1907 Scherzer Rolling Lift Bridge CAD designed and 3D Printed

[Jim Donovan]

This tread will feature the use of 3D resin printing. It is not a typical thread but intended for those having an interest in how 3D printing can add something unique to the hobby, something other methods of modeling would be hard pressed to duplicate. I will be showing how the files are designed, parts printed, cleaned and assembled. In addition to 3D printing I will be using wood and airbrushing. I intend to take my time as many of the parts needed will be pushing the printer to its' absolute limits of detailing. Upon completion I will be uploading the files to the 'sharing' section of Tinkercad so others can download the files for their own use.

I've been assembling a shelf layout scene of NW Ohio featuring the Miami-Erie Canal as seen in 1912.  Researching bridges of that era I came across detailed photos and diagrams of the Monroe Street bridge in Toledo crossing the canal. To recreate the bridge as realistically as possible most parts will be made with an AnyCubic 5s Pro, a resin 3D printer first introduced 2023. It has a large printing plate and high vertical lift allowing for rather large detailed parts to be made. It is able to reliably print a single layer at.05 mm or approximately 1/500 of an inch. This allows parts as thin as .20 mm, which in HO scale, is just under 7/10 of an inch. Much of the iron parts will be an inch or 1.5 inches thick. It can make all the parts needed with no variation easing assembly. Due to the size and more importantly the complexity of the bridge I need to make the bride in sections, much like the original and then assembled it like a plastic kit.

So here is the project bridge:

[Jim Donovan]

Here is a photo of the printer which is located in my garage, note that I keep it in a soft frame enclosure (Amazon about $60) which includes an exhaust fan. I have it vented through a window to the outside. Liquid resin printing produces an odor that while not unpleasant is noticeable and I'd rather not have it smelling up the garage. Further, the resin is toxic much like fiberglass when in wet form so needs to be handled with nitrile gloves until processed. Another good reason to vent it, just to be safe. 

After a part is made on the printer it needs to be washed in isopropyl alcohol to remove excess resin. I use 99% (bought from Amazon by the gallon). and for most parts place them in a washer/ curing machine I bought from Anycubic for around $129. For parts that are too big to fit I have a 12 x 12 lidded plastic container filled with the alcohol and simply wash them by hand (gloves on). I only replace the alcohol when it gets cloudy which is maybe twice a year. After being washed the parts have all supports removed using very sharp flat angled shears, Sometimes for really tight areas I use nail scissors.

[Jim Donovan]

There will actually be two bridges crossing the canal eventually this one for vehicle traffic and a second located a little ways away for trains. This first bridge will go straight across from the seen road across the canal with the rolling lift section located closest to you in photo. There will also be an operators building on this side. I plan to locate to bridge in the middle where the water currently stops to hide any line that may be seen when the rest of the water is added. The train bridge will be where the canal curves off the layout into the background. You can see the rough marker lines on the foam board showing where canal will go.

[Jim Donovan]

That provides the background on this build. I have designed much of the lift portion of the bridge using Tinkercad and have made some test parts to see how they turn out. I've already learned this one is going to take a lot of patience.. The parts are so thin coming out of the printer they must be handled gently in washing and support removal or they wil tear. Once they are placed in the UV curing station to complete the drying process they are firm and can be handled a little easier.

In addition I am really working Tinkercad right to the edge. It is a good program but really not made for the number of associated parts and complexity I am making. It has limits in size I am going to have to work with but through some tricks I can make it work. Here is a couple of screen shots showing the lift section side girder trusses. One while the program complained at complexity (it finally got there) and the one showing the finished part. However I found I had to break each side section into its seven sub assemblies as the file was too large for Tinkercad to export as a whole.

Next post I will get into the bolts of design and printing.

[elwoodblues]

Jim,

This is going to be a very interesting project to follow along.  I personally don't use Tinkercad as I use Fusion 360.  I use Fusion 360 as I make my 2d patterns in Autocad, import the dfx file into Fusion 360 and then extrude the 2d pattern.  While Tintercad seems to be a basic program I see you can get some very complex parts out of it.

Looking forward to the next update.

[Rick]

Jim, I don't have any plans to do 3D printing but I do find the process interesting.
Thanks for sharing your setup, what you plan on printing and how you're going to do it.

[TomO/Tloc]

I will be checking in. Bridges fascinate me. I just finished a Swing Bridge kit for a friend and am now kit-bashing the approach bridges to it. Watching a 3d built bridge come together will be great

TomO

[KentuckySouthern]

Well presented, I might get around to showing off my printing plant one of these days, too. 

I did finally get a handle on printing, now to find something useful to print.  I'm back to negative territory in CAD.  Fusion360 passed me by like an express train in the night.  Still in sub beginner with the FreeCAD.  Most tutorials list themselves as beginner but few really are. 

Love the bridge project, Jim, coming along well.

KarlS

[deemery]

Jim, can you tell us about the oil derrick?  Was that from a kit?

dave

[Bernd]

I'll be following along on this adventure. I've always fancied Scherzer Rolling Lift Bridges. I'd like to build one using brass and animate it someday.

Do you plan on animating the bridge?

Bernd

[Larry C]

Jim not that I ever intend on 3D printing but this project seems fascinating both on design and approach; I'll be following along and see how things develop.