(click on images for larger view)

Background

Shortly after the Shoreline Model Raceways Club began the transition from plastic to wood tracks about 2 years ago, the three co-authors of this article began kicking around building a portable track. Over the next year or so, discussions continued – as a result, some general design goals evolved and were firmed up. Key goals included:

The portable track would be a classic "D" shaped tri-oval constructed from ½” MDF with 5 lanes, 3-1/2" lane spacing and 5/16" deep slots. The overall footprint would be approximately 21' long and 9' wide at the dogleg. Construction and wiring would use the same basic techniques employed when building other club member’s wood tracks. Most materials were available locally – remaining materials were widely available through the internet. The track would consist of seven (7) track segments which could be assembled and disassembled quickly and easily. Modular legs which could be easily removed for transport would provide a sturdy base for the track. The wiring and track power would be as straightforward as possible for reliability yet permit some "tuning" of individual lanes to ensure cars running in each lane would be as close as possible when actually racing (to offset lane lengths ranging from 39' to 46'). Dead strips and a computerized race management system would handle lap counting and timing chores.

In the following sections of this article, details of various aspects of track design and construction (including braiding, wiring and installation of the race management system) are provided. Readers should keep in mind there are often many ways to complete a given design or construction task. The material presented herein is not intended to be "THE only way" or "THE best way" to perform a given task. Instead, this write-up shares how our club approached various tasks - you may decide to take the same approach we did, modify our approach or take a completely different approach altogether. Our primary goals in writing this article are twofold - first, to share information, and second to (hopefully...) inspire other clubs/individuals to build a portable track and share their experiences with other slot car racers as well.

Fabricating the Track Modules

Track construction began in the Spring of 2006. The first task was to firm up the design of the track modules which would ultimately be assembled to form the layout. In keeping with the club's design goals of simplicity and minimizing cost, the seven (7) modules which make up the portable track layout were cut from just three (3) sheets of 1/2" MDF. Click on the link below to see a diagram which shows how this was done.

Gypsy Track Modules

The individual track modules were then fabricated including the underlying support members and knockdown legs. Frames for the track modules were constructed using 1”x4" #2 pine.

Tip:Even if you are very careful to hand select your lumber at the time of purchase, it will not be perfectly straight. Be sure to examine the edges of all lumber and place the "crowns" facing up when constructing the frames.

Once the MDF racing surface is attached to the frame, it acts like a stress skin panel which adds further strength. The accompanying picture was actually taken during the wiring phase of the project; however, it provides some insight into how each track module was constructed. The numbered circles are described in more detail below.

The racing surface was then brush painted with 3 coats of flat interior latex (light gray). No primer was used. The paint was lightly sanded with 600 grit sandpaper between coats. Once the paint dried, a razor blade was used to carefully remove any high points or particles from the paint. The accompanying pictures show the Gypsy modules being test fitted together for the first time.

Lesson Learned: Were we to do this again, we would have painted all surfaces including the underside of the MDF and the frame members on the underside of the track at this point in the construction process.

Construction - Braiding

One of the key decisions during the design and construction phases was whether to use copper tape or tinned copper braid (we ruled out steel Magnabraid for a couple of reasons – cost and the Shoreline Model Raceways club runs non-magnet cars only). Copper tape was less expensive and easier to install (less preparation) while tinned copper braid offered more durability but required more upfront preparation and was more costly. In the end, the decision was to go with braid - the extra durability was a key factor as the track would need to stand up to the rigors of transport and being frequently setup and taken down. Braid also simplified track wiring somewhat (more on this later). We purchased the tinned copper braid from Allied Wire & Cable in Merrimack, NH – the price was very reasonable and our order shipped quickly. Despite our rather unique application, our Account Representative (Alana) was very helpful and ensured all 600’ of braid arrived in perfect condition.

Tip: When calculating how much braid will be required for your project, don’t forget to take into account the power tap “drops” and braid required to run down the ends of each track section and secured underneath.

Here are several pictures of the braid installation process.

The first picture shows the "gains" which were routed on both sides of each slot where the braid will be attached. The gains have been carefully cut slightly wider than the braid (to ensure car guides will never foul the braid) and to a depth so the top surface of the installed braid will sit just slightly (.005") below the track surface.

In the next picture, Dick Mcmanus (aka "mcmannix") is spreading contact cement in the "gains" cut on both sides of the slot.

A clean plank was set across some scaffolding to cut and prepare the braid for installation. Once the measurements for each braid segment were determined, braid was carefully unrolled on the plank and cut to the correct length.

Here Mike Chiocchio (aka "Smokeio") is using a dispensing bottle to run a fine bead of contact cement along the entire length of the braid (less the last couple of inches on each end which would be dangling from the underside of the track section once installed).

A second club member, Larry Sorensen, follows closely behind with a small brush to smooth out the bead of contact cement ensuring the braid has a complete, smooth coat. The contact cement is then allowed to dry for about 15 minutes until it is no longer tacky.

Of course, every job goes smoother with a "supervisor". Here Dick Mcmanus is overseeing Mike and Larry applying contact cement to the braid.

Once the contact cement has been applied to the track surface and allowed to dry, braid installation can begin. While a single person could install the braid, a second person makes this task much easier. Here Dick Mcmanus (right) is carefully applying the braid to the track surface. Dick is being very careful to ensure one edge of the braid butts up against the "back" side of each gain. Larry Sorensen (left) holds the remaining portion of the braid away from the track surface to ensure it does not accidentally touch any of the contact cement on the track module. Braid installation is surprisingly fast and straightforward (faster than copper tape) - the real work is in preparation of the track surface and applying the contact cement.

Here's is a close-up which shows the braid being carefully applied to the gain cut on one side of the slot. This particular track module is the dogleg curve - applying braid to curves is much easier than copper tape because of the braid weave. Once installed and rolled, the braid is perfectly flat.

This picture shows braid segments installed for 2 of the 5 lanes on one of the straight track modules. As each braid segment is installed, a "J" roller is used to ensure the contact cement on the underside of the braid is making firm contact with the contact cement applied to the gains in the track surface. Note the braid was run straight down each end of the track module (where it was secured using contact cement) and through pre-drilled holes. The ends of the braid segments were eventually cut and secured to the underside of the track module using a wooden “keeper”. When the track is assembled and all track modules bolted together, the braid from adjacent track sections will make firm contact with one another ensuring excellent electrical conductivity around the entire layout. Should there ever be any problems with electrical connectivity between track sections, the ends of individual braid segment can be temporarily wired together if necessary.

Here's a close-up of how the braid was secured to the end of each track module.

Braid installation for this track module is complete with the exception of trimming excess braid from the loose ends and securing the braid to the underside of the track. The braid will be rolled several more times to ensure the contact cement makes the best possible bond.

Track Power and Wiring

In keeping with the overall design goals of the track, wiring was kept as simple as possible. Steve Sawtelle from Slot Car Corner and Dick Mcmanus developed the overall track wiring plan.Slot Car Corner also provided most of the wiring components including a custom wiring kit. The five (5) driver’s stations are split between the two (2) straight track modules leading into and out of the dogleg corner. When you are standing in front of the dogleg, the straight section to your left (the straight leading into the dogleg corner) includes the driver's stations for lanes 1 and 2. The driver's stations for the remaining 3 lanes are located in the straight section to the right of the dogleg (the straight section leading out of the dogleg). Wiring for both track modules needed to be completely self-contained for easy of assembly, disassembly and transport. When the track is setup for racing, the power supply is located under the dogleg section. A terminal block mounted to the underside of the dogleg "splits" power to the two (2) adjacent straight track modules. Temporary jumper wires are wired between the terminal block under the dogleg with terminal blocks on both straight sections. Here are some diagrams which provide additional information about how we approached this.

Track Wiring Diagrams (Small Format)

Track Wiring Diagrams (Large Format)

The accompanying picture shows the underside of the straight section leading into the dogleg. This track section houses the driver's stations for lanes 1 and 2. The terminal block in the upper right-hand corner will be connected via temporary wiring to a corresponding terminal block on the underside of the dogleg. The picture also shows the "+" (white) and "-" (red) wires feeding each of the driver's stations. Wherever possible, wiring was run along structural members to help protect the wiring from accidental damage. Wiring clips were used to secure the wiring - again, this helps reduce the possibility of the wires being damaged if they were to get snagged on something.

Here is a close-up of the wiring for one of the driver's stations. A ring terminal has been crimped and soldered to the braid segment on either side of the slot. Heat shrink was placed over the braid before hand to prevent accidental short circuits. In addition to hookups for alligator clips, an XLR jack was also wired into each driver's stations. If you look closely, you will see short lengths of heat shrink covering the 3 wires where they are attached (soldered) to the XLR connector. Each length of wire was cut to the exact length required - excess wire increases the chance of damage during transport and assembly. Stranded copper wire (12 gauge) was used throughout except the XLR jacks (14 gauge because of the size of the solder pots on the jack).

Eye bolts were used instead of traditional brass posts for a couple of reasons. First, we wanted to avoid anything sticking out from the side of the track modules since it would be prone to damage. The ends of the brass posts would have a tendency to catch on things when you least expect it. Second, while brass posts could have been shortened to fit inside the recesses, the short posts make it difficult to hookup a controller. The round profile of the eye bolt is safe and easy to make controller connections to. An XLR jack and 3 amp thermal circuit breaker round out the driver's stations.

Power is provided by a Pyramid PS26-KX variable DC power supply. This is a regulated power supply which can be adjusted from 6 - 15 volts. The PS26-KX is rated at 22 amps of continuous current so there is more than enough power on tap for the 1/32 cars the Shoreline Club typically runs. Power supply voltage is set between 9 and 10 volts for racing.

Track Tuning

One of the inherent downsides of an oval design is the difference in lane lengths - in our case about 7' from the inside lane (39') to the outside lane (46'). Even before installing the race management system it was obvious the inner lanes were the quick way around the track. There are two (2) general approaches to deal with this:

Our club opted for the second approach since a couple of our member's tracks have been tuned in this fashion with very good results. Here's the approach we took.

A single diode was then inserted into the "+" wire leading from the power supply to the driver's stations for the 2 innermost lanes. This reduces voltage to these lanes by about 3/10th's of a volt. The track wiring design anticipated the possibility of adding diodes to adjust performance for a given lane. The accompanying picture shows 2 white wire segments attached to the upper left side of the terminal block. The upper white wire is from the power supply (there is actually another terminal block between the power supply and this terminal block to provide a feed to each of the driver's stations). The lower white wire is eventually connected to the white "post" on the driver's station. On most tracks, this would be a single piece of wire. If you look carefully, you will see 2 bridging clips attached to the 3 upper right screws/posts of the terminal block which effectively connect these 2 white wire segments. So why did we do this? The terminal block provides a very easy way to wire one or more diodes (in series) into the wiring for a given lane. To add a diode using this setup, follow the steps below.

After inserting the diodes (1 diode for each of the 2 innermost lanes), the same testing process described earlier in this section was repeated. Lap times across all 5 lanes are now within about 1/10th of a second. Variations in car setup, driving styles and other variables can easily account for a 1/10th second difference in lap times so no further tuning was performed. Should additional tuning be required in the future, the same basic technique described above will be used.

Race Management

Because all existing Shoreline Model Raceways club tracks use Trakmate race management software, Trakmate for Windows was a natural choice for the portable track. Dead strip sections were included in one of the two straight sections which form the main 16' straight. The dead strips are located near the end of the track section - this is the same end which gets bolted up to the adjacent straight track section. With this arrangement, the dead strips are located roughly halfway down the main straight when the track is assembled.

The Trakmate for Windows interface board was installed beneath the dogleg track section - this is the same track sections where the power supply connections are made. A slightly different wiring arrangement was used for the track call button. On many tracks running Trakmate, the wires leading to the track call button are wired directly into 2 connectors on the interface board. This works well if the track call button is permanently mounted (e.g. alongside the driver's stations and/or at the race director's table). However, since our track call button was a hand held setup on the end of a long wire, the interface board could be damaged if someone pulled too hard (or accidentally tripped) on the track call button wire. To prevent this, a 2 position terminal block was installed close to the Trakmate interface board. Two wires were then run from one side of the terminal block to the interface board. The 2 wires from the track call button were then wired into the other side of the terminal block. With this arrangement, if someone pulls too hard on the track call button wire, the terminal block serves as a buffer to prevent damage to the interface board. It also makes attaching and detaching the track call button when setting up and taking down the track easier.

The end of the dead strip interface cable which is attached to the actual dead strips is permanently attached - it gets coiled up and stored in a special protective sleeve under the straight section during transport. To install, the cable is carefully removed from the protective sleeve and uncoiled. The cable is run across the "inside" portion of the track so the other end of the dead strip interface cable can be connected to the Trakmate interface board. A tie wrap is used to fashion a temporary strain relief to prevent damage to the interface board from the weight of the cable. A serial cable (provided with the Trakmate setup) is then run from the Trakmate interface board across the "inside" of the track and connected to a PC laptop computer which is used to run the Trakmate software. When actually assembling the track, the wiring connections described above for the Trakmate race management system only take a couple of minutes.

One final item which works in conjunction with the race management software is a light box. This was originally designed for hearing impaired racers (who have difficulty hearing the “beeps” during the countdown sequence at the beginning of a race or a restart). While they could look at the computer screen to see a visual countdown (“lights” on screen), doing so would require them to take their eyes off the car. This can be very awkward, particularly on restarts where the car is in a corner or technical sections. With the light box setup, racers can remain focused on their car while watching the light box out of the corner of their eye. The accompanying pictures show the box which was designed and fabricated by Dick Mcmanus. A removable cover protects the light bulbs during transport.

The light box is setup in the middle of the layout when racing – here it can easily be seen by all racers. Wiring is straightforward; a 12V relay inside the light box operates in conjunction with the 12V relay which controls track power. When the track relay is “closed” (power flowing through relay to track), the light box’s green light is on; when the track relay is “open”, the red light is lit.

The First Test...

The first complete test of the portable track took place on September 10, 2006. Several Shoreline Model Raceways club members helped setup the track and complete the wiring for the Trakmate for Windows race management system. Several test races were then held to ensure everything worked properly - this included running several actual races using the Trakmate for Windows race management system. The track, wiring and race management system worked flawlessly!

Here are some pictures taken during the testing session.

Pictures courtesy of Rich ("Dr. D") Dumas.

Pictures courtesy of Larry “IROC” Sorensen.

Pictures courtesy of Don "Bubba" Willis.

The track was subsequently transported to Massachusetts early in October 2006 where it was one of two tracks the New England Challenge (NEC) was contested on. Transporting the track was uneventful – once onsite, setup took about an hour including unloading the track from the pickup truck used to transport it. Over the course of the 1-1/2 days of the event, an estimated 7,000- 8,000 laps were run with only one minor problem. The XLR jacks were a different make/model than those we used on our other club tracks – this particular design has a rather flimsy release tab. On one of the jacks, the tab jammed and eventually broke rendering it useless; however, we were able to use the eye ring hookups and an adapter so controllers with XLR connectors could continue to be used.

Note: The original XLR jacks have since been replaced with the beefier XLR jacks we use on the other club tracks.

Both the Nextel and JGTC cars performed well on the track.Traction was excellent – most Nextel cars used PPR’s while the JGTC’s used a spec IndyGrips tire (1103). Lap times during the race ranged from the high 3.4 to low 3.6 second range for the Nextel class – the JGTC cars were just a couple of tenths slower. Racing in both classes was close, competitive and fun! All-in-all, the track’s racing debut was very successful – many participants complimented the Shoreline club on the track. The 2 track format for the event which was made possible by the portable track was also a big success – racers had far more track time as a result. Over the course of the event, each of the 23 racers actually raced for almost an hour (9 lanes * 3 minute heats * 2 classes). Whenever logistics permit, future NEC races will continue to use this 2 track format. Here are a few pictures from the NEC event.

Before Hitting The Road...

To help ensure everything works right when the track is transported to an off-site racing venue, a pre-transport checklist was developed. Many of the items are obvious (e.g. the 7 major track sections); however, even seemingly obvious items can be easily overlooked or forgotten when getting ready to take the track on the road. The checklist also includes spare parts which might be required should repairs to the track become necessary. The checklist will continue to evolve based on lessons learned when transporting the track. To view the checklist, click on the link below.

Pre-Transport Checklist

Some Final Thoughts...

In retrospect, this has been a very rewarding project for the entire Shoreline Model Raceways club. The finished product is something all club members can be very proud of - the workmanship and attention to detail is evident throughout. Special thanks to Dick Mcmanus and Mike Chiocchio for keeping the project moving along over the course of several months and engaging other club members throughout the construction process whenever possible. Thanks also to club members who helped out by making donations to defray expenses and giving up their valuable time to help turn a sketch on a piece of paper into reality. This was a great learning experience for everyone involved.

Future enhancements are already being discussed such as additional track modules which will transform the current "D" shaped oval into a road course layout.

For other clubs who might be considering a similar project, please contact us if you would like more specifics.

About the Authors

Mike Chiocchio (aka “Smokeio”) lives in Branford, CT where he is currently undergoing therapy after the Shoreline Club lost the prestigious New England Challenge (NEC) Trophy to the H.O.S.T. (New Hampshire) club. Mike is a co-founder of the Shoreline Model Raceways Club.

Dick Mcmanus (aka “mcmannix”) lives in Clinton, CT. Dick is the club’s resident woodworking and mechanical genius. Dick recently won his first ever slot car race (at least according to Smokeio…) despite racing slot cars competitively for over 20 years. Like Mike, Dick is a co-founder of the Shoreline Model Raceways Club.

Steve Sawtelle (aka “SlotCarCorner”) lives in Storrs, CT. Steve is an official SCI advertiser who offers custom fabricated driver’s stations and high-quality wiring products through his Slot Car Corner website. Steve is busily making preparations to host another Endurance Race at Area 51 Raceway sometime in early 2007 (the last one drew 32 racers from as far away as Canada…).

Mike, Dick and Steve are frequent contributors to many of the Slot Car Illustrated online forums.

Copyright © 2006 by Shoreline Model Raceways – All Rights Reserved.

Copyright © 2006 by Slot Car Corner L.L.C. – All Rights Reserved.

Copyright © 2006 by Slot Car Illustrated – Used With Permission.