pritch Posted February 22, 2015 Share Posted February 22, 2015 Hi guys I'm trying an experimental 8x8 build using a couple of cheap Himoto 1/8 scale crawlers I picked up at wholesale prices. This is basically the same 1/8 crawler as HSP / Exceed - just the colour is different. At first I was just going to make one cheap 1/5th scale out of two chassis as Medic did on rcsparks.com, but then I got a bit more ambitious What you see below is where I'm at after a bit of tinkering - I can route the links to make it just about work but may need to add a third set of chassis plates (spare Exceed chassis is on its way) to get decent suspension range on the middle two axles. I'd rather not though... it's long enough already and I'd prefer all the axles closer together to improve steering and help avoid it getting stuck. I've got the front and rear axles steering which I plan will be done via a Y lead and servo reverser. Question is, I've got two ESCs and 4 motors (2 per ESC) - can I control these from a single throttle channel? In my mind first and third axles would be supplied by one ESC, the second and fourth by the other, so like two models overlapping each other. Advice gratefully received before I buy any radio gear etc. http://www.msuk-forum.co.uk/gallery/image/32391-/ http://www.msuk-forum.co.uk/gallery/image/32392-/ http://www.msuk-forum.co.uk/gallery/image/32393-/ 1 Quote Link to comment Share on other sites More sharing options...
evssv Posted February 22, 2015 Share Posted February 22, 2015 Wow...looks awesome!! And complicated. ....cant help I'm afraid though.....sure someone will be along who can.. Quote Link to comment Share on other sites More sharing options...
Mitrab36 Posted February 22, 2015 Share Posted February 22, 2015 Hi Pritch Excellent build there, will be following it closely. As long as you run the servo's and RX off a decent BEC, I can't see there being any problem with running the 2 esc's with a Y lead just as you would 2 servo's. Just remember to snip the red wire from each esc leading to the RX. Then each esc will receive the same signal so should behave the same. 1 question....... I take it both esc's are identical??? Good luck and keep us updated Quote Link to comment Share on other sites More sharing options...
Gaz! Posted February 22, 2015 Share Posted February 22, 2015 Yep, as mitral just said pretty much do that. Only issue I can see is steering, centre axles going straight ahead and locked will push against the turning axles making corners difficult. Why not do both front axles steered and the rear two locked like a regular 8x8? Lastly, I would for ease of maintainance have one esc powering the front axles and one esc powering the rear axles. Both esc's and all motors need to be the same too otherwise your going to have wheels going at all speeds..... Quote Link to comment Share on other sites More sharing options...
pritch Posted February 23, 2015 Author Share Posted February 23, 2015 Thanks guys. Can anyone recommend a decent BEC for larger heavier models at this point? I've never been entirely happy with the 5A Turnigy one on my X-Crawler which is another large motor on axle affair. Don't want to spend too much though until I've satisfied myself this thing could actually work and be fun. All components are in theory equal, though in my experience even with dual motors and/or battery packs, there's frequently imbalance and I'm doubling the potential for that here. I often throw the stock electrics away with the cheaper stuff, but with crawler ESCs and high-turn brushed motors I'm hoping they'll just do a job. I would have preferred the front two axles steering as Gaz says, but unfortunately not possible in this current layout as the chassis plates foul the steering radius for the middle two axles, not by much annoyingly. One of the reasons why this may not be the final configuration by any means. I have this spare Exceed chassis hopefully on the way from the US - it's basically the same with just slightly different shapes, but I'm sure the overall dimensions will be the same and the mounting points will line up if I decide to use it. There will be a couple of cross braces with that and some hardware too, but I'm also going to stiffen the chassis across a few of the spare holes with some M3 threaded rod cut to 120mm and some nuts/washers. It's worth me saying that a viable 6x6 layout is easily achieved with one HSP / Himoto / Exceed crawler plus an additional axle, relevant links and chassis side plates. This doesn't have to cost very much and could be the basis for some large scale custom builds, a dump truck etc. I know Exceed offer a 6x6 now but that's only available in the US I think, but you can easily make one up yourself. But of course I couldn't leave well enough alone and have to put the fourth axle back on somehow As parts and whatnot arrive in the post and I steal a bit of time to fiddle with it some more, I'll keep taking photos and update the thread. Quote Link to comment Share on other sites More sharing options...
Mitrab36 Posted February 23, 2015 Share Posted February 23, 2015 Everyone expects a build to be a 4x4 so good on you for giving something far more complicated a go! Steering is always going to be limited as you can't lock and unlock the diff's, even a standard 4x4 crawler has compromised steering for this very reason, so don't worry to much about that. I hope the build goes well mate and there's a bit more input into the thread for you............. But as this is not a mega bucks Axial build, with all billet parts from America, many on this forum will just breeze past it and dismiss it . Thankfully there are a few helpful chaps like Big Gaz, who's advice helped my Maverick Scout build. Keep up the good work fella ! 1 Quote Link to comment Share on other sites More sharing options...
pritch Posted February 23, 2015 Author Share Posted February 23, 2015 Thanks mate. Indeed, to each their own, and that's fair enough. To be fair I am not expecting great things from this performance-wise, it's just a bit of fun. And I kind of want to be true to making it cheap, anyway, as Medic's original idea was to build a viable 1/5th scale crawler for about 200 dollars, and he pretty much succeeded. I'm at the point in the hobby, and perhaps the age too lol, where I've owned most types of things so I just want to mess about with stuff and be creative these days. I like anything that is a talking point and will get people and kids interested in the hobby. Gunning the Revo on 6S is one way to do it, but I reckon an enormous 8x8 on a sunny day on the beach may do the trick too lol One idea is to build a sort of enormous military shell for it maybe - like an Argonaut or similar. I'd have to do something about the look of the wheels, though. I've got spare four of the "real thing" - Proline Moabs on Weld Racing rims - ironically probably worth more than one of these crawlers lol - but that won't cover all eight wheels. Anyway, cross that bridge when I come to it. For now I'm thinking, may extend the chassis as discussed, may space out the front and rear two sets of axles and have all four axles steer (!) who knows, will see how it goes. I love it when you don't quite know what's going to happen with something Quote Link to comment Share on other sites More sharing options...
Tamiyacowboy Posted February 23, 2015 Share Posted February 23, 2015 (edited) couple ideas. Western Star Edited February 23, 2015 by Tamiyacowboy Quote Link to comment Share on other sites More sharing options...
pritch Posted February 25, 2015 Author Share Posted February 25, 2015 Thanks Tamiyacowboy Yeah the HEMTT has sort of been in my mind, just googled it and it is the one I was thinking off. Could have a go at making a HEMTT body out of balsa or something when it comes to it. I think even quite thin alu sheet metal would end up being too heavy on something potentially this big... Anyway first things first, sort the drivetrain and the wiring out! Quote Link to comment Share on other sites More sharing options...
Tamiyacowboy Posted February 25, 2015 Share Posted February 25, 2015 (edited) wiring: go a ladder runner chassis, you can use the side C sections to hide away the powerleads . you only need 1 wire from each of the esc's to talk to them, ie send command pulses. your not going to need to run all those bec's. i would run a seperate bec to power the rx and servos for steering. steering, if you want both servos to turn on one channel do the same as you have done to the esc's. take the signal wires only and have them plugged into the rx channel signal pin. you can power them from the seperate bec you install. Body work, i would use modeling plastic, you can get all different moulds, sheet, RSJ C , U ,T so you can build a body. some glue and milliputty filler and you have your bodywork. ( its how the scaler guys make one off bodys and add ons ) yeah i to like the Hemtts, they have the duck nose like amphibian look, have a google on hemtts in wikipeida they have a set of different chassis layouts the military use, loaders, flatbeds, wreckers and im sure a craner Edited February 25, 2015 by Tamiyacowboy Quote Link to comment Share on other sites More sharing options...
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