Dirty_Vinylpusher

Looks good

superchip

Received some bits today, fuel tank, 10mm pillow block to support the longer rear drive shaft mid way and some fuel pipe. Well I wanted to start the engine to cure the exhaust paste and what happens? The so-called ez start cord to start the engine goes floppy after the third pull! Looks like the return spring has had it so I'm going to remove the pull start and use a drill to start it from now on because those pull starts are a total waste of time. Only had a couple of hours on it today, hopefully I'll have more time on it tomorrow.

superchip

Got the steering nearly sorted out , the plate that originally covered the worm drive had to be permanently removed so I could fit the servo horn. I'm going to make panels for the roll cage so no dirt should get in.I temporarily wired the motor up and was very pleased with the steering action, although it was a little slow but that was because the battery was nearly flat lol. All I have to do to finish is to find a good place for the potentiometer then the steering is done. I'm still waiting for the other wiper motor to be delivered but once it comes I'll make a start on the throttle/brake servo. More to come .

Dirty_Vinylpusher

Soooooo......how are you wiring this all together...?

superchip

Quite simple when you think about for days on end like I did lol. I purchased two servo Thor-15 motor controllers, they basically mimic the circuit board in a regular servo only everything is beefed up to take a max voltage of 16v at 15a (if I remember correctly). The controller has four sets of cables coming from it, one is the normal three wire servo lead that plugs into the receiver, two main battery wires and two motor wires and finally a cable with a potentiometer on the end for the positional feed back. Even I can't get these mixed up lol. The receiver lead also provides +5v to power the receiver so I only need the 7ah 12v lead acid battery in the car to power both servos when both are installed. To protect the controllers from any feedback from the motors I have incorporated a 10a inline fuse. The controllers are very small, the circuit board being about the size of a postage stamp. However, they get a bit warm so I'm going to direct an 80mm pc fan on them which will turn on with everything else. I'll post a video once I have it wired up to show how it works, I highly recommend these controllers, a very cost effective alternative to the more pricier solutions. The second controller, I may have to disconnect the 5v power feed to the receiver because it's already getting power from the first controller and leave the neg and signal wires as they are, I don't want to blow the receiver lol. I hope I haven't confused you, I do babble on sometimes lol.

Dirty_Vinylpusher

Oh right.

Will be interested to see how this works.
Seems easier that hacking an RC servo like a few people have attempted with mixed results.


Look forward to more details on this.

superchip

You can still hack a servo purely for the pot and carcass, simply for ease of installation which I did because the original pot is far from being mount friendly, it just meant de-soldering the original pot and soldering the servo one to the wires. Futaba 3003 servos are very cheap on eBay and I bought 4 for about 5 pounds so I had no problem pulling two apart although this practice is frowned upon by some people lol.

Dirty_Vinylpusher

Mmmm the wiper servos other people have built seem to involve more electrickery with H-bridges and circuits and 12V etc.

superchip

That's because most of them either wanted to make their own h-bridge or opted for the more expensive pololu controller or the like so they can either make their own program and set their own parameters or were told that option was the best, and I suppose in some respects those boards are better. But these Servo Thor-15 controllers were specifically designed to mimic hobby servo electronics with the intention of controlling a much bigger motor and that's exactly what they do. OK they get a bit warm when used but that's to be expected because of their small form factor but once I place a fan in front of them then heat shouldn't be an issue. I just can't justify spending £90+ on a single controller board when I can get these for less than a third of the price, especially since they're going in a creation that was born on the work bench in a garage lol.

superchip

Finished the wiring loom today . Starting from the top and working in a clockwise direction, box which houses the receiver and main power switch, next is the main battery cable, the short blue and yellow wires with the connector block attached go to the throttle/brake servo, bottom right is the pot for the throttle/brake servo, the rc receiver, steering pot, steering power cable and in the middle are the two motor controllers. They are sharing a common power feed at the moment and also share the main battery fuse. I blew the 15a so I replaced it with a 20a. It all works fine with the uprated fuse but I'm only testing the motors under no real load so I may have to step up to 25a or maybe even 30a seeing as each controller is rated at 15a each.

Close-up of one of the controllers , great little pieces of electronics these.

I received the other wiper motor today and I modded it in much the same way as the other one, just need to figure out where to put it lol.

Dirty_Vinylpusher

superchip

Well I had a bit of a set back with the electrics. I did the classic foul up and accidentally got two wires crossed. This resulted in frying one of the controllers and I'm really not amused, I should've known better but oh well, no use getting irate lol. So now I have to buy another but I'm not sure whether to buy another Thor. They're good for what they are but they're not hugely precise I've found, the steering doesn't always return to neutral and it requires a giggle on the transmitter to make it centre. All the linkage is good so it's not that. The pot is new so it can't be that either. I might just look into making one instead lol.

Dirty_Vinylpusher

Aaaaaah the old "crossed wires" trick eeeeeyyyy?
Yeh once you let that magic smoke out it's all over haha.


I was messing around with a PSU from an old Apple Mac a while ago, trying to locate the different power outputs.

Switched it off, removed the circuit board and dropped it on the metal casing.
Shorted it out from the residual charge in the capacitors (I think) and BZZZZZT

Dirty_Vinylpusher

There was a guy on this forum who just added some extra gearing to a 1/4 scale servo and moved the pot to the new setup.
It gave him double the torque I think (and half the speed).

Dirty_Vinylpusher

Ah yes, here we go

http://www.rcuniverse.com/forum/rc-g...ach-buggy.html


The gearing from an old circ saw could work.....

superchip

I fashioned a pc power supply to provide 12v and it works great. I've been lucky in the respect that I didn't drop it thoug, that was bad luck lol.

It's interesting that you directed me to that particular build, I just so happen to have the same gears that he used to bolster the servos torque. It would greatly lighten the car if I went down this particular avenue but would it be fast enjoy enough? He doesn't mind that it's slow because the car wasn't fast anyway, but would it be fast enough to react when my buggy is travelling at 40 + mph? Circular saw gears then hmm..... Not sure, I'll have to look into this servo gearbox thing. Thanks for sending the link it's definitely given me food for thought.

superchip

I went off half cocked in my last reply, I saw his test drive on you tube, the steering isn't all that slow after all. I'll be definitely looking into this.

Dirty_Vinylpusher

Yeh I use a lot of PSUs for powering small stereo amps etc in the shed and home made boomboxes.
That was the only one I stuffed up though, which was a shame as it was a big one with lots of outputs....



I think I still salvaged some fans, diodes and other bits from it though.

superchip

I've been looking into ditching the wiper motor steering servo in favour of a duel 40kg servo steering setup as well as an additional 40kg servo for throttle and brake. I think 80kg of steering force should be plenty as the steering is nice and light considering the size of the car. In addition I was thinking of buying a 6v 4.5ah lead acid battery to power the whole lot, I was looking at lipo batteries are only rated in mah and unless I get two or three and wire them in parallel which wouldn't be cost effective and would add more wire than I'd care to manage lol. What are your thoughts on this? Would a lead acid battery ruin the receiver? It's rated at 6v max so it should be fine yes?

Dirty_Vinylpusher

I used two of these in parallel.







Wired in series here though......
hmm


Oh yeh I think I charged them with a 12v charger.
And probably used them for something else as well...

Who knows

superchip

Only reason I asked if it was safe is because although I used a lead acid battery in the wiper motor setup, the battery went to the motor controller first then receiver. I haven't tried wiring a lead acid battery direct to the receiver before, oh well, the receivers are cheap to buy if I fry this one lol.

Dirty_Vinylpusher

As long as it's the correct voltage there's no issue

mooman007uk

looking good so far, consider using tonegawa ps050 servos, super strong and will take some voltage.
Also i noticed that you have a tuned pipe...good... but have a stinger as long as an elephants weener which will kill performance...bad

Dirty_Vinylpusher

Mooman!

Long time no see.


You still tinkering with your hillclimb monster?

superchip

Many apologies for not updating my lately, I have since moved and everything is up in arms. But don't worry I haven't forgot about my project and I have every intention of finishing it.

Mooman, forgive my ignorance but what is a stinger and can I rectify it?

Oh how I'd love to get my hands on a couple of tone servos, alas, I cannot make my budget stretch that far and when they do make an appearance on eBay they're snapped up as soon as they're put up lol.