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Tiamat - My 6WD/6WS Clod Buster based truck

Discussion in 'Road Giants 6x6/8x8/10x10' started by potatocat, Dec 31, 2015.

  1. potatocat

    potatocat Well-Known Member

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    I built Tiamat in an attempt to make a peerless 6x6 truck, and to push the envelope of what could be done on the Clod Buster platform. I knew going in there was no way to be the best at everything, so I focused on power, solid construction, and reliability at expense of light weight and speed. It was originally built in the fall of 2001, and has been incrementally revised ever since. It currently is undergoing a major refit... while structurally complete, a lot of parts are being upgraded one by one.

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    Some general specifications about the truck:
    Overall length: 36"
    Wheelbase (F/M, M/R): 15.5", 8"
    Electronics: Triple HK100A ESCs slaved to a single channel, triple Hacker C50MAXX 10T sensorless
    Steering: Triple servo (2x Futaba S3306, 1x Hitec HS645MG Standard) slaved to single channel
    Weight: 25 lbs

    The original motor specifications were a triplet of 540 silver cans, which then was upgraded to Kyosho Magnetic Mayhems, then for a very brief period Trinity 9T brushed motors- and finally to the current Hacker C50MAXX 10T brushless setup vintage 2003 which is still in use today.

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    The chassis was actually made with hand tools. At the time I only had a drill press, and this truck marked my entry into being more serious with R/C but from a self-fabrication point of view. I began to collect tools and learn fabrication methods on my own instead of racking up aftermarket parts. This allowed me a lot more design freedom since a lot of the basic structural parts on the truck were self-made and do not exist in the market.

    (an old photo, pre-brushless days in 2002)
    [​IMG]

    Gearcases were the RC4WD units- While they are pretty good to me now, when released they were half-baked. I chose to buy these rather than mill out my own cases at the time because I could not spend as much time as I wanted to machine something so large on my own. The RC4WD cases came with some serious alignment issues (holes drilled in wrong places, and such) which I was able to address only because I had a vertical mill. Without that kind of tooling the average end user would have been seriously screwed. All internal counter gears are now machined out of 8620 steel. The diff and spiders are still plastic, but they have held up quite well so far. The one weak spot in the counter gear setup which required a single 8x5mm ball bearing is now a sleeve which allows me to run three 8x5s side by side. I experimented with roller bearings but found they wore prematurely and eventually detonated because they were generally not happy with the high RPMs found in this part of the truck.

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    Originally my ESCs were a triplet of Novak Super Roosters - which seemed to be reliable in the beginning but became increasingly erratic over time. They would keep losing their neutral settings, and go into thermal protection mode seemingly at random every once in a while. I think I had a bad batch. They were replaced with first generation JETI 85A ESCs which ran in the same configuration. Those units served me unbelievably well. Rock solid, no-nonsense ESCs for brushless motors. I currently have a triplet of HK100A ESCs and we will see how they hold up. I made the change mainly to get compatibility with LiPo packs. For all my ESC setups, I disabled their onboard BEC by removing the red pin from each plug. That's why the truck needs four stick packs to run. Three are for the motors, and the fourth acts like a big receiver battery.

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    Steering duties are performed by a triplet of quarter scale servos- two Futaba S3306 in the rear, and a single Hitec 645MG up front. The reason for the split in vendors is that Hitec and Futaba have reversed default servo rotation directions. I could have servo reversing without using a dedicated reverser or mess with adjusting my linkages. Servos are fed direct 7.2V line power from the accessory stick pack. This is done by sending the single white lead to the receiver bus, while the positive and negative leads went to the accessory pack.

    [​IMG]

    Recent upgrades were the removal of all plastic 4-link rod ends with alloy 3/16", 10-32 threaded Heim units. Aluminum rods were substituted with stainless steel ones. An increasing amount of raw materials that I use actually come from salvage. The steel from the suspension links came from discarded paper roller rods inside laser printers for example.

    [​IMG]

    Also recently, I converted RC4WD beadlock rims to use an air valve from footballs to give the tires a fully pneumatic setup. This was needed because of the higher ground pressure of the truck because of its bulk. I don't need to inflate the tires very much. It's probably only a few ounces of air pressure at this point but the wheels are holding up very well. I also ripped out all of the wiring and rerouted/simplified everything as much as possible. Current/amperage sensors, thermistors, and reed switches were also installed all over the truck for eventual use in an avionics and telemetry suite.

    [​IMG]

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    I have a ton of relatively small upgrades in progress for the truck, to address known deficiencies one by one.

    Well, enough of my blabbering. You've made it this far and deserve a medal.
    Thanks for reading!
     
    #1 potatocat, Dec 31, 2015
    Last edited: Nov 7, 2017
    walter, Bluedually, Sgt. Ryan and 3 others like this.
  2. Antho11

    Antho11 Studio Forums Elite
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    You have nice Clods! I like the pneumatic wheels!
     
  3. potatocat

    potatocat Well-Known Member

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    Thanks! I started working on this truck recently again after not having any time for R/C a while. Wanted to share a fix to an engineering problem which I thought was pretty neat. Bonus points in that I didn't actually have to make anything and just raided the spare parts bin.

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    This is a linear servo saver. The inset picture should show more clearly how it works if you never saw one before. It's basically a linkage which surrounds the servo with springs. I did the same thing except using the shock body from a T-Maxx and the damper shaft of an HPI Savage. One spring is visible, but the other is inside the shock body.

    I decided to make this after what seemed like an endless cycle of dead Kimbrough savers. It's not 100% elegant in appearance but it can really take a pounding better than the Kimbroughs did. Granted... the kind of loads on the servo saver were far more than it was originally designed for.

    Thanks for looking!
     
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  4. Antho11

    Antho11 Studio Forums Elite
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    Cool servo saver!
     
  5. Bluedually

    Bluedually Studio Forums Elite
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    Really badass truck. Should have kept my Clod...
     
  6. potatocat

    potatocat Well-Known Member

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    Thanks guys! Despite their design shortcomings in certain areas, there's something unique about a Clod, no matter if it's bone stock or modded. I haven't done much with this truck recently but those servo savers have gone a long way in making steering/handling much snappier.
     
  7. potatocat

    potatocat Well-Known Member

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    Very minor update... I finished the body work back to its original state. Had experimented with a stencil design but after much trial and error (and brake fluid stripping paint) was not able to get what I wanted. So the truck is back to its original paint scheme for now.

    [​IMG]
     
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