Holt 150 Ton Field Monitor

[rifleman]

wow thats awesome looking great cant wait to see more well done

[rockpaperscissor]

The build continues.

Photos 1 and 2 show the front piece in place. I glued the hatches and machine gun port to the piece, then I started gluing the part in place starting with the white valley folded section first, then the floor of the gun mount. I left the front flaps open so that I could insert a mat board reinforcement piece to the floor of the gun mount. When dry, I folded down the front section and glued it in place. So far so good.

Photo 3 shows the open hull with the lower deck piece to be glued in place next. You'll note that I added a couple of mat board bulkheads for strength. I left these @ a 16th of an inch short and glued a long piece of mat board on top. Then I folded the glue tabs down over top of the mat board. Finally, I glued a single layer of paper to the top of the mat board, but not over the tabs, so that I would have a strong level surface to glue the lower deck onto.

Photos 4 and 5 show the lower deck in place. The ventilation grates, exhaust flanges and rear machine gun port have already been glued on. Visible in photo 4 are a couple of mat board strips that I affixed in place to glue the angled side wall of the upper deck support to. Note that the top of the upper deck has been prepared in the same way as the lower deck: mat board support glued in place, glue tabs folded over, and a piece of paper glued to the mat board to provide a level surface for the topmost skin. I also glued in a couple of Q-Tip shaft axles before closing up the box. The rest of the photos are just additional views of the build so far. Some are redundant.

The next installment will (hopefully), have the main gun mounts in place and the top deck skinned.

[rockpaperscissor]

An update for your viewing pleasure.

The main gun emplacements have been installed. The first photo shows the unassembled parts. The front shroud is made up of three pieces. Each gun mantlet, for lack of a better word, is also made from three pieces of paper. I assembled the shroud first. The mantlets are shorter so that they can fit inside of the shroud. The gun subassembly is then glued into place. I cut out the round openings for the gun barrels which will be installed at the end of the build.

After the gun mounts were in place, I glued a rectangular cover piece to the top which will support the forward part of the upper deck skin. The installed assembly and "roof" are shown in the next two photos.

The last photo shows the upper deck skin ready to be installed. To prepare for this part to be glued into place, I found it necessary to cut off the rearmost glue tabs and add a bulkhead to spread the opening at the rear - without support, the sidewalls had a tendency to cave inward.

Once the upper deck skin is in place it'll be time to work on the turrets. I'm really looking forward to this part of the design/build process.

[CharlieC]

Coming along very nicely.

Did you consider putting a bulkhead on the back of the gun mantlets with a hole in it so the barrels are supported in two positions? I can see the barrels being a problem with sagging if they were located in only one hole. It would certainly be necessary if you wanted to scale the model up to 1:50 say.

Regards,

Charlie

[rockpaperscissor]

Thanks for your thoughts, Charlie. Yeah, that would have been smart. My plan now is to plug the rear end of the gun tubes. They will be passed through the hole in the mantlet, and after 7mm or so they will butt up against the white panel that lurks behind the guns. I intend to elevate one or both of the guns a bit, so they will have to be cut at an angle at the back so they butt squarely against the white panel. This will serve as the primary glue point, with the opening in the mantlet providing forward support.

[rockpaperscissor]

Here are a few more progress pics.

Photo one shows (not very well) the texture strips that were added to the sloped sides and fascia of the roof over the gun mounts. These strips cover the exposed edges of the reinforcing cardboard.

Photo two shows the exhaust pipes for the kerosene burners that heated the steam vessels. I just made stubs with hinged caps that would close when the burners weren't running to keep dust and water out. The British modeler's scratch built interpretation of the vehicle has long muffled exhaust pipes that extend back far beyond the rear of the hull. I didn't like the look of this arrangement at all. For all we know, the burner exhausts could have exited out the back of the hull, or even from underneath.

Photo 3 shows the upper deck skin in place. The ventilation grate/hatch was glued in place prior to attaching the skin. This was the final piece of the hull.

I drew up and assembled one of the hatches in B&W. Everything fit perfectly, BUT once again, I must have had the page magnification wrong when I drew the height of the turret sidewall. As a result the turret was significantly too tall. I didn't realize it until I placed it on top of the hull. D'oh! Everything else was fine, so I only had to redo that one piece. I'm not going to bother to build a new B&W turret, so I'll progress straight to texturing.

[Vermin_King]

Even at 1/72 scale, this is going to be huge. Did you choose the color based on the first image?

[FRD]

Excellent subject to model..

[CharlieC]

I think your intuition about the exhaust pipes is probably accurate. Steam engines don't have mufflers because the last thing you want is any restriction in the exhaust which reduces the draft on the boiler. In fact steam engine designers went to a lot of trouble to try to increase the gas flow through the boiler by piping the exhaust steam from the cylinders to the exhaust stack just to get more draft through the boiler. (It's what causes the "chuff-chuff" sound on steam locomotives).

The Doble steam engines were a little different since the steam was recirculated via a condenser and the firebox had an electric fan to provide the draft. If interested there are videos by Jay Leno on YT on his collection of Doble cars.
1925 Doble E-20 Steam Car - Jay Leno's Garage - YouTube

Charlie

[rockpaperscissor]

Yeah, it's pretty huge VK. The hull measures 8 3/8" x 3 1/4" by 1 3/8". The wheels will add quite a bit more to the overall dimensions. I was shooting for a khaki brown color along the lines of the illustration you referenced. In some of the photos it appears more yellowish than it actually is.

FRD, I believe that I'm the first to tackle this beast in paper. I like to model these little-known subjects.

I'm glad you concur with my interpretation of the exhaust, Charlie. I'll check out Jay's video. He has some very rare and unique cars in his collection.

The first turret is built and in place. I double checked the page magnification this time. It went together without a hitch and is the most parts intensive bit up to this point. That will change soon though - lots of parts in each wheel. I've been working on the B&W alpha drawings. They're so big, each wheel will take a full piece of letter sized paper.

To the pics...the first photo shows an "exploded" turret. The center strip has a wide glue tab, but I cut it off and glued it inside to make an internal joining strip. It makes for a much nicer looking assembly, I think. Unfortunately, the turrets will be fixed in place. I suppose I could have cut round holes in the decks and glued an extra cylinder to the bottom of the turrets to make them rotate, but I didn't plan for that and didn't want to risk the possible damage that might happen if I got scalpel crazy at this point in the build.

The next couple of photos show the front and back sides of the assembled turret. The last two photos show the upper turret in place. I oriented it a bit to the right. The lower turret will be rotated to the left. This way the viewer will be able to see both sides of the turret from one vantage point.

The next installment will be some shots of the completed hull with both turrets in place. Hopefully I'll have an assembled B&W wheel to show off too.