The Sarlacc Pit?

 

Mock up of engine storage tracks

I was distracted for a few days by an interesting track plan assignment. So today, I started building the pit for the turntable. If you recall, I built this turntable for the Road Show several years ago. I saved the rotating wooden part, but not the pit. So I had to make a new pit. Note that this pit is a conical shape, like the Sarlacc Pit in Star Wars. Now I need Boba Fett figure for the turntable scene. 

I thought, "no problem, I have the files for the parts on my computer, I'll just cut an another set and glue them up." That went well enough for the main pit. But,... for some reason, the wedge-shaped pieces to make the surface of the pit were not the correct size. I must not have saved the final version of that file. So I had to redraw those parts. Now, they are tricky to design as I had to cut the parts in 2D but rotate up to make a 3D cone. It's kind of like trying to make a model of a building with hipped roof from 2D plans, except a bit trickier as this is a truncated cone or frustum.

I could have spent a few hours doing the math, but instead I got out my calipers, measured the required shape and cut the parts on the laser. It took a try or two but I got the parts I needed. I cut those parts from 0.032 in thick laser board. 

Plan B v2 with storage tracks

Now the decision is where to place the turntable. I am coalescing on a modified version of Plan B from my earlier post.  Note that I am adding two engine storage tracks to the design. I like how the parked engines look alongside the engine house. The storage tracks are needed as I have 6 engines, but we usually only use 2 or 3. 

I did a short video describing how the turntable could fit in the space. 

My wife was wrong...

I did use that piece of wood I was saving for 10 years just in case I needed it. But I'm getting ahead of myself.  I have been  laying and spiking track pretty diligently in the past few days. I now have all the turnouts and almost all the track installed. I just need to add one engine  storage track off the turntable and to replace the flex track on the bridge with hand laid track and I'll be done with track. Yes, there will still be several thousands spikes to go but the track will be useable.

The last turnout is installed 

With the track done, the next step was installing the turntable. I am reusing the turntable from the old Falmouth. I was able to disassemble it and save it. The trick was finding a place to fit in the new plan particularly to avoid the benchwork. I had to work around the Ikea legs and a joist that was screwed to those legs. I also did not want the electronics from the bottom of the turntable to interfere with the view of the TV under the benchwork. I decided to install the turntable at the far left end of the lead to the engine terminal. There will be just one storage track and that is a reverse move off  the turntable. That arrangement spreads the engine service facilities along the turntable lead. I think it looks good and allows me to access the turnout switch stands behind the turntable lead without interference from the water tank or workshops.  It also makes the run to the turntable longer. 

I knew the wood scraps would come in handy.

To use the existing turntable base I had to cut the plywood the turntable was formerly mounted on. This was tricky as the existing electronics for automatic reversing and hub for the turntable extended below the bottom of that piece of plywood. So I could not just place the base of the turntable on my MFT and cut away. Instead, I set up my saw horses and used some scraps of plywood that I have been saving for years for a job like this. They raised the plywood base off of the deck and allowed me to use my track saw to cut nice straight lines to trim it. I knew those wood pieces would come in handy!

Fitting the pit around the legs and joist limited
my choice of possible locations for the turntable.

Next I had to cut the hole in the existing plywood bench top for the turnable. I aligned everything as precisely as I could and drew lines for the center line of the track. I took care to avoid the Ikea legs under the table top. I drilled a half inch hole on the plywood table top to accept the turntable axle. Then I used the turntable spinning in that hole as a trammel to mark the circle necessary for the pit. I added a half inch to the radius to allow room for the wooden retaining wall. Then I used my Carvex saw with a fine blade to cut the circle. 

Instant turntable

 I had to notch one corner of the turntable base to fit around the Ikea legs, but the turntable popped right into place. Four screws pulled the turntable tight and secure. I must say it was gratifying seeing the turntable installed in the pit and even with some existing ground cover on the pit floor. 

I installed railroad ties around the pit wall to act as a retaining wall. The ties give the pit a rough and temporary look perfect for a military structure. 

I put a quick coat of paint on the fascia and its starting to look like something. The new Falmouth with its long sidings and greater track capacity should allow more involved  operations. Plus, I think it is going to look really cool.

The installed turntable, painted fascia and some ground cover looks good.

No matter how many times I cut it, it's still too short

I installed the tracks on the turntable and lead. Here is a short video demonstrating its operation. It is a manual turntable both in model and prototype. 

The turntable is based on a design used by the USMRR in several locations. Here is an image of one in Alexandria, VA

As the table turns

The turntable for the road show is nearly done. I completed the pit and the bridge. Once the glue holding the pit in place dries, I'll be able to spike in the rail and finish up the track on the road show.

Look ma, no guard rails!

I installed the last turnout on the portable layout. All that remains are a couple guard rails and the track to the engine house and then all the track will be done. I am pleased to report that the turnouts are working just fine without the guard rails, but I will add them anyway.

I started building the turntable. I opted to go with a common USMRR design. This style of turntable is visible in at least three different locations on USMRR lines. It may be a standard design, though I have not found any documentation that can prove that.

The tricky part was designing the sloped pit. The photos show how I went about building it. Once the putty is dry, the pit will get a light coat of dirt and small rocks.  One prototype photo shows brick lining the upper wall of the pit. I may do that here too as I think it looks neat.

Historic Princeton Junction Photo

Doug Gurin recently gave me a copy of this photo. He didn't have any additional information about it so I posted it here in the hope that someone might know more about it. I did some web searching and found that Princeton Junction was the location where a short branch line connected the town of Princeton to the New Jersey Rail Road and Transportation Company in May, 1865 (see here, here and here for more info.)

There are several interesting things I noticed in the photo. The obvious gallows turntable in the left foreground. The engine has an enclosed tender and it has the passenger car on its nose. The passenger car has a plain, arched, non-clerestory, roof, and small windows.  Note the exterior bracing under the passenger car body.  I am not sure why the wood is piled up by the track, possibly fuel?

Also note the lack of trees in the background. There also appears to be a cemetery or perhaps encampment in the background.

There is currently a legal fight between historical preservationists and the University of Princeton who want to relocate the station and convert it to a bus line.

If you know anything about this photo, please post a comment.

  

Different Viewpoints

I tried a couple photos from different viewpoints trying to show an engine coming off the turntable at Falmouth. I used my  Canon 5D with the 28mm lens. This didn't allow me to focus as close as needed. I'll have to try with the macro lens later.

Need more sharpness in the foreground on this one

Reconfiguring Falmouth Engine Terminal

I built a tool shed structure for Falmouth. This structure is based on a building at City Point, VA as I don't have any photos of the actual facility at Falmouth.

The structure is a laser cut core from 1/8th inch plywood with Mt Albert Board and Batten siding applied. The window and door are Tichy parts. The roof beams, rafters, purlins and joists are strip wood, but I didn't detail them because they can not be seen.

I originally was going to add battens to the roof, but the photos at City Point show a double layered type roof using overlapping planks and not battens. I may retrofit another set of planks over these to simulate that, but I like the look of this roof. The chimney is a piece of brass tube with a small section soldered on top to make a smoke jack.

Initially I had planned to put the tool shed between the back storage track and mainline curve. The idea was that the building would hide some of the sharp curve.  The problem was that the building just barely fit in that spot.  Furthermore, that spot is where a safety track for the turntable lead would reside. The safety track would be a short section of track that would prevent engines that overshoot the turntable from going in the pit.

So I decided to move the building to the location shown in the photo.  In this spot the building still provides a view block function, but it looks like a more balanced composition. I had to shorten one of the storage tracks to make room for it. Instead of engines, this track will be used to store spare wheel sets and trucks.  General Haupt is standing at the site of the new safety track.   I still plan a few more smaller sheds and lots of details for this area, but it is coming along.

Wiring Completed...

The wipers are clearly seen in this view.

 Well not totally, but it is completed in the main layout room.  With the additional of the auto-reverse control unit for the turntable, and laying and wiring the final tracks in the Falmouth engine terminal, all track and wiring is done in the main room. I still have to lay track and wire the Aquia Landing area, but the rest of the layout is operational.

The auto-reverse unit and its bracket.

The first two photos at left show the auto-reverse unit and the wiper mechanism I used to power the turntable. The auto-reverse unit is an On Guard auto-reverser unit from Tony's Train Exchange. I bought several years ago.  Unlike the Frog Juicers, this unit will reverse polarity for both rails. Like the Frog Juicer, this unit does not require a separate power supply. Just connect the DCC bus lines to one terminal and the track feeders to the other. It has provisions for a LED output, but I opted to not connect it as the unit is under the bench work and the whole idea is to make the operation transparent to the user.

The On Guard unit is now obsolete as it can't handle the current demands of numerous simultaneous sound decoders. For now it is working as I only have one non-sound decoder on the layout. We'll have to see if multiple sound decoders cause it to malfunction.  My layout even at its peak will be a light density operation with at most 5 locos running at the same time. According to information at Tony's Train Exchange web page, this unit should be OK under these conditions, but I won't know for sure until I actually test it.

If I run into problems I can add additional boosters. Having more than one booster is a good idea in general because it isolates the layout into electrical sections. These sections are not like the traditional electrical blocks where you have to manually control the throttle connected to each block. The booster sections are transparent to the operator. All they do is help limit current flow in each booster by spreading the load across multiple boosters. More importantly, they prevent a single short from taking down the whole layout. So for example, if an operator at Aquia Landing causes a short, an operator at Falmouth on a different booster would not be affected.

I have wired my layout into three separate power districts. So typically I will see a max of perhaps three locos operating in any one district.  But for now I am running the whole layout on a single booster.  I will need to purchase additional boosters at a later point.

The bracket is scrap wood, so please ignore the black
writing as it doesn't pertain to this application.

The third photo shows how the electrical wipers rub against the metal bands on the turntable shaft creating a home-made commutator. The design will allow the turntable to be removed for maintenance or scenery installation.  The wipers are twin sections of 0.032 inch phosphor bronze soldered to a brass plate.

The two white wires are frog feeders for the double slip switch at Falmouth. Those feeders must run the full length of the room to reach the Frog Juicer circuits.

I decided to add wipers to the tender of the Haupt to improve its pickup. It was running pretty well without them, but I want to see how much of a difference all wheel pick-up on the tender would make.

First I installed an insulating tab on the bolster beam of the tender trucks. The tender trucks are hot, so without insulation the new pickups would short.

Then I fabricated electrical wipers. At first I tried using 0.010 inch flat brass stock. But these did not work well as the wheels have a fair amount of lateral play, and the brass did not have enough flexibility to maintain contact with the backs of the wheels. So I modified the tabs by cutting off the brass extensions, and soldering on 0.010 inch phosphor bronze wire wipers. I arranged these to wipe on the surface of the wheel. They are flexible enough to track the wheels as they move laterally. I applied a liberal amount of 5 minute epoxy to hold the tabs and wipers in place.

I had to drill two holes in the tender frame to run the wires from the new wipers to the motor lead. I cut the existing red wire to the decoder and soldered in the new feeders, covering the joint it with heat-shrink insulation. I actually did this before adding the wipers.

I tested the connections and they worked. The tender will now run without the engine attached.
With the engine attached it runs nearly flawlessly. It takes a fair amount of dirty track to stall it.

So with the engine reassembled. I did some test running. I ran a train from Aquia to Falmouth, reversed on the turntable and then back to Potomac Run to drop off a flat car of lumber. Everything worked, so I can declare the layout operational.

Overall view of the tracks at the engine terminal at Falmouth

Falmouth Engine Terminal

The turntable structure is complete with the final details added. I started to install the storage tracks that are served by the turntable. I considered adding an engine house, but the overall area is too small and even a single stall engine house was too big. This is probably not a bad thing, as I think it unlikely that they would have built an extensive shop at the south end of the line. Still, I do plan to add a tool shed.  The engine shed will be installed at Aquia Landing.

The completed turntable. The pit still needs to be finished.

Staining the staves

I built a single water tank as part of the engine terminal.  I modified a design from City Point, where the tank is tapered and the top open.  This was a fun project that took an afternoon and evening.

The tapered tanks takes shape

I laser cut the staves so that each one had a .005 inch taper on each side. This was sufficient to allow the staves to line up on the tank with the proper taper. The diameter of the upper tank is 0.25 inches less than the bottom. I laser cut these with a central support to keep everything centered and square.

Trying to keep the deck square to the beams.

 I built up the deck board by board on 0.25 inch square and 3/16th inch by 3/8th inch timbers.

The rings are 0.010 by 0.020 inch styrene with Tichy turn buckles.

The canvas hose is a piece of masking tape painted and detailed with styrene strip clamps.

The valve mechanism is brass rod and scrap pieces of timber. I used two pieces of bird shot as weights for the pull cord.

To make the exposed water surface, I puttied and painted the top disk a midnight blue color. Once all the parts were added, I painted the blue surface with two thick coats of Vallejo Gloss Varnish.

Next up is a wood rick and a tool shed.

Does anyone know how they filled these tanks? I see no evidence of a supply pipe in the photos.

I also am thinking about adding an ash pit.  I will probably place  it on the turntable lead, near the water tank.

Here is the finished water tank.

Haupt and Stevenson observe the water tank in action.

Engine Whiton rides the competed turntable.

Falmouth Turntable - Part 5

Another view of the Manassas turntable from Alexander's book credited
to the Southern Railway Colection. Abdil also has this photo in his book.

The Falmouth turntable is nearly done.

 I noticed in Alexander's book, Civil War Railroads and Models, a photo of the Manassas turntable from a slightly different angle than the photo in the on-line National Archives. I initially thought the photos were the same, but in studying them I realized they were two different shots. Compare it to the shot in this first post  Falmouth Turntable in progress. It would have been nice to have a good side view too, but none exists that I am aware of. Many of the details of the two shots are the same so I surmise they were taken in rapid succession.

From this photo it is clear that the upright posts on the end are inclined and not vertical. I also concluded that the upright posts are tapered. So I cut some fresh uprights on the laser  from 3/16th inch basswood. While I had the laser fired up I cut  the iron end caps (rub plates) too. 

I added the truss rods using 0.032 inch piano wire as it was the only rod I had on hand that was long enough. 

The wheels are also laser cut. They are more cosmetic than functional in the model as the weight of the locos is too great for the plastic wheels. I also did not get them all perfectly aligned, but they do add an intricate look to the model.  I added 3/16th inch thick (tall) rub strips under end of the turntable. These bear the weight and keep it level, while also adding a bit of friction that keeps the turntable in place once it is situated. I laser cut the pit rail from 1/8th inch plywood, with 0.015 inch laser cut strap iron on the top. I painted the pit rail a tan color as I assumed it is either stone or wood. The strap iron is painted rust.

 These two photos demonstrate the turntable in action.  The engine was able to load and unload without problem. The turn table spins easily, but with enough friction to avoid accidental overshooting.


I still need to add some details to the turntable, finish the pit and add the wiring including the auto reverse unit for polarity control.

Now that it is mostly complete, I can conclude that.... it sure is an unusual design.

Turntable - Part Four

Time to install the turntable and see how it works.

I made a new shaft for turntable Mark II. The bands came out a bit nicer than the earlier version as I learned from that experience. I tinned the brass shim stock before wrapping it around the shaft, then a quick touch with the soldering iron secured it in place without melting the plastic shaft.  Note that I have not soldered the wire leads to the brass bands at this point. They are dangling from the center of the turntable.

Before attaching the shaft, I placed the turntable on the terrain surface at its intended site and carefully marked the center line of the pivot point. Then I drilled out the center with a 1/2 inch bit to create the pivot hole in the base plywood. The foam here is 3/4 inch thick.

Next I measured the center of the turntable and installed the shaft, taking care to keep it square and plumb. I epoxied the shaft and a laser cut collar on the bottom of the turntable ties. I could not laser cut everything to exact center due to the design of this turntable, so I had to measure the center by hand.

 Once the 5 minute epoxy was cured, I soldered the wires to the bands in holes that I drilled in the shaft.

The turntable pit after hogging out the foam. 

Shaft and collar before the wiper wires are installed.

I marked the perimeter of the turntable on the foam  with a pencil on the end of the turntable as it rotated. Then I hogged out the foam and removed any traces of hot glue that held the foam in place. Luckily there wasn't too much hot glue, but there was a glob right where the shaft went.

I tried two different height collars to see which one gave the proper rail height. Then I glued the appropriate collar in place. I  temporarily placed the turntable in the collar and kept it spinning while the glue on the collar set. I again used 5 minute epoxy as it sets faster than yellow glue, yet gives time to make adjustments and is very strong when dried. When that epoxy was cured, I again checked the turntable and made some minor adjustments. Then I went underneath and glued a second set of collars on the bottom of the plywood. These two collars are providing the precision placement of the turntable, not the hole drilled in the plywood.


Once everything was cured, I tested the turntable again. The spin is nicely centered and smooth. It is easy to line it up by eye, a good thing as this is a manual operated turntable.

The shaft and collars not strong enough by themselves  to prevent the turntable from rocking as the engines roll on them. These engines are quite heavy, perhaps three or fours pounds, each with the weight concentrated in the tender. In the prototype the turntable wheels control the rocking, but I am not sure the model wheels will be strong enough.  I think I will install two rub plates under the ends of the turntable that will lightly rub along the pit rail. These should prevent any excess rocking and thus the wheels will be mostly decorative. The rub plates will be almost invisible, so they will not ruin the look of the model. Unlike the prototype, I have essentially unlimited torque to spin the turntable, so the rub plates friction shouldn't be a problem.

Turntable - Part Three

I continued work on the rebuilt turntable. I removed the ties as my attempt at making the turntable look "homemade" just made it look like I was a bad builder. I trimmed all the ties to the same length and reinstalled them. Then I added the NBWs along the chord. These bolts are what hold the ties to the chord, as there is no wooden support member  under the ties other than the pivot pedestal. I did not add the NBWs on the bottom of the chord as I don't think they will be visible.

Before I added the rail, I measured the proper location and drilled two holes for the turntable feeder wires. Them I soldered the feeders to the bottom of the rail. By running the feeders through the ties I ended up with no visible solder joints. Then I spiked the rail down. The overall length of the table will be 12.5 inches, or 50 scale feet.

Next I have to build a new shaft and pedestal, as well as all the rest of the details. I'll probably laser cut the roller wheels. In careful study of the picture I note that they are not flanged. Also, look at the pit rail it rides on. It doesn't look like rail to me. I suspect that it is a wood base with a strap iron railing.

A mock up of the engine terminal at Falmouth. A wood rick, water tank and engine house are still to be built, as well as the terminal tracks.

Here is a close up of the turntable

I received a question about the bearing plates on top of the trusses from the ACWRRHS Yahoo forum. Yes, there are metal bearing plates on the tops of the posts. These prevent the truss rods from cutting into the wood. They also shed water off the end grain, though that may be a secondary concern as the whole turntable doesn't look like the builders were concerned with longevity. There also appear to be iron end plates at the ends of the chords. I plan to use my laser to cut the plates from 1/16 inch acrylic.

What thickness iron do you all think those truss rods are? The heaviest wrought iron rods specified in Haupt's bridge book is 1.5 inches. That scales to about 0.032 inches nearly perfectly. But to me they look beefier than that.

Finally, I wonder why they mortised the posts into the chords. The mortise joints don't appear to be that tight. The joints would significantly weaken the chords in bending, but not so much in compression, since the upright post would see a compressive load acoss its width. The design of the truss does put the chord into compression, but it would experience bending moments as the live load moves along the turntable. The chords are relatively massive, especially for such a small structure. They help give the turntable a "chunky" look. But I think the iron rods are providing most of the strength of this bridge.

Turntable - Part Deux

I was not happy with the look of the first turntable. The actual Manassas turntable was quite rough in construction. Mine was looking too "square and regular."

Excerpt from Railroad and Engineering Journal, Vol LXIII, No 10. 

Further research into early turntable designs revealed that gallows style turntables did not have rail stringers. In looking at the Manassas turntable, I concluded that it was very similar to a gallows style where the ties form a suspended deck. However, the Manassas turntable uses a wrought iron rod tension truss instead of a gallows.  I was concerned about racking and twisting  forces on such a design without a rail stringer, but a passage from an engineering book on early turntables explained that due to the low speed involved, those forces are minimal.



So I am rebuilding the Falmouth turntable be be a closer match to the Manassas prototype.   I did not use the laser to cut these parts as I intentionally wanted some subtle variation in dimensions that comes with hand cut parts.   I sanded the sharp corners and distrressed the wood slightly to make the parts look more "homemade." These parts form the main chords. I find it hard to believe that they mortised the main chords to accept the vertical truss supports, but the photographic evidence clearly shows this.



I am going easier on the black stain this time around as the wood should not be overly weathered. I'll have to make a new shaft and pedestal to make sure the height is correct.

Each tie has 4 visible bolts that hold it against the main chord. The bolts are in a distinctive pattern (see the prototype photo on the previous post). Adding these will be tomorrow's project. You really have to like adding NBWs to be an O Scale modeler in this period.

Falmouth Turntable in progress

I nearly finished all the wiring in the main room this weekend, but I need 3 Frog Juicers to wrap it up. I ordered two more Hex Frog Juicers (enough for 12 turnouts) so I can finish the wiring here and be ready for the yard at Aquia Landing.  Even with incomplete wiring, I ran the Engine Haupt with a short train to test track. Now that the double crossover in Falmouth is operating with auto reverse units on the frogs, I discovered that some fine tuning of the turnouts was needed.


      This turntable at Manassas served as inspiration for my
Falmouth turntable. Note the lightness of the rail, and the
crude level of  construction. It is hard to tell if there are stringer beams
under the ties and rails.  I assumed there were.


So with wiring on hold, I started construction of the Falmouth turntable.  The turntable is needed at Falmouth to turn locomotives so they can make the return trip nose first.
The turntable is loosely based on the prototype at  Manassass seen in the famous photo after Jackson's Raid in 1862.  Edwin Alexander made a set of plans based on the photo, but something about his plan didn't look right to me, so I modified the design to reflect how I think it may have been.

I used laser cut 3/16th inch basswood for the main structure and sugar pine ties from Mt Albert.  I added many Tichy NBWs to simulate the bolts holding the beans together. However, I did not simulate the laminations of the beams. I still need to add the truss rods, wheels and other details.

The pedestal separated from the shaft.
The pedestal will be glued to the pit floor. 

The shaft is a set of 1/2 inch and 7/16 inch Evergreen styrene tubes that telescope tightly together. I epoxied the tube to the center hole in the turntable bridge.

To make the conducting bands, I soldered 26 gauge wire leads to strips of 0.005 inch shim brass.  Then I drilled holes in the shaft, ran the leads into the holes. Next I wrapped the brass bands tightly around the 7/16ht inch shaft and quickly soldered them without melting the plastic.

Close up of the turntable shaft

With this design, the turntable shaft can slide into the pedestal. The pedestal will be glued to the pit floor.  If all goes to plan,  I'll be able to drop the turntable through the hole. Then add electrical wipers to the bands. I'll use a digital autoreverse unit to control the power to the rails.

This is a manual turntable, so I will not be using an indexing system. It's "armstrong" all the way.

It just occurred to me that this is the first turntable I have ever built either from scratch or kit. I had a Walthers N Scale turntable, but never installed it.

I am keeping my fingers crossed!

Overall view of the 12 inch turntable in its approximate location before I drill the shaft hole
and hog out the styrofoam.