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Laser Etching a Stone Arch Bridge's Facade

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Posted by richhotrain on Wednesday, April 22, 2020 10:37 AM

Don Z

Not trying to be the wet blanket to this party, but do you think a railroad would really go to the expense of buidng all of those arches instead of using fill for the upslope until it reached the spot where the span is needed?

I know, I know...it's my railroad and I'll do it my way. Too many arches was the first thing that caught my eye.

How about the Old Stone Arch Railroad Bridge in Minneapolis? 

There is a prototype for everything.

Rich

Old-Stone-Arch.jpg

Alton Junction

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Posted by Don Z on Wednesday, April 22, 2020 10:22 AM

Not trying to be the wet blanket to this party, but do you think a railroad would really go to the expense of buidng all of those arches instead of using fill for the upslope until it reached the spot where the span is needed?

I know, I know...it's my railroad and I'll do it my way. Too many arches was the first thing that caught my eye.

Regards,

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Posted by tstage on Wednesday, April 22, 2020 9:15 AM

railandsail
I realize that it would take X amount of time for the laser etch machine to make each arch piece (or perhaps each 3-4 arch singular piece),...but isn't that just machine time? In other words it doesn't require a person standing by doing the process, nor reprogramming the machine for each piece? Thus the cost could be very reasonable?

There is machine time.  There is wear 'n tear on the [limited life] cathode and ruby, which would probably be reflected in the machine time.  There is the setup cost of the material with the machine, as well the drawing/programming of the CAD/CAM file.  All those combined can really add to the cost of a project.

Bottom line: It would probably be less expensive for you to purchase a decent 3D printer and print them up yourself.  You just have to determine if it's worth the investment.  You could also contact Shapeways and have them quote you on a 3D project to give you and idea of the cost.

Tom

https://tstage9.wixsite.com/nyc-modeling

Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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Posted by railandsail on Wednesday, April 22, 2020 8:31 AM

Plaster Castings vs Etched Taskboard

I've not worked with either so my questions might appear novice.
 

Wouldn't the plaster pieces have to be of a considerable thickness to be durable during trimming, handling, and mounting? Making the arch pieces curve compliant might also involve other problems with these rigid pieces? I assume it could also be a little messy and dusty?
 

I realize that it would take X amount of time for the laser etch machine to make each arch piece (or perhaps each 3-4 arch singular piece),...but isn't that just machine time? In other words it doesn't require a person standing by doing the process, nor reprogramming the machine for each piece? Thus the cost could be very reasonable?

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Posted by railandsail on Wednesday, April 22, 2020 8:27 AM

wvg_ca

you should add a filler or liner to the arch inside, would look quite a bit more realistic

 

I have been considering that arched liner, and perhaps that could be added later. That flat curved piece very likely would NOT have to be etched, etc,...just stock piece of plastic stone sheet

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Posted by mbinsewi on Wednesday, April 22, 2020 7:16 AM

I'd carve it all out of styrofoam.

Mike.

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Posted by Doughless on Wednesday, April 22, 2020 7:14 AM

I think it looks pretty good as is, with maybe more honing of the color to look less gray.  Kinda looks like a simple black and white photo rather than a color image.  And I would think about adding some sort of liner on the inside.  Lots of dark shadows there, so you wouldn't see much detail at all beyond a few feet of the inside.

Many modelers are beginning to build structures in the same way.  Highly technical and crisp digital photos glued onto simple foam board.

If you listen to the mathemeticians in the room as it applies to scale, we probably would not see a lot of 3D texture from that real distance anyway.  So the cast type of arches probably have too much detail for what should be seen.  (Kinda like ballast, where modelers might want it more coarser than scale because it suits their eye) 

Edit: While the columns or pilasters in between the arches look good, you may want to try to add a bit of 3D texture to them.  Place a strip of styrene under the photos slightly narrower than the columns.  Then when you crease the photo around the column as you glue the whole thing, the column stands a bit proud of the remaining arch.  A little actual 3D texture if you want to go that extra step.

I think that if you cut the photo and then add somehting to it, it will show rather badly.  I'd want to photo to stay seemless by simply putting something under each column then wrapping the photo over it.

- Douglas

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Posted by tstage on Tuesday, April 21, 2020 6:37 PM

And the more arches you have laser-cut; the cheaper each one will be per piece.  They might even have a forum you could join...

https://tstage9.wixsite.com/nyc-modeling

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Posted by wvg_ca on Tuesday, April 21, 2020 5:47 PM

you should add a filler or liner to the arch inside, would look quite a bit more realistic

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Posted by richhotrain on Tuesday, April 21, 2020 5:37 PM

railandsail
 

Can I find someone with a laser etching device willing to tackle this project ? 

Just Google 'custom laser-etching services'. There are a number of online firms that provide such services.

Rich

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Posted by railandsail on Tuesday, April 21, 2020 3:24 PM

Laser Etched Substitute

Next I took my scissors to those arch hollows to see what this might look like,...not bad.

 

My current thoughts are how might I substitute some sort of laser etched piece of plastic for those paper/cardstock pieces I used in the mock-up??

Lets just say that at the present moment I do not really need a total 3-d relief for those stone facades, just enough to represent stone faces, ….not the fully developed proud stone columns in between each arch.
 

This should be relatively easy, and quick for a laser etching of a thin (.040-.050”) piece of styrene plastic,...and just repetitious ?? The 'hollow' in the archway would be just left un-etched, then scissors used to cut out the hollow. The heights would also be adjusted by scissors. Perhaps the arches could be 'printed out' in groups of 2-3 rather than just singles?

 

That piece of thin styrene will easily bend to the curves of my roadbed. Perhaps some other plastic material might be suggested?....or thin sheet PVC to mate with the cellular PVC of my frame structure.
 

Can I find someone with a laser etching device willing to tackle this project ?? (correct me if I'm wrong, but it should be pretty simple as I have laid it out?)

 

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Laser Etching a Stone Arch Bridge's Facade
Posted by railandsail on Tuesday, April 21, 2020 3:22 PM

Laser Etching a Stone Arch Bridge's Facade

In the past I have spoken and posted a number ot things about building a Stone Arch Viaduct.
Some construction methods got pretty involved with molds and multiple plaster castings, etc, etc.

At this point of time I do not have the time, nor inclination to get that heavily involved with a true 3-d
replication. Rather I am considering a method somewhat similar to the mock-up method I utilized. I took a photo representation of a single arch, resized it for my needs, then made multiple paper copies that I glued onto heavier card stock paper, then trimmed with scissors, and joined together at preset seams.

I taped these temporarily to the cellular PVC frame roadbed/structure I had built to display the track's inclination.

As you can see I have MANY somewhat duplicate arches in the overall expanses of my

via-duct,..except in multiple heights from low to high on both sides.

This would involved a LOT of plaster castings !

 

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