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Another RC model side project

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crueby:
Well, its finally here! I was able to keep this one a secret from the shop elves till now. They saw the box coming in, smelled gear oil coming from it, and attacked the box with a knife to get it open:

they were really intrigued when the first layer of packing came away...

with the bubble wrap off, the cheering started

they were able to elf-handle it out of the box and onto the table...

and they flipped it over to get a better look at the underside too

Here is what its going to be:

A while back I had found sources for copies of some of the old Ruston-Bucyrus cable driven excavators, the RB-19 and RB-22, very similar to each other but with different cabs. I had found that the Magom HRC (company in Spain that makes RC excavators and trucks with full hydraulics operating them) also sells parts and subassemblies for some of their models. This one is for a 1:16 scale modern excavator, but its the perfect track length/width to make a 1:12 scale version of the RB-19. Rather than the hydraulics, I'll be making this a cable shovel powered by a set of GoBilda robotics gearmotors, which are available in a whole range of speeds, all quite powerful - the bucket lift cable will have a power of at least 60 pounds on this model. The Magom chassis comes with metal tracks, the motors inside the tracks to power each independantly, as well as a smaller gearmotor to spin the turntable on top. I did not buy any of the rest of the model, I'll be setting it up with these three gearmotors (I 3D printed the motor holders and cable drums), making my own booms/bucket and cab:

It may look like the motors are too big, but the cab for the RB-19 is wider/longer than the top plate the chassis came with, so plenty of room for the motor, radio, and overhead pulley system it will need. The chassis has a slip ring built in for the wires, so it can spin the cab round and round without messing up the wires to the track motors. I have a bank of speed controls for all the motors (6 of them), plus one servo for the bucket door tripper. There is one motor for each track, one to spin the cab/boom, one to tilt the main boom in and out, one for the bucket crowd movement, and one for bucket hoist. A friend of mine who casts bullets gave me a box of 1 pound lead ingots he had left over with lead that was too soft for his use, I'll seal them with epoxy and use them for counterweight on the back of the cab. The main boom is 18.75" long, dipper stick is 14.75" long at this scale. The manuals I have include detail parts drawings with enough dimensions to make everything accurate.


I picked this cable shovel partly due to the way Ruston did the crowd mechanism - all cable operated from winches in the cab, the dipper stick is a large square shaft running in a pivoting long bearing on the boom, the cables run up to the bearing and out to each end of the dipper to move it in and out. Also found some videos on YouTube of real ones in action, plus the Ruston patents with details of the crowd mechanism.

Should be a fun project! This chassis is something I COULD have made, but Magom had it all ready to go out of the box, very good engineering on it, and saves me a LOT of time just to make the tracks. When done, it should be plenty strong and heavy to do some digging in a sand/gravel/dirt pile, though not enough to dig through sod. Have to set up a sandbox for it! I have some Gauge 1 gondola rail cars for it to fill, also have an old RC offroad truck that could be refitted with a new body to add a vintage dump truck.

This will be a good side project alongside the Kearsarge winch/windlass engines that I'm currently building - that still takes priority over this build. I wont be doing a full build log on this, but will post progress now and then as it comes together...

Chris
 :cheers:

ozzie46:
Oh boy Oh boy Oh boy! Another great thread coming up :pinkelephant: :pinkelephant: :pinkelephant:

Ron

cnr6400:
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn: The Magom chassis and the mount / drum printed parts look great Chris! Look forward to seeing this model come together with your cab and dipper parts.  :cheers:

crueby:
Thanks guys!  :cheers:

Did a little playing around with laying out the parts (radio, speed controls, batteries, motors, etc) on top of the cab floor plate (allowing for the fact that the RB-19 cab is a little larger) and decided on a plan forward for it all. Well, at least an approach to making the plan!   :Lol: 

I'll put the electronics/batteries on the floor level, and make another floor above it to hold the gearmotors/cable drums. Otherwise things would be too crammed in and hard to work on. The cable drums dont have to be aligned directly to where they leave the cab - they can be routed through a pulley or two if need be. I really want the layout to be structured such that its reliable and easy to maintain. The motor floor will be removeable from its supports to allow easy access to the electronics level.

Will need to take a bunch of measurements and model it all up in CAD - lots easier to move things around there till a good layout is laid out! Sounds like a start on a good tongue twister!   :Lol: My old favorite: How Much Work Could A NetWork Work If A NetWork Could Net Work?   :Jester:

Kim:
What fun!  A new RC project!  Looking forward to following you on this one too, Chris.  Look's like a very fun project.   :popcorn: :popcorn:

Kim

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