[kvom]

This ongoing project began in December, 2010. I reached the first landmark with a chassis running on compressed air in November, 2011. The second landmark was the first steam up in April, 2013. I am continuing to make parts on the engine.

My machine tools include a Novakon NM200 (series I), a Monarch 10EE from 1942, and a Bridgeport J-head from 1962. I purchased the NM200 in 2009, with the machine being delivered on Feb. 9. Here's the machine after assembly when it was clean:

Attachment 194290

I subsequently bought the coolant tray and pump the following year. As can be seen, my machine has the tall column casting, which in retrospect was a mistake. While I could mill parts with a need for lots of Z clearance, the reality is that I needed to raise my vises 6 inches above the table for 99.9% of the parts I make.

Attachment 194294

I normally have a Kurt 6" vise installed, but in the past have also mounted two 4" vises side by side to accommodate longer workpieces.

Attachment 194296

[kvom]

The first parts made for the locomotive were the two side frames, each being hot-rolled steel bars 36x2x1/2". Most of this involved drilling on the Bridgeport, but the NM200 was used to mill this odd-shaped opening in each:

Attachment 194298

The first parts made almost entirely on the NM200 were 4 "stirrups". These sit on top of the sliding axle boxes and attach to the spring rigging.

Attachment 194300

Attachment 194302

I use Draftsight for CAD and CamBam for CAM. The plans for this locomotive are published in the book "The Pennsylvalia A3 Switcher" by Kozo Hiraoka. The plans as published are for a 3/4" scale model. I am building a 1" scale version (1 inch to the foot, or 1/8 the dimension of the prototype locomotive), so I needed to draw the parts myself copying Kozo, then scale 2x in CAD. Typically I used the NM200 on all parts having round or odd-angled sides where otherwise I would need a rotary table, sine bar, or swivel mount for the vise.

I also used CNC when I needed large holes for which I didn't have a drill bit. An example is the axle bearing holes in the axle boxes. Here the holes are spiral milled in 660 bronze:

Attachment 194322

And then an oil "well" pocket is machined in the bottom half of each axle box:

Attachment 194324

[kvom]

The brakes for the loco involved lots of CNC parts as they are odd-shaped. The first parts were two brackets that mount to the frame and attach the lever arms. The stock was first squared and drilled on the Bridgeport, then screwed to a fixture plate.

Attachment 194330

Then the profile was milled:

Attachment 194344

Attachment 194346

This bracket attaches to the rear footboard of the loco and supports the shaft for the brake foot pedal.

Attachment 194348

The brake lever links needed a fair number of operations. First, mill the profiles in some HRS bar. They were all milled at one time and then sawed apart:

Attachment 194350

Then a matching pocket was milled into some aluminum soft jaws:

Attachment 194352

The links were then clamped to facemill the reverse,

Attachment 194354

Attachment 194356

Holes for pins were drilled.

Attachment 194358

More ops:

Attachment 194360

And the finished parts:

[SCzEngrgGroup]

Nice! I've always wanted to build some kind of engine, but too many other projects....

BTW - Looks to me like you might be using kinda dull tools. You shouldn't be getting those burrs along the tops of the cuts. You should be able to get nice, clean edges.

Regards,
Ray L.

[kvom]

Here I'm making the brake levers. The profiles cut into the HRS bar with holding tabs.

Attachment 194520

Used soft jaws again to mill to the correct thickness:

Attachment 194526

Attachment 194532

The brake equalizer beam was made in the identical way.

Attachment 194534

Here's a technique for using two vises to hold long bars. Using soft jaws, cut slots across both vises at the same time. No need to tram!

[kvom]

This entry starts with machining the front coupler pocket. First op is doing the front and side profile:

Attachment 194566

Next, the mounting holes and the pocket for the square coupler shaft. Since I needed almost square corners I predrilled them and also milled out most of the material with a larger endmill.

Attachment 194568

Then a pocket on the bottom to create the impression of webs on the side.

Attachment 194570

Attachment 194572

The remainder of the work was manual filing plus drilling for a pin to hold the coupler in place. The pocket and coupler shown on the front buffer beam later on in the build:

Attachment 194574

[kvom]

The side rods are another pair of "dog bone" shaped parts. I milled the profiles for both at the same time.

Attachment 194646

After drilling and reaming the end holes, two-part bronze bearings were loctited in each end.

Attachment 194648

And test fit to the crank pins. This is where you find whether your wheel quartering is successful.

Attachment 194650

The return crank is the first part of the valve gear I made. Here are the steps:

1) profile

Attachment 194652

2) slot. I like to use the NM200 when cutting deep slots with endmills less than 1/4" diameter as the feed rates are constant. Less breakage.

Attachment 194654

3) drill and tap for the clamp screw

Attachment 194656

4) face mill the reverse side

Attachment 194658

5) test fit on the rear crank pin

Attachment 194660

[LeeWay]

Wow! I have always wanted to build things like this. I used to make vehicle models out of wood from my own design before cnc, but this is much cooler. Really looking forward to this completion. Good luck with it too.

[kvom]

The main rods were machined on the NM200 is an manner identical to the side rods.

Attachment 194778

The cylinders were the most labor/operation intensive parts of the loco. I started with a pair of grey iron castings from Friend's Models. This material machines easily, and the castings were excellent - no voids or chilled spots.

Attachment 194780

The first steps were non CNC. Square the top and sides sufficient to get a grip, mount on the 4 jaw chuck, and face the rear. Without removing, bore the cylinder. This is important so that the rear cylinder head and the bore are orthogonal. The cylinder head face forms the primary datum for all the rest of the ops. The bore is 1.75" and the stroke is 2.5".

Attachment 194782

The front can then be faced to bring the cylinder to its final length, and the top and side faces likewise milled to final dimension relative to the bore. Then it's time to move to the NM200. The curved profile is milled. Given the length of the cylinder it needs to occur in two ops, flipping for the second.

Attachment 194784

Holes for mounting the cylinder heads and steam chests are drilled and tapped, as well as for attaching the cylinders to the tee.

Attachment 194786

Next, the steam and exhaust ports are milled in the top face of each cylinder. Being that each are deep relative to the 1/8" endmill, I decided to predrill for chip clearance.

Attachment 194788

Afterwards the steam supply and exhaust holes are drilled at an angle manually. This is really the most nerve wracking part of the job, since the drill bits need to exit at the right spots:

Attachment 194792

Attachment 194790

All done. Each casting starts off weighing 12+ pounds and ends up less than 6.

Attachment 194794

[kvom]

Next are the steam chests, machines from cast iron barstock. First ops in vise:

Attachment 194958

After machining the extra stock from the bottom to get to proper thickness, a check that the valve does fit:

Attachment 194960

Then round the front boss where the bushing and o-ring will go.

Attachment 194962

After drilling the opening for the bushing/o-ring/valve rod, showing with the rod and valve:

Attachment 194964

[SCzEngrgGroup]

This is quite a large project! How many hours will you have into it by the time it's done?

Regards,
Ray L.

[rayoung]

I've been following your build on HMEM and it's looking great. I started building the New Shay but have been so busy lately that I haven't done a thing on it in months.

Ray

[kvom]

This is quite a large project! How many hours will you have into it by the time it's done?

Regards,
Ray L.

I'm not keeping score, but probably 2000 hours to date. Since this is the Novakon forum I'm only showing CNC jobws/parts.

[kvom]

This is the yoke plate posed on the fixture plate after being finished. It mounts across the frames and provides the base support for all the valve gear. Stocjk is 1/4" HRS. The circular cutout is clearance for the boiler tube.

Attachment 195048

Mounted on the frames and showing the brass yokes. I later remade the yokes from steel after discovering a dimension error in the plans. The spring rigging is also shown in the photo for test fitting.

Attachment 195050

The next parts are the crossheads. First stage is profiling on the NM200.

Attachment 195054

Next, to create the closed pocket, a round "slug" is silvered soldered in and milled flat.

Attachment 195056

Drill and tap holes for attaching the piston rod and the link bracket.

Attachment 195060

Here's the pin for securing the main rod to the crosshead. It's drilled to allow the bronze bearing on the rod to be lubricated.

Attachment 195062

[kvom]

Union links and link brackets:

Attachment 195092

Attachment 195094

The combination levers required several operations:

Attachment 195096

And the radius rods similarly:

Attachment 195098

A mockup of all the valving components thus far:

Attachment 195100

[kvom]

Next is 4 brackets that attach to the yoke and suspend the eccentric.

Attachment 195266

Mill soft jaw as a clamping fixture:

Attachment 195268

Face, then mill relief:

Attachment 195270

Finished:

Attachment 195272

Test fit:

Attachment 195274

[kvom]

The cylinder heads were machines from some 4" diameter round brass rod. For the front heads, I used a parting tool to slowly slice off some discs. Then mounted on the NM200 vise in machined soft jaws:

Attachment 195276

Using the same jaws, I drilled mounting holes in some aluminum round as a fixture. Tghe fixture will be used in both front and rear heads.

Attachment 195278

Now drill the mounting holes. Notice that the inside of the head is stamped R or L, as the boss in the center will be carefully sized later to be a tight fit in the cylinder.

Attachment 195280

The head is flipped to mill the outer side of the head.

Attachment 195282

Now with the head attached to the fixture, the sides of the head can be cleaned up on the lathe. The diameter of the inner boss is also turned down to fit the cylinder using the fixture mounted in the lathe.

Attachment 195284

And a test fit to the cylinders:

[kvom]

One of the trickier parts to make (and one of the smallest) is the die block for the eccentric. This small block needs to slide smoothly in the curved slot of the eccentric. That curve's radius matches the design of the radius rod. So first, mill the inner and out curved sides on some 3/16" HRS:

Attachment 195406

Now check for a good sliding fit inside the slot:

Attachment 195408

Since I milled the slot and the block using the same endmill, I would be able to compute a correction if the endmill diameter were to be off. For example, if the em were smaller than it's advertised size, the slot would be too narrow and the block too wide. In any case, I used a new carbide tool and got a good fit. Normally the die block should be made from tool steel to eliminate wear, but I didn't use it. Next cut and deburr the block from the center of the fixture.

Attachment 195410

Attachment 195412

Another part needing CNC for profiling is the quadrant stand that guides the reversing lever (also called Johnson bar).

Attachment 195414

Attachment 195416

[kvom]

I don't have a CNC lathe, but I can use the NM200 to rough out a circular convex profile. Center the workpiece on the mill:

Attachment 195578

Then successive layers. I think each was .05. This forms the upper half of the sand dome.

Attachment 195580

Then on the lathe with file and sandpaper to finish:

Attachment 195582

The base needs a concave profile. First mill a boss to fit the top part:

Attachment 195584

Then profile the rest.

Attachment 195586

Now the base needs to fit the curve of the boiler. So I drilled two mounting holes to attach the base to a 90-degree angle plate. Then profiled.

Attachment 195588

Top and bottom assembled:

[kvom]

Here's the first cut at the front number plate, engraved on the NM200 with a 1/16" EM. The font is what was actually used by the Pennsylvania RR.

Attachment 195974

The base for the smokestack was profiled in the same way as for the sand dome.

Attachment 195976

Attachment 195978

Then turned and bored on the lathe to match the top of the stack.

Attachment 195980

The brake shoes are made of aluminum. In addition to the overall profile the part that contacts the wheel was tapered to match the wheel taper. Unfortunately I didn't take any in-process pictures.

Attachment 195982

Next, I machined the yoke plates from HRS to replace the brass ones,

Attachment 195984

And a fitting of the yokes and runnuing boards to the chassis.

Attachment 195992