Potatocat's 6WD/6WS E-Raminator

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potatocat

potatocat

Active Member
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Location
NYC
I like building 6x6 solid axle vehicles and consider it a bit of a specialty in my little corner of the hobby. Pictured below are some of my previous 6x6 projects and some of their attributes. My goal is to build up a larger scale machine that incorporates all of the aspects that I like from previous projects all together. As of now the project is un-named. I'm sure something neat will float into mind eventually.

https://imgur.com/Mdg33KB

I have to warn everyone that this might be a slow build at times. I probably only have one or two nights a week to work and random parts of a weekend for the most part. I'll try to post weekly updates. Its a rather ambitious project which as some components going in separate revisions because I need to test/evaluate what the final choice will end up being.

Right now I don't have much to show for progress yet. I am still waiting for some raw materials, fasteners, and tools. Right now this is just a table with a pile of parts - basically three Raminator V2 front axles. I have to upgrade a bunch of my logistics and tool chain. For example I had to get myself a proper grease gun for the first time ever. I also need to get a larger base to convert my lathe to be able to handle the longer stock that I need to turn out things like suspension links, etc.

https://imgur.com/nrUeiwz

For reference this is one of my smaller trucks and how the chassis will look like to some level. I have started off by turning a bunch of smaller parts from aluminum and steel rounds that I will need to assemble the axle stanchions. Nothing fancy, so far its just spacers, conical washers, horizontal chassis braces, and other doodads.

https://imgur.com/dZqfsGf

While the chassis will seem ho-hum and not so innovative, other parts will be more interesting. One of these things is the use of an outrunner instead of an inrunner brushless motor. I am starting off with a 50cc equivalent to test out and if it works well, I will make the jump to a larger 100cc or 150cc equivalent depending on how well this motor holds up. The speed control is an old school, first-generation 170A unit that I am taking out of retirement. It may be missing features like LVCO, sensor support, and programming but will still work perfectly fine as an appetizer and to get a feel for how much additional power I will need for the next revision. I will need to remove this shaft and turn out something that inverts the motor output through the other side of the bell in 10mm 4130 steel.

https://imgur.com/FnJE0g9

The driveline will be similar in some ways to what I did with Pickle Time- which is a stupidly fun truck to drive. Instead of belts I will use double chain drive. This may take a little bit of time to get right, since I need to output power to the rear axle with an offset output since there is no pass-through support.

https://imgur.com/71hGrB6

Take a closer look. Because of the 'free' gear reduction of an outrunner I can get away with the most minimal transmission setup ever!
I am aware of the limitations and drawbacks of using an exposed outrunner can for off-road, but I have some tricks up my sleeve to deal with motor protection. My driving style is also to treat my trucks like overgrown rally cars. They spend very little time in the air and more of their time tearing it up on hard pack dirt surfaces.

Thanks for reading!
 
Thanks everyone for the warm welcome! I don't have any significant updates but still wanted to share with you a neat trick that I applied on one of my older builds which will also carry over to this project.

The subject here is fully pneumatic tires. For one of my trucks it was getting just too damn heavy, and even though I placed the center of gravity fairly far back for a 6x6 truck, the front tires were suffering from a big amount of squish just by sitting there. Stiff foams would help but the truck had reached a point where this was not going to be ideal, and the foams were not going to help with cornering scrub. This was affecting performance in a bad way. The solution needed to be fully pneumatic tires, but there is just not enough room inside the rim for a Schraeder or Presta tire valve. What to do?

It turns out that the answer was something very simple and elegant... simple inflation valves that come from basketballs/soccer balls/footballs! Having beadlock rims are an important requirement of course, so that there can be minimal leaking and reduce the risk of blowouts between the tire bead and rim itself.

https://imgur.com/C441c86

The first step was getting a bag of these (like 25x) and modifying a needle valve by bending it a bit so it would fit inside the rim. Then the valve was screwed into the back of the rim with a supporting washer. I don't have any pictures of this on my older project but I will definitely take better shots when I do this on the Raminator rims.

https://imgur.com/ZDYRI2r

Here is the valve mounted cleanly into the rim. The amount of tire pressure used is only just a few ounces to be effective. I deliberately overinflated the tire here to show it in comparison with a stock one.

https://imgur.com/Woj0Xna

In summary, I just wanted to share this in case anyone has a need for a stiffer tire and foams are just not cutting it. Hopefully I will manage to get some work done on the truck for at least part of the weekend, but we shall see.
Thanks for reading!
 
Nothing major to report on this weekend. I only had a little bit of time for working on things which was mainly spent turning things out on the lathe.
Below is the relocated suspension setup on each side of the axle. I moved the coilover outwards. There is clearance even when the tires are turned in fully. This was done to allow me to build up a wider chassis, which in turn gives more room for internal components and in particular batteries. I will be using 6mm paracord to setup axle limiting straps, using one of the 'loops' that i made from adding spacers as shown below. They may not be super important with a 4WD but limiting straps are absolutely vital with a 6x6.

https://imgur.com/k78tlwn

I turned out a whole bunch of sundry items as well, like thick conical washers for the suspension links and rod ends. I am using M8/1.25 threaded female rod ends which might not be a great idea, but the female housing gives more clearance than the larger male housing. Of course with a 6x6 its always a process of "make this thing 6 or 12 or 24 times". This stuff is really boring and not sexy at all to make, but it really helps tie the build together.

https://imgur.com/OvNOPM5

Thanks for reading!
 
Hi everyone, only some minor updates so far. I turned out the first two of the six planned lower suspension link rods. These are made from 4130 chromoly steel round bars. Heavy but strong stuff! The remaining six upper link rods will be made from aluminum as they will not require abrasion resistance. The front and middle link rods are 12.125" long and 0.6875" thick.

https://imgur.com/BuuoIGd

The first link rod took me almost three hours to cut to finished dimensions, drill down, and tap, but the second link rod only took me an hour. This is my first time working with 4130 so it took me some adjustments to get used to it. I originally planned on using 304 stainless but opted to use 4130 instead. It may not be as pimped out in its finish but it still looks great. You can see some of the mistakes (like tool marks) i left on the first closer link rod while no such defects are on the further second link rod.

https://imgur.com/4SD6qWe

These were tapped to M8/1.25 thread using a set of TiN coated taps and that went realllllly smoothly. I was actually surprised by how easy the tapping process went compared with the 304 stainless that I am used to. Hopefully I will be able to finish most of the link rods this weekend.

Thanks for reading!
 
You should find chromolly fairly easy to work with vs a stainless. My younger brother spent many years working for a chassis shop that specialized in custom drag car parts, but branched out into control arms, 4 link suspension, independent suspension conversions and the like. They used lots of chromolly In their suspension and sub/k frames. He really enjoyed working with it. Light and very strong.
It is an interesting build. I do wish you would have considered keeping a gas powered set up. Would have been very cool, and kept the scale theme well.
 
Seandonato73 said:
You should find chromolly fairly easy to work with vs a stainless. My younger brother spent many years working for a chassis shop that specialized in custom drag car parts, but branched out into control arms, 4 link suspension, independent suspension conversions and the like. They used lots of chromolly In their suspension and sub/k frames. He really enjoyed working with it. Light and very strong.
It is an interesting build. I do wish you would have considered keeping a gas powered set up. Would have been very cool, and kept the scale theme well.
Click to expand...
Thanks! It took me a little bit of adjusting to 4130 but found it a pleasant surprise. Tapping is super easy unlike the horrorshow that is aluminum if you don't use a spiral/multiflute tap. I had to drop the feed rates even further than documented because I am using a small tabletop sized lathe, but you're right- 4130 is really straightforward to work on. I would have loved to keep a gas engine but where I live a gas engine would seriously limit where I could drive the model. Also one of the main reasons I decided to build this truck was because its size will let me experiment with high powered, massively parallel battery module setups.

In any event I finally got some time this weekend to work on the truck. Nothing groundbreaking but 2/3 of the link rods are done and some of the holes are drilled in the stanchions. Its finally starting to look sort of like a chassis now instead of a pile of parts!

https://imgur.com/nGnoiMs
 
potatocat said:
Thanks! It took me a little bit of adjusting to 4130 but found it a pleasant surprise. Tapping is super easy unlike the horrorshow that is aluminum if you don't use a spiral/multiflute tap. I had to drop the feed rates even further than documented because I am using a small tabletop sized lathe, but you're right- 4130 is really straightforward to work on. I would have loved to keep a gas engine but where I live a gas engine would seriously limit where I could drive the model. Also one of the main reasons I decided to build this truck was because its size will let me experiment with high powered, massively parallel battery module setups.

In any event I finally got some time this weekend to work on the truck. Nothing groundbreaking but 2/3 of the link rods are done and some of the holes are drilled in the stanchions. Its finally starting to look sort of like a chassis now instead of a pile of parts!

https://imgur.com/nGnoiMs
Click to expand...
I can understand the electric then. This world we live in 🙄 very cool build at any rate. Keep up the work, very interested to see how it turns out!
 
Thanks again everyone! I don't have any build updates yet for this week, but am hoping to get some work done tomorrow and over the weekend. I did want to share some performance related goals for the truck and how I plan to meet them along the way.

The first topic is the subject of weight balance. Most 6WD vehicles in the 1/10 size class suffer from having too much weight on the front axle. If you plan on pulling a loaded trailer around this is a good thing, but I am not planning to do that at all, so in my case weight needs to be shifted as far back as possible. I have found the ideal center balance point to be somewhere right near the front side of the middle axle, so I can take advantage of all that tire contact patch.

You can get a sense of this from one of my 1/10 trucks that has been suspended on some string. This is about as close to what I consider ideal for my specific use case. The center balance point is right where the strings tie down on to a lift bracket I installed on the truck. The large scale monster I am building is aiming for a balance point at almost exactly the same relative spot.

https://imgur.com/sxdqhfW

The next topic is six wheel steering. I absolutely depend on this, because my driving style is more like that of treating my monsters as overgrown rally cars and not really doing big aerial jumps or freestyle inspired sort of driving. I just like to drive fast around large open dirt spaces. I also like to use claw style steering, with all servos harnessed together without separating the axles into different channels. This keeps thing really simple. Servo draws power directly from its own main battery without using a BEC. The PWM signal line goes into the receiver. This setup works great for my needs.

Below is a short clip filmed way the hell back in 2003 of the same 1/10 scale truck prior to switching over to LiPo just tooling around on hard pack dirt. Believe it or not this is plain old NiCd in the video, but the motors are brushless. It is simply three battery packs driving three separate ESC and motors (this being a MoA design) on one single parallel ESC harness. I am looking for a similar relative speed for the size of the truck, so I'm aiming for high 20mph/low 30mph as a starting point. I am aware that the 50cc outrunner might not give me anything close to the top end that I am looking for, but it will at least let me figure out how much more power will be needed. Maneuverability should be about the same as 1/10 scale with these Raminator axles.


Anyhow, thanks for reading!
 
spents said:
not sure if you said already mate, but what total length are you gonna have on this big one, it's gonna be huge (y)(y):D,
hurry up and get it built, i wanna see a run vid (y)
Click to expand...
Thanks! The final length is still TBD but it cannot be any longer than the 60" table that it is sitting on or else it cannot fit comfortably in my 1:1 car. I really want to just wrench away at this and finish it, but responsibilities interfere with my slacking haha. I really hope I can keep the weight under 120 lbs but we shall see.
 
You should really look into programmable steering, seen lots of multi wheeled, multi steer trucks in real life and the tires don't all turn at the same rate or angle for efficient steering. During tandems rear steer the arc the tires traverse is different and require different levels of steering input for a nice transition and not scrubbing the heck out of the tires. May not matter much on dirt, but i would expect better steering response non the less. Look up Mobil cranes for some easy reference material. Something above 75ton lift. (Largest I know of that does not have rear steer as standard) the 210 we most recently used had triple rear and duel front axles. They all steered. Was just art to watch it move around obstacles.
 
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