By Lee Thomas

Author  Bio The purchase of an IDA was a decision made after scratch building two live steam "Project" Engines and deciding to move into conventional G-Scale Live steam.

The purchase of an IDA was a decision made after scratch building two live steam "Project" Engines and deciding to move into conventional G-Scale Live steam. My interest has always been in back country logging or mining. This meant a Porter Type locomotive built for negotiating a tight radius.

The Ruby Line of locomotives seemed to be popular as a beginner's model, with the IDA being closer to the "look" that I wanted, which closely resembles the Porter. It did not run well right out of the box, I found that a few important parts were loose or out of adjustment. With some patience I got it going. It is fun to operate just like it is, but it is not a working locomotive. It benefits from some improvements that make it perform even better.

The stock IDA often needs a gentle push to get it to "break out" and go, and it usually has to run fast to stay in motion (speed is out of scale), and must be on fairly flat track (no grades), with only one or two if any rolling stock. Others have had better luck with theirs I'm sure, but that's how it went for me.

The "Porter" was a light-duty railroad locomotive built in the USA by H. K. Porter, Inc. starting in 1866. The company became the largest producer of industrial locomotives and built almost eight thousand of them. The last locomotive was built in 1950. Porter was known for building locomotives that were much smaller than those normally used by the larger Class I railroads. The company's locomotives were small enough that they were often operated by only one person. (ref: Wikipedia)

These photos show the "Before" and "After". Out of the box, the IDA has manual controls and link and pin draft gear. It has been transformed into a Porter Type that was used in many mining and logging operations. The research, experimenting, and reworking of this little locomotive during the transformation process has been fun and educational. This transformation has converted the "Beginners" locomotive into a full time working locomotive. It is now a pleasure to run from the sideline with radio control.

Many modifications have been performed on the Ruby line of locomotives. This model is perhaps one of the most bashed models today. I have studied many of those modifications and have discussed them with those that have incorporated them. The following is a description of the modifications and improvements that were done to make my IDA what it is today. Some were done for appearance while others were done for performance.

Some of these processes require precision machining skills and equipment. In a follow-on article I will provide details and drawings for the manufacturing and replacement of the big cylinders.

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Reversing Valve - Many have found that the Ruby line of locomotives run better in reverse. There have been many technical documents written on this topic and are available in numerous places on the web. Due to the design of the valve, when in the forward position, the valve restricts the flow of the steam. To correct this, the valve grooves were widened, additional cross ports drilled and the bore enlarged to increase steam flow in the forward position.

Steam Chest Valves - The valve design did not open the exhaust path soon enough at the beginning of each exhaust stroke. Therefore, the steam in the cylinder restricted the piston travel. This caused a dead zone between one valve closing and the other opening, causing a pressure bump in each stroke. The motor was trying to lock up on every stroke.

The valve grooves were re-machined wider to improve the internal timing. This is a critical operation requiring precise geometric measuring and calculations to get it just right for your engine. I cannot provide drawings for this modification because I have no way to know if your engine needs to be modified or that the dimensions that I used will work on yours.

After this change, it was necessary to retime the cams to open at Top Dead Center (TDC) instead of opening late (retarded timing). Note: I experimented with "advanced" timing like the full scale engines, but this little engine did not like it.

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Cylinders - The IDA runs very fast, has low power, and could rarely "break out" from a standstill and go on its own when put into forward or reverse. The original 0.375"cylinders were replaced with big bore 0.630" cylinders. Others have successfully incorporated a 0.500" big bore. I measured the original cylinders and realized that the bore could be up to 0.630" and still have sufficient wall thickness and clearances.

I figured if 0.500" was good, then 0.630" must be better. This nearly tripled the displacement of the engine. This change produced many benefits. It cut the speed in half, making it run more scale like. The power was doubled, allowing it to pull rolling stock up a grade. It was now able to "break out" of a standstill and to stop and restart smoothly in either direction.

These larger cylinders also provided a side benefit of a more realistic appearance. To facilitate timing operations, each cylinder has a 6-32 tapped hole at each end to install air hose fittings. These holes are plugged with 6-32 set screws during steam operation.

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Whistle - I just had to have a whistle. The whistle (PM Research SW-4) was installed in place of the sand dome and relief valve just in front of the cab. The relief valve was relocated to the cab area in place of the filler plug. This whistle has a high pitch due to its small size.

There are others available which will also work well. The valve allows a high volume of steam to pass when opened fully, which in addition to hurting the sound quality, also discharges so much steam from that small boiler that it kills the steam pressure and the locomotive performance suffers. The whistle (and locomotive) performs best when the valve is barely cracked open. It is also prudent to use it sparingly to preserve the steam pressure for running.

Hint: Don't blast it just before starting up a grade. It is pretty tough to operate the whistle manually and only crack the valve. Consequently the use of a radio allows you to adjust the servo travel to just the right amount.

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Relief Valve - 20 psi was barely enough to run this locomotive. The operating pressure was increased from 20 psi to 30 psi by shimming the relief spring with washers. This valve must be pressure tested with compressed air and an accurate pressure gauge before steaming up, then monitored during runs.

With the relief valve now located in the cab, where the water filler plug used to be, it is removed before each run to service the boiler water level. The knurled body of the valve is annoying to remove after a run due to the tight area and the heat. The valve body was modified by replacing the knurl with a 7/16" hex for easier servicing.

The knurled area was turned smooth in a lathe and the hex portion of a brass fitting was cut and bored to fit, then soldered in place. The relief valve is easily (and safely) removed and reinstalled using a standard nut driver.

Overboard Steam Vent - The pressure relief valve sprays the steam straight up when it vents. With the valve moved into the cab area, this vents against the underside of the roof of the cab. The venting was redirected down and out below the cab floor by installing a 1/8" copper tube alongside the oiler to redirect the relief steam down through the cab floor and discharged into the roadbed.

The relief valve is connected to the vent tube with a short section of silicone hose (model airplane fuel line). This hose is easily slipped on and off the vent tube when removing the relief valve to service the boiler water.

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Oiler - The oiler works very well. I find that I get two runs for each load of steam oil. However the cap is also annoying to remove and replace after a run due to the tight space and the heat. The cap was modified in the same manner that the relief valve was modified to provide a 7/16" hex for easier servicing. The oiler cap is easily (and safely) removed and reinstalled using the same nut driver.

Cab - The original IDA cab is made to be completely removable. It lifts off easily as one piece, leaving everything in the cab area easily accessible. However it is clumsy to reinstall repeatedly when steaming up, and with a radio being installed it limits your options to mount servos.

Many other live steam locomotives have stationary cabs with hinged or removable roofs. The roof was detached (4 screws) and was made removable by using alignment pins where the screws used to be, which slip into the same screw holes. The remaining cab wall assembly was attached permanently to the floor with four screws in the lower outside corners. These were drilled and tapped into the existing floor flanges.

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The cab can still be removed for maintenance if needed. The cab also needed "the look". Although there are several replacement wood cab kits and drawings available for the Ruby's, I decided to simply glue wood siding and window trim to the outside to give it a wood cab look. An unplanned benefit is that the cab is robust enough (all metal) to lift the locomotive with two fingers stuck through the windows. This is a big help when it is hot.

Details - A conservative number of details were added to give the IDA a more realistic look. Air tanks, air compressor, transfer pump, and marker light castings by Ozark Miniatures were installed. A cast generator was also added atop the smoke box just behind the stack. This was a mistake due to the extremely high heat in the smoke box.

It melted the generator! Hint: Don't attach any castings to the smoke box. A solid brass replacement generator was acquired from one of the name brand manufacturers and installed. Running boards made from thin sheet brass were also installed along the lower edges of the saddle tank on both sides. These are held in place by the same screws that retain the saddle tank to its brackets.

Headlamp - The original headlamp is soldered to its mounting bracket. The solder melts with extended use due to the high heat in the smoke box area. The base was drilled and tapped to provide a more secure mounting with machine screws.

Burner - The stock burner of the Ruby line makes a loud annoying whistling noise. To quiet it down it was wrapped with a fine stainless steel screen. This was cut from a grease splatter cover, obtained from a gourmet cooking store. The burner now burns quieter as well as hotter.

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Tender - I needed a place to hide a radio. A small wooden tender was scratch built and rides nicely on fully sprung flap journals by Ozark Miniatures. The journals must be modified by drilling out the axle hole to accept a brass tube (.125" ID) liner for an axle bearing. The Tender is permanently attached to the Locomotive with a flat brass draw bar.

The attachment is robust enough to lift the locomotive by the cab with the tender unsupported. Many detail castings were added including, steps, bolts, grab irons, log chains, tools, etc. (Ozark Miniatures).

Radio control - With lots of airplane RC supplies already scattered about, I chose to use a Futaba system (surface frequency). Their micro servos are extremely small. Four were placed in the cab to control gas valve (burner), steam valve (throttle), Johnson bar (fwd/reverse) and whistle. The servo for the Johnson bar is attached upright and securely attached to the floor of the cab with screws and tall spacers.

The throttle and burner servos are lying on their side on the floor of the cab and secured with 2-sided "servo tape" (RC hobby shop). The whistle servo is attached to the inside of the forward cab wall between the windows and secured with 2-sided "servo tape". With the tiny servos and wiring painted flat black they are nearly invisible.

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The receiver and a 250 mAh battery pack were installed in the tender, hidden by a load of freshly split wood. The top layer of wood is glued to a removable cover. Note: The first battery pack that I tried was only 100 mAh and did not last through a long day of running. It's also interesting to note, that when the battery dies, the servos all go full travel to one end.

In the case of the whistle, this was full open! Needless to say everyone knew when my battery went dead! For added convenience a mini switch and a charging plug were installed with external access.

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Fuel Tank - The gas tank is OK where it is; however, the gas valve stem was very long and stuck straight out the back with a black plastic knob. The stem was cut as short as possible and a flat brass control arm soldered to the shaft for the servo control. During a run, the tank also heated up continuously (because of the heat in the confined cab area) causing a constantly changing burner setting (the gas gets progressively hotter as it ran, resulting in the burner burning progressively hotter).

I had to turn it down multiple times throughout the run to maintain a constant setting. A heat shield was installed that wraps half way around the fuel tank on the side facing the boiler with an air gap between the shield and the tank. The tank likes to be heated somewhat to make the fuel perform better, but you can't let it get too hot. The partial shield allows it to heat but is more stabilized.

To improve appearance, the whole tank was rotated about 45 deg. to swing what was left of the valve stem, inside the cab. The associated piping is soft enough to be reshaped carefully by hand to reconnect to the burner.

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Steam (throttle) Valve - The throttle valve stem was very long and stuck straight out the back with a black plastic knob. The stem was cut as short as possible and a flat brass control arm was soldered to the shaft to connect the servo. The adjustment of the throttle was also very sensitive.

I reduced the sensitivity by changing the taper of the needle to a longer, shallower angle in the lathe. Care must be exercised to maintain straightness and roundness. You must also do some measuring of the orifice and make sure you do not cut too much. This resulted in a less sensitive adjustment, but it was not a dramatic improvement.

Couplers - The IDA comes with Link and Pin Draft Gear. Although these are actually more authentic, they can be frustrating to use, especially if sharing rolling stock with your friends. Kadee Large "G" scale (not their smaller 1 Gauge) couplers were installed directly to the wood bumpers on the front and back.

Paint - The entire locomotive and tender was painted Grimy Black. The wood parts were brushed with a thinned down watery Grimy Black so it was more like a washed finish rather than a sprayed finish. Weathering streaks were added to the saddle tank and cab roof using darker shades of blacks.

The Transformation of IDA has been a good experience.

Steaming up 1.5% grade past Green River Station at Bel Del.

IDA Upgrades

Lee, You've put together a very detailed, easy to understand article. Folks with an IDA should have no problem flowing your modifications to gain a more efficient steamer. Thanks for taking the time to share your experiences with this little kettle.

JD Miller - 10/28/2009 - 06:16

IDA Upgrades

Lee: Nice article. I don't have any live steamers, but after reading your input, I may have to give it a try.

Jim O'Connor - 10/28/2009 - 17:19

Follow up?

Is there a follow up to this article with details of the cylinders yet?

Paul Knoerzer - 12/01/2011 - 12:20

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