Papers

Tripod Legs

Sat, 12 Sep 2009 16:42:57 -0400

The most common question I’m asked is “Where did you get those legs?”

They’re photographic light stands.

When I was planning the layout I knew that I would end up setting up and taking down the modules by myself, at least from time to time. I realized that a couple of tripod stands with small table tops could hold two modules in mid-air while I assembled end plates.

Lightweight lighting stands are suitable for my lightweight modules. The mini-tabletops shown are cut from cabinet plywood; The shape was developed after some trials for flexibility and light weight. A recessed tee-nut creates a threaded connection for the stud on the tripod top. The adjustable stands allow the layout to be set up from 34 inches to 7 feet high.

If you decide to use stands like these, be sure that they are rated for at least most of the weight of your modules. Choose stands with knobs that securely tighten the height adjustment - they are better than friction levers that may slip and allow the height to “self adjust” downward over time. Microphone stands can fail suddenly and unexpectedly, so avoid using those.

The stands I use are about 2-1/2 pounds apiece. I carry all the supports for the Berrett Hill layout in one large suitcase.

Kevin Hunter

About Detail

Fri, 4 Sep 2009 22:38:20 -0400

It’s been said that super-detailing is a kind of slight-of-hand. The fine details shown at the front of the layout draw the eye, and distract the viewer from the (likely) fact that the modeling in more distant parts of the layout is not finished to the same level of accuracy. Many fine modelers, including John Allen, and Malcom Furlow, knew that if a building wasn’t visible from the rear, that it was a waste of time to detail or even paint the back side.

I internalized this idea one evening when I found myself installing sixty tiny nut-sand-washer castings on the bottom of a turntable bridge, which was about to be installed in a pit, where the underside would never be seen again.

Unfortunately I have chosen to build a layout on which none of the scenery ends up more than 8” from the viewers eye. A few nice details suggest more just past the edge of the layout.

I like to think that my best modeling is just beyond what can be seen.

Kevin Hunter

Module Construction, or How Things Don't Work

Thu, 26 Feb 2009 10:11:00 -0500

The Berrett Hill On30 modules are built to provide both a shelf railroad, and a traveling sectional railroad. Using a 12 inch width, and 4 inch nominal thickness, I am able to move the entire railroad in a 4x4x6 foot trailer, and still maximize the length of run. The design guidelines may be found at:

http://www.berretthill.com/trains/pdfs/berrett_hill_sectional_guideline.pdf

There has been a clamor for details on how the Berrett Hill modules are built. I have been cautious in documenting them because I would not build them all quite the same way again.

In the interest of guiding others away from the more treacherous rocks and stony beaches, here is our story thus far...

Existing Construction

I insist on a foam top on the modules, because in central Maryland there are no flat spots, so every square inch of layout has to slope in one direction or another. A hot wire cutting through foam is so gratifying in creating satisfying drainage patterns. Since I prefer deep cuts for dramatic scenic contours, many of the modules are built on a 2 inch base of foam, over a plywood center platform.

In theory the heavy styrene block adds stability to this design, but it flexes more than is desirable both in end-to-end upward bow or sag, and in twist along the module length.

The plywood facia is intended to be the primary vertical beam strength in this design. As shown it allows too much deformation and movement, particularly when the lower part of the facia flexes in or out from it's vertical alignment.

A more shallow styrofoam top layer is typical of modules that contain switch motors. They are built so there will be enough height inside to protect the connections and machine mounts.

Problem #1 :: Humidity

As it happens, wood parts swell and shrink depending on humidity. Acrylic sheet (Plexiglass) swells even more. Styrene and metal don’t react to humidity at all. Sections built in the dry winter air, and run in the humidity of east coast summers, can have the main line move up and down in unexpected ways. A "ski jump" problem can form at the rigid supports installed at the end plates under the construction guidelines.

Note that this issue only rears it's ugly head when building modules with rails-to-the-end design. No such problem will be noticed on a module built with 1" rail setback and floating connector rails -- the minor change in elevation would just be adjusted out of existence at the time of setup...

Anyway, the little ski jump may be great for demonstrating how well 4-4-0s can deal with rough trackage, but without a better design long wheelbase engines with may need to be sidelined during the bad months.

I should note here that a previous version of this paper included a statement about humidity affecting styrene and styrofoam. It does not swell in humidity (according to the “Styrene Council” ). I mis-attributed this characteristic from acrylic plastic, which can swell quite a bit in humidity. Take care then, when building in Plexiglass. I hope my error caused no inconvenience.

Thin 1/2" or 3/4" foam creates considerably less movement, but providing close support for the track bed with end grain plywood is the best bet.

A plywood "track beam" under the roadbed will improve the track support, and eliminate foam shrinkage effect. A thin bottom plywood sheet provides a more rigid construction to prevent twisting and stabilize the facia.

Joe Balint of the North Carolina Sipping and Switching Society has worked out many of the details, and named this "waffle construction".

The underside/cutaway view shows the plywood panel box design. The large holes lighten the structure, and allow access to wiring and fasteners.

Note that the curved corners of the cutouts are important. Curves prevent single point stress fractures; failures that can create "rips" in thin plywood. (This is the same reason airliner windows are not square!)

Also note that blocks along the sides of the holes both provide stapling surfaces and support against the stresses of human fingers using the holes as handy carry handles.

Similar "track beam" construction can be applied to modules with a thick foam base.

Spline construction of the beam below the track bed can be bent and formed to follow curves or sinuous trackwork.

Track beams can be notched for bridges and scenery if they are sufficiently tall to start with.

Foam blocks can be fit for any contour, and sliced in place with a hot wire. Facias can be trimmed to the contour before mounting, or cut in place with a jig saw or roto-tool.

Here's a sketch of a typical two foot wide FreMo module built with the same techniques.

The Mid-Atlantic On30 Group Standard and others could be built in this fashion.

This is a view of the construction from the underside.

The additional depth of the 6 inch facia could be used to accommodate folding legs, as shown here.

Banquet legs are about 8 pounds, card table legs a bit less. The convenience of folding legs could justify the greater difficulty in handling on all but the largest of modules.

Leg extensions will be required in either case. Simple slip on tubes with pin-through-hole adjustments would be easy to make from plastic plumbing. Nate has executed a clever modification to card table legs using pegboard holes to simplify construction.

Problem #2 :: Temperature

Metal rails expand and contract in changes of temperature, and when attached to end plates can create significant stress against the module. Sections built in the summer, and chilled in winter storage, will become significantly damaged. Either the frame will bow as shown, or the solder joints will fail, or curves in the track will become dislocated or destroyed as tension tries to pull the track into a straight line. All of these are bad.

The solution for this situation is to install an expansion joint.

This is an unsoldered rail joiner used as an expansion joint. You may have these on an existing module, probably installed by accident.

Though functional, the limitation of such a joint is obvious. When the rail contracts a large gap forms in the running surface of the rail. Should the rail expand the rail ends will butt and unplanned events may occur.

This is a half lap joint. Technically elegant it can be created with a file in about five minutes. Sliding a rail joiner over the joint will hold it together for an almost invisible installation.

As with any unsoldered joint, be sure to run a power feed to every piece of rail for dependable operation.

I'll keep you posted on ease or difficulty on installing this as a retro-fit. I expect to be trying this a number of times...

A discussion with Bob Wynne came up with this approach, for folks more comfortable with a Fast Tracks jig. Similar to the half lap, rail ends are filed to points and installed in the same manner.

Be sure to file down the sharp ends before installing this. A rail might stick out a bit after some expansion and bite unexpectedly...

Later discussion about this technique indicated that it was too easily “stretched thin”, though it may perform well with a long enough taper. The consensus was that this method might be more trouble than it’s worth.

I’ll try to keep this page up to date as info accumulates...

Kevin Hunter

Electrical Connections

Wed, 21 May 2008 08:45:17 -0400

After working out a system to connect Free-mo style train modules, it turned out to be the same as one developed by Ron Wm. Hurlbut, and others, with minor variations. The rule is that facing the end plate of any module (from outside the module) connect the Red pigtail to the Right hand rail of the track. Black goes to the left.

Red on the right - facing the end of a module means that if you turn around to look at the module coming to meet it should also have red on the right, and (because you turned around) the right rail will meet the left, the OPPOSITE, rail of the first module. In this system the red on the right will always meet the black on the left of the next module.

I will note here that this cross-wired arrangement is the only method that will mate consistently in a system where either face of the module may be considered the front. Straight through wiring can work, but the colors will not match consistently. Trust me on this - or work it out for yourself...

Anyway, Non-polarized Anderson PowerPole Connectors are ideal for this because each single wire connector can mate with any other. A pair of individual Powerpoles clipped together into a multi-pole plug in an over/under fashion will always cross wires, red to black, when connected to an identical plug . (They become traditionally polarized, red to red, black to black, when hooked together side-by-side).

The universal nature of PowerPoles makes them ideal for quick repairs in the field. A couple of my modules had reversed track feeds. Reversing them in place took only seconds by pulling the multi-plugs apart and hooking them up "wrong". (I marked the lead with yellow tape to remind me to fix the colors later)

Quick disconnecting connectors are great for testing during setup, because isolating any module is a snap. Literally.

Installing Powerpoles can be tricky. The $30 or so for the official crimper is a good investment.

About terminal strips:

It's been noted by some that terminal strips aren't needed once using the PowerPoles. I have decided it is wise to use them anyway because:
• Terminals are universal. Not everyone I ever meet will have PowerPoles. But they will have wire.
• Things are never complete. Terminals make great places to add in fixit jumpers with few tools in the rush of setup
• Things pull. Terminals that are screwed to end plates are really well anchored. A yank on a jumper tied to a terminal strip will not remove all wiring from your module
• Things break. Terminals give you a starting place from which to fix them.

I have adopted the white "european style" strips available in any Radio Shack. (See the Photo Above). They are sold as a long 12 terminal block, but become shorter terminal blocks with the swift application of a razor knife or Xuron cutter. They are designed to clamp directly to the stripped wire, so they cut costs and save the fuss and bother of crimp on terminals. They mount best with #6 pan head screws through the holes down the middle. You will need to stock a small (aprox. 1/8") flat screwdriver in your kit to tighten the terminals. Don't use tiny terminal blocks for large wire or you will hate yourself when you find yourself trying to put three wires into a hole barely big enough for one, all while standing on your head.

Kevin Hunter

Wiring Turnouts For Uninterrupted Operation

Tue, 1 Jan 2008 09:41:30 -0500

Keeping a Resolution...

Operations at Kimberton 2008 were pretty smooth once all the setup was complete. The biggest operational problems were dead, dirty, and dysfunctional power on a number of turnout points. During the breakdown, a chorus was heard all round that we'd install positively powered frogs to guarantee smooth low speed operations.

While testing my own track-work recently, I determined that my turnouts urgently needed the wiring upgrade. With a show coming up in a month, it's time to keep the resolution.

Here's what I've learned, and how I'm applying it:

These are the parts of the standard turnout that affect the electrical connections talked about here.

Guard rails and other details have been left out for clarity.

This is the original standard for 2 rail turnouts; Elegantly simple.

The stock rails are powered North and South, and the Points and Frog connect by direct contact to the "correct" stock rail for through traffic.

Since all electrical switching is done by the points - Dirt, loose ballast, glue, and dust can all prevent a good contact, and a smooth running train.

Peco Electro-Frog turnouts come wired this way.

A common solution to the inconsistencies of the point contact is to provide a positive switch action using a hidden switch or contacts. These contacts are provided on many turnout motors.

Short circuits can be created in two ways with this arrangement:
• If the switch points do not move precisely with the electrical contacts a short can be formed if one makes contact before the other.
• Any slightly misaligned metal wheel can short out the narrow space between the open point and stock rail. There is full track power across that narrow gap. Derailments at the points will ALWAYS cause a short.

Pico Electro-Frog turnouts can be modified to eliminate both shorting problems. [The green lines in the diagram show insulating gaps]

Here the points are constantly electrified with the same polarity as the adjacent rail.

The frog section is positively connected by the remote contacts without a concern of being out of alignment with the points. This arrangement is much less likely to cause a short.

The Hex Frog Juicer
New technology to the rescue! Forget the impossible under the layout contacts! The new Hex Frog Juicer (what a name) now being sold by FastTracks looks to be a really helpful tool in powering turnout frogs. Minimal wiring and no moving parts makes for a great solution for the hand-throw crowd. Connect to the DCC power and one wire for each frog. That’s it.

Promising also for those of us who’ve had the DCC buss power hit the output end of a DCC switch controller and let the smoke out...
Optimizing A Pico Electro-Frog Turnout

Pico turnouts are tricky to add remote electrical contacts to, as delivered. The strong snap spring on the throw bar works against the spring in an operator and makes the moment of contact a constant surprise. I remove the spring for operation with Tortoise switch machines, but I understand that a Tortoise will operate a Peco sprung throwbar if a stiffer spring wire is used in the Tortoise.

The following modification will work with any configuration.

The operation is in two simple parts:

• Isolate the frog by cutting the closure rails.
• Electrically bond the stock rails to the points and closure rails.
• Connect a power feed to the frog from the turnout operator, or frog juicer.

Follow the photos to see my technique.

Here's the turnout already installed.

A cutting wheel in a Dremel tool will make the cut.

Note that I'm cutting near the middle of the closure rails. Leave supporting ties on either side of the cut to securely support the rail.

Move straight down slowly with a fast spinning wheel, and don't let the wheel twist or bind. Wear eye protection! Don’t breathe the dust from the rail!

NOTE: This, by the way, is not the best place to learn this cutting technique. If you are not familiar with roto-tool cutting I'd suggest at least fifteen minutes practice on some old stock before you attempt this. A bound-up wheel will shatter immediately. Your turnout could be significantly messed up by a runaway wheel.

Here the cut runs all the way through the rail. Don't cut through the plastic tie strip if you can help it. It will help keep the turnout stable.

It is good practice to come back and fill these gaps with epoxy. The filler will prevent a conductive shaving from getting stuck in the gap and driving you crazy. I'll wait till later to fill the gaps, because it is much easier when working with epoxy to do all your turnouts at one time.

For bonding I used my handy de-soldering braid and some Xuron nippers.

I snipped a bit of braid...

... and placed it just above a cross-tie...

...on both sides.

Solder in place.

The finished work is shiny bright.

(I know that there are dozens of more delicate methods to do this. Smaller wires, and subtle installation from below come to mind.)

I use Floquil "Tie Brown" to disguise the connection.

Here's the final result waiting for ballast and scenery.

Run the frog power lead from the turnout operator contacts and connect it to the rail.

Note: I solder an automotive tail light bulb into the frog connection wire, to protect the layout from shorts. Use of lightbulbs is an old technique that's well covered elsewhere...

I hope this information is a help. Shoot me a note if I've created more confusion than clarity.

Kevin Hunter