Another Friction Drive

S

snath

100 W
Joined
Jan 4, 2010
Messages
126
Location
Colorado, USA
Used Kepler's idea of running the motor on the tire and EV Todd's idea of a sliding mount to build this drive for a Dahon Boardwalk around a 1"X2" piece of 8020 extrusion and an 8020 linear motion guide. A spiral wound piece of a sanding belt held on with carpet tape provides excellent traction and hall sensors ease takeoff.

Here are some pictures.
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The outfit works well on my Dahon but doesn't have enough power to assist me up Atlanta hills without my knees hurting so I am working on another drive using a motor similar in size to EV Todd's and, like his rig, hanging off the side. It's almost finished.

It will have halls as well and for those following the fitting process to outrunners, here's a tip.... stuff them edgeways (but oriented the same.. i.e. dots all facing the same direction) into the groove; they don't care.

You can also use three-wire strips torn off ribbon cable to hook them up... makes it easy to keep track of which wire is which. Here's a picture.

Larry Barefield
 
Nice adaptation snath. What type of Hyperion motor did you end up using? I like the sandpaper idea. I'm tipping that could even work in the wet.

I really need to get my head around fitting Halls to these motors as it solves so many issues. What controller are you using?

Looking forward to your MK drive2. More pictures on the hall install, controller, etc. I promise I won't copy :mrgreen:
 
Very very cool. That's a fancy mount. Are those Delrin slides? I bet the motion is very smooth. That's probably fancier than the ways on most of my cnc machines! :shock:

I'm looking forward to seeing a video of it working.

What kind of volts are you running right now? It looks like you're running it on the front wheel kind of like a Solex setup.
 
Kepler said:
More pictures on the hall install, controller, etc. I promise I won't copy :mrgreen:
Click to expand...
Hi Larry, beautiful work. Thanks for posting. 8)

I'm going to do 2-4 builds using friction drives. I have never worked with RC motors, gluing magnets, setting hall sensors, etc. Any detailed pictures and steps will definitely help me with my builds. I promise I will try to copy your methods if I can apply them to my projects. :mrgreen:

(Highest form of compliment, btw.) :p

1) Yes, what motor did you choose & bat volts? What loads weight-wise were you pulling up hills?

2) Did the halls allow you to take-off from a stop, or did you need to be moving a few mph first?

3) Are you using a small roller for your new build to get more torque and start-ups from stop or hills? What size roller? What motor?

TIA :D
 
Kepler said:
Nice adaptation snath. What type of Hyperion motor did you end up using? I like the sandpaper idea. I'm tipping that could even work in the wet.

I really need to get my head around fitting Halls to these motors as it solves so many issues. What controller are you using?

Looking forward to your MK drive2. More pictures on the hall install, controller, etc. I promise I won't copy :mrgreen:
Click to expand...

I used a HP-Z4045-14 motor. Two initial trials were in the rain... couldn't wait to try it out and it didn't slip. I personally think most folks have an under appreciation of the drive. There's a gazillion miles of conveyor belting in this world all driven by friction between a belt and a roller. There's a lot of "grip enhancing" technology in the industry that is still to be explored in our application; enhanced roller coatings up to and including ceramics and the like.

Fitting Halls is pretty easy I think and stuffing them in the slots is a lot easier than fabricating external mounts or machining pockets.

I'm using a little 20A Crystalite controller that I got from Ilia at ebikessf. It may be a little small.
 
EVTodd said:
Very very cool. That's a fancy mount. Are those Delrin slides? I bet the motion is very smooth. That's probably fancier than the ways on most of my cnc machines! :shock:

I'm looking forward to seeing a video of it working.

What kind of volts are you running right now? It looks like you're running it on the front wheel kind of like a Solex setup.
Click to expand...

The slides are Delrin or something similar and the motion is smoooth and will get better when the mating surfaces wear in a bit. It will make the action of the "return" spring a little more positive. The pictures don't show it but there's two screws in the slot on the back side that limits travel in each direction. Currently, I'm having a little trouble finding a spring and location combination that keeps the roller off the wheel and lets the motor jump into the tire upon acceleration.

I'm not very technology savvy when it comes to movies and such but I'll work on it.

I'm running 36 volts and yes, it is like a Solex setup.
 
If you end up putting the motor off to the side and use a roller with a one way bearing instead of the motor itself you won't need a return spring. You can just keep the roller on the tire all the time with light pressure and you won't even know it's there.
 
EVTodd said:
If you end up putting the motor off to the side and use a roller with a one way bearing instead of the motor itself you won't need a return spring. You can just keep the roller on the tire all the time with light pressure and you won't even know it's there.
Click to expand...
Yep, I have a piece of hardened linear way and some one way bearings just for that purpose but I thought I would give a try and see what happens. As noted, I have already made an extended shaft out of drill rod so I will go ahead and try it and give the spring another chance.

This 8020 stuff has so much potential in terms of ways to mount things and the slots just begged for a spring :)
 
EVTodd said:
snath said:
This 8020 stuff has so much potential in terms of ways to mount things and the slots just begged for a spring :)
Click to expand...
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Just out of curiosity, what is the pricing like on their stuff?[/quote

They have an ebay store (type in 8020 extrusions) where you can get odd lengths pretty cheap. The slides I thought were pretty expensive at $31.00 each.
 
snath said:
Kepler said:
Nice adaptation snath. What type of Hyperion motor did you end up using? I like the sandpaper idea. I'm tipping that could even work in the wet.

I really need to get my head around fitting Halls to these motors as it solves so many issues. What controller are you using?

Looking forward to your MK drive2. More pictures on the hall install, controller, etc. I promise I won't copy :mrgreen:
Click to expand...

I used a HP-Z4045-14 motor. Two initial trials were in the rain... couldn't wait to try it out and it didn't slip. I personally think most folks have an under appreciation of the drive. There's a gazillion miles of conveyor belting in this world all driven by friction between a belt and a roller. There's a lot of "grip enhancing" technology in the industry that is still to be explored in our application; enhanced roller coatings up to and including ceramics and the like.

Fitting Halls is pretty easy I think and stuffing them in the slots is a lot easier than fabricating external mounts or machining pockets.

I'm using a little 20A Crystalite controller that I got from Ilia at ebikessf. It may be a little small.
Click to expand...

That motor should take you up nearly any hill you can throw at it. Sounds like your 20A controller is doing a good job of current limiting. I would suggest you need atleast a 50A controller on 6S LiPo
 
I wondered about that. I'm trying to get my arms around the controller thing. I'll have to change out the sensor connectors but I think it will be worth it to try a larger capacity controller.

I'll let you know how it works out. I find it so amazing that such a small motor can develop so much torque.

What voltage are you running yours at? If I understand it correctly operating at a higher voltage requires fewer amps????

Thanks,
Larry
 
snath" The outfit works well on my Dahon but doesn't have enough power to assist me up Atlanta hills without my knees hurting so I am working on another drive using a motor similar in size to EV Todd's and said:
Larry,

That is a nice friction drive. If you are new to cycling, you might not know that hurting knees could mean that you need to raise the seat.

Bubba
Click to expand...
 
I run my drive mostly on 5S and 18.5V nominal. I also run it 6S at times but the 320kv motor give me more then enough speed on 5S. Yes higher voltage means lower amps for the the same kW input so if you have a controller that is limited to a 20A output like what you are using, a higher voltage is the way to go. I presume you are running 6S. With a 20A controller, you are only feeding 440 watts to the motor which isnt going to conquer too many hills. You need atleast double that to give you reasonable hill climbing ability. The motor can handle tripple what you are putting into it at the moment without breaking a sweat.
 
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