Small Delivery from Model Train Stuff
With the pain booth being back in business I decided it was time to try out the wheel masks offered by American Model Builders.
New Air-Hose Installed
The new air hose and Iwata airbrush come post locomotive display case, so I made a few modifications to facilitate painting. Swapping the hose with the Badger fitting for the hose with the Iwata fitting was easy enough. A few turns with a wrench and the job was done.
The air tank is positioned where the air line comes through the floor from the garage below. I decided to place three brass hook under the display case to hold the air hose as it extends from the air tank to the paint booth. This keeps it out of view and always handy. I also place a couple of hooks on the side of the pain booth that fit around the moisture trap on the hose and feed it into the paint booth.
Looking forward to doing some painting soon.
Iwata Revolution HP-SAR Arrives Today
The Meridian Speedway paint shop has been inactive for some time now. A couple of packages arrived in the mail today that will change that!
I was quite displeased with the spray consistence of the last cars I painted with my once trusty Badger airbrush. These cars were the four Y&MV Thrall all-door boxcars. At the recommendation of Matt Sugerman, I decided to make the switch to Iwata. My comfort zone lies with single action, so I elected to get the same brush Mr. Sugerman has, the single action Iwata Revolution.
At first glance, this feels like a finely machined instrument! The weight and motion of the pieces are impressive. The kit comes with some needle lube, a wrench, and a bottle. I also got a badger hose with a moisture trap and the Iwata fitting. I was quite pleased with the Badger hose I was using before.
I look forward to great things from this airbrush!
Busy Week - Update
Since my last posting on Friday much has happened. Determined to get some NTO gondolas created I managed to push the painting process for four more Gunderson 2420 gondolas into the routine. Friday night while watching A Christmas Story with the family I multi-tasked, using the Solvaset and Scotch-Tape method to remove the logos and numbers from four gondolas: 1 MP, 1 CNW, and 2 SSW cars. The process worked very well.
Then on Saturday, after work and before attending an Ugly Christmas Sweater Party at a co-worker's house I prepared the cars for painting, applying shop trucks and couplers to all four. Additionally I have decided to go with brown for the truck color on the rock gon fleet, so I removed the trucks from the two cars already painted, TGN 403056 and TGN 403222.
The wheelsets were removed from all of the truck frames and the inner parts were masked. I had recently purchased a Bluecell Alligator Clip Stick set off Amazon for painting small parts. I used these for the first time, mounting them in a block of Styrofoam from an old Walthers kit to hold the truck frames for painting. The clips were very cheap, about $5.00 for 25. The wooden sticks are pointed at one end and can double as uncoupling sticks for Kadee couplers as well!
I also nailed one more snap-track panel to a scrap MDF strip for car handling in the paint booth. This brings the number of these done to four. They are very convenient for placing and removing rolling stock on the turntable in the paint booth.
After work on Sunday the cars got painted. A bottle of 50/50 mix of Scalecoat II Bocxar Red and Boxcar Red #2 was made. One small bottle was more than enough to paint all four cars with a little left over.
First I painted all four cars upside-down with the shop trucks removed. Once all four cars were painted this way I reapplied the shop trucks and painted the cars right-side up. This allows for even coverage of all of the detailed surfaces of the cars.
By the time Monday evening rolled around, the paint had cured enough to apply decals. On Monday cars NTO 403305, NTO 403472, TGN 403110, and TGN 403129 had identities and were added to the equipment database!
Now sporting matching brown trucks, the two cars done earlier also posed for new builders' photos:
So six down...18 to go! Then I should have the start of a respectable unit rock train.
Also on Monday a small package arrived from Internet Trains. I had ordered some paint to keep the paint shop in business. While looking though their website I was a bit disappointed to see that some of the colors I was looking for were out of stock. There seems to be a consensus that MinuteMan Scale Models will be a reliable steward of the Scalecoat line of paint which it purchased from Weaver Models which went out of business this summer. Therefore I am not too concerned about the out of stock colors. Paint can also be ordered directly from MinuteMan Scale Models. The button below will take you to their site:
The order received from Internet Trains on Monday 12-7-2014 included 4 bottles of Scalecoat II Paint: 1 x S2002 Oxide Red, 2 x S2027 IC Orange, and 1 x S2087 Boxcar Red #2. Since IC Orange makes up 75% of my Y&MV freight car mix I ordered the two bottles to keep my bottle of Tuscan Red going. I see many more Y&MV freight cars in the future! The Oxide Red is a new color for me to experiment with. And the Boxcar Red #2 is of course part of the TGN/NTO brown formula. The Boxcar Red that goes with it was out of stock.
I also made my first Tru-Color Paint purchase - 1 x TCP-017 flat and 1 x TCP-018 gloss. This is part of my effort to find a replacement for the "Floquil Weathering Trinity" discussed in an earlier blog post. Give the endorsement of Tru-Color Paint by new model manufacturer ScaleTrains I figured it is time to become familiar with their products.
On 9-17-2015 I received two of the three numbers of the Atlas DOWX 23500 gallon tank cars--DOWX 40033 and DOWX 40040. I had noticed that the third number, DOWX 40037, was available at Internet Trains so I did add that single car to this order. I really like the appearance of these cars.
Well I guess this is enough for a week in review!
Compressed Air Routed Through the Floor
As my air compressor is rather large and noisy, it belongs in the garage...at all times! My newly confiscated man-cave room that will house my first serious HO scale railroad (Meridian Speedway Vicksburg Terminal) sits directly above the garage. I used my vacation time this week to take advantage of that positioning and drill a hole. A simple task...or so I thought.
A 20-foot reinforced 3/4-inch diameter water hose from Home Depot was my conveyor-of-choice to transfer air from the compressor in the garage to the air tank in the train room. Again I enlisted the assistance of my uncle, Joseph Scorsone, for the project. We figured we should have this done in about an hour.....not!
As it turned out there is about 18 inches between the floor of the train room and the ceiling of the garage which meant a second trip to Home Depot for a LONG bit and then a third trip for a bit extension. I do feel better about the house knowing how much insulation there is around the garage!
Also it seems that the width of the wall of the garage is wider that the width of the wall of the train room. The first hole, and the second hole we drilled down from the train room ended up in the wall of the garage. At last, the third hole drilled about six inches from the side wall of the train room landed in the garage! The hose fit snugly to the bit extension and was easily pulled through the floor into the garage. Success at last!
A metal file cabinet used to store indexed photographs fits nicely over the hose's entrance through the floor, both protecting and camouflaging it at the same time. The 15-foot hose from the tank to the airbrush will allow me to not only easily paint items in the paint booth, but also paint items on the railroad as it takes shape.
The entrance in the garage ceiling is nothing spectacular. It is directly over some wall-mounted shelves, also camouflaging the air line's entrance into the garage. This hose was fitted with male Quick-Connect fittings at both ends. The air tank valve and the air compressor hose are now both fitted with female Quick-Connect fittings so that when disconnected, the air in both the air tank and the compressor will be bottled.
And the timing of this project while my wife was out of town on a business trip...strictly coincidence!
Moving Forward - First Meridian Speedway Railroad to be Built
Yesterday I noticed that one of the two light bulbs in the Paint Booth had burned out rather prematurely. After opening the package I noticed that the fine print said that the bulbs should not be oriented upside-down. Perhaps that had something to do with it.
After dropping the kids off at school this morning, a quick visit to the Home Depot yielded a pair of new GE LED bulbs. Man they are nice! Great light and no heat! A bit pricy, $15 for the pair; but, given the proximity of the bulbs to where I am working, having no heat is a great thing.
Onto bigger and better things, I have decided to build a railroad in my current house. I had originally planned to wait until we moved into our next home with a bigger space by design, however, my wife is not quite ready to move yet. Some nonsense about the kids and high school and blah, blah, blah!
It has been nearly two years since I moved back to Fort Worth, TX from Lincoln, NE and I have the itch to build something. Today I evicted my kids from the spare bedroom that has become their playroom. Really superfluous as the kids live on the xBox anyway.
I have big plans for the room - my Man Cave. This will be the test bed for me to learn some modeling, scenery, and electrical skills. I spent a good portion of the day clearing out all of their stuff. It is nearly a clean palette for me to start. There will be updates coming soon!
The room is 10'X12' and will house my office with several work stations, including the paint booth. Sitting directly over the garage, the room is positioned perfectly to run an airline from the compressor. That will be tomorrow's primary task...
More Hooks Added - 11-30-2015 Mods
Everything has its place in a clean and safe shop environment. The paint booth is no exception.
Another dozen brass hooks were strategically placed within the painting chamber of the air brush paint booth.
A single row of seven hooks spaced two inches apart on the right hand wall are now home to seven pair of shop trucks.
Three hooks in vertical formation on the right wall between the front panel and the electrical box will house shop couplers.
Finally an additional hook was placed on each wall about 2 1/4 inches to the front of the existing airbrush hooks to cradle resting airbrushes.
Everything in its place.
Floquil Crystal Cote, Glaze, and Flat Finish
Now that I am getting back into the swing of painting and decaling, it is time to focus on the next step - weathering. Because I have been detached from painting for about five years now, since brfore I moved to Lincoln, NE, my experience lies with products that are no longer available. I'll pose the question here, looking for answers on FaceBook....
Back in the day, my trusty standby mediums for decaling and weathering were Floquil Glaze, Floquil Crystal-Cote, and Floquil Flat Finish. If using Scalecoat II paint, the finish was always glossy enough that I would apply decals directly to the painted surface. If I were painting with Floquil or some other paint that dried with a dull finish, I would spray a coat of Floquil Crystal-Cote to the model before decaling.
Once decaling was complete, I would usually spray either Crystal-Cote or Glaze to the model to seal in the decals before weathering. Floquil Flat Finish was always an ingredient in the weathering colors I concocted to spray on the decaled models. Some Glaze or Crystal-Cote might be mixed in as well to achieve the look I may have been aiming for.
After the weathering layer dried, I might even spray the model with some mixture of the Trinity to tweak the final finish and seal in the weathering layer. A hint of a secondary weathering color might be included at this level. I found that several clear layers as well a a weathering layer do an excellent job of hiding the edges of the decal film.
While I still have a few bottles of the "Floquil Trinity" in my secret stash, I guess it is time to search for a replacement. What are the expert painters using today? I have seen posts touting the use of aerosol cans of flat or gloss finish, however I do not intend to point an aerosol can at my models!
I pulled out of couple of CCBX ElastoFlo covered hoppers I painted and weathered several years ago to review. The aim for these cars was a very light weathering with some luster in the finish. The Floquil Trinity was used to achieve this.
I look forward to hearing from the airbrush weatherers out there. What are we using today now that Floquil is no-longer?
ICG 822649, TGN 403056, and TGN 403222 Get Decals
Today some decaling was on the task list. Specifically the three cars painted yesterday would become ICG 822649, TGN 403056, and TGN 403222.
ICG 822649 is the third Walthers 50' Seico Pulpwood Flatcar I pained Scalecoat II IC Orange and lettered for the Illinois Central Gulf using Daniel Kohlberg's decal set ICG-32. The earlier cars completed are ICG 822604 and ICG 822676.
The other cars and Daniel Kohlberg's template made fast work of the decal application. I do enjoy working with these decals. Putting the cars together reminded me that the underframe should be painted black. I am not really sure that I will take the time to correct this as I plan to keep the car upright!
Next on the work table were the two Gunderson 2420 gondolas. Since I repainted a MP car and a CNW car one has black trucks and one has brown trucks. I am thinking about painting all of the trucks brown but I have not made up my mind.
And below are a few more imags of the work completed at the end of the day:
Black trucks or brown....that is the question!
Booth Upgrade and More Cars Painted
Hopefully you all had an excellent Thanksgiving! I am starting a week of vacation which means lots of projects around the house. One of the many tasks is the conversion of the kids playroom into my new office and the transformation of the loft into the new playroom. This is a good move for me.
Among some of the adjustments today was the movement of my paint booth to my new office. The window exhaust panel fits nicely in that window as well. Of course a test run in the new location was in order!
Once in position in the new office I decided to make a modification to the paint booth. I installed six brass hooks inside the booth to hold paint droppers. This will make it easy to find these items and keep more objects with wet paint contained within the painting chamber. This was a very easy mod to make!
I had taken the lettering off two of my new Gunderson 2420 gondolas this morning - one MP and one CNW. With another 14 coming to make an even two-dozen, I had better get started painting the fleet. I also needed to an another coat of orange paint to the Seico Pulpwood car I have been working on. Only the upward surfaces needed painted so this car would only get painted upside down.
Before painting came some of the preparation - getting everything in order. These gondolas will be the first NTO/TGN cars to be painted brown. For this color I have decided to use a 50/50 mix of Scalecoat II Boxcar Red S2013 and Scalecoat II Boxcar Red #2 S2087. Similarly to the bottle I marked for the Y&MV 25/75 brown formula, I marked a bottle for this 50/50 mix.
First up for painting was the ICG Pulpwood Car.
My son Jacob took a quick video clip of the paint booth in action:
Next up were the two gondolas. I decided not to prime these cars to see just how well the Scalecoat II paint covers the models. With a total of 24 of them in the works, priming each would be a lot of extra paint. This is why I decided to start with one green one and one brown one to see if I can tell the difference once the cars dry.
All done. At first glance it appears that the single coat covered the gons quite well. Tomorrow they will get a closer inspection once they are dry.
Freight Car Paint Stock
As I continue with the cataloging of my freight car fleet I have decided to create a separate section in the Meridian Speedway Freight Car Index for equipment purchased for future custom painting. This will allow me to focus on specific projects and identify surplus equipment.
A new page was created for Freight Car Paint Stock. This page can be accessed from the Freight Car Main Index page via a button in a new section under the Rolling Stock Alphabet Section.
The button below will also take you to the new page:
Pulpwood Flat and Thrall Door Boxcars Painted
This morning I was able to do some painting in the new paint booth. It has been almost five months since I applied primer to the first two Y&MV Thrall All-Door boxcars with unsatisfactory results. It was this event that inspired me to build a paint booth for future painting.
In the interim I have formulated the color for my brown Y&MV freight cars. The formula is 75% Scalecoat II S2027 IC Orange and 25% Scalecoat II S2012 Tuscan Red. Yes, I know that the Scalecoat brand is changing hands...we will have to wait and see what the future holds.
Since I would be painting with the IC Orange, I decided to first paint the Walthers 50' Seico Pulpwood Flat that I had primered with Joe Bohannon's Chinook Lines Gray straight orange. I have already painted and decaled two of these cars ICG, and I have on-hand three more ICG pulpwood car decal sets.
After a thorough cleaning, my trusty Badger single action airbrush was ready for painting.
I had hoped that painting in a more controlled environment would allow the less-than-perfect primer coat on the Thrall-Door boxcars to remain. As the final paint layer dries, it looks to me like the cars will be just fine! Once the cars are decaled, gloss-coated, weathered, and clear-coated I am certain they will be sharp looking models.
I am very pleased with my color selection for my Y&MV brown. The shade of brown is very appealing! Using IC Orange as the base for this color subliminally ties this equipment in with IC/ICG orange equipment that will be roaming the rails of the Meridian Speedway with them. Below are a couple of shots of these cars drying this evening:
Air Tank Upgrade, Compressor Failure, and First Paint
Last Friday, yes...Friday the 13th, was a busy day for Meridian Speedway Paint Shop progress! The morning began with a trip to Home Depot for a few components to upgrade my air tank, followed by the disappointment of the failure of my compressor to start up. That evening Joe Bohannon of the Chinook Lines and his wife came over for dinner. He quickly found the issue with my compressor and fixed it. He also brought a few locomotive shells, his own paint experiment, and his airbrush. All of this led to an impromptu test-run of the new paint booth!
The air intake valve that I have used on my air tank will work with any hose fitting that will air-up a car tire. I have had this tank for over 20 years and it was designed to take to the corner gas station and fill with air. Moving forward, I never have made adjustments to the original plumbing (built by Lenny DiMartino), not even after I purchased a large air compressor over 15 years ago. This meant that as the tank ran out of air I had to stop the painting process and manually refill the air tank.
Considering the time invested in this paint booth project to the end of a better painting process and higher quality painted models, I decided now was the time to fix this. I was hopeful that there would be quick-connect appliances that would fit right onto the current threaded intake pipe, however, I was not to be so lucky!
Instead I decided that the best route would be to install a quick connect valve between the tank and the existing piping, allowing two methods for filling the tank with air. The below slideshow hi-lights the modifications to the air tank.
Modification complete, I was now ready to break-in the paint booth with a test run...or so I thought! I had the window exhaust panel in place and connected to the paint booth. The air tank hooked up to my airbrush via a new hose (the old one desperately needed to be replaced), and I had hooked up the compressor to the air tank. I was excited by this arrangement as the compressor hose is long enough to allow the very noisy compressor to remain in the garage while connecting to the air tank several rooms away.
Then I plugged in the compressor, flipped the power switch, and...nothing! My trusty compressor of many, many years decided to pick this moment to not start! I was displeased. To YouTube I went to research this issue and figured it was probably the starter switch.
Coincidentally fellow DFW area model railroader Joe Bohannon had reached out to me on this day to see if there were any opportunities to do any model railroading. I explained to him my task for the day and my obstacles. By the end of the conversation a plan was in place and we had company lined up for dinner.
Joe and San Antonio area modeler Anthony Lorch had already collaborated on the issue of the disappearing brands of paint facing the hobby and are experimenting with a creative solution. Joe has some unique colors for the locomotives of his Proto-Freelanced "Chinook Lines". Most notably is a difficult to describe gray/blue/green...ish color that he got from a German military color pallet. He thought I might be interested in this as the greens for my T&GN and NT&O locomotives were victims of Testors' genocide of the Floquil line of paint and are no longer available.
Joe, with a clear head, quickly honed in on the issue with my compressor, a power wire had come off the connection under the starter switch cover. The fix was very simple...and we had air! Joe did bring his own compressor and airbrush along with a quart of acrylic enamel paint from Sherwin Williams to test. The quart, matched to his model paint using Sherwin Williams' "Spectrometer", cost $22. The quart of course yields 32 ounces. Considering that most model paints are sold in the range of $3 to $6 per ounce, the cost savings is worthy of notice.
After dinner, it was time to paint. I decided that the Chinook Lines color would make a good primer so I grabbed a Walthers 50' Seico Pulpwood Flatcar from my repaint stock, removed the couplers, installed shop trucks, and we were set. Unfortunately I guess I failed to properly clean my airbrush after the last use and an unexpected blast of air went into the paint bottle, instantly adding a neat gray/blue/green...ish explosion pattern to the inside of the paint booth. It was christened properly!
Deciding to deal with that later, we substituted Joe's double-action paint brush and we were spraying. A few test sprays were in order and the paint/water mixture was adjusted. The below slide show shows the the painting of the pulpwood car as well as one of Joe's GP7 shells.
So I was definitely out of my comfort zone here. I have never before sprayed with a double-action airbrush, never before airbrushed a water-based paint, and of course the painting environment was new. The paint booth worked like a charm! No explosions, no fire, and excellent ventilation. The ultimate test came from Joe's wife who declared that she could not smell paint in the house.
I must admit I was a bit skeptical about using house paint on a model. The result of this test has my attention! The finish was remarkably smooth and thin. I think that once I get comfortable with the properties of this paint there are excellent results to be had.
Many thanks to Joe Bohannon for his assistance! Now to get this airbrush cleaned out...
Paint Booth Ready For Service
It has been a while since my last update on the paint booth. My children's football, cheer, and gymnastics schedules have cut into my available blog time considerably. I am pleased to announce that all components are complete, tested, and ready for service! Going into off days here, I intend to get a few items painted.
The last booth update included the initial plans for the window exhaust panel. There are only two major design changes to this panel.
First, the plan called for an enclosed chamber with a connection to the paint booth duct on the interior panel and a louvered vent on the exterior panel.
The exterior panel design was changed, with the center being left open for the entire width and height of the chamber. This was done to allow for better ventilation and dilution of the contaminated air.
Another design change was to the top of the panel. Instead of having the top a single panel that tucked behind the window, a channel was created that would cradle the bottom of the lowered window, creating a more secure and air-tight fit.
A late modification to both the paint booth and the window exhaust panel was the addition of stainless steel handles to assist with movement of the items as their size makes them a bit cumbersome.
The below slideshow hi-lights the window exhaust panel and its placement in the window opening:
Once installed in the window, a 4-inch dryer duct with specially designed PVC sockets fits snugly on both the fan motor exhaust and the back of the window exhaust panel. There were some holes in the metal casing of the fan which I sealed with silicone.
The next series of images show what the window exhaust panel looks like from the outside. You can notice the change in position of the center louvers when the paint booth fan is turned on.
I also created a few accessories to assist with painting. I made a turntable using a couple of scrap pieces of MDF as well as a ball-bearing turntable bracket which cost about $5.00 at the Home Depot. This works remarkably well and was quite simple to make.
In addition I nailed two pieces of snap-track to two separate scrap MDF strips for models to sit on during the painting process. These track panels will allow the painted models to be removed from the paint booth without having to be touched. In order to help secure the models during the painting process I used crazy glue to lock one axle on each of the four "shop-trucks" that I put under the models. This is essentially like securing the equipment with a hand brake as I do not want free-rolling equipment on the turntable during painting.
A late modification to the paint booth was the addition of a brass hook to each of the side walls inside the main painting chamber. These were stretched open with pliers to allow the paintbrush to fit. This now provides a secure place to rest the airbrush with bottle attached during the painting process. The below slideshow hi-lights this mod as well as the operation of the turntable in the paint booth:
It seems like this project has taken an eternity to complete! Many thanks to my uncle Joe Scorsone who did most of the actual construction work on both the paint booth as well as the window exhaust panel. Looking through my blog posts, however, reveals that the timeline for this project only lasted four months! The first blog post was published on 7-9-2015.
I hope to be able to share many great projects that will come form this paint booth!
Window Exhaust Box Concept on Paper
The Airbrush Paint Booth is designed to capture all of the air contaminated by harmful vapors during the painting process and keep them out of the indoor breathable air supply. The design of the Paint Booth itself has to be functional and efficient. Once captured by the ventilation process, there must be a seamless flow to export the contaminated air to the outside. This is where the Paint Booth Window Exhaust Box comes in.
The fan exhaust is a 3-inch diameter pipe which can easily connect to 3-inch foil dryer duct. While this duct could be run to the outside through an open door or window, that would leave an opening that would allow outside air (even the exported contaminated air) to flow freely into the indoor environment where painting is taking place.
I decided that the logical exit port should be a window as it could be closed tightly around an exhaust panel that was sized properly. Off to Home Depot I went to examine available components and formulate the design. There is enough wood left over from the 4'x8' piece of plywood used to construct the paint booth itself, so additional wood was not needed. I also had on-hand a 16-inch by 4-inch vent panel that I had purchased earlier for the paint booth but ended up not using. This also will fit into the Exhaust Box design.
Additional materials purchased for the exhaust box were:
1) One 3-inch x 25-foot flexible aluminum foil duct
2) One 3-inch to 4-inch diameter duct increaser
3) One 4-inch diameter louvered exhaust hood (6" x 6")
4) Two 3-inch adjustable metal worm gear clamps
Next I picked a window and took some measurements. It is important to note that the dimensional specifications in the below design are specific to fit the window frame opening that I will be using. If you will be building a window exhaust box, you will need to adjust as appropriate to fit your window design and opening.
The width of the main window opening is 32 inches. This 32 inch width which fits snugly under the raised window and fits flush against a slightly narrower external opening. This will make it very easy to seal off the outside air from the room interior.
Looking at the hardware components and sill/frame outline, I decided that a height of 12 inches would be appropriate for the design of the Window Exhaust Box.
Rather than free-handing the design drawing like I did for the Paint Booth, I decided to use PowerPoint for the below drawings. These drawings are NOT to scale! Hopefully they are easy to understand:
Drawing 1 - Exterior Window Panel
The exterior window panel is the largest component. This is the exterior wood face of the Exhaust Box that fits snugly into the window opening. This window opens by lifting the bottom window upward. The bottom and two sides will be surrounded by the window frame. Once in place, the window can be lowered until it contacts the top of this panel, completing the seal between the outside and the inside.
The 16-inch by 4-inch vent cover is the only piece of hardware that will be attached to this panel. This vent will be cut directly in the center of the panel.
Drawing 2 - Interior Room Panel
Opposing the Exterior Window Panel is the Interior Room Panel. This panel does not need to be as wide as the window panel, but it does need to be wide enough for a connecting chamber to be built between the two panels containing airflow between the two. Therefore the 16-inch wide exterior vent cover and the 6-inch square louver cover will have to be within the dimensions of the inner chamber. I decided that a width of 20 inches and a matching height of 12 inches would be sufficient
Drawing 3 - Exhaust Box Top View
The top view shows how the panels will come together. Airflow from the 3-inch diameter flexible foil duct will enter the chamber via the 3-inch to 4-inch adapter that connects to the 4-inch diameter port of the inward-facing louvered exhaust hood. The louvers open easily in the direction of air-flow and shut when the fan is off keeping small critters outside and sealing off any reverse air flow.
From here the air enters a small chamber that forces the air to exit the window through the 16-inch by 4-inch vent in the exterior window panel.
Drawing 4 - Exhaust Box Side View
The side view reinforces the top view. Measurement of the window revealed that the top of the window sill is actually 1/2-inch lower than the top of the window opening on which the Exterior Window Panel will rest. There is also a 1-inch lip extending upward from the window sill that seals off the bottom edge of the window when it is fully lowered. Therefore, the bottom of the enclosed chamber connecting the interior and exterior panels much be high enough to clear this lip. The interior panel will also be placed 1/2-inch lower than the exterior panel to compensate for the lower sill. This will make sure that the exterior panel is "At Rest" in the snug position in the window opening.
For the purpose of these drawings I have indicated a depth of three inches for the connecting chamber between the two panels. The sill dimensions will allow a total depth of seven inches. As I review the proximity of the Louvered Exhaust Hood to the external vent I ma consider some additional depth - perhaps five inches to reduce the velocity of deflected air off the inside of the external window panel.