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Discussion Starter · #1 ·
Caspar Lumber had two Mallet engines purchased 20 years apart. The later one was Samson which had the build log posted previously. The Trojan was the first one and differed from The Samson having slide valves and saturated steam.
Here is a photo of it working
Motor vehicle Vehicle Wheel Rolling stock Mode of transport

And here is a drawing showing most of the detail which I have produced in 1/20.3 scale.
This was a very small Mallet and doing it in 1/32 would in my opinion make it look too toy look.
Rectangle Font Parallel Schematic Engineering

I start by making the cylinders in similar fashion to prior builds. Rather than using a cross port plate I made a similar plate with machining on both sides but with straight porting as shown in the upper plate.
Rectangle Font Gas Screw Metal

i must run now and will post more later.

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Discussion Starter · #3 ·
Thanks Russell
I was a little rushed on my last post and should have given a little more info on the Caspar Lumber operation.
The Caspar Lumber Company operated its own private railway which extended east from the Pacific 26 miles into the lush redwood forest area,125 miles north of San Francisco. It ran a vast array of locomotives but was best known for its two Mallets. It was also known for its massive timber trestles. The railway moved giant redwood logs as photographed bellow.
Art Slope Drawing Rock Illustration

Back to the build. My cylinders were bored out from square stock which was rounded over with 1/4 round roundover router bits. I use my router but these bits can be also used in a mill. The high pressure cylinder is bored out to 5/8" and the front low pressure one is 13/16". The boring is done on the lathe with a self centering four jaw chuck.
The valve plate is cut at 30 degrees to mate with the valve body which extends out from the side of the cylinders.
Wood Rectangle Metal Household hardware Aluminium

The valve body has rounded edges. I use a 3/16" roundover bit mounted in the mill to do this.
Drill Milling Drill presses Jig grinder Drilling

Here you can see the cylinder on the right has had the roundover treatment.
Wood Gas Art Cylinder Cork

And here are the four cylinders so far. I still have some work to do to them but the rough shape is done
Wood Rectangle Gas Household hardware Cylinder

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Discussion Starter · #6 ·
I was wrong about running out of Ft. Bragg. It was the California Western RR that ran out of that area. See the map bellow
World Map Rectangle Font Atlas

Back to the build
Dennis cut out the frame rails from my CAD drawing and I made the crossmembers and assembled them
Wood Flooring Hardwood Plywood Art

The cylinder heads are turned from brass bar stick and the covers are turned from aluminum bar stock
Font Silver Art Circle Jewellery

Wood Gas Metal Auto part Plywood

The valve bodys bolt on to the cylinders with four flat head stainless screws and the covers cover them up and are held on by the snifter which is threaded to 2-56. Below you can see the underside on the left
Wood Gas Electronic device Metal Circle

The LP cylinder has a strange (to me) setup which I have tried to duplicate.
Gas Auto part Metal Fastener Wood


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Beautiful work Bill, and thanks for showing the forming of the outside curve of the cylinder with the router bit on the mill, sounds a lot safer than doing it on a woodworking router, with the cylinder bar stock firmly held in the milling vice.

I am glad I have gotten back to making rolling stock after two years moving and getting over an illness and two years building my pike and pointwork. I will post that in the rolling stock section. Keep up the great series on how to do it; very useful for those like me who don't have a model engeneering training.

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Discussion Starter · #8 ·
Thanks Simon
Here is a few photos of the side rods drive rods and axle blocks
The drive rods and axle blocks are fitted with M5 x 10 ball bearings and the side rods have a pinned slot and tongue connection
Tool Wood Kitchen utensil Metalworking hand tool Hand tool

The side rods are cut on the CNC mill by Dennis to my CAD drawings, On the mill, I cut the slot and tongue wit a 1/16" slitting saw. Note how two pieces of 1/8" material are used to clamp ihe rod between the ends
Gas Milling Machine Machine tool Composite material

1/4" 303 stainless is turned down to 1/8". The side rod is slipped on so that the E clip retainer will be flush with the rod.
The groove cutting tool is at the bottom of the photo.
Wood Gas Tints and shades Metal Auto part

The end is then trimmed to leave about .020 past the groove with the cutoff tool

Gas Rectangle Automotive tire Metal Engineering

The pin is then parted off
Gas Wood Tool Metal Household hardware

Bicycle part Rim Metal Circle Gas

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Discussion Starter · #9 ·
I received the wheels from Walsall and here is what they look like
Automotive tire Rim Circle Metal Monochrome photography

The first thing I do is mount them in the lathe and trim the back to reveal the spokes
Engineering Gas Auto part Machine Metal

I then spot the axle hole
Machine tool Motor vehicle Gas Engineering Auto part

and drill a 3/16" hole
Wheel Automotive tire Motor vehicle Propeller Rim

and finally ream it to 5 mm
String instrument Auto part Folk instrument Metal Gauge

The wheel is then mounted on my home made arbor and the tread is rough cut
Automotive tire Wood Gas Automotive wheel system Auto part

The wheel is then mounted in the outside gaws of the chuck and the hub is turned.
Automotive tire Motor vehicle Rim Machine tool Gas

Here is the jig I use for drilling out the crank pin hole. this makes sure all of the wheels are drilled the same
Tire Automotive tire Wood Tread Bumper

Automotive tire Product Tread Gas Asphalt

The wheel tread is finished on Dennis' lathe
Automotive tire Engineering Gas Machine Auto part

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Hi Bill :
For my 2D2 9100 which I entirely rebuilt from an ex Kesselbauer model made for France Miniature amusement park who never paid for them, thats how I got it in a Paris hobby shop, I consider it as a scratch built engine as there is practically no items in it that I haven't modified on it I reshaped the body completly added considerable details (the metal straps on the bodywork had been done in plastic tape...) Rebuilt the chassis completly, turned new drivers, then junked the original transmition and made a new one with module 5 brass gears 2mm thick brass chassis for every reductor, ball bearings and Maxon coreless motors and brass sheet shrouding to protect the gears from dirt and crap it could pick up outdoors.It is direct drive (no worm gears) and nose suprended motors. Unfortunatly I considered that my machining skills were not good enough to tackle a real Büchli transmition, which wouldn't have stood up outdoors so well too.
One of the only thing on it I hadn't rebuilt where the two leading bogies, although I had added some details on them. So last year I decided to rebuild them completly and ordered castings from Mark Wood, as these had a large center boss which I wanted to find. His castings are superb, but pricey. I turned them pretty much in the same way that you described, except that to do the final profiling with a form tool I had bought on Ebay Deutschland I used a different Arbor as described in mark Woods advices on his site. This grabs the wheel at the rim with a dished washer up front so that the boss wont interfear. The idea behind his Arbor is that as his spokes are very fine if you hold the wheel by the rim during this last operation which does exert quite a lot of pressure, you won't break the spokes. Of course thes have an insulating bush for two rails, which is why the axle (thread on the arbor) is so big.

Household hardware Gas Cylinder Auto part Machine

Here is the finished bogie without all the brake gear, cylinder and axle guard:
Train Wheel Land vehicle Vehicle Rolling stock

the rest of the engine can be seen in another post Ii did recently :
Getting back to building rolling stock, at last!
Cheers, Simon

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Discussion Starter · #11 ·
I have been remiss on posting and photo taking but here is what I have
Here is the cad drawing I used for the crossheads and a crosshead fresh off the mill. the mill steps are easily smothed over with a file.
Font Material property Parallel Handwriting Circle

I use my own design for the expansion link. It is silver soldered together at the pivot and pivots on a double row of ball bearings.
At the far left is the pivot with the two bearings then going to the right are the pivot, the link back, two spacers, the link with the radius rod inserted. two link screws and the combination lever
Motor vehicle Wood Font Automotive exterior Automotive tire

Here is the HP crosshead guide bracket with the link bracket attached and the bearings now set with 680 loctite
Automotive tire Motor vehicle Bicycle part Bicycle tire Rim

and the LP setup
Automotive tire Motor vehicle Train Camera lens Wheel

And the assembled expansion link in place
Wheel Automotive tire Motor vehicle Bicycle part Bicycle tire

Wheel Automotive tire Motor vehicle Automotive design Vehicle

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Discussion Starter · #12 ·
here is a little more on the build
I have finished timing both chassis. Here are both showing the steam port fully open. it is timed so that the openings are the are the same front and rear. This centers everything and the valve opening timing is controlled with the combination lever.
Electrical wiring Gas Automotive exterior Auto part Machine

Material property Gas Technology Metal Machine

The tubing is installed on the LP chassis and then the valve covers and front cylinder caps. It has a successful air test and then the covers are installed. Next up will be the HP chassis.
Here id the LP in forward and reverse.
Wheel Tire Vehicle Automotive tire Motor vehicle

Wheel Vehicle Automotive tire Motor vehicle Tire

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Discussion Starter · #13 ·
this is a mini valve i use for my lubricator and startup valve. it has a 4-40 thread
Brown Textile Wood Font Pattern

And here are the valves in the chassis
Motor vehicle Vehicle Automotive exterior Gas Auto part

The axle pump and trailing truck are added. Here is a view of the underside
Motor vehicle Office equipment Gas Automotive exterior Machine

And the top view
Automotive lighting Motor vehicle Automotive exhaust Automotive tire Font

The pilot truck needs some special attention because of the small wheels. I make a special bracket to step down from the frame rails
Brown Textile Font Wood Pattern

Automotive tire Camera lens Wood Gas Reflex camera

Motor vehicle Font Auto part Automotive exterior Metal

And here is the rear truck suspension which doesn't require anything special because of the frame shape
Motor vehicle Automotive tire Automotive wheel system Gas Auto part

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Discussion Starter · #16 ·
A trackside detail cowcatcher is modified to attach to the front buffer
Gas Auto part Metal Musical instrument Machine

The front deck is pretty plain, just a sheet of brass with what I believe is the pilot truck mount and a sand box
I had to modify the sand box to clear my steam piping so it has a cantilevered mounting. The soldering was tricky as I had to clamp the box at the very front where it was only thousands of an inch from teetering forward or baxkward,
Wood Gas Household appliance accessory Office equipment Machine

The deck and sandbox are then painted with low gloss black paint
Motor vehicle Combat vehicle Self-propelled artillery Military vehicle Machine

I still have a few things to do to the chassis but I am now starting the boiler and will finish them between firings

The boiler shell scales down to what would be a 2-1/4" copper pipe (2-5/8 OD). Since they don't make that size, I need to cut a 2-1/2" pipe down. The 1/4" reduction in the diameter results in a .785" reduction in the circumference. I mark the line to cut on the table saw with the additional marks for the saw blade width so that I don't cut on the wrong side of the line and then slide it along the fence for the rip cut.
Musical instrument Idiophone Wood Bell Tints and shades

I cut the smokebox at half the cutout as it needs to be 1/8" bigger to go over the boiler
I use the cutout piece to reinforce the silver solder joint.
Wood Cabinetry Gas Cylinder Drawer

Everything is heated to red hot to anneal then for forming.
Wood Road surface Automotive tire Rectangle Automotive exterior

And then pickled in citric acid to clean them up for soldering
Wood Gas Building material Brick Rectangle

The tube holes are drilled through the frount tube sheet and throat sheet at the same time
Hand tool Wood Stonemason's hammer Tool Metalworking hand tool

And everything is soldered and cleaned up again. Note the PVC fittings which I used to form the round tubes prior to soldering
Wood Material property Office supplies Tool Kitchen utensil
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