The J.L. Mott Iron Works Building

After nine months of design, experimentation, and construction, my bridge project is finally coming to an end. Time for allowing myself more distractions. My recent acquisition of a Beamo laser cutter was another reason to try out new ideas. I didn’t have to look far for a new project, though. I now had the Bruckner Building and the Third Avenue Bridge. But there was a third landmark structure missing from my original layout: the J.L. Mott Iron Works building located on Third Avenue across the CNJ Bronx Terminal.

History

Over time I had collected a number of photos from archives, websites but also from my own explorations of the neighborhood. The building must have been in a pretty bad shape for a long time but it still radiates some of spirit of the industrialization of the South Bronx. We know little about its construction except that its different sections were built between 1860 and 1892. Jordan Laurence Mott commissioned them for the production of his iron cast products. The original owners used them until 1902 when they moved their production to Trenton, NJ. See a good summary of J.L. Mott’s history here.

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The building is part of an entire factory complex with the two oldest sections attached perpendicular at the the back. From structural details we must assume that the main building along the Harlem River was built in two stages. The front section closer to Third Avenue must have been built first in 1880. Its decorative side faces the street as the main facade. It reached to the edge of the underpass. Two different kinds of bricks form a clear line between the older and newer sections. The newer section was added only 12 years later. The second half of the building begins with the already mentioned underpass. In the first half on the 20th century, a railroad stump track lead through the building into its backyard and further to the Bruckner Building where it served the loading docks.

Layered Design

I already had an Inkscape design from an earlier attempt to scratch-build the structure. We can get the main building’s measures from a survey map. It is about 197 ft long and 37 ft wide. I had to estimate its height using the photographs and came up with about 60 ft without the cornice and the little turrets. In retrospect I may have underestimated the height slightly. For the proportions, the archive photo taken from across the river in 1932 showing the facade along the Harlem River turned out to provide good guidance. With those measures, the building will end up 36 cm long and 7 cm wide (or about 14×3″) in N Scale.

As material, I chose 1/16″ MDF. My tests with smaller samples turned out to be very positive. It was soft enough for engraving brick structures from a photo as well as patterns. But it was also strong enough and would not break as easy as basswood. And I could cut it at a reasonable speed with two passes on my 30W laser cutter. As I had done before with the Bruckner Building, I used .017″ lazerboard for the windows.

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I engraved and cut the walls of the building in several layers. The primary wall (layer C in red) is cut of MDF but only after several layers of patterns have been engraved: A grayscale photo (BW1) with the actual brick and other wall structures; a brick wall pattern (BW2); areas where lintels, window sills, and other elements like the wall anchors will be placed (E). The window layer (W1) is made from separately cut lazerboard. The second window layer (W2) is used for the upper half of the double-hung windows. Also not shown is the glazing layer which I hand-cut of 0.3 mm strong transparent (probably PE) plastics sheets. The construction of the windows leaves a recess of about 1.2 mm. This translates to about 8″ in the real world.

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Engraving, Cutting, Painting and Weathering

Once I had figured out the settings for cutting and engraving the MDF, producing the walls was straightforward. I was particularly happy with the engraving. Engraving elements of the actual building surface through a heavily edited grayscale photo greatly improved the prototypical look of the model. To paint the model, I started by applying a coating of matte clear finish followed by a layer of diluted Testors enamel white paint. This will fill up the engraved mortar lines and other wall textures. I then carefully applied a mixture of raw umber and yellow oxide lightened up with white using a sponge. Where that coating was too heavy, I added back some heavily diluted white enamel paint. Close to the roof and around the downspouts I weathered the bricks with diluted black India ink to mark superficial water flow.

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In a next step I cut and painted the window sheet from lazerboard. To increase the depth of the windows, I only cut the lower sash of the double-hung windows but left open the upper sash. After I had glued the painted window sheets to the finished wall, I glued upper sash separately onto the W1 layer from the outside. That way the upper sashes were flush with the back of the wall (layer C in the diagram above) and on top of the windows (layer W1). As the last layer, I added the glazing on the back of the window (W1) layer.

The Decorative Facade on Third Avenue

The short front facade along Third Avenue needed a separate design. After all, I wanted to preserve its decorative nature in my model even if I had to simplify it a little bit. Rather than making it from one piece, I cut it from 13 different pieces (center and right photo above). The outer frame, the inner walls and the brick infills under the windows had to be glued on three staggered different levels, each one 0.5 mm apart. The building has an entrance on the ground floor and on the second floor two pairs of arched windows with a mullion. While I simply engraved the the horizontal structures like lintels and sills and painted them in a lighter brown, I designed the mullions as a vertical element from bottom to top. This helped with the staggered assembly of the pieces, but it also made the entire wall very robust.

Structural Support

Even though the MDF sheets I used are strong, building an N Scale structure of this dimension wouldn’t be possible with structural support. I included it in the design from the beginning. At the core of the building is a system of interlaced horizontal floor and vertical wall elements. Again, for reasons of size I had to split them in two sections. The precision of the laser cutter is such that the well fitting floors and walls do not need to be glued to form a stable structure. The floors are shaped like a frame with a 2″ wide opening in the center. The walls can be inserted diagonally so that the notches interlock with the floors. The inner wall then can be rotated until it is perpendicular to the outside wall and snaps into the end position.

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The outside walls are attached to the framework through the lintels. Tabs of 2 mm depth at the outer edge of the floor frames serve as lintels. Every second window has an opening where the lintel would be that matches the corresponding tab (see right photo above). This way, the walls fit exactly onto the frame with maximum accuracy. Obviously, the window sheets also have the same openings to let the tabs of the frame pass through the MDF.

Detailing

Two weeks after having cut my first facade, I was able to glue the walls to the interior framework. Now I had a complete structure with just exterior details missing. I had to add the lintels made of lazerboard and sills for which I used 0.5 mm strip wood. On the Southeastern part of the building, I also had to add round steel plates for the wall anchors. For these I used small lazerboard discs less than 2 mm in diameter. Furthermore, I covered two loading docks, one on each side, with rusty doors made of styrene. Also, the staircase inside the building needed stairs from the exterior ground level up to the elevated interior ground floor. At some point in the future I’ll also add interior lighting. But that can wait.

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I was able to complete my first scratch-built structure for which I cut the wood on my own laser cutter and engraver in less than a month. The advantages of having my own device are obvious, even if it’s an entry model. The capability of doing rapid prototyping – try something, design and cut it and use it if it works or forget it if not – makes the process more efficient and less frustrating. The approach of improving the design incrementally yields to better results. Also, I’m no longer bound to what the market offers in models, kits or components. And the best of all, the process is repeatable, reusable and scalable. For instance, I can easily re-cut a piece of wood in case I messed it up with painting or weathering. Or I can build an entire ensemble of similar buildings.

Epilogue

While digging through some material on the Iron Works building, I came across the redevelopment projects mentioned in an earlier blog. In the meantime, those projects have progressed and are being realized. I was not really surprised to read that a demolition permit was granted to the developer of the lot on the westside of the Third Avenue Bridge. Earlier project documentation said that the building (which is not a designated and protected landmark building) would be integrated. I was relieved that when I recently made the hike up to the Bronx, the building was still there. Though no longer as this proud free standing structure.

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