Andy
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Post by Andy on Mar 18, 2015 16:23:57 GMT
Look out for my TW 20 build in the coming weeks! I'll put it in the appropriate section in the forum. There won't be an arduino in this model, just straight radio gear. Motor, speed controller, steering servo and receiver. Plus an operating hitch and an electric PTO for trailer or implement power operated by separate radio channels.
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Post by RC Tractor Guy on Mar 19, 2015 12:31:54 GMT
Great it'll be very interesting to see how others build their tractors and lots of people will be interested in your use of standard radio gear for sure. Wow PTO as well, not sure if ambitious or madness is the right word Just joking hopefully it will go smoothly, if you get a PTO working you might be able to make some nice implements like a road sweeper with the brush turning or something like that.
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Andy
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Post by Andy on Mar 22, 2015 19:45:43 GMT
Ah, when i say PTO, i don't mean an actual mechanical PTO, i really just mean an electrical feed (-+) that can power a motor to raise and lower a trailer (similar to your Krampe Half Pipe) or reverse a plough. I did have an idea for a muck spreader that would spread 'muck', but that's another story!
This would be a miniature socket situated somewhere at the back of the tractor that you would then plug your implement into. I believe Siku have something similar.
I should have been reviewing the 6mm motor today, got my package from China, but they got my order wrong. Instead of getting the motor, they sent me a Stufz burger press!! (?) It was funny i guess, but they'll have to send me my motor otherwise i'll leave 'em bad feedback.
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Andy
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Post by Andy on Mar 22, 2015 19:53:29 GMT
I did get the N20's from my other source though, wow, what great little motors they are! They're smaller than i thought they'd be, which is a bonus. As i suspected the 60rpm has more torque than the 100rpm, but i don't think any of them will find it too difficult to propel a tractor along. The build quality seems very good. You could be right about these motors RC, they seem to be the way to go.
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Post by RC Tractor Guy on Mar 23, 2015 11:03:24 GMT
Oh I see what you mean now, I do something similar only I'm sending a UART signal to the trailer so that I can control lights too. Since you're using normal RC gear maybe a servo signal would be best and just put an ESC in the trailer.
That's a crazy mistake with your order, I've had the wrong parts come before alright but never so wildly wrong.
Yes I'm very fond of the N20 motors they seem to have more than enough grunt for the job. I'm pretty sure they've more pulling power than the siku motors and those models are pretty good. Just a pity there isn't one in the same configuration as the siku motors with the long axle so that you could easily fit it in the models.
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Andy
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Posts: 13
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Post by Andy on Mar 23, 2015 20:18:33 GMT
I don't think an ESC in the trailer is necessary, i'll just use a really low geared motor, maybe that 10mm @ 29rpm. Anyway, that's thinking too far ahead just now. Not sure about lights yet either.
I'm intending using a 6 channel flight TX. I think i might even try controlling tractor movement from one stick (forward, backward, left, right). Not sure how well this would work, but it would give me the other stick free for other stuff. Controlling a fast racing car like this might pose problems, but a slow tractor might even work better.
I got the Britains TW20 model the other day, and i have to say it looks more realistic in the photos! There are things that let the model down, like the tires, some of the fittings, how the indicators are mounted, the way the cab is put together. It does not have a very good turning circle (i can improve this) and the steering rack and linkage is very sloppy (hard to correct) but i guess that's why its cheap. On the plus point i've located a good position for an N20. Lights look like they'd be very difficult to fit too.
The tractor is now completely disassembled whilst i ponder what to do next.
From here on in, i'll start taking photos to post in a build thread.
What i'd really like to see is a dual shaft N20 fitted with a flywheel. A heavy brass flywheel would make this motor an absolute joy, so smooth and controllable and the model would just glide to a stop, rather than stopping too suddenly, if you know what i mean. It would give you a kind of built in 'braking' effect after power was cut. Recently, manufacturers have been putting flywheel drives into model locomotives, and the difference is night and day - - just that little bit of inertia the flywheel gives you makes a big difference in performance. Anyway, i digress...
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Post by RC Tractor Guy on Mar 24, 2015 11:05:06 GMT
I controlled my tractor like that before and it worked okay except the more I steered the further back the xbox joystick went and the slower the model went. You probably don't have that problem with your controller, the flight controller joystick probably has better range of motion.
That's a pity about the TW detail but at least you wont be too worried about damaging it on your first conversion attempt. My universal hobbies ford models have poor turning circles also, I think siku are the only company who made a good job of the steering although it is not nearly as realistic looking as the other manufacturers.
That would be a nice touch alright, I could easily enough add that into my code to just ramp the motor down rather than dead stop instantly but a bit trickier for you. If you wanted to add a flywheel to an N20 you could buy one with an encoder and just replace the encoder with your flywheel.
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Andy
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Posts: 13
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Post by Andy on Mar 24, 2015 14:57:01 GMT
You controlled your tractor with an xbox joystick? Wow, that sounds pretty good from a technical point of view. I understand what you mean about the range of movement, but on a flight TX you'll get full range whatever position the stick is in.
Yeah, it's a pity about the turning circle, it's because the axles are oversize, and also the boxes that swivel on the axle ends (where the wheels attach) are oversize too. They need thinning down with a needle file to enable more movement.
I might do a tuition on how to do this. The trouble is setting my ancient camera up. It eats batteries for breakfast and really hates focusing in anything less than direct sunlight, so getting decent pictures is an issue, plus i left my tripod behind in the last place i lived....ggrrr!!! So it's all a bit of a faf at the moment to do tutorials and stuff, but i'll see what i can do. If i want to post pictures of the TW20 build i'll have to set it up anyway.
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Andy
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Posts: 13
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Post by Andy on Mar 24, 2015 17:42:51 GMT
Talking of turning circles, i spotted this on ebay: It's a Valtra 6850 made by Joal and judging by the picture looks like it might have an acceptable turning circle. It's an attractive model, devoid of a lot of the detail of UH models, but at only £15.99 i might buy this for a project. It's also a tad smaller at 1:35 scale, but that won't notice. I found a picture of the underneath and it looks like it might accept certain UH or Britains implements. One thing i've noticed, it seems hard to find pictures of models that show the turning capabilities. I must apologise, this thread started off as a discussion of the 6mm motor, but has turned into a general discussion of ideas!
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Post by RC Tractor Guy on Mar 25, 2015 11:53:52 GMT
That Valtra does look to have a good steering setup, every joal I've taken apart so far has been well made and easy to screw apart so it's probably a good choice of model. Also my JCB is 1:35 and you'd hardly notice a difference in the scale when it's beside the other models really, the Revell kit Liebherr is supposed to be 1:32 scale and I'd question it's scaling more.
Don't worry about the thread going off a bit, it's good to see an active thread on the forum. It doesn't get a lot of traffic, probably because there aren't too many discussions for the search engines to figure out what it's about so for now any relevant content anywhere in the forum is probably good.
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