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KidsWheels
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#135607
I have been discussing this build in the general discussion section and have decided to continue it here. viewtopic.php?f=3&t=18749

I have a Berchet F1 and plan to build a new aluminum frame to handle more powerful motors.

IMG_0068.jpeg

IMG_0104.jpeg


Here is what I have so far in sketchup. The planned improvements are a more rigid frame with battery trays on the side of the driver, adjustable front camber and the ability to mount go kart slicks. I ordered some used Bridgestone slicks that will fit perfectly.
Berchet F1 frame v7.jpg
aluminum frame design in progress


bridgestone slicks.jpg
4.5 x 10.5 fronts and 7.1 x 11.5 rears


I have questions on drivetrain options. Per Toycrusher's suggestion, I ordered 2 1000W scooter motors with gearboxes. I think I have 4 ways to build the drivetrain.

1000W direct drive motor.png
scooter motor with gearbox


single wheel driver.jpg
1. single direct wheel drive


dual wheel drivers.jpg
2. dual direct wheel drive


quasi live axle.jpg
3. single with quasi live axle


dual connected.jpg
4. dual with quasi live axle



I need some help on which way is the best way to drive this project. I read through all of the dual motor and live axle setup threads but still cannot find an answer. The dual direct drive looks interesting but what if the motor running in reverse is slightly running slower than the other side? Would that be a problem? The connected live axle might cause some issues turning on asphalt. I hope the experts can help point me in the right direction.
Last edited by Gwagon on Mon Oct 09, 2017 8:17 pm, edited 3 times in total.
User avatar
By toycrusher
#135609
Personally, solid axle not worth the handling issues. I wouldn't worry about the difference in power between the two sides, the traction of the tires will more than overcome any slight power differential ;)
By Gwagon
#135613
toycrusher wrote:Personally, solid axle not worth the handling issues. I wouldn't worry about the difference in power between the two sides, the traction of the tires will more than overcome any slight power differential ;)


That sounds good TC.
The motor company is customizing the rotors for me to change the motors from 390RPM to 450RPM at 36V. The speed calculator says using 11" rear tires at 450rpm will yield 15MPH.
Each motor will provide 20.0N.m of torque. What are the pros and cons for using 1 vs 2 motors? Do I need more torque or more run time? The need to carry more batteries for the second motor is also a consideration.
User avatar
By toycrusher
#135614
For a solid axle you could use one motor but independent you definitely need two or one will spin out on take off or corners
User avatar
By Shurik2001
#135641
Gwagon, Judging by your setup it will be an amazing build. I’m very envious of your project.

In my humble opinion this car can safely go faster than 15 mph and I would use chain drive to easily control max speed and torque.

I have some experience with the above DC motors as I was modding electric scooters for a few years now. And again IMHO you need a decent H-Bridge ESC or a 60+ amp relay for reversing. Relay is probably a cheaper option as high current H-Bridge ESCs tend to be expensive. One way or the other you need an ESC with strong protection against overcurrent and some additional circuitry to enforce a stop cycle when reversing (much like a real car does it).

Changing motor direction even at low speed without going thru a stop cycle first generates tremendous currents that can easily destroy most cheap Chinese scooter controllers and burn out motor brushes. A damaged controller can unleash full battery power directly to the motor(s) rendering a car uncontrollable (been there, done that).

I recommend installing an easily accessible circuit breaker (40 amp Blue Sea Single Pole Magnetic Circuit Breaker) and train your kid to use it if something is wrong. I use one as a main power switch and it is very convenient. Also I would build a simple circuit to automatically shut off power when accelerator pedal is not pressed and any of the motors is powered on.

Anyways best of luck with your build.

I’m looking forward for your project completion
By Gwagon
#135695
Thanks for the tips guys. I already ordered the motors with gearboxes so hopefully they will work well. I was checking out Jonesee's RZR and it was running at over 20MPH on 24V. If I can achieve that on this car running on standard voltage, I will be a happy camper. When I use a speed calculator I only get 15MPH though.

I will look into the relay for reversing and the circuit breaker. I am thinking about using Kelly Controllers as they are programmable. Good to know about the stop cycle. I will have many more questions about electronics when I get into it. The aluminum came so I will start cutting when I have some time. Thanks for the support.
User avatar
By toycrusher
#135698
The difference in speed is due to the tire diameter. As far as relays, duty cycle is an important criteria. Do a search for another Jonesee project "nitemare". In that one it took a couple tries to find appropriate relays for the high amperage motor
By Gwagon
#135751
I just read the Nightmare build and it blew my mind. What an awesome project. I will look further into the relays later. For now I have been reworking the design on Sketchup. The frame will have adjustable camber for the front spindles. I have been trying to come up with the best way to mount the direct drive gear box motors. I am going to order some 3/4" motor shafts, get them drilled and welded to the smaller 15mm shaft. I need to find someone with a lathe to help me drill a 15mm hole. In the image you can see how the motors will be mounted and also the outriggers to support the extra long shaft and wide wheels. What do you guys think?

Berchet F1 frame v12.jpg
working out the motor mounts and shaft support


The Bridgestone tires are too small so I am ordering some Maxxis tires that match the original tire sizes a little better.

I have been looking at the Kelly controllers. Should I be looking at regen braking for the rear if I plan on front disc brakes? How many amps should I be looking at? for the controllers I will be running the motors at 36V first and then possibly 48V. Would 48V kill the motors? Running at 20mph would be ideal.
User avatar
By Shurik2001
#135754
I would go with two of these: http://kellycontroller.com/kds48100e100a24v-48v-mini-brushed-controller-p-285.html

With 100 amp at @ 36v you will get some serious torque and impressive burnout on a toy car! 48 volts would not kill these motors but I think it is an overkill. I use a similar motor on a standup scooter and @ 60 amp 36v I can do a willie. 36v LiPO or LiON should be more than enough.

I prefer to build motor controllers myself and thus have no experience with Kellies. I do not know how they would behave if you reverse motor polarity at full speed. Judging by the Kelly’s wiring diagram the controller is unaware of a forward/reverse switch state.
Even if their controller survives the overcurrent, the mechanical stress from the suddenly stalled motor would be considerable.

Like I said in my builds I go thru a stop cycle but I am not an expert.
It would probably be a good idea to post a question on https://endless-sphere.com/forums/ as they seem to be more experienced in power setups like yours.
User avatar
By toycrusher
#135786
There's a pretty easy workaround to avoid shifting fwd/rev while in motion. Using this diagram, you basically create a "brake lock-out" feature that prevents the ride from being shifted into reverse unless the brake pedal is being pushed. Once it's shifted into reverse the brake can be released. See if this diagram makes sense.

Stop to shift jpg.jpg
User avatar
By Shurik2001
#135795
Here is a simple and elegant flip-flop based solution that will do the trick.

Stop Enforcer.jpg


As long as the motor is rotating in any direction relay K2 keeps the “reverse” switch circuit open. A flop-flop trigger made of a 2 NAND gates (4011) continues to maintains its state. As soon as the motor stops K2 reconnects the “reverse” switch which can now change the state of the flip-flop trigger that controls motor polarity relay.

This circuit will allow direction switching only when motor is idle or almost idle depending on the release voltage of K2 relay.
User avatar
By toycrusher
#135796
Shurik2001 wrote:Here is a simple and elegant flip-flop based solution that will do the trick.

Stop Enforcer.jpg


As long as the motor is rotating in any direction relay K2 keeps the “reverse” switch circuit open. A flop-flop trigger made of a 2 NAND gates (4011) continues to maintains its state. As soon as the motor stops K2 reconnects the “reverse” switch which can now change the state of the flip-flop trigger that controls motor polarity relay.

This circuit will allow direction switching only when motor is idle or almost idle depending on the release voltage of K2 relay.


:shock:

Yeah, I'm not familiar with most of those symbols. Do those components go on a printed circuit board?
User avatar
By Shurik2001
#135797
Yes, PCB is an natural choice for these but you can wire them without any PCB. I prefer perforated boards (http://www.instructables.com/id/How-to-Prototype-Without-Using-Printed-Circuit-Boa/) even for much more complex projects.

Flip-flops are the basis of all modern digital electronics. https://en.wikipedia.org/wiki/Flip-flop_%28electronics%29

If you have time you may want to build this thing just for the fun of it.
Last edited by Shurik2001 on Fri Oct 16, 2015 2:02 pm, edited 1 time in total.
User avatar
By toycrusher
#135813
So they are basically giant sized versions of what's inside a typical ic chip?
By Gwagon
#136189
Here is an update on this build.
Parts and materials are rolling in. I just receive the motors but mounting tabs were broken off during shipping. I hope the factory will get me replacements soon. I signed up for a TIG welding class and bought a TIG machine so I can do my own welding. My employee bought a MIG for a work project but I was not too happy with the quality of MIG welds. I want to have clean welds that they do not need to be ground down afterwards. I hope to be able to make clean welds without too much trouble. Tires, wheels, rotors, calipers, bearings and hubs arrived. Time to start cutting as soon as my cold cut saw arrives. I worked on the design some more. The front arms have more support now.

Berchet F1 frame v26.jpg


I first started with tires for 5" wheels but now will use 6" wheels. The front tires will be 6"wide 11" in diameter
front tire choices.jpg
front go kart tires


The rear tires will be 9" wide by 12" in diameter. I am not sure if the massive grip of 9" wide tires will be too much traction or drag. What do you guys think?
rear tire.jpg
rear go kart tire next to original plastic wheel


I don't trust the plastic wheel so I am changing it to an aluminum wheel. I will be adapting front go-kart brakes.
aluminum steering wheel and rotor.jpg
aluminum wheel and rotor


the metal gears are pretty beefy. Does the grease look synthetic to you? It looks similar to my mobile one synthetic grease.
gearbox insides.jpg
a peek into the metal gearbox
User avatar
By toycrusher
#136196
the metal gears are pretty beefy. Does the grease look synthetic to you? It looks similar to my mobile one synthetic grease.
gearbox insides.jpg


You just can't leave things alone can you? Gotta open it up and what's inside... :lol: :lol: :lol:
By Gwagon
#136247
toycrusher wrote:
the metal gears are pretty beefy. Does the grease look synthetic to you? It looks similar to my mobile one synthetic grease.
gearbox insides.jpg


You just can't leave things alone can you? Gotta open it up and what's inside... :lol: :lol: :lol:


I couldn't help myself. : )
By Gwagon
#136309
I did not plan to get so deep into this build but reading all of the cool projects here inspired me to make this ride on a cool one. You guys rock and I am learning so much from the posts.

My shop is setup for woodworking so I need to get some metal working tools.

I am taking my TIG class next week so I can learn to make clean welds in aluminum. I hope the learning curve is not too steep. Here are some tools I received already. Will be cutting material soon. : )

Miller DIversion 180.jpg
Putting together a TIG setup


Cold Cutting saw.jpg
Makita metal saw
User avatar
By toycrusher
#136312
"For those about to rock... We Salute You! 8-) 8-) 8-) :lol:
Last edited by toycrusher on Fri Nov 06, 2015 11:00 am, edited 1 time in total.
By Gwagon
#136375
IMG_0371.JPG
brake rotor mount

The hubs came with threaded holes for 1/4" and 5/16" bolts. I used the extra holes to connect the two hubs and also to mount the rotors.

IMG_0374.JPG
Final checking of the mounting position before I start drilling and cutting.

FIne tuning in a mock up beam before drilling holes for the tubes.

IMG_0388.JPG
rotobroach in action

I used Rotobroach Cutters for the first time and they cut beautifully and accurately. I couldn't trust my standard hole cutters to get a precise fit.

IMG_0392.JPG
it fits!

The tubes fit snugly into the holes. I was worried about alignment so I took my time setting up. I am still waiting for a 24mm cutter to drill a hole for the bearing to hold the short end of the shaft.

IMG_0411.JPG
moment of truth

The shell fits the newly cut chassis. This is going to be a strong frame. I hope it is not going to be too heavy. It has been a game of strengthening and lightening. It has been a tug of war when I am designing in sketchup.

IMG_0415.JPG
support beams for the tub

I am thinking about an X brace right under the rum area. I noticed a few cracks forming right around the seat area. I will do some ABS repair with Weld On and plan to support the stress points better to prevent future cracks.

I will be taking my first TIG welding class this Friday.
By Gwagon
#136469
Here are some scraps I welded in class. They don't look too pretty. I just need to practice now at home and get my skills up to speed before I weld the frame. Tig welding is pretty fun actually.
image.jpeg
Tig Welding intro class


It would be nice if I can make hub centric rings for the rotors. This F1 car will stop very quickly with these rotors.
image.jpeg
These rotors fit the hub bolt pattern better
#147520
It's been almost a 2 year hiatus but I'm back on this project. My son is now 19 months so I expect him to be ready for this car when he is around 2.5-3 years old. I am almost done with his Lamborghini in the background.

The motor mounting plates and front arms are now designed and the 3D printed prototypes are being test fitted. We will have the designs sent out to get the aluminum parts cut out using a water jet hopefully this week. The guys at work helping out are pretty excited about this project. I am increasing the track of the car to about 38" which is close to ideal for the 47" wheelbase.

Wesley suggests me to get a 4QD controller so I'll be ordering that soon. I am also looking at using lifepo4 batteries. I can fit a 48V 28ah pack right behind the driver.

Stay tuned. More to come soon.

F1  and Lambo in shop.jpg

F1 motor mounts 3D printed.jpg

F1 front spindle and rotor on 3D arm.jpg
Last edited by Gwagon on Mon Oct 09, 2017 8:18 pm, edited 1 time in total.
#147525
Hey! Welcome back!!! :D

Has it seriously been two years? :shock: Time flies! Can't wait to see more 8-)
#147528
Thanks Toycrusher. Time does fly especially for me after my first child who was born 19 months ago. The time off gave me some time to refine the front arm and motor mount designs.
#147606
The project is picking up pace.
The 1" tubes have been turned, keyed, and welded to the gearbox shaft. We mounted it on the frame with the 3D printed plates and fired it up using 38V. There is a small vibration but it should be livable. The hubs can be adjusted so the track can be 36-38.5" wide. The part files have been sent to the water jet company. I can't wait to see all of the aluminum parts cut out.


https://youtu.be/JBolLhiTRRo
Attachments
F1 rear wheel side view.jpg
F1 wheel test.jpg
1" axle welded.jpg
F1 Axle turned and keyway.jpg
#147991
Here are some updates.

The water jet cut parts are here.
IMG_7905.jpg

IMG_7903.jpg


The parts fit
IMG_7904.jpg

IMG_7906.jpg


The hub centric rings for the rotors are being cut and then installed
IMG_7907.jpg

IMG_7902.jpg


The lifepo4 battery and the 4QD controller are here
IMG_7908.jpg


After I drill the spindle holes, we should be ready to start tig welding the chassis together.
#148001
It's coming together.
The front beam has been drill and tapped for the spindles.
IMG_7933.jpg

IMG_7934.jpg


The motors are attached to the inner motor plates.
IMG_7935.jpg
#148009
Looking good -- really like watching this one come together!
#148073
Thanks Hammer. It's been a fun project so far.

Here is a pic of the rear motor and wheel being test fitted. I hope the inner and outer aluminum bearing support plates will be strong enough to hold the axles without deflecting. Using the laser cutter to prototype the parts in hard board helped get all of the dimensions and holes in the right places. Without the laser, I'm not sure how I would do so before the water jet stage. Time to weld the ladder frame together next.

IMG_8005.jpg


IMG_8006.jpg
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