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R/C Steam Locopede
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Email: dogsbody@steamhobby.com     Home: http://steamhobby.com


1. Credits & Specs
2. Mechanics  
3. Body  
4. Materials

See Also:
Face Shovel Excavator
Steam
Face Shovel
Steam Tractor Tank
R/C Steam
Tractor Tank
Turret Tank
R/C Steam
Turret Tank


1. Credits & Specs
  
A while back I'd purchased a Mamod SE3 in moderate condition, needing a few parts & cleaning.   Later I stumbled upon the Gakken Mechamo Centipede kit, and recalled Crabfu and his R/C Steam Centipede.   The result was inevitable...  the centipede arrived, got assembled, and then the real construction began!

ChassisGakken Mechamo Centipede
Power: Mamod SE3 Boiler, two Wilseco D49 Marine Engines
Fuel: Denatured Alcohol (ie: paint thinner)
Boiler Pressure: 15 PSI
Body: Aluminum Sheet Metal & Brass Fittings
R/C: Spektrum DX6, two Futaba S3010 servos
Runtime: 10 minutes
Weight: 6.5 lbs (empty)

   


2. Mechanics

As does Crabfu's, my R/C steam centipede/locopede uses 100% steam power provided by an old Mamod SE3 boiler for propulsion.   Batteries only power the Spektrum r/c receiver.



Wilesco D49 steam engines replace the small electric motors the centipede kit came with, and I used some old Futaba servos I'd laying around to control the fwd/reverse engine throttles. 

Structurally the LocoPede chassis was strengthened with two large u-shaped brackets.   These stiffen everything, but mainly provide clearance over the cams which move the 32 legs.  In the very front a smaller u-bracket helps support the boiler and provides an attachment point for body work.  

On top of the u-brackets the discarded base-plate from a Regner marine MIDI plant used in my R/C Steam Tractor Tank was attached (see below).   Always good to recycle & it gives solid support for the boiler.
Wilesco D49 Marine Plant
Wilesco D49

U Brackets Motor Bracket
Mounting Brackets

Additional brackets were fabricated to support the steam engines & R/C servos.   See drawing to right for details.  

The R/C steam engine bracket is made from 0.064" aluminum and attached to the u-brackets.   In addition to the engines, it firmly holds the R/C servo bracket & rear-cab body work in place.

The R/C receiver & battery are attached with velcro to the back of the servo bracket.


Mounting Brackets
Mounting Brackets
Design Drawings
The motors need down-gearing to have enough torque to move the locopede.   Crabfu got away with only sprockets providing a 16:1 reduction.   However after much frustration I decided my version needed more.   I'm not sure why.  Some combination of the locopede possibly being heavier, the engines weaker, or the boiler less productive.

In any case, an extra 2:1 reduction was added onto the motors using 19t & 38t Meccano gears.   I fitted a small aluminum bracket between the engine's flywheel & frame, then drilled a 4mm hole for the new axle.  This yields a 32:1 reduction.  On the plus side the extra gears enhance the Steampunk look I think.

Meccano trunions -- triangle shaped brackets --  were attached to the rear of the centipede chassis to support axles for the sprocket reduction gears, and hold a full width axle for chassis stiffening.


PM Research Whistle
Engine Reduction Gears
Closeups


 

Internal Pictures


3. Body

The Locopede's bodywork was based on Crabfu's early centipede pictures.  He had a steam locomotive look going I really liked.  Unfortunately the rear-cab on his was removed, but I decided mine would have one.   A little wood trim & brass thrown in enhances the Victorian look.

The body is made from 0.032" aluminum sheets, which are easy to cut & bend.   The frontend was made from a single large sheet in two mirror images, bent into shape, then JB Welded together down the center of the  "cow-catcher".   The rearend was made from K&S sheets in smaller pieces, then bolted together with brass hex screws.  

Nothing but hand tools, drill & a vise were used.    I did upgrade my toolbox with a metal nibbler however to make cutting square holes easier.
 

Locopede Before Painting

Because of all the odd angles, I first created templates from paper before cutting metal.   Good thing too since my initial guestimates were way off.   Once the shapes were finalized I traced the outlines onto aluminum sheets & started cutting.   The interior holes were first drilled, then nibbled, then filed into shape.

The fenders were a bit tricky.  The sidepanels are inclined, and I wanted the fenders level with the ground.   To keep the curved portion tight against an incline required a little math. A few measurements & minutes in a spreadsheet yielded the necessary template.

The hand rails were made from 1/16" brass rod & mounts I made from 1/8" square-bar brass.   I drilled holes, then cut the bits to length.   Each handrail mount was fixed in my drill & filed down on one end.   All the bits were then soldered together.

Some mahogany strips cover rough edges, fire resistant bbq paint in the front & engine enamel paint in the rear & fenders, and more soldered 1/8" square-bar brass was used to make the cow-catcher (or pilot) mounted on the front for finishing touches.   The R/C steam locopede/centipede for your viewing pleasure:

Completed Locopede after Painting



4. Materials List & Vendors
  • Other Supplies (Home Depot, Kragen, etc...)
    • Mahogany Strips (1/8" x 1/4" x 24") - Rear cab window trim
    • Black BBQ Paint (1200 degree) - front side-panels
    • Ford Blue High Temperature Engine Enamel Paint (500 degree) - rear cab
    • 4-32 screws/washers/nuts
    • Loctite Thread Locker
    • J-B Weld
    • Velcro