2.4ghz cars

Tips and tricks about building a car. painting it a making it run smooth.
kiklo
Posts: 175
Joined: Mon 9. Nov 2015 11:49
Location: Norway

Re: 2.4ghz cars SXC conversion front axle

Post by kiklo » Fri 6. Apr 2018 11:24

Racing Regards

Kim K.

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

Re: 2.4ghz cars scx conv. parts

Post by kiklo » Fri 6. Apr 2018 11:31

My printed part.
v850-2e.JPG
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Racing Regards

Kim K.

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

Re: 2.4ghz cars scx package

Post by kiklo » Fri 6. Apr 2018 12:51

Even with full connector it is not to crowded.
scx-packing.JPG
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Racing Regards

Kim K.

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

Re: 2.4ghz cars

Post by WesR » Sun 22. Apr 2018 18:57

DSCF0507 (640x378).jpg
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Pic shows the 3 cars I have built so far. Two have the servo mid chassis steering the track rod plate and one has the front mounted servo. The first two run perfectly, much better when running 'off the wire'' both forward and reverse than our earlier cars. The front servo car I cannot yet get to run anything like as well. Maybe I am doing something wrong but I am running out of patience with it!
My biggest concern is the hard wiring to the receiver. This would be too difficult for many people. Standard connectors are just too tall. We need some much shallower connectors. It would be nice to be able to change ESCs, servos etc. without having to unsolder everything.

Ned
Posts: 315
Joined: Sun 13. Apr 2014 01:02
Location: Sedona, AZ USA

Re: 2.4ghz cars

Post by Ned » Wed 25. Apr 2018 02:57

WesR wrote:
The attachment DSCF0507 (640x378).jpg is no longer available
Pic shows the 3 cars I have built so far. Two have the servo mid chassis steering the track rod plate and one has the front mounted servo. The first two run perfectly, much better when running 'off the wire'' both forward and reverse than our earlier cars. The front servo car I cannot yet get to run anything like as well. Maybe I am doing something wrong but I am running out of patience with it!
My biggest concern is the hard wiring to the receiver. This would be too difficult for many people. Standard connectors are just too tall. We need some much shallower connectors. It would be nice to be able to change ESCs, servos etc. without having to unsolder everything.
The steering in my chassis with the servo mounted between the front wheels works fine on my track. The magnet in the guide arm is 3mm diameter x 2mm thick. The one in the servo arm is 2mm diameter x 3mm long. In last 2 photos below, the ring of plastic around the guide magnet is .8mm thick, so the gap between the magnets is .8mm. I suspect that a gap of 1 - 1.5mm between the 2 magnets would work well. Of course the poles of the magnets must be properly oriented. Note that the centerline of the servo magnet is level with the top of the guide magnet. This is probably the best arrangement. See photos.

I suspect it would also work if the magnet in the serov arm was 1.0mm higher than shown. But, as the servo swings away from the neutral position, the distance between the magnets increases and the force between them decreases. A large change in the diameter of the front tires would probably require a change in the length of the servo arm. Performance is highly dependent on the location of one magnet relative to the other. A change of ½ mm in the x, y, or z direction will affect performance.

Future versions of my chassis will include servo arms of different lengths to accommodate different diameter front tires.

Moving the electronics from one car to another is time consuming but not as bad as I had first thought. I moved the electronics from the first version of CK7 to the first version of CK8. I had to replace the wires from the ESC to the motor which required redoing 4 solder joints. Also had to redo connections at the battery terminals. Did not redo any other connections. After widening the opening for the guide arm to swing left and right, the chassis will follow a 9” radius corner.
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WesR
Posts: 323
Joined: Fri 21. Dec 2012 17:37

Re: 2.4ghz cars

Post by WesR » Fri 27. Apr 2018 18:23

Thanks for the info Ned. It encouraged me to have another go and I have now got the car running reasonably well. The difficulty I feel is that the two magnets are operating at right angles to each other and, as you say, adjustment is a little tricky. Certainly more so I think than with the mid-mounted servo, which is easy to adjust. I am still running the 4mm magnet in the steering arm and it seems to need a 3mm x 3 in the servo arm to work. I have only run the chassis so far. With body fitted, adjustments may be needed. I shall persevere and, when we start racing, I will know more.
Made a number of changes to the track today. I will post photos tomorrow.

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

Re: 2.4ghz cars

Post by NFBrown » Fri 27. Apr 2018 22:06

Kim,

How did your Delrin ball work out on the track? Does it slow down the car much? I suggested a tiny wheel but the ball is much simpler.

Nick

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

Re: 2.4ghz cars

Post by kiklo » Sat 28. Apr 2018 16:51

To get the Delrin balls to work you got to have a good seating, read FREE spinning. They wear fast if stuck. Less resistance then guide touching track. 3.5 or 4mm is probably the best to use. 2 sidemounted work well if Your wire is not flush.
Racing Regards

Kim K.

Ned
Posts: 315
Joined: Sun 13. Apr 2014 01:02
Location: Sedona, AZ USA

Re: 2.4ghz cars

Post by Ned » Sat 28. Apr 2018 19:01

kiklo wrote:To get the Delrin balls to work you got to have a good seating, read FREE spinning. They wear fast if stuck.... 3.5 or 4mm is probably the best to use. 2 side mounted work well if Your wire is not flush.
Kim, how do you suggest that 2 balls be mounted along the side of a guide magnet? 3.5mm seems too big. Are the balls available in 3mm which is the same as the thickness of the magnet in the original magracer? What gap do you recommend between the bottom of the guide magnet and the track surface?
Seems to me that a ball on each side of the magnet would significantly limit the distance that the guide arm can swing left and right. This would significantly reduce the maximum steering angle left and right and thus the ability of the car to go around tight corners.
Perhaps one 3mm ball just in front or behind the magnet would work? What do you thinK? Will it really make much difference in lap times?
Please post some pics of your use of the Delrin balls.

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

Re: 2.4ghz cars

Post by WesR » Sun 29. Apr 2018 19:03

I have thought about this idea several times in the past. I did make a hinged guide arm once but couldn't find a suitable roller wheel and more recently I ran a car with a smooth plastic shim under the magnet. It went quite well.
Kim's ball idea sounds good but, thinking about it, what are we trying to achieve here? I think that I felt that it would produce a constant gap between the wire and the guide magnet which would give more reliable steering. However, thinking further, I am not sure it would be a major improvement.
If the wire is below the track surface at some points, even using a ball/roller, the gap would still increase, as now.
If the wire is above the surface at some points, the ball/roller would tend to run to one side or other of the wire. This would not be good, particularly when you come to a lane change.
So I think that the track surface still has to be perfectly flush with the wire, certainly for a few mms each side of the wire.
This idea could be helpful if the rest of the track was not flat i.e. if one front wheel dropped into a pothole, the magnet gap would be maintained.
If the track had a twist in it's surface i.e. when going into a banked turn where one wheel can lift off the track, the magnet gap would also be maintained.
If produced accurately and precisely, I guess it could be an improvement.
For now I think I will just make my track flat. Easy enough with plaster!

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