N scale 2900 Class ATSF Northern Build

[superturbine]

Of the various engines I have built I still find myself coming back to the ATSF Northern.  I’ve built this engines before but, here is a new casting and there are several to be built by others. I thought I would include a detailed “How to” build thread.  The other reason I am doing this thread?  To me it’s abundantly clear…
GOD blessed the 2900 Class Santa FE Northern!
Here is the first built engine of this casting. 

And the prototype

Not a valid youtube URL
The second of the class is to follow-

Jason Smith
Tomball Locomotive Works

[garethashenden]

I don't know much about Santa Fe steam; Is this what the Bachmann Northern is supposed to look like or is that a different engine?

[RWCJr]

Yes, Jason's model is what Bachmann's northern is supposed to look like. The 2900 class northerns were the last group of 4-8-4's purchased by the Santa Fe. This group had all of the design advances that came from earlier classes, but because of WWII restrictions on the use of light weight alloy's, these were the heaviest of the ATSF northerns. Because the engines were well designed, well balanced and efficient steam producers, the additional weight provided greater traction than that of the earlier classes. Thanks for starting this thread, looking forward to following it.
Robert

[randgust]

I got a casting set from Jason and I was just about to request this!

[draskouasshat]

Hands down the best one yet of any 4-8-4. It just did the mech perfectly!  I can't wait to build my fleet!

[arbomambo]

Outstanding!..
I'd love to model a 3776 class 4-8-4 and a 5011 class 2-10-4...have you ever made molds and castings of these?
My modelled year-1957-witnessed THE last stand of Santa Fe steam...on the Clovis sub as helpers, assisting drag freights up, out of Belen, through Abo Canyon, and up to the summit at Mountainair...sometimes assisting freights up, out of Belen, westbound to Dalies.
I don't own any steam, but these two would be the ones I'd HAVE to have!
Respectfully,
~Bruce

[Cajonpassfan]

Jason, excellent work, as usual!
And she runs great, too. Do you have a Tsunami 750 in it? If so, your getting fine motor control out of it....
Keep'em coming!
Otto K.

[superturbine]

Thanks Otto,
Actually the engine does not have sound.  As you here I have a large number that do and it gets a little noisy, so having a few that don't is ok.....even if its the crown jewel!

The motor is controlled by a TCS M1

[arbomambo]

I'm just going to have to 'break down' and aquire one.....it'll be 2907...part of the last stand in 1957...I'll need advice on detailing and, more alien to me, a proper mechanism to power it.
~Bruce

[superturbine]

I'm just going to have to 'break down' and aquire one.....it'll be 2907...part of the last stand in 1957...I'll need advice on detailing and, more alien to me, a proper mechanism to power it.
~Bruce

Well then you are in the right place.  I will begin posting pica of the build process today.  Needed is a Kato Gs4,  Bachmann Northern tender trucks and the castings, which if you want I will get ready.

[superturbine]

So here begins the modifications needed to turn a Kato GS4 into a ATSF Northern-

The stock GS4 mechanism has frame material in locations (such as under the skirting) which must be removed.  The goal is to reduce to amount of frame material to allow the boiler casting to be installed.  So here we see the frame material needs to be reduced from the stock mechanism to what we see on the bottom of the pic.  Do not be concerned about weight loss, it will be more than made up for with tungsten.

Here we see the upper frame half being removed. The worm and clip must be removed to disassembly the frame. The upper half will be discarded of course- keep the motor. 


 When dropping the drivers and valve gear out you will need to gently pry out the valve gear pins which brace and secure the valve gear to the frame.  Try and drop the valve gear and drivers as one unit.  Once all drivers, valve gear  and all other parts are removed from the frame.  With a small flat head screw driver gently "slowly" pry the 2 frame halves apart.  Be very careful there are 2 alignment pins which can be broken off.  They are at the front and near the back of the frame so evenly separate the frame.  Once this is done, be sure to removed the alignment pin insulators and the brass strips (springs) over the rear driver bearing boxes.  Before milling make sure all part are off of the frame.  It will get hot and plastic parts will melt
Using a dremel tool with a reinforced cutting disk removed parts of the frame as shown.  I recommend having water nearby to cool the frame.  Be very aware of the mounting points for the valve gear and cylinders.  "Mark these points"  especially the "raised pin hole behind the cylinder".  The pin hole must remain to properly brace the valve gear


Next, when removing the side frame material make sure to not strike the bearing box locations on the frame-



Next for additional clearance angle cut the area of the frame that will be located inside the fire box (the frame material between the drawbar and last driver).  Here is the top view of the frame which is now ready to be reassembled.
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[superturbine]

Clean and deburr the frame of any small material which can get in the gear or cause a dead short.  Very lightly oil the frame at the gear bearing pockets.  Make sure the brass strips are installed over the rear driver and the alignment pin insulators are installed.   

Test fit the casting
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[RWCJr]

Bruce, the 3776 and 2900 classes were both built from the same plans. The 2900's were part of a War order and was subject to restrictions in the use of light weight alloys (which were needed for the arms production). 3784 and 3785 were the only two engines to receive the light weight roller bearing rods when they were built. The remainder of the 3776 class and 2900 class got theirs during rebuilding after WWII.
But as far as external appearances, the 3776 and 2900 classes were identical.
Robert

[Ed Kapuscinski]

Can someone explain the extended stacks for me? I've always been curious.

Otherwise, that looks beautiful, as usual.

[up1950s]

Can someone explain the extended stacks for me? I've always been curious.

Otherwise, that looks beautiful, as usual.

The higher the stack the less smoke gets in your eyes , ........... a great song too .