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Ian's Steam Locopede
Contents of this website are freeware and/or copyrighted material, and may not be sold under any circumstances.
Email: dogsbody@steamhobby.com     Home: http://steamhobby.com


1. Credits & Specs
2. Mechanics  
3. Body  
4. Materials
See Also:
Face Shovel Excavator
Face Shovel
 Steam Tractor Tank
Tractor 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!
Chassis:  Gakken 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 motors 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 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 - Click to Enlarge

Additional brackets were fabricated to support the motors & r/c servos.   See drawing to right for details.   The motor 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
Click to Enlarge
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 Gears
Click to Enlarge
 

Click on pictures for larger images


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 enhance 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 rc steam locopede/centipede for your viewing pleasure:
Click on pictures for larger images



4. Materials List & Vendors
  • Other Supplies (Home Depot, Kragen, etc...)
    • 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