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:Toledo Lift Bridge over Canal.jpegBridge from Back.jpegBridge from Side.jpegFront of Bridge.jpeg
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.Anycubic Mono 5S Pro In Enclosure with Vent.jpegPower Venting of Printer.jpegwash and cure.jpeglarge cleaner.jpegsnips.jpeg
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.Location of Bridge 2.jpegCanal Road.jpegcanal 1.jpeg
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.
Tinkercad Computing Side Girder System.jpegCAD of Side Bridge Girders.jpeg
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.
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.
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
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 ::)
Jim, can you tell us about the oil derrick? Was that from a kit?
dave
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
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.
Jim very interesting how you do this. I'll be foolowing along also.
Jerry
5-2_Faurot_Oil_Well_00 near canal.jpg
Hi Dave;
The oil derrick was made from an old Campbell kit I bought at a yard sale up in Toledo years ago. I was the first wood structure I ever built. The directions provided by Campbell were amazing it was only later that I learned their original kits have some of the best directions in the industries. You could make the structure with just the directions, the wood was a bonus.
I located the rig on the bank of the Miami Erie since there actually was one. Here is a photo of the original.
I'm curious and have a place for a large, complicated swing bridge on my layout, so I'll be following along.
WOW. What a great project!
Good stuff.
Looking forward to seeing more.
Suggestion
Us old guys have trouble with the green font on blue background.
Black & white is better.
MJinTN
Quote from: labdad on November 14, 2025, 06:52:44 PMWOW. What a great project!
Good stuff.
Looking forward to seeing more.
Suggestion
Us old guys have trouble with the green font on blue background.
Black & white is better.
MJinTN
Thanks for the feedback, I will make the change. We will see how this project goes.
Jim
Quote from: jbvb on November 14, 2025, 11:14:21 AMI'm curious and have a place for a large, complicated swing bridge on my layout, so I'll be following along.
Thanks for following, hope the thread helps.
Jim
Quote from: Jerry on November 12, 2025, 11:43:06 AMJim very interesting how you do this. I'll be foolowing along also.
Jerry
Thanks Jerry
Quote from: Larry C on November 12, 2025, 11:15:29 AMJim 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.
Thanks Larry;
I am going to try and push the equipment and myself to see if we can make a realistic copy of the original bridge. Thanks for following.
Quote from: Bernd on November 12, 2025, 09:51:42 AMI'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
Thanks for following Bernd. As a matter of fact I do indeed hope to animate the bridge, in the same manner as the original bridge operated gear wise. I have a couple of 30 rpm geared motors that should fit where the actual 25 hp electric motor was located so we will see if we can repeat how it worked.
Jim
Quote from: KentuckySouthern on November 12, 2025, 08:15:47 AMWell 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 ::)
Karl, thanks for following along. Hope you get something out of it that helps your own 3D printing.
Jim
Quote from: TomO/Tloc on November 12, 2025, 08:01:13 AMI 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
TomO thanks for following along.
Jim
Quote from: elwoodblues on November 12, 2025, 07:38:00 AMJim,
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.
Ron;
How you are using Fusion is interesting. I will indeed be pushing Tinkercad and using all the tricks I know but so far it is handling the file size complexity so I should be good on this one but I will be learning either Fusion or FreeCad next. I want to do more than Tinkercad was ever designed for. Th.anks for following along
Jim
Quote from: Rick on November 12, 2025, 07:46:46 AMJim, 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.
Rick thanks for following along, hope you enjoy the ride.
Jim
OK, time to start working my way through the various steps. Before I can print or even design a part I need to understand how the bridge was made and how it looked. In this case I also need to know how it operated since I want to recreate a working model. I saw a photo of the bridge years ago and kept it on file. It was one of the previous photos shown and on Monroe street in Toledo Ohio. Going on-line I hit the jackpot finding a tremendous amount of information from the Toledo Museum and the Toledo Historical Association's websites. I printed all the information and placed it in a 3 ring binder for easy reference. The photos are especially helpful. I was even able to get the blueprints, many have been blurred or reduced in size during the past so when I enlarge them to see the details often times I can't read what is written. Still a big help. Finally I found a book at Amazon detailing the history of this type bridge including documents (and photos) of many of the actual Scherzer bridges in the world. All in all I think I have enough to make a reasonable replica.2 Bridge Project Binder.jpg1 Book on Bridge.jpg3 Side Truss Blue Print.jpg4 View of Rivit pattern and plate thickness.jpg located
Are you worried about the strength of the 3D printed parts when the bridge operates? Certainly the engineering of the bridge should help mitigate that risk. One clever thing I remember seeing before 3D printing was on a Silver Crash tank car kit, the railing posts were a composite part. There was resin castings for appearance with a slot for thin brass strip for strength.
dave
A quick note, I am not a mechanical engineer so my determination and use of dimensions are simply my best guess based on observation. I also adjust as needed in order for the model to be structurally sound. In other words the dimensions are a SWAG and good enough for government work!
So now I need to make a list of the various beams and other parts that make up the bridge so as I design the parts I will have a starting point and goal for the CAD model. I will do this one section at a time, the first being the lift section of the bridge beginning with the two side trusses that support the roadbed.
Reviewing the photos and diagrams I settled on the following dimensions:
Since HO is a metric scale with 3.5mm = 1 foot all measurements are in metric for printing purposes. I have converted each to scale inches to show what they would be if 1:1 in scale.
The U channel main beams are being sized at .5mm thick, 1.5mm wide and 3.5mm high. This makes the beams 1.7 inches thick, 5 inches wide and 12 inches high for HO scale. They are used for the side bottom and side top trusses.
The plates used to tie the main beams together are .75mm wide, .2mm thick and 6mm long (rounded ends). This would work out to .69 of inch thick x 2.5 inches wide and 6 inches long. Each plate is tied to the beams and each other by rivets. I designed the rivets to be .3mm diameter by 1mm long resulting in 1 x 3.5 inches. Still close to original just a little higher to stand out.
The diagonal beams are 1mm wide x 3mm high and .3mm thick. In 1:1 scale they are 3.4 inches x 10 inches x .3 inches. The diagonal plates and rivets are same as used on main beams.
Finally, the upright beams that hold the diagonal beams together are .4mm wide x 3mm high and .2 thick, or 1.4 inches x 10 inches x .7 inches thick. The diagonal plates are the same .2mm thick and sized as needed.
Not exactly the original sizes but they are in the ballpark and allow the model to be sound and printable by the 3D printer. .2mm thick parts are right at the limits of my 3D printer converting to .00787 inches, really thin.
These are no means the original specifications just where I ended up in the end. In the beginning I attempted to match exactly what I saw in the diagrams and photos. Then, through trial and error over the past week I test printed each part comparing it to the information I had. Some parts like the rivets ended up having to be larger than original in order for the detail to be seen. Some of the beams needed sections made thicker in order to offer proper support for the model.
I wanted to capture as much detail as possible. The real riveted plates in the V formation consist of flat iron plates overlapping each other and held together by a single large rivet at each end of the plate. So three rivet were needed for every two plates. These rivets also passed through both U channel beams to created a complete truss the upright trusses attach to. To simulated this I offset the V of the plates so they look like one is over the other (but still part of each other for model support) and the rivets are long enough that when dry brushed they will show up against the background.
Here is how the parts look like in the Tinkercad CAD program when put together on these specs:
Upper and Lower Girders with diagional plates.jpg
With the design finalized I export the items one at a time creating separate .stl files. This is a file type commonly used when dealing with three dimensional objects. In order to print the file I need to imported the .stl file into an application called a 'Slicer'. These applications take the .stl file and allow you to make the item 'printable'. The application has the parameters of the 3D printer being used as well and the liquid resin type (you tell it what you have). Further it allows you to set up the necessary supports to hold the item in place while it is made. You can use the program to do this for you, do it yourself or a combination of both. I use a slicer application from a firm called Chitubox. The version I use is free but still has way more ability than I need. After importing I orient the object in the manner I want to minimize the number of supports needed versus the time needed to print the item. It is a trade off, the more vertical space the object takes up in the print space the longer to make but the fewer supports usually required. For example if I printed these trusses as shown in the CAD photo they could be made in about 30 minutes but would require a whole row of supports across the bottom to keep the part in place. Maybe 50 supports each needing to be removed and each might leave a blemish on the item. If I print them on end vertically I can reduce the support count to just 4 but it will take almost 8 hours to make. Since I am more interested in great detail and not time on this project I went with the vertical option. A side note, the slicer programs are getting better but learning how to place supports manually is still a great help. I usually have the program place the initial supports and then I make adjustments. However for complex or really detailed items I add the supports one at a time by myself. This allows me to adjust support size, placement and type.
OK, a lot of explanation. Here is how the trusses look in the slicer program after all supports added and everything checked to make sure it will print:
Top Side Girder Lift Section.jpg
I sent the file to the printer and here is how those parts came out:
Removing the parts from the printer using a plastic scraper I wash the parts in isopropyl alcohol to remove all excess resin, Supports are removed with a sharp sprue cutter, making sure I don't break any of the soft fragile parts since at this point the part is very pliable and easy to tear. Finally they are placed in a UV dryer to complete the hardening process and we have a finished part!
Lowe Lift Section Side Truss.jpgClose Up Lower Lift Section Truss.jpg
So that is today's update. As I write the printer is busy making the other parts I designed for the two bridge side lift sections. I am now designing the roadbed girder system. Till next time.
Quote from: deemery on November 19, 2025, 11:21:31 AMAre you worried about the strength of the 3D printed parts when the bridge operates? Certainly the engineering of the bridge should help mitigate that risk. One clever thing I remember seeing before 3D printing was on a Silver Crash tank car kit, the railing posts were a composite part. There was resin castings for appearance with a slot for thin brass strip for strength.
dave
Dave that is a great idea for something I have been worried about. I will slide cut to shape brass plates though the bottom trusses to improve strength when I get to the construction part. Great idea and thanks for the tip.
Jim
Great looking parts Jim! Tinkercad is finally beginning to raise the bar with the new latest functions. I wish they would add Bevel/Chamfer on path.
Philip
Thanks for following along, I have finally made enough progress to share.
I ended up creating 14 various sections and used thick CA glue to assemble the sections together creating the lift section.
Diagional Truss on Support.jpeg
Here you see a couple of the diagonal truss sections still on their supports having just come out of the printer. An important consideration in 3D printing is where, how many and what size of supports to use when preparing the design for printing. All major 3D print programs have an automatic support function where the program will make and set the required supports. I use this feature to see where the computer thinks the supports should go then delete them and go to manual support. Almost always the program will overdo the supports needed, the fewer supports you can use and the less thickness at contact with the part, the less clean up work you have removing the supports and better finish the part will have. That said you must have enough support, and the right type in order for the part to print correctly. Not enough and the part will fail and oftentimes make a mess in the print tray. Cleaning the mess is not hard but it must be done. Learning to find the right mix of number and size of supports is definitely a learning process.
Adirondack Chairs HO Scale.jpeg..
I will often test making a part using the absolute minimum supports I think needed. If it fails I look at where and why it failed, have the machine clean the tray bottom, correct and try again. I alway have 'anchor' supports, these are either medium or heavy supports located where the most stress and weight will be on the part as it is formed. The further a support is needed away from the printing plate the smaller the support I use is as it will not need to carry the weight or have the stress of the bottom sections. If you look at the above photo of an Adirondack Chair (I am making these for the winter challenge) you will see there are only 10 supports used, 1 medium in the middle and the rest light supports. I was able to simply grab the chair gently with my hand and pull the chair off the supports. For the O scale version I was able to reduce the number of supports to just 6.
The parts are removed from their supports after having been washed in an alcohol bath but before they are placed in a UV dryer to complete the curing process. When you buy 3D resin parts make sure the supports have been removed . Finished parts can be brittle and may very well break if the supports are cut off after the part has been cured.
Thanks for the "lesson". Good information for those of who think we want a printer.
MJinTN
Truss on Left Bottom road base on right.jpeg
Above are the Rolling Section Trusses glued together on the left and I was able to make the under road support section in one shot, it is seen on the right.
Lift Section with 3 x 12 planks.jpeg
In the above photo you see the completed lift section of the bridge. I place a couple of 3 x 12 wood boards in place to make sure I had the clarence correct. The original bridge had diagonally planks as the road surface. The planks were two high and each layer was placed in the opposite direction of the other. Wood was used to keep the weight of the bridge down. If each board went completely across the bridge they would have been about 36 feet long. The diagrams and blueprints I am working from are silent on the issue of if the boards were this length or spliced together. The bridge had asphalt put down sometime much later when it no longer opened so I can't determine the length of the boards. If anyone has an idea on the matter let me know.
Having a wood board surface with the ends of the boards locked under the steel truss was one of the neat features I want to capture of this bridge.
Lift Section Front.jpeg
Here is a look at the section from the front.
Quote from: labdad on January 18, 2026, 08:25:00 PMThanks for the "lesson". Good information for those of who think we want a printer.
MJinTN
Thanks for stopping by. I enjoy 3D printing and especially its ability to create items not usually seen in train modeling, like this bridge. In the beginning I simply made items from files I had downloaded at websites like Thingiverse.com, then as I understood the process better, I started to design simple items like barrels, sacks and such. Today I have a pretty firm understanding of Tinkercad along with the time and patience needed to do CAD design. I'm retired, my layout is a small shelf set up so I use my time to build details. However, 3D printing is definitely not for everyone, if I did not have a vented climate controlled garage to keep it in I would not be printing
Jim
With the lift section finished as far as I can go for now I have begun designing the rolling mechanism part of the bridge.
Development of Rolling Section.png
In the above screenshot you can see the lift section in gray and dark blue. The parts making up the rolling lift section are to the right. The key to getting the bridge to rotate upward correctly is to make sure it pivots around an imaginary center of a circle of which the light blue curved sections seen in the picture is part of. The center point will be where the gearing and shaft will go so when the bridge 'lifts' the shaft will turn, the gearing will cause the shaft to track backwards which makes the rolling section turn as well raising the bridge. Because everything pivots around the center point and there is a counterweight on its 'backside' very little horsepower is needed to accomplish the raising and lowering of the bridge. The actual bridge used a 25 hp electric motor that was housed on top of the red flat section seen in the picture. I will be using a very small geared electric motor that will turn at 30 rpm. Hopefully I can make it work.
Section First Look.jpeg
In addition to designing the next section of the bridge I have started making the diorama part it will go into. The above photo shows the lift section across the canal with pink foam on either side. This rectangle will be the bridge diorama scene when complete. It is obvious that I am going to have to make changes to the layout to make this all work. First the train track on left will need to be moved away from canal and instead be placed against the back wall of the layout. All the building to the right will be moved out (urban development in 1910!). The gray tray the bridge crosses will be filled with epoxy resin to match the rest of the canal and hopefully I will be able to feather the resin in a way so the seam is not apparent. If it is I will think of something to hide it. The gray tray was easy to design and 3D print. It will easily contain the epoxy resin and ensure no leaking occurs.
First Look Bridge Section In place.jpeg
Here you see the section pulled off the layout and some more foam work accomplished. The cut out on the right will end up being an underground walkway for the mules and mule handlers that pulled the canel boats in those days. On the left side you can see I will have a pretty large slope going up to the bridge. While not ideal it was not uncommon back then for roads to be narrow and grades more severe then we see for the most part today. The road will be brick. On the far left you see the flat area where the new track will be located.
Foam Cutter Straight Cut.jpeg
I will finish this update with a couple of quick comments on how I cut and shape the foam board for this project. A couple of years ago I treated myself to a MicroMark foam cutter. Above you can see it with a sheet of foam board about to be cut. I thought I was buying it just because I could but it sure has come in handy. Truly straight clean lines are easy to achieve with the hot wire cutter. There is a variable temperature knob with 5 settings but I keep mine at 3 and it works fantastic. You can see there is an adjustable bar, note that I put a heavy block weight on the far side so that the aluminum bar does not move as I put pressure on it while cutting.
Foam Cutter Free Form.jpeg
In addition the wire cutter can make free form cuts just as easy. No more ugly cuts and foam pieces everywhere. What is really neat is taking the 1 inch foam board and slicing it to 3/8 thick, straight, neat and ready to be used. I used the cutter to create the slope grades on this scene. Overall a great tool.
Until next time, thanks for visiting, I hope you got a idea out of the report.
Jim
Nice machine Jim. Looks like it really can do some nice cutting.
Jerry
Jim, your 3D printed parts look outstanding.
I can see how that foam cutter would come in handy.
Jim,
Been following this project since it's inception. Nice job on getting it printed in resin. I look at that bridge and wonder what it would look like in brass. :o ;)
Bernd
That is quite a complex bridge project, Jim. The printing is well done and your CAD drawings are more artistic in themselves. CAD is where I've fallen short in my 3D endeavors. So far I've found enough drawings online to keep printing as much as I can. There are some nice projects ready to slice and print available.
I've also been following. Congratulations!
Howdy Jim,
Wow, the bridge looks amazing. It's well-engineered and printed.
Have fun,
mike