10 exposing for 2.5 seconds.  I print mainly HO scale but my brother pushes for N scale items for him.  Detail isn't bad.  I do have to work for the best supports and print orientation.  I recently tried Sunlu grey for 2 second exposures.  It seems the detail is better defined with this resin.  However, cured parts don't flex as well. 

The main issues I have remaining are where supports attach.  I'm looking for a cleaner transition and the membrane drawings are interesting. 

Mike

[bnsfdash8]

I switched to Siraya Tech "Build" a little over a year ago and haven't looked back.

I run it at 0.05mm layers with 1.9 second exposure on the Mono X

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