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Hi Everyone, I've been lurking on this forum for many years but never posted. Then I went away from it for a while, but now that there is something I would like to share, I am coming back. Few words about myself, my name is Nik, I was first introduced to the hobby at the end of the 70's, then got my first set in the early 80's as a 10 year old and have been a fan ever since. Ten years ago I built my first simple single sheet of MDF, figure of eight, track. Ten years later and a couple more simple track builds, plus one somewhat more complex (all in MDF), I decided to embark on a project that had been on my to do list for quite a while, a 1/32 slot car powered by a brushless motor. I know quite a few people have discussed this and there are some videos out there showing few drag slot cars using brushless motors but I have struggled to find any "normal" circuit racing ones powered by brushless motors. I fully appreciate the simplicity of the normal brushed motors (I am a mechanical engineer by the way) but I like challenges, so I couldn't not do it. I am also privy of the RC car hobby where the advantages of the brushless motors are very apparent.

I am very pleased to say that the experiment was successful, despite having to cram motor, controller and receiver inside the little car. The chassis and the body are 3D printed to a styling study I had done previously (a successor to my favourite rally racer Lancia Rally 037), while the mechanical parts like gears, axles, bushings, wheels and tyres are from slot.it . The weight came at 90g, with the body itself being 18-19g, which I would say is not too bad at all. This of course, is offset in a negative way in terms of centre of gravity height, by having to package the motor controller over the motor, both of which are sourced from Turnigy. The motor is sensorless 1230 size (I.e. 12mm outside dia, 30mm length), 4500kv, and designed for nominal 2s battery (~7.6v), and I guess it is maybe capable of providing around 30W of power at that voltage, while the receiver I use is an old fashion 2 channel 27MHz one (I haven't yet made the switch to the 21st century here). All these components can be found in a small scale RC car, something like 1/24, but luckily it was possible to squeeze them under the body. As an added attraction, I decided on functioning lights, which in fact works out great as I have a constant supply of power to the track with the brushless motor. My gearing is 9 tooth pinion and 30 tooth crown gear using 1mm offset setup.

As has been discussed numerous times in various forums, if the brushless motors are to come on stream in slot cars (which I appreciate many are against), the receiver and controller will have to be combined into one compact unit, which is very much doable. And considering that the power of the motor used, is excessive for these little cars, a smaller unit, can provide similar levels of power to a brushed motor.

Anyway, I hope you like this little project, which was a great fun to design and built.

Regards,

Nik

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And a video:

 

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Nice, love the 3d printed stuff...looking into that part of the hobby. I'm having various forum members print 3d files I have acquired. I am considering creating files for a long defunct manufacturer of 1/32 chassis and bodies for which I have negotiated an exclusive world wide license. I look forward your continued efforts.

I too am a mechanical engineer, long retired from IBM. I have been experimenting with bits and pieces salvaged from inexpensive Chinese 3.7 vdc 2.4Ghz RC cars equipped with the much tinier ultra high speed coreless motors (40k rpm geared down 1:9) in 1/24 and 1/32 hard body model conversions. The resultant cars weigh less than 60 gms and can achieve speeds comparable to the current RTR offerings at a constant 3.7 vdc supplied through the rails. I am tempted to punch up the voltage through my variable power supply, but I am afraid the additional juice will fry the onboard ESC pcb/receiver or make the car an uncontrollable rocket.

The neat thing about 2.4 Ghz RC is that you can have a bunch (e.g., like 16) independently-controlled cars running on a 2 lane track using an adaptation of 55 year old speed/inertia controlled lane change technology for which I am negotiating a license to produce for adaptation to any existing plastic sectional track and routed MDF.
 

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Really nice work here. I love it when people push the boundaries.

Brushless Slot cars seem to be gathering momentum. There is another recent thread where someone is adapting a Scalextric Porsche, bit I dont think he has it running yet.

Heath
 

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Rally interesting build, thanks for sharing.

All that wire must weigh half the car! Lol

Seriously though i've been thinking about brushless for a while and haven't found a specific use (in my analogue mind) for it. Slotcars go plenty fast enough already and as it would effectively mean all racing were digital (I think that's what it means) it would exclude a lot of people.

But....

I think that if a really tiny motor could offer the same output as say a current 25k slimline AND the computer could provide the braking then my F1 rear ends could get EVEN smaller. The question is, do they NEED to get any smaller?

Cheers
Andi
 

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Nice work NikS... a really great achievement and early demonstration :)

As Heath mentioned, I am working on a similar project with a 130-size brushless motor which fits into a slot.it motor pod andthen into a Scalextric 911 bodyshell. In terms of motor control, my approach is based on the design of an interface controller board which takes a SSD PWM output signal from a standad digital decoder and uses this waveform to control the brushless interface controller board. This will give brushless motor together with lane changing and digital lap counting. Not as yet finished building the interface board but have powered up the chassis using an esc. All the running gear is functioning correctly... just need to finish the interface board...

Its a fun project... and really enjoying seeing the great progress you have made... including the 3d bodyshell...

C
 
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novice jazz player &
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Also, just to mention my design will include PWM braking... using the same circuit approach as brushed SSD braking but times 3!
C

https://www.slotforum.com/forums/index.php?showtopic=55347&p=2212599

And

https://www.slotforum.com/forums/index.php?showtopic=55347&p=2213053

Links showing design approach and rollng hardware awaiting fitment of the SSD decoder, IR LED and the custom 11783 interface driver board... I think the approach would integrate nicely with NikSs brushless motor, 3d printed chassis and body... :)
 
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Discussion Starter · #8 ·
Thanks for the encouragement all, it is genuinely appreciated.

Viejoronnie, good luck with your projects - I am considering upping the voltage too (from 8v on the PSU) just for the sheer joy of experimenting, as additional power is hardly required, but am worried too, so will probably give it a miss. In fact the first time I was about to run, I almost burned the electronics, but leaving the voltage at the level of the brushed cars and stopped myself at the very last moment before I placed the car on the track J If I have the chance to experiment with combined receiver and motor controller, it will either be 2.4GHz or it might use Dr_C's approach.

Heath, thanks for the suggestion, Dr_C it is then.

Drifter2, thanks a bunch, it makes a difference.

Andi, thanks, and you are of course spot on with the wiring, it was my impatience to see it running and leaving tiding up the wiring for later - it is mainly the LED wiring, which I need to take care of. I still need to pain the car (again impatience to see it running), which might be doable in terms of small free time slot, this coming weekend, thinking about a red colour. Nevertheless, you are of course also correct if smaller motor size will bring any advantages, it remains to be seen, for me what drives me is the desire to experiment.

Dr_C, thank you, I will follow with interest your project as your approach is very promising, something that once again may happen for me if I go ahead with second iteration, though this is not certain at all, as being a father and the long hours at work make it very challenging to devote the time required for the hobby. Thanks for the links by the way, which I still need to check up as I saw them as I was about to post my reply.

Thanks again guys.

Nik
 

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Rich Dumas
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As far as I know you are the first person to build a slot car with a brushless motor. It looks like you have validated the concept. A friend of mine was an R/C racer and he was constantly rebuilding or replacing motors, that was both expensive and time consuming, so for him brushless motors were the way to go. In the case of 1/32nd slot cars we have run 24 hour races using a spec $8 motor which is just about as powerful as you can use without recourse to traction magnets. We have never had a motor fail and the lap times have not dropped off either. In our case the incentive to switch over to brushless motors is simply not there.
 

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My direct source of 2.4Ghz RC cars and parts is relatively inexpensive so burning up a few chips/boards is not necessarily a problem. I got part of my inspiration from the rather unsuccessful DMX multi-slot RC toy rug racing concept from a few years ago. They first came out with the wireless IR/on board battery true RC cars that could steer to multiple slots in a plastic track and were going to offer multi car 2.4 Ghz RC, but sales tanked and the IR sets are now being sold at huge discounts. It appears their 2.4 Ghz cars never came to fruition, but such toy RC cars are widely available.

I looked around for a Hong Kong manufacturer of cheap 2.4 Gh RC and found one that offered small, light, and incredibly rugged units. They just happened to be equipped with the small, light high speed coreless motors. The onboard ESC/receiver board is less than 1 square inch in size. I had been a proponent of ac2car for running multiple analogue cars per slot and I kind of married the two concepts: wireless 2.4 Ghz RC for speed control only of multiple cars with constant DC power from the rails and "automatic/selectable no digital sensor-required" lane change control from the ac2car track. The cars have a braking system of sorts. Tests are promising enough that I am talking to a well known legacy manufacturer of toy slot systems to see if they would like to get back in production.
 

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Hi RichD... I personally believe it is too early to come down firmly in favour or against brushless motors.

When a brushed car is raced hard... how often is the $8 motor replaced? For example would you enter a car into a fresh endurance competition with a brushed motor which has previously run for 24hrs non stop? How many $8 motors would a chassis and running gear use during their lifetime of racing? So how do the overall costs of the hobby change if you replace the old (but proven) $8 brushed technology with a modern cool running $20 brushless motor?

And in addition to reduced motor maintenance/replacement there are further potential benefits too... reduced wear-and-tear of all electrical and mechanical parts (including pick-up brushes)... less sparks, less emi interference... and thats before we get on to the added opportunities for increased functionality that come with brushless... lets press on with developments and trials... in 1:1 scale racing the passion for innovation continues... so why not in 1:32 scale racing too?

C
 

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Well done Nik, great to see something different in slot cars.
It would be interesting to hear how well you think the car goes compared with a conventional one.

Several people have tried brushless motors in slot cars, here's an example of a slot dragster with one some 5 years ago


I've seen 3 brushless circuit racing slot cars on social media in recent months. They've all used a radio control set up to drive the brushless motor. How did they go - apparently more development is needed.....

... I personally believe it is too early to come down firmly in favour or against brushless motors.
Agreed and who knows what might be achieved if it is developed further,
With radio control, a more efficient motor that makes better use of the very limited power from the on board batteries is a huge advantage. Probably the biggest single reason brushless took over in RC so quickly. With slot cars that improved efficiency is much less important.
 

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Impressive bit of work there Nik!
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There is a lot to this, home made chassis and a fantastic body. I think you are probably over-egging the wire size to the lights, and you can probably drop quite a bit of weight if you trim back all the wiring to make it handle better, not saying that it didn't go well, because it did...

Nice bit of work, a big step forward - well done
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...

With radio control, a more efficient motor that makes better use of the very limited power from the on board batteries is a huge advantage. Probably the biggest single reason brushless took over in RC so quickly. With slot cars that improved efficiency is much less important.
With the advent of LiPo's r/c battery power now is huge and no longer a limiting factor. Long gone are the Nickel cells from competitive racing. Brushless motor ESC technology now enables you to tune a motor to suit a wide range of uses, although more to tweak and get lost in the adjustments available there's no going back to the 80's for those guys.

The r/c guys could pop in a brushless setup and race as before, we can't do that with our controllers unless we do all the programming on the car and vary the voltage to the ESC via the track. Obviously the best way is to go wireless, this would mean replacing all our kit and controlling the car voltage onboard via the ESC.
 

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Dunno anything about electronics but I do know the car you have all that stuff in is one nice looking car.
 

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This article popped up in my inbox a while back.

https://www.kjmagnetics.com/blog.asp?p=bldc-motor

The first thing I thought was, I wonder if I could scratch build a slotcar motor this way. It seems like a possible good compromise between the performance of brushless and the simplicity of brushed.
That article is a nice demonstration of the principle of a brushless motor, thanks for posting.
However that is a non starter for slot car use - as the video shows it needs a push start.
Brushless motors with any worthwhile performance need more parts than that simple demonstration.
 

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A couple of things have come back to me concerning ESC's, you can get them with electronic gyro...traction control, you can also get ESC's with voltage boosting...cheating.
If we're going down the same road as RC cars why not go the whole hog and fit transponders for lap timing. I still have a couple, I'll hang on to them 😉
 

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That article is a nice demonstration of the principle of a brushless motor, thanks for posting.
However that is a non starter for slot car use - as the video shows it needs a push start.
Brushless motors with any worthwhile performance need more parts than that simple demonstration.
I wouldn't write this concept off quite so fast. There is no reason a person couldn't build a 3 pole version of this design which fixes the self starting problem the same way a brushed motor does.

From a performance standpoint, I agree it would be impossible to truly match the performance of an off the shelf system with ESC. But, could you make something that pushes a 90 gram slot car around a track? I think the answer is yes. As usual with questions like this, it gets down to deciding what itch you want to scratch. If you want to scratch the "I hand built my own custom designed motors itch", this is a novel approach. It may end up configured like a pancake motor with a bunch of extra gears, but it would be interesting.

For me personally right now, that isn't the itch I'm trying to scratch. :)
 

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There is a similar discussion at the moment on the BSCRA Facebook page. The possibility of reducing the current cost of buying and maintaining Group 12 and strap motors may be influential in the pursuit of a brushless alternative. The problem maybe that a can of worms may be opened re the possible reconfiguration of motor performance via software changes? I don't know enough to understand what is possible, hopefully someone can enlighten me?
 
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