Building a car

Tips and tricks about building a car. painting it a making it run smooth.
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HeliumFrog
Posts: 82
Joined: Tue 7. Oct 2014 22:28
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Re: Building a car

Post by HeliumFrog » Fri 5. Jan 2018 22:01

Hello All
Nice to see you are all still experimenting. I too over Christmas tried to return to the coil setup, I tried two magnets, one magnet, one coil, two coils also and double wound ones (which do help), but the strength is very minimal and as with Wes's original the magnets have to be close to the coil (really close) otherwise there isn't enough strength to pull the steering when needed. on major drawback is magnet strength is related to number of coils and current, but if you do any of this you basically drain the battery more quickly, which is not what we want.
I actually have renewed admiration for what Wes achieved as he said almost every thing you change affects everything else and the mechanism is really on a knife edge to get things working, and even the screw in the back of the coil makes a big difference (An "iron" core focuses the magnetic strength). steering geometry also affects the strength required to operate the steering.
I am back to the servo type steering which has its own issues, but over christmas have now got it to work successfully. The magnet also provides a centre bias to the steering so tends to remove steering shimmy on the straights.
I am very close to releasing the new chassis and electronics for sale using this method. The reason its taken so long is that I wanted to get a car with much better dynamics and an easier setup which i think we now have. everything is now in place so i should have about 5 or so chassis to send out for testing so let me know if you want to be on the list for the first few. I'll probably let these go a little cheaper just to get the ball rolling.

NFBrown
Posts: 23
Joined: Mon 13. Nov 2017 21:40

Re: Building a car

Post by NFBrown » Sat 6. Jan 2018 04:26

Wes , I'm impressed with your servo steering solution. I'm working on a method that uses magnetic repulsion rather than attraction but it's rather more complicated than yours. I'll post a photo when it's farther along. I'm using a servo like yours so maybe I'll try your method also.

I'm afraid reversing the throttle on the transmitter only changes which way is full throttle on the transmitter. There's some info on Utube about reprograming a brushless ESC to provide forward and reverse to a brushed motor. There's lots of small almost free brushless ESCs out there.

Nick

NFBrown
Posts: 23
Joined: Mon 13. Nov 2017 21:40

Re: Building a car

Post by NFBrown » Sun 14. Jan 2018 23:34

Here's my first try at a servo chassis. The servo moves the two side magnets to repel the one in the middle and steer the car. It's all from scratch with the exception of Ned's steering knuckles. It sort of works but needs more development. I need to make it more compact and more adjustable.

Nick
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magracer chassis 3.jpg
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magracer chassis 2.jpg
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NFBrown
Posts: 23
Joined: Mon 13. Nov 2017 21:40

Re: Building a car

Post by NFBrown » Sun 28. Jan 2018 19:20

Here's rev 2 of my servo steering. I think this one will work and it actually fits inside the 917 slot car body. I don't think everything would fit in an open car so there's still more room for development.

Nick
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WesR
Posts: 323
Joined: Fri 21. Dec 2012 17:37

Re: Building a car

Post by WesR » Mon 29. Jan 2018 17:32

DSCF0405 (640x384).jpg
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Good work Nick! I am progressing slowly. I had the steering servo mounted on a 5mm approx. packer so turned it over to lower it. The servo arm now points up instead of down. I reduced the magnet diam. to 3mm. Had to raise the track rod screw to match it. After a couple of adjustments, it worked perfectly. I have to say that, from what I see so far, if I were starting this project again from scratch, I would probably go for the servo steering. It is much easier to adjust and could easily be modified for heavier or 1/24 cars by using larger magnets whereas a coil would need a rewind. The car steers better free running off the guide wire, runs straighter on the wire and will, I feel sure, steer better in reverse (when I get a reverse to try!)
Still using a two speed resistor controller although I have made a smaller one using the small servo. I have bought 3 ESCs so far. I tried the first one but couldn't get it to work. The biggest problem I feel is getting rid of the connectors. 'Hard wiring' would be so much neater but modifying the rx board is not easy. The easy answer is probably to go to 1/24 scale in which case the connectors could be retained and probably the slightly larger servos could be used which have the same connectors as the radio.
I am sure Keld would approve!

NFBrown
Posts: 23
Joined: Mon 13. Nov 2017 21:40

Re: Building a car

Post by NFBrown » Tue 30. Jan 2018 00:03

Wes, I've got to put some more effort into your servo arrangement. When I tried it I couldn't get it to steer if the the cars wheels were turned to the lock. But first I need to get my car running and try it on a test track.

I have one of the 10 amp escs from aliexpress that works but not on one li ion cell; I've built my chassis to hold two. As you say, the first thing I did was unsolder all the esc wires and hard wire it. I should be able to post a photo of the completed chassis with all the electronics in the next day or two.

Nick

kiklo
Posts: 175
Joined: Mon 9. Nov 2015 11:49
Location: Norway

Re: Building a car

Post by kiklo » Tue 30. Jan 2018 16:11

While waiting for Flysky and servos to arrive.

Testing some variation of magnetic repelling steering.

Hoping to be able to have a standing or hanging servo with horizontal arm to avoid extra linkage.

Thinking this design will allow the steering to pivot more freely as it is moving away from servomagnets when steered by magwire.

Still a bit sloppy as I use a to thin wire to connect arm to kingpins.

Also testing to see if magnetshape will make any difference.
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Racing Regards

Kim K.

NFBrown
Posts: 23
Joined: Mon 13. Nov 2017 21:40

Re: Building a car

Post by NFBrown » Thu 1. Feb 2018 00:57

It's time for me to build a test track; my car chassis is read to test. I'm waiting on Li ion batteries but it's been sort-of tested with a 2 cell Lipo pack and it runs and steers with the servo. The receiver is a Frsky mounted in the front. I don't think the Flysky receiver would fit there and anyway I had this one already. Now I'm working to get the 917 body to fit with all the detail bits (like headlights) in place.
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kiklo
Posts: 175
Joined: Mon 9. Nov 2015 11:49
Location: Norway

Re: Building a car

Post by kiklo » Thu 1. Feb 2018 18:36

Dry run ESC

Just got my Flysky transmitter and receiver and testing ESC : Still missing servo.

https://www.banggood.com/10A-ESC-Brushe ... rehouse=CN

With our std Magracing motor I can do fw and rew.

Now I just have to find a car and mount it in.

Found this one at a friend last night. That would have been a nice servo for steering.--- to bad it is not available, and I think it's analog.
https://www.hobbydirekt.de/sonstiges/so ... 31325.html
Racing Regards

Kim K.

NFBrown
Posts: 23
Joined: Mon 13. Nov 2017 21:40

Re: Building a car

Post by NFBrown » Thu 1. Feb 2018 22:29

Kim, what battery voltage are you running your motor on? I tried that same ESC on about 5 volts and couldn't get a 6volt motor to do more than tick over. I'd love to use one Li ion cell but I've planned on two. Maybe I need a different motor. The ESC did power the radio and servo ok on 5 volts. I'm still waiting on Li ion batteries.

I don't think you need a digital servo with the Flysky radio. Analog or digital should work fine.

Nick

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