Scratch Building Project

Note: Everything in here is DIY and at your own risk, this stuff WILL void your waranty

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Scratch Building Project

Postby Badtoe » Thu Mar 02, 2017 7:36 am

I have already tried to fit proper car bodies onto RFX chassis with unsatisfactory results (Toy or
Hobby). So I decided to try a scratch build based on the RFX electronics as part 1 of my quest to
replace slot car technology with this great idea!
GT40 project 02.jpg
GT40 project 02.jpg (218.31 KiB) Viewed 592 times

Above left is the dismantled RFX car parts and right is a 1/32 slot chasis, wheel and motor kit from Pendle Slot Racing, where I also source body kits.
Next step is to cut off the bits of the new chassis I didn't need – side flanges and front axle section. Then I glued on two AAA battery holders as side pods – these will take 3.7v 10440 Li-ions from china. Then I cut a 0.5mm carbon fibre sheet to form the bottom front wishbone and glue it in place.
Next, I shape two upper wishbones in carbon fibre and attach the RFX stub axles. The steering arm is a bent piece of piano wire to connect to the RFX servo mounted behind it – so the polarity had to be reversed! Next the sensors and processor board ar wired in and attached with glue (!). Then I fitted a Slot-it GT40 body – the wheelbase had been designed to fit this bit. Then paint and decals and ready to go – (newbie on airbrush!). Believe it or not it all still works in AI mode!
GT40 project-9.jpg
GT40 project-9.jpg (96.25 KiB) Viewed 592 times
GT40 project-10.jpg
GT40 project-10.jpg (87.65 KiB) Viewed 592 times

I'd like to see the electronics sold separately for scratch builders but as that's pretty unlikely my next project is to replicate the electronics using the open source Arduino platform and easily available sensors and circuits. First step will be simple track following with manual steering input …. no frills. I'll publish if it works!
Badtoe
 
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Re: Scratch Building Project

Postby Dash cohen » Sat Mar 04, 2017 1:58 am

Aw Man!, Now I'm going to have to do one (or more). That is great work, I wondered, and you answered, so it works in AI on the track? in Expert mode etc.?
And are you using a voltage regulator or diodes for the Lipos? That board won't handle 8.4v for long,
B
http://realfxandhotwheels.blogspot.com/
Dash cohen
 
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Joined: Sat Jan 07, 2017 3:24 pm

Re: Scratch Building Project

Postby Badtoe » Sun Mar 05, 2017 1:00 am

I just tried it in practice mode and it kept to the track - haven't raced yet!
THe Lipos are wired in series so it's running at 3.7v but will last a bit longer. If I get the Arduino version to work it will be ok at 7.4v which will drive it a bit quicker....though I don't find flying off the track difficult at 3.7v! I have always used 3*1.2v rechargeables in the standard cars and found them fine.

I have another set of circuits ready from a donor car (I got 5 while the sets were cheap on Amazon last year) to go into a Ferrari GTO, 1964.........

I think I'll keep the standard cars left for the grandkids - this one is not as durable as they are and they aren't as nerdy as I am yet!!
Badtoe
 
Posts: 7
Joined: Mon Oct 24, 2016 3:29 am

Re: Scratch Building Project

Postby Badtoe » Sun Mar 05, 2017 1:28 am

Just tried and it follows ok in championship mode and expert. It doesn't always recognise the lap line though- I think I have set the sensor a little too low.
I have to say my aim is to do away with all the gimicks and try to replace slot-guided steering with an AI assisted one. I'd leave lap timing to external devices (RFID??) which would be more trustworthy and ditch the 'hazard' stuff altogether for grown-up racing!

A few other lessons learnt are...

I tried leaving off the rear sensor but the circuit doesn't work without it - you can tape over it and it doesn't seem to affect things much, but it needs to be wired in though.

I used a new motor that came with the slotcar kit as it was an in-line drive chassis. I used the RFX motor wiring with the little coil to connect it. One set of wiring must have developed a short circuit and the system started with a hard left steering which turned to hard right when I pressed reverse on the handset! New wiring fixed it. I wonder if that is the cuase of some other folks' problems with locked steering? I will try using my own wiring without the little coil soon.

I ground off about half the USB connector on one circuit to gain some headroom - didn't seem to affect anything! I have given up on getting hold of the reset kit so losing the USB access didn't bother me too much!

The circuits are quite resilient and have survived much resoldering of all the connections.

The steering servo has been wired with its power input reversed as I have positioned it behind the steering arm instead of the standard position. THhs effectively reversed its direction which makes it steer correctly in this format.
Badtoe
 
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Joined: Mon Oct 24, 2016 3:29 am

Re: Scratch Building Project

Postby Dash cohen » Mon Mar 06, 2017 3:35 am

You mean parallel wiring? i hope you do, any way I think maybe the rear sensor is/was too high. I run wide, hard bigger tires on my Hot wheels cars, but if you raise the Real FX rear ends via bigger tires, they seem to track really funky, not usable at all, so no fatties for them.
Dash cohen
 
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Re: Scratch Building Project

Postby Badtoe » Mon Mar 06, 2017 6:12 am

Parallel of course!!! I have read somewhere else in the forum that taping over the rear sensor made no difference so that's why I wasn't too bothered about it.Will try moving the rear too, thanks for that!
Badtoe
 
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Joined: Mon Oct 24, 2016 3:29 am

Re: Scratch Building Project

Postby Dash cohen » Mon Mar 06, 2017 4:27 pm

I figured you knew, :) I just did a new mod/paint scheme but this forum doesn't allow pix from Smartphones, i.e. Too big so if you want, go here http://realfxandhotwheels.blogspot.com/ to check out my latest,
B
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