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 Linear steering servo

Post by kiklo » Mon 26. Feb 2018 20:41

Just tested with these small linear servos.
Gives smooth steering at all steering angels.

Pro: small, fast enough, linear action comply with the steering action.

Cons: Open, fragile? Make sure you do not bend / apply force angled to the servo horn.
Attachments
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linear-servo.JPG (130.41 KiB) Viewed 2349 times
Racing Regards

Kim K.

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

Re: 2.4ghz cars

Post by WesR » Wed 28. Feb 2018 19:03

https://youtu.be/QyEYYsH9HeA Radio squeezed under an old short 3" wheelbase McLaren. Nicer to drive than the Nascar saloon because of less weight. Spent nearly an hour trying to get it running quietly and one small piece of foam eventually did the trick.

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

Re: 2.4ghz cars

Post by WesR » Wed 28. Feb 2018 19:49

DSCF0442 (640x364).jpg
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DSCF0438 (453x640).jpg
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Flexy GRP chassis with a top wire link. Guide magnet has a thin plastic cover. I think it may allow the magnet to run lower but ride the high spots in the wire better. Seems to work anyway.

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

Re: 2.4ghz cars

Post by Ned » Wed 28. Feb 2018 22:22

WesR wrote:
DSCF0442 (640x364).jpg
DSCF0438 (453x640).jpg
Flexy GRP chassis with a top wire link. Guide magnet has a thin plastic cover. I think it may allow the magnet to run lower but ride the high spots in the wire better. Seems to work anyway.
Some interesting ideas. Plastic cover over the bottom of the guide magnet makes sense.
Does the top wire link eliminate the need for magnets embedded in the frame on each side of the guide magnet? Or is there some other purpose? Does the chassis exhibit much front end shimmy?

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

Re: 2.4ghz cars

Post by WesR » Fri 2. Mar 2018 20:05

There is little doubt Ned that some degree of flex, ie ability to twist, in the chassis helps to keep the guide magnet in closer contact with the wire. With a rigid chassis, when one front wheel goes over a bump, or there is a twist in the track such as you get when you have a banked turn, the other wheel will also lift and the magnet will do likewise. With a flexible chassis, only one wheel should lift and the magnet will lift only half as much. This is a very simple form of suspension of course. The wire is a simple top skin to stop the chassis bending. This may, or may not be a good thing depending on how the body is fixed.
The problem I have always found is that fitting a body invariably stiffens the chassis and detracts from the roadholding.
When I was developing the Nascar cars, I moved towards a horizontal front peg on the chassis . This enables the front of the chassis to twist independently of the body and I have now done this on the McLaren with good results. I still have hopes of one day racing these cars and this sort of improvement would be essential.
The esc's are back in stock now so I have ordered another.
Re. shimmy, my track is too short to tell properly but having the servo magnet must be an improvement.

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

Re: 2.4ghz cars

Post by NFBrown » Fri 2. Mar 2018 22:02

I had thought of trying little rollers(tiny wheels) on the magnet arm that would set the clearance to the wire. I'd have to actually get something running first, of course.

Nick

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

Re: 2.4ghz cars

Post by WesR » Fri 2. Mar 2018 23:06

Yes, a roller is a good idea on a hinged arm. I did try it once but couldn't find a satisfactory roller wheel but that dosen't mean it wouldn't work. This time I was making a hinged arm to have the magnet sliding over the wire with a plastic spacer under it.
After all slot cars really only run on two rear wheels and the pick ups. But I made a mess of the hinge and gave up! More determination needed!

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HeliumFrog
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Re: 2.4ghz cars

Post by HeliumFrog » Sat 3. Mar 2018 00:21

I have had some success with the roller bearing on the steering arm. The servo steering now gives enough force to overcome any excess side friction. I mounted a small roller bearing just behind the magnet (i think it was a 2mm bore bearing about 5mm O/D). It worked quite well. The only downside is that it is quite noisy on the track. Not so noticable with solid wheels, but quite noisy when fitted on a car with rubber tyres as these run smoothly with little noise. Worth a try though.

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

Re: 2.4ghz cars

Post by kiklo » Sun 4. Mar 2018 15:33

Embedding the steering servo between the front wheels makes room for some nifty small chassis. And yes if you drop reverse and go for the FRSKY receiver with onboard ESC you even can get smaller. Maybe thinking of a different shaped battery.
Attachments
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DSC_2824.jpg (134.6 KiB) Viewed 2290 times
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 » Sun 4. Mar 2018 16:16

Kim, could you provide us with a link to the servo?

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