Monthly Archives: March 2016

Baldwin Unitah 2-6-6-T Superstructure Mods

This engine is being bashed from a Roundhouse Outside Frame 2-8-0 kit and a Roundhouse 3 in 1 kit.  The superstructure will primarily be made up of components from the 2-8-0 kit.  This superstructure project will have us doing the following:

  • Extending the 2-8-0 boiler.
  • Relocating domes.
  • Scratch building side tanks.
  • Bashing the cab to add a side door, shorten its length and add a bunker.
  • Extending the front pilot deck.
  • Detailing with brass parts.

Here is a Jon Davis drawing of a Unitah 2-6-6-2 articulated locomotive.

Unitah Mallet Davis Drawing

Extending the Boiler

Note that the front of the smoke box falls at about the midpoint of the front cylinders.  The following photo of the Roundhouse boiler shows the extent to which the boiler needs to be extended so that the smokebox falls in the right place.  By my calculations, the boiler needs to be extended by 0.8″.

2-6-6-2 Unitah Boiler Ext

A consideration in the boiler modifications needs to be that the underside if the boiler needs to be open to handle the drive train that will be powering both sets of drivers.  This image shows the underside of the boiler.  The drive train slot works fine for a 2-8-0.  Not so much for an articulated 2-6-6-2.  Note that the weight (silver object) is held in place by rivets.

2-6-6-2 Boiler Underside

The logical places to make the cuts to extend the boiler is shown in the following image.  One potential cut spot is right behind the smokebox (right cut line).  The problem with this location is that the splice will be fairly visible.  Another potential cut place is behind the right dome.  That cut/splice would push the dome closer to the front of the engine but the splice would be less visible as it would be hidden between the saddle tanks.

2-6-6-2 Boiler Cuts

In either case, the cut would be through the weight.  I’m considering relocating the weights to the saddle tanks, freeing up space under the boiler for the drive train.  At this point I prefer the right cut point as engine smoke boxes are often a slightly different diameter than the boiler because of the lagging applied to the boiler.  In addition, the splice may be far enough forward that the underside doesn’t need to be open to accommodate the drive train.

Plastruct makes tubing that is available in a variety of different diameters including 0.75 inches, the measured diameter of the Roundhouse boiler.  The Plastruct tube walls are 1/16 inch thick.  The next smallest tube (0.625″) slides tightly inside the 0.75″ tube allowing very solid support of the splice.  I may have to either taper a bit or shim a bit on the roundhouse sides of the splice depending on the thickness of the Roundhouse boiler casting.

So I cut the boiler at the right cut line and ended up with this.

2-6-6-2 Cut Boiller

All I have to do is make this work is:

  1. Remove the weights from both cut sides – doesn’t look easy.
  2. Cut a 0.8″ piece of the Plastruct tube and order the next smaller size so I can splice the three pieces together.
  3. Slot the bottom to clear the drive train.
  4. Cut off and relocate the domes.
  5. Whatever else is needed to make this work.

Or I could replace the entire boiler with Plastruct tube.  I would need to:

  1. Slot the bottom to clear the drive train.
  2. Place the domes where I need them – brass domes on order from Wiseman.
  3. Add a smoke box cover – on order from Wiseman.
  4. Fabricate a fire box – would need to be scratch built.
  5. Put bands on the new boiler – some styrene strips.
  6. Whatever else I need to do to make this work.

Somehow the latter sounds easier than the former so that is what we’ll do.

Saddle Tanks

Support of the saddle tanks is already cast into the Roundhouse boiler in the form of running boards. Or I will need to add supports to the new Plastruct boiler.  The saddle tanks will be scratch built from styrene.  Th hollow space inside the running boards will be filled with sufficient strip weights to more than offset the loss of weight inside the boiler.

Bashing the Cab

Not counting the bunker, the cab on the 2-6-6-2 is shorter than the Roundhouse cab.  With the bunker on the rear, there is no rear access to the cab so doors or door openings need to be added.  A consideration in bashing the cab and adding a bunker is that DCC and sound are anticipated. So the cab/bunker will need to accommodate a speaker and provide a space for the Soundtraxx Ecomomi DCC unit and sound circuit board.

Extending the Front Pilot Deck

Logging articulated engines had relatively long front pilot decks.  That was certainly true of the Unitah 2-6-6-2T.  There are a number of options for extending the depth of the pilot deck and putting a more prototypical front beam on the unit.

Detailing with Brass Parts

Wiseman just released an array of detail parts for HOn3.  I have a representative sampling coming to me.  Some of the parts are going to be used to give my engines a family feel.  Others are very specific to the Unitah Mallet including a deck mounted headlight, a potential front deck, Unitah front trucks, etc.  Check the Roundhouse Kits Detail Parts post for more details.

Baldwin Unitah 2-6-6-2T Frame Mods

I’ll be referencing the takeoffs that were shown on the page you used to navigate to this page.

Unitah Takeoffs

Also, the frame image on that page is the starting point for the discussion on this page.

2-6-6-2T Frame3

The takeoff table shows the spacing between the rearmost driver in the front block and the front driver in the rear block (Driver Front/Rear Wheelbase).  Using the drawing it was estimated at 1.016″.  In the bashed drive train it was initially estimated at 1.37″. We want to reduce that discrepancy.  In the above photo a portion of the rear frame protrudes from the cylinders.  In addition, in remeasuring, I found the cylinders were too far forward.  So I moved the rear cylinders back to a position where their distance from the front axle in their motor block would be the same for both cylinders.  I then cut off the protruding section of the rear frame and rounded the end so when the front driver block rotates to the right and left there will be no interference.

Unitah Frame Mod1

I also notched the frame where the cylinders will ride, but not as much as I originally anticipated.  I realized the the slide plate mounted above the front cylinders would raise the total height of that unit.  In this photo you can see where I filed the front cylinders to receive a brass plate that will allow the boiler to slide as the front driver block rotates.  The brass plate is not shown in this photo.

Unitah Frame Mod2

The slide plate is effectively a place for the boiler to slide and a shim bringing the saddles of the two sets of cylinders level with each other.  I have additional work to do on the drive train before making final adjustments to the relative height of the two sets of cylinders.  But here is how the drive train would look with the front and rear frame aligned as they will be once the frame is complete.  This is a much more compact unit than the image near the top of this page.

Unitah Frame Mod 3

This shot shows the front/rear driver block wheelbase.  The length of 1.111 inches is just a bit longer than the converted takeoff from the drawing which was 1.016″.

2-6-6-2 Front:Rear Whlb

While I had the digital calipers out I also wanted to measure the boiler extension needed for the front of the smokebox to fall at the midpoint of the front cylinders.  The calipers are telling me I need to add a 0.8″ extension to the boiler that comes with the Roundhouse 2-8-0 kit to meet that objective.

2-6-6-2 Unitah Boiler Ext

My next step was to clean out the wheel bearings.  No, your wheels are not going to drop into the bearings and turn nicely for a number of reasons.

  1. Your axles may be rusted.  After all, this is a 40 year old kit that was stored in somebody’s damp musty basement.  A little work with some very fine sandpaper will get them shiny again.
  2. The bearings have flash or were cast undersized.  A small rat tail file will solve this problem.  But go easy here.  You want an axle that turns freely but is not sloppy.  Make sure you have addressed the third problem before finalizing work on the second problem.
  3. You violated the Roundhouse 2-8-2 blind/flanged driver rule.  You see, on a 2-8-2 the flanged drivers go in the two outside bearings and the blind drivers in the two inside bearings.  If you are building a 2-8-2, simple.  Move the flanged wheel set to an outside bearing.  Roundhouse designed the kit to make sure you didn’t screw up the driver order.  If you are building a six coupled wheel set, you have a problem.  You need to put a flanged wheel set in an opening designed for a blind wheel set.  This photo illustrates the problem.

Mallet 2-6-6-2 Wheels1

The driver won’t even go into the bearing — because the flange is hung up on the frame.  Set this assembly aside until you have accumulated a fair amount of patience.  Then get out your small set of files.  I used a rat tail, a triangle, and a moon shaped file with one flat side.  Then work on the inside of the frame element where the flange contacts the frame.  Figure 30 minutes to do two sets, one for the front wheel set and the other for the rear wheel set.  Resist the temptation to get out your Dremel, your table saw, your chain saw or some other weapon of force.  Keep saying to yourself, “This is an antique part.  If I screw this up, I’m going to have to buy another whole kit to get this part.”  When you are finished cutting the notch where the flange hangs up, you should have something that looks like this.  All three axels should spin freely.

Mallet 2-6-6-2 Wheels 2

Smile.  You just beat one of the more frustrating problems in building this loco.  Yes, I realize my shaft on the blind driver is rusty.  Fixing that problem is nothing relative to what I just fixed.  But notice how nicely polished my bearings are.  That is the result of addressing the second problem in the above list.

We are not ready to put the plate on that holds our drivers in place for two reasons.

  1. The plates have not been modified for the six coupled wheel sets.  We’ll do that next.
  2. This locomotive isn’t going anywhere without gears.  No, I’m not going to attempt to run live steam in HOn3.  We’ll deal with the gears in the drive train section.

Underframe Modifications

All I did here is screw the under frames to the frames and mark the cuts needed to shorten the under frames to match the frames.  While I was doing it I did the same for my 2-4-4-2 frames.  This shot shows the bashed under frames in their correct orientation.

Mallet Underframe1

And this shot shows them laid in place on the undersides of the frame.

Mallet Underframe2

There are two places on the 2-6-6-2 frame and two places on the 2-4-4-2 frame where the end of the underframe is not secured by a cross piece.  See the photo before this one for visual look at the problem.  These are white metal castings.  Those ears without cross pieces are weak.  A small brass strip will be superglued to these pieces across the bottom of the engine strengthen these parts and to keep them in alignment.  I also need to fabricate the piece that connects the front and rear driver blocks and provides a hinge on one end so my frame can articulate.  Finally, holes will need to be drilled and tapped for screws that will secure the underframe to the frame in at least two places.  The steps discussed in this paragraph will be the next steps in frame modifications.

Baldwin Unitah NG 2-6-6-2T

Two of the few US narrow gauge Mallets were Unitah 50 and 51.

Unitah Mallet Proto 1

This is a side tank saddle tanker that served a mining road and later a couple of timber roads.  With the exception of the fact the Roundhouse 2-8-0 and 3 in 1 kits are outside frame locomotives they match up fairly well.  I printed and did takeoffs from a Jon Davis drawing.

Unitah Mallet Davis Drawing

My ruling dimension for takeoffs is driver diameter which was known to be 42″ on the prototype.  What follows is a takeoff table comparing HO dimensions converted from the drawing to actual dimensions from the model.

Unitah Takeoffs

Note that overall length is almost identical as is the wheelbase between drivers in driver blocks.  Driver diameter is a bit smaller on the model which will give it more of a hunkered down look.  The wheelbase on the model is quite a bit longer but is adjustable due to bashing.  The model makes up for the longer block to block wheelbase with a shorter front deck.  As the wheelbase in the model is adjusted, room will be gained for a longer deck.  Heights are close.  The cab is longer on the model but needs to be bashed to add a door and bunker.

Distance from the rearmost driver to the rear truck and frontmost driver to the front truck are adjustable.  The side tanks need to be scratch built so can be adjusted to fit the space.  Overall, the model is close enough to the prototype for my purposes.

Here are some more prototype photos and in one case a LGB Unitah photo for details.

Unitah Mallet Proto 2

Unitah Mallet Proto 3

Unitah Mallet Proto 4

Unitah Mallet Proto 5

Unitah Mallet Proto 6

I will keep a builders log as I proceed with this project.

Baldwin 2-6-6-2T Logging Mallet – Frame

In order to create a 2-6-6-2T, two Roundhouse 2-8-0 frames are required.  The first is used to create the rear 6-2T portion of the frame.

2-6-6-2T Frame1

A number of cuts are required, along the red lines in this image.    The front cutoffs are discarded.  Click the image for a larger view.

The second frame is used to create the 2-6 portion of the frame.  A single cut is required along the red line.  The rear cutoff is discarded.

2-6-6-2T Frame2

In the following photo the modified frames are placed in the approximate locations they will assume once the frame modifications are complete.  The approximate location of the cylinders are also shown on this image.  The exact placement of the rear cylinders is not absolutely crucial as the cylinders connect to the piston rods and the yokes.  The driver wheelbase is crucial as it affects the side rods.  But those distances are cast into place on the model.  Note that the rear motor mount is intact.  It is designed to power the second set of drivers on a 2-8-0.  This drivers are the front set of drivers on the rear portion of the 2-6-6-2T frame.  There is not sufficient room to place a motor to the rear of the gear mount in the front portion of the frame.  I’ll deal with the motor mount issues in a separate post.

2-6-6-2T Frame3

This view of the rear (top) and front (bottom) portion of the 2-6-6-2T frame shows the resting places for the cylinders.  Note that this area is notched in the front portion of the frame.  A similar notch will need to be filed into the top of the rear portion.  Doing so will weaken the frame in the notched area as a slot for the fourth driver on the 2-8-0 runs through that area.

2-6-6-2T Frame4

This shot shows the underframes that hold the drivers in place.  The right underframe is in the correct orientation.  They are screwed to the underside of the frame.  In this shot the frames have been inverted.  You can see one of the threaded holes that allow the under frame to be attached to the frame on the right frame.  Because filing the recess for the drivers weakens the frame in the area of the front driver notch, the underframes will need to be modified to tie the front portion of the rear frame together to overcome this weakness.  To accomplish this strengthening, a second hole will need to be drilled into the front portion of the underframe just behind the notch.  A matching hole will need to be drilled and tapped into the frame.

2-6-6-2T Frame5

The frame will need to pivot (articulate) just in front of the rear set of cylinders.  So a suitable connector will need to be fashioned that ties the two halves of the 2-6-6-2T frame together.  I’ll fashion that connector out of a piece of brass strip.  Lets get to work on these modifications.

Baldwin 0-4-2T Switcher

A number of related posts show a 2-8-0 Consolidation, a 2-8-2 Mikado, a 2-4-4-2T  Logging Mallet, a 2-6-6-2T, and a 0-6-0 Switcher being built by bashing Roundhouse 2-8-0 Consolidation and 3 in 1 kits.  With this much slashing and bashing, there are going to be parts left over.  So why not use them to bash something.  A 0-4-2T switcher immediately comes to mind.  So here is a Baldwin prototype.


Here are its specifications.



So lets start scrounging for parts.  In building the 2-6-6-2T Mallet, two kits were used – an outside frame 2-8-0 and a 3 in 1 kit.  The two frames were cut as follows.  The right side of this cut went into the 2-6-6-2T Mallet.  What if we used the left side for the Porter frame along with …





2-6-6-2T Frame 1

The part cut off from the second frame.  The left portion was used in the 2-6-6-2T.  the right portion of the second frame could be joined with the left portion of the first frame to create a frame for the 0-4-2T.

2-6-6-2T Frame 2

The boiler-tank-cab-bunker from the 3 in 1 kit was use in building the Mallet.  that’s the top portion of the next image.  The boiler and cab from the 2-8-0 were surplus (bottom portion).


Of course, the boiler would need to be shortened (chop – chop) and a bunker placed on the back of the cab.  And a saddle tank would need to be constructed.  A set of cylinders was surplus from the bash along with a set of piston rods and associated gear.  Side rods would need to be fabricated,  Of course this is an outside frame loco – a bit of a stretch.  “But boss, the parts were just laying around …”  The North Pacific Coast had a machine shop and the expertise to do this.

It would be a fair amount of work, but there would be no parts to buy – except for the motor, gearbox, sound board, and detail parts.  The whole engine could be done for $175.  Let’s park this project and see what happens.



0-6-0 Porter Switcher

Now that I have the concept of a 2-6-6-2 down, what else could I do with the Roundhouse kits?  How about one of my real needs, a 0-6-0 switcher?  Here’s a Porter saddle tanker prototype.  No 65 is a working engine, toiling for the WK&S in Kempton, PA.  Photos by Jeff Z are used with Jeff’s permission.

0-6-0 Porter Saddle Tanker

Another photo of her current state shows off her switching pilot, air compressor, and headlight.

0-6-0 Porter Saddle Tanker 2

A third shows off the domes, bell, tank hatch and the generator.

0-6-0 Porter Saddle Tanker 3

Here is her builder’s photo.

0-6-0 Porter Saddle Tanker 4

OK, she’s very cool.  And Jeff is an excellent photographer.  But how do I build her in HOn3?  First of all, I wouldn’t be going for an exact rivet by rivet replica.  An engine with the same look and feel would do for my purposes.  Call it a freelance engine based on a prototype.

I could use the boiler-tank-cab-bunker shell from a Roundhouse 3 in 1 kit.  I’d need to shorten the tank a bit, reducing the distance between the two domes closest to the cab.  Some bashing of the cab would be necessary including removing the rear portion of the top and cutting off the lower portion of the front of the cab.  The 3-1 kit part is the upper portion of this photo.  The way Roundhouse designed this shell, it makes the door height look out of scale.  I might also remove the door and show an additional step inside the cab.  I’d live with the vertical bunker instead of the slanted version on the prototype. As this is the Sausalito switcher, I’d convert to oil as oil tanks are near by on the docks.  In the following photo, cuts are the area inside the red rectangles.  After doing the first boiler cut between the domes, I’d evaluate whether I need to do the second.

0-6-0 Porter Upper End

Then I would need to do some surgery on the frame.  The surgery involves three cuts, two taking out the front set of driver bearings and the third taking off the road pilot.  Because the drivers are powered at the second set, the mechanism for powering the locomotive won’t change.  The front pilot would be replaced with a switching pilot like on the prototype shown so nicely in the second photo.

0-6-0 Porter Frame

Am I troubled by the fact I’m using an outside frame kit to model an inside frame locomotive?  Not really.  This is a freelance engine based on a prototype.  And the rotating counterweights on the model will add visual interest.

I’ll need to shorten the side rods.  If I’m careful with my cuts, I may not need to modify the piston rods and associated gear much at all.  Another engine parked at the concept stage waiting for parts.

Of course, I could also consider a 0-4-0T or 0-4-2T Porter switcher.  Same concept, different cuts.  So many engines to model, so little time.


Baldwin 2-6-6-2T Logging Mallet

The project is based on this locomotive, a 2-6-6-2T  Logging Mallet that once ran for the Clover Valley Lumber Company. This locomotive doesn’t exist in HOn3 space.


Then I came across this eBay listing.

Roundhouse 0-8-0

This is an old Roundhouse kit that allows the construction of a static (non-powered) steam engine.  The photo shows an 0-8-0T.  But this kit was designed for kit bashers – like me.  The kit offers another option, a 2-4-4-0T articulated shown in the bottom of the following photo.  This engine would never have existed in the real world.  But it sure fired my imagination!

2-4-4-0T Option

If you look at the parts set, it includes the components to model the above 2-4-4-0T.  If you look more closely, the frame and running components are the same as those in the Outside Frame Roundhouse 2-8-0 Consolidation kit with the exception of the connecting rods and piston rods.  But as you can see, these parts are in the kit.  If you compare the two kits in the following photos, the locomotive frame is the same as are the counterweights and under frame.  There are two sets of pistons in the bag as well as the drivers.  There are two sets of piston rods.


I happen to have two of the 2-8-0 kits. Those two kits are powered.  I also have quite a few brass detailed parts, an extra set of drivers and extra front and rear two wheel trucks that are part of the extended parts set in one of the two kits shown in the following image.  The parts set has a set of drivers in the upper left corner, a set of tender trucks, and front and rear pilots.  There is a second set of tender trucks under the tender.  There is also another complete set of drivers in the box on the right side.  There is a fairly complete set of brass detail parts.  Not shown is two brass domes (one sand and one steam) a brass air compressor, and a brass pilot I picked up in separate auctions.

2-8-0 bund

I know how to make these kits run smoothly.  The drive train parts are available from North West Short Line – gearbox, axle gear, and can motor.  You can see that the 2-8-0 parts set already has upgraded NWSL gears.  Did I mention that all three are HOn3 kits?

The 2-4-4-2T would be created by cutting the frame for a 2-8-0 Consolidation in half and inserting an additional pair of cylinders from the 3 in 1 kit.  The boiler-tank-cab-bunker from the 3 in 1 kit is almost perfect in size for this locomotive.

Logging Mallet Frame 3

The next logical step might be to use a Roundhouse 2-8-0 Outside Frame kit and a 3 in 1 kit to produce a 2-6-6-2T like the Clover Valley Mallet.  The first frame would be cut into a 2-6 block by removing the last driver pair and the remainder of the rear frame.

2-6-6-2T Frame 1

The second frame would be cut into the 6-2T block by removing the front driver pair and the rest of the front part of the frame.  The second set of cylinders would go between the two driver blocks.

2-6-6-2T Frame 2

The boiler would need to be extended to deal with the longer frame.  The boiler diameter is from the 3 in 1 kit is 3/4″.  Plastruct makes a tube in that diameter with 1/16″ walls.  Or the size of the boiler could be upgraded to 7/8″ or 1″.

2-6-6-2 Boiler ExtSide rods could be cut down to handle a six coupled driver set rather than the eight coupled sets in both kits.  Cylinder mounting would be similar to the 2-4-4-2T including piston rods, yokes, etc.

Note that this is an outside frame locomotive and the Baldwin Mallets were all inside frame engines.  But virtually all of them are standard gauge locomotives with 4′ 8″ between the rails.  Had Baldwin been asked to produce a logging Mallet for 3′ 0″ narrow gauge, they may well have recommended an outside frame.  An inside frame locomotive would be a bit tippy on curves if armed with a large boiler.  Given this is a freelance locomotive and the parts are outside frame parts hopefully the rivet counters will forgive me for deviating from the norm.

Of course there is the difference in the cylinder sizes to deal with.  Or is there?  I was poking around on Jon Davis’s web site, Mallets in the Tall Timber and came across his discussion of simple Mallet Type Articulateds like  Weyerhaeuser 111 with both sets of Cylinders the same size.  Note the double stack.


At his site Jon has a very useful discussion of the advantages of simple versus compound Mallets including this drawing of the steam routing on a Simple Mallet Type Articulated.

Simple Mallet Articulateds

Check out his discussion on this page and let Jon fill you in on the details.

Powering this unit would be less of a challenge than with the 2-4-4-2T as there would be plenty of room to mount two motors.  The 2-8-0 Consolidation powers the second driver pair from the front,  That driver pair exists on both driver blocks.

Given that this is an easier bash than the 2-4-4-2T, I think I will take it on first.  A builders log will be maintained.  Individual posts for that blog will be shown below.

X-8-X Kits Drive Line

This shows the drive line components that are in the three kits.  These are the drivers.  There are four pair in the bag.  There is another four pair loose. There is another three pair loose.  Finally, there are four pair unassembled at the bottom of the photo.  The unassembled drivers all have flanges and are from the 3 in 1 kit.  That is more than enough to assemble three kits.



The following is a photo of trucks and pilots.


At the top are three sets of tender trucks including the set on the tender.  The bag also has drive line components including gears.  At the bottom are an assembled lead truck and an assembled trailing truck.  In addition there are two pair of wheels, each for a lead truck.  There is also a plastic truck that came with the 3 in 1 kit.


This is the parts set that came with the 3 in 1 kit.  There are four driver axles and a lead truck axle.  There is also a smoke box cover for the boiler.  The brass parts are for the crossheads.


The above photo compares the NWSL can motor 1630D-9 (below) to the Sagami open frame motor (above) that comes with the powered units.  NWSL indicates that the open frame is a quality motor.  But neutral is exposed all across the frame, making it difficult to isolate for DCC.  The NWSL is insulated.  NWSL indicates the can motor may not fit.  But it is smaller in most dimensions than the open frame, included the space needed to run one flywheel.  I’m going to attempt to use the 1630D-9 with both the 2-8-0 and the 2-8-2 builds.

I do have two NWSL 1220D-9s on order just in case the larger motor doesn’t fit.  Because these motors are so small (less than 0.8″ long) I may be able to use two in the Mallet, one powering each driver unit.

Skookum Drawing Takeoffs

The objective of this page is to determine whether a visually convincing model of the Skookum, a Baldwin 2-4-4-2, can be assembled using Roundhouse parts from their inside frame 2-8-0 Consolidation and their 3 in 1 kit aimed at producing either a x-8-0T or a X-4-4-0T in HOn3.

Noting the proposed service is important.  This engine will pull lumber consists out of Duncan Mills.  A 2-4-4-2 is desirable because of its combination of tractive power and the ability to navigate relatively tight curves.

HOn3 is already a deviation from the prototype which was a standard gauge engine.  I would expect had Baldwin produced a 3′ narrow gauge version of the Skookum, it would have been lower and shorter as was typical of narrow gauge engines in relation to standard gauge.

Here is a set of Skookum drawings.


Dimensions are visible.  I blew this drawing up to fill an 8 1/2 by 11 piece of paper.  Coincidentally, the drawing is close to HO as you will see from the takeoffs.

Skookum Takeoffs

My ruling dimension from the drawing is the wheelbase of the rear pair of drivers which is 66″ from the drawing.  I took off length using my digital caliper and it turned out to be 0.779″ on the drawing.  Dividing the 66″ wheelbase by 87 (HO) translated to a 0.759″ wheelbase at scale.  The actual wheelbase measured on the Roundhouse frame is 0.52″ which translates into 45.24″ at 1:1 scale.

So the separation between the drivers on the frame (45.24″) is undersized in relation to the prototype (66″).  I would expect the narrow gauge locomotive to be shorter.  But the rear drivers wheelbase in the models frame is only 68.5% of what would be expected from the prototype drawings.  Of course this wheelbase could be changed with quite a bit of hacking of frame, side rods, cylinder rods and other components.  I’m going to park that problem for now.

Overall wheelbase including tender is 662 1:1 scale inches which translates to 7.609″ in HO scale.  That is about the same as the 2-8-2 Blackstone Mikado.

Driver diameter is 46″ on the prototype which translates to 0.545″ at HO scale.  The drivers on the Roundhouse models are 0.443″ which translates to 38.5″ at 1:1 scale.  Changing the model’s driver diameter would be a major issue on the Roundhouse kits.  The kit drivers are 83% of the diameter of the prototype.  With smaller drivers, you would expect to see closer spacing (wheelbase).   Other dimensions are not far out of line.

The next photo compares the drive train of the Roundhouse 2-8-0 to the drawing of the Skookum’s drive train.  Given that the drawing is close to HO scale, the drivers and the driver spacing is small in relation to the prototype.  Of course we are looking at the Roundhouse Outside Frame.  The Roundhouse Inside Frame  anything would look even smaller although it would be the same length.


Does this kill the concept of using the Roundhouse kits to build a 2-4-4-2?  No, but it will need to be a freelance locomotive.  Calling it the Skookum would draw hordes of deceased rivet counters out of their graves like zombies, all headed in my direction.  Visualize that scene for a second.  It runs chills up my spine.

The next photo shows the Roundhouse Boiler in relation to the Skookum boiler.  It is a bit shorter but given the fact the freelance 2-4-4-2 will have a shorter wheelbase, it will work.


Getting the boiler out brought another issue to my attention.  The following shot compares the Roundhouse 2-8-0 boiler and cab to the boiler/saddle tank/cab from the 3 in 1 kit.


Yikes!  What should be my smallest locomotive, the 0-8-0T, would be the tallest and possibly the biggest.  What was Roundhouse thinking?  I’m going to have to give the solution to this dilemma some thought.  I could use the 3-1 kit parts for bashes with other Roundhouse kits.  I could fabricate (scratch build) a shell for a 0-8-0T.  But it turns that locomotive not a much bigger project than I anticipated.

Another alternative might be to build a 2-4-4-2T Logging Mallet.  Something along the lines of this Booth Kelley Mallet, except as a 2-4-4-2T rather than a 2-6-6-2T.  Such an engine should have a chunky look.  The outside frame with its counterweights would give that feel.  And the cab/bunker looks a lot like the cab/bunker in the 3 in 1 kit.  Hmm.  But the tank is different.



How about this 2-6-6-2T logging Mallet?


The boiler is a bit longer than the boiler in the 3-1 kit.  But there would be only four driver wheels rather than six.

Roundhouse Kit Detail Parts

If I want these engines to be a family, they should have a similar look.  That gets down to paint and lettering.  But it also applies to detail parts.  Here are the detail parts selected for all four engines.

All will have the same stack with the following spark arrestor.  I’ll pick the stack once the spark arrestor arrives.

Spark Arrestor

All will be oil fueled.  An appropriate oil bunker will be added to the tender and to the bunker on x-8-xT engines.  A hatch will be located for oil and another for water.  Here is the water hatch.  The water hatch will be on the tender for engines with tenders and on the bunker for the x-8-xT locomotives.

Water Hatch

This will serve as the oil hatch.

Oil Hatch

All will have the same headlight, mounted on the boiler.  Attempts will be made to electrify the headlights with LEDs,


All will also have tail lights on the rear of the tender for this with tenders and on the back of the bunker for x-8-xT locos.  These will also be electrified.

Tail Light

In some cases, headlights will be mounted on the pilot.

Pilot Mounted Headlight

All will have generators mounted on the top of the boiler.


All will have air compressors mounted on the side of the boiler,

Air Compressor

All will have air tanks mounted below steps on the boiler.  Lines will need to be run from the compressor to the air tank, and from the tank to appropriate places on the locomotive sand tender.

Air Tanks

All will have cylinder lubricators mounted on top of the cylinders.

Cylinder Lubricators

All will have a brake cylinder mounted in a visible area below the tender.  Lines will need to be run to the brake cylinder.

Tend Brake Cylinder

All will have air whistles mounted on the side of the steam dome.

Air Whistle

All will have air ringer bells mounted on top of the boiler.

Ringer Bell

Here is the Pilot Beam for yard switchers.

Pilot Beam

Note: Other detail parts will be added as the project evolves including piping, back head details, tender details, etc.

Backhead Parts – Diagram shows back head for NPC No 21

The problem with back head parts is often, nobody sees them.  But I’m going to list them and show examples.  The following diagram was a collaboration between David Fletcher, Keith Christensen, and yours truly on what the back head might have looked like for North Pacific Coast No 21, my Holy Grail locomotive.  Keith has since passed away and owned the last remaining Class A Climax.  NPC No 21 was unique in that it was the first railroad engine with a marine boiler, and the first cab forward locomotive.  It was also arguably the first locomotive designed from the beginning to be oil fired.  What I’m saying is this back head illustrates parts placement for a very unusual locomotive.


Parts shown on the drawing (along with a few others) are:

  • Throttle
    Backhead Throttle
  • Johnson Bar
  • Gauge Cluster
    Gauge Clusters
  • Brake Stand
    Air Brake Stand
  • Oil Firebox door
    Oil Firebox door
  • Lube Tray
  • Hydrostatic Lubricator – Oil
    Hydrostatic Lubricator
  • Calledan Injector – Water
    Injector with PipingSteam Locomotive Injector
  • Sight Glass
    Dual Sight Glass
  • Tri-Cocks
  • Drip Funnel – Tri-cocks output through the floor
    Drain Funnels
  • Engineer/Fireman Seats
    Engineer-Fireman Seats
  • Auxiliary water pump – Water or oil
    Feedwater Pump
  • Feedwater Heater
    Feedwater Heater
  • Turret – distributes steam to various devices
    Turret Valve

Mallet Specific Parts

  • Pilot Mount Headlight
    Pilot Mount Headlight
  • Unitah Lead Truck
    Unitah Lead Truck
  • Pilot Deck
    Pilot Deck
  • Double Stack
    Double Stack