Kepler Friction drive comes of age.

Discussions related to motors other than hub motors.
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urga   100 mW

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Re: Kepler Friction drive comes of age.

Post by urga » Mar 09 2020 9:46am

Great.Thanks for the pics.
I think I understand how you can use the existing Ardunio setup to acheive regen. Think I would miss the 2 power options though.
I'm thinking that since I've been unable to program a single Arduino with the code you sent me,nor been able to get a HM-10 bluetooth module to talk to either my Focbox or Flipsky mini,I might be better being spoon fed with your products ie purchasing a pre programmed arduino with the two power options and regen.
Does the motor still rattle over bumps with this setup? Scottish roads aren't getting any better,and my previous setup drove me crazy, hence why I went with the constant contact setup. Is the cadence setup fairly simple to get it talking to the Vesc ? I also have a Trek Domane which is similar to your Madone in that I could use https://www.trekbikes.com/gb/en_GB/equi ... r/p/08298/
that maye could talk to the Vesc via the bluetooh module that I can't get to work :roll:
They're a bit pricey but would mitigate any more wires on the bike
Just as an aside,I managed a 83 mile ride on the Crux, using a lot of assist(4620 ft of climbing) by using my homemade bottle battery(6s2p) and a Turnigy 8Ah battery in the saddle bag. I ran the saddle bag battery feed down the seat tube and into the bottle battery and connected them in parallel to increase the range. Cells were sitting at 3.4v at the end,so imagine the range I would have if I can factor in regen and twin batteries :D

scottorious   1 mW

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Re: Kepler Friction drive comes of age.

Post by scottorious » May 23 2020 12:44pm

I just had a sad realization. The bike i ordered to make this work has a bb386evo bottom bracket. Anybody that watches this thread know of a conversion option? The bike is a diverge carbon comp. I got a decent deal and the bigger tires seemed like a good option. Also has bottle attachments on the bottom side if the downtube that look prime for a custom battery and electronics mounting. Or, whats the possibility that those 3 attachment points could handle the torque of the motor?

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Kepler   1.21 GW

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Re: Kepler Friction drive comes of age.

Post by Kepler » Aug 09 2020 3:19am

Put together this bike to use as a low cost commuter. The bike is an Aldi special hard tail that for the bargain price of $400, came surprisingly well equipped. Included hydraulic discs and Shimano SLX group-set.

Installed my standard drive bracket but added a mechanical activation lever but this time used used a cheap front derailleur activation lever.

Installed a Vesc 4.2, Ardunio interface, custom button throttle, and a 6S 6 Ahr battery hidden away in a water bottle.

Looking forward to using this a my new commuter once we get out of lockdown.
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Lightest true ebike on the planet: ON ROAD viewtopic.php?f=6&t=74269
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MJS   1 µW

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Re: Kepler Friction drive comes of age.

Post by MJS » Oct 24 2020 4:16am

Hi Kepler

I came across your videos on YouTube which led me here.

Like you, I was looking for the cheapest, lightest, simplest ideas to give me a little help up a hill or into wind when needed. Your designs and ideas are the best I could find, thanks for sharing all your work.

I particularly liked this last build of yours, a cheap Aldi bike conversion, because another problem with Ebikes is they have become desirable to steal..Having something that doesn't look expensive for a daily runaround is a big advantage.

What motor are you using on this latest bike? And what is that tape wrapped around the centre of the can?

Best regards

Mark

gianfr80   100 µW

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Re: Kepler Friction drive comes of age.

Post by gianfr80 » Jul 19 2021 4:38pm

hi i made a nice setup that work awsome on a straight road, can reach up to 50km/hrs, also on hills no more than 15% can reach up to 33km/hr with pedal help. the problem its on high angle hills, there is no way for it to work, i have to change shifts on the bike an end up peddaling all the way up with almost no help of the motor an really slow.

have a:
Flipsky FSESC Mini V4 rated 50A
TURNIGY AERODRIVE SK3 - 6374-192KV MOTOR OUTRUNNER rated 80A
An a hailong 48v 12.8ah with BMS rated as 30A continuos discharge. made of lg mh1 3200mah, 13s4p

an running on FOC mode
set 80a on motor
an 30a on battery

any idea what could a change to improve the uphill performance?
(its ugly as hell , but it works :P)
[youtube]https://www.youtube.com/watch?v=381T4H5lJiI[/youtube]

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Kepler   1.21 GW

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Re: Kepler Friction drive comes of age.

Post by Kepler » Sep 26 2021 2:38am

I thought I would post an update on my latest friction drive design. Although the previous design made from 304 stainless has been very successful, there were elements to the design that I wanted to improve on.

Firstly, I wanted to see if I could come up with a 3D printed design that would be robust enough to handle the rigors of hard every day riding.

I also didn't want to be reliant on a commercial laser cutting company to make the required parts as I tend to get an order or 2 a week and really liked the idea of just running off the parts when an order was placed.

The core of this design is the pivoting swingarm that the motor is attached to. The previous design relied on metal to metal pivot point which when clean and lubricated, worked well. However it was important to keep the pivot clean or the pivot action became sticky and less effective.

It also had a tendency to rattle when not engaged. This didn't effect its performance but it was a common complaint. I had built a fully ball raced porotype that I still use on my road bike now. This design always pivots perfectly and due to its smooth action, didn't need a gravity spring. Also there was no rattle from the drive when not engaged.

However building a ball raced version of the previous design added complication and would double the cost of the bracket so I stayed away from this path as I wanted to stick with the $100 USD price point.

So enter the new 3D printed prototype and its new design features.

The positives:
Firstly, the swingarm has dual 8mm sealed bearings fitted providing a super smooth rattle free and maintenance free pivot.

No gravity spring is needed to assist with engagement due to swingarm moving so freely. Added a cam style endstop adjustment making setup much easier.

Added a built-in cable guide for installations that want to be able to lock the drive in the fully engaged position from the handlebars.

Lowered the parts count to 4 x 3D printed parts, 2 bearings, 2 washers, and 7 off the shelf fasteners.
Halved the weight of the bracket. (from 200g to 100g)

Still working though a few things. So far I have been making the bracket from PLA. I need to do some warm weather testing to see how the PLA stands up. I may need to switch to PETG or some sort of composite filament in the future.

I am fairly new to the world of 3D printing and so far my prints in PETG have not been great. As anyone who 3D prints would know, its a hobby in its own right.

And now the negatives.
The attachment on the bottom bracket now moves the Q factor out by 3mm. The 304 stainless design moved it by 2.5mm. I will need to see if this will be an issue.

There is more bulk to main support bracket which may effect clearances on some bikes. So far on the bikes I have tested, it has been fine but it may be problematic on carbon frames with bulkier bottom bracket areas.

Anyway, I am really pleased with the design in its current state and think it has a heap of potential. Below are some renders and a photo of an assembled drive.
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SlowCo   10 MW

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Re: Kepler Friction drive comes of age.

Post by SlowCo » Sep 26 2021 3:31pm

That's a very nice "new" design. It seems the stainless steel version was at the end of its development where this 3D printed design opens up new possibilities for further evolution using this technique :thumb:

LewTwo   1 MW

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Re: Kepler Friction drive comes of age.

Post by LewTwo » Sep 26 2021 9:19pm

Kepler wrote:
Sep 26 2021 2:38am
Still working though a few things. So far I have been making the bracket from PLA. I need to do some warm weather testing to see how the PLA stands up. I may need to switch to PETG or some sort of composite filament in the future. I am fairly new to the world of 3D printing and so far my prints in PETG have not been great. As anyone who 3D prints would know, it's a hobby in its own right.
PLA is not a good choice for anything that will be used outside. It was always "intended" to be a biodegradable material. Regardless of what you do to it (coatings, annealing, etc) it will eventually start to break down. It is however fairly strong for such an inexpensive material.

ABS was the original 3D printed filament and still a good choice for parts exposed to the weather. ASA is the modern replacement for ABS. I believe that Nylon is still "King" among the "engineering grade" filaments. PEEK is far stronger but hugely expensive.

Most "engineering grade" filaments need both an enclosed printer and a high temperature hot end (160 degrees Celsius or better). Some specialty composite materials (especially carbon fiber filled filaments) need a steel nozzle rather than a brass nozzle.

If you have not already found it, then see CNC Kitchen on youtube for real world practical information on various filament materials.
https://www.youtube.com/channel/UCiczXO ... hOL16EZiTg

Your design looks fairly compact. What is the build volume (x,y,z) needed for the largest part?
The more I learn the more obvious the immensity of my ignorance becomes.
Weight Wennie E-Bike https://endless-sphere.com/forums/viewt ... 3#p1173723
Shaft Drive Grocery Getter https://endless-sphere.com/forums/viewt ... =6&t=90718
...and thanks to Justin!

ahagge   1 mW

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Re: Kepler Friction drive comes of age.

Post by ahagge » Sep 28 2021 9:00am

Hi Kepler,

That looks like a design with lots of possibilities, though I agree with LewTwo that aside from prototypes, you'll probably need to work with a material other than PLA. I have ABS, but have never used it due to what I perceive as the complexities of the printing process. I've also printed in PET-G, which I think would be a better choice than PLA, assuming you can get your printer dialed in.

A question or two about the new design:
  • Do you really think that a gravity spring won't be necessary with this design?
  • Is this design limited to using 50mm outrunners? Seems like the larger, heavier 63mm ones might have issues. What's your preferred motor these days?
  • Any issues with squishing the bottom bracket mounting ring? Seems like the amount of torque necessary to keep it from rotating might deform/crack the material.
  • Any chance you'll consider selling just the STL files for those of us who have 3D printers?
I'll be interested to hear follow-up posts about how well this holds up after hundreds (& thousands) of km. Good luck!

chilau2000   1 W

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Re: Kepler Friction drive comes of age.

Post by chilau2000 » Sep 28 2021 9:41am

Looks awesome.
I have a PETG 3D printed bracket on my sons friction drive bike, the motor mount is in carbon fibre.
The PETG part is holding up really well, my experience of PLA is that it will be to brittle for this application.
I do notice that my sons mount does have some flex in the mount even though the motor mount plate is 4mm carbon, wonder how PETG would cope with the flexing.
My son will need to move to a bigger bike next year and a 3D printed holder with bearings sounds great for his next bike.

My sons friction drive
viewtopic.php?f=28&t=96581&p=1656493#p1656493

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Cowardlyduck   1.21 GW

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Re: Kepler Friction drive comes of age.

Post by Cowardlyduck » Jan 03 2022 6:51am

PETG is the way to go. I find that a spool of PETG needs to be used pretty quickly after opening or it will start to absorb moisture and then it's all over unless you want to print spaghetti.

I would be interested in any improvements on the design that might work well with knobbly tires. I have a few projects in mind that could use this kind of setup if it works ok with more off-road type tires.

Cheers

Andre   1 µW

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Re: Kepler Friction drive comes of age.

Post by Andre » Jan 04 2022 3:09pm

Hi all!

I'm back with another version of the friction drive...
Screen Shot 2022-01-03 at 6.29.58 PM.png
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Screen Shot 2022-01-04 at 1.56.21 PM.png
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Video here:
https://youtu.be/8FUkQn2LDEk

I kinda went all out this time :D

Features:
-integrated into a handlebar bag
-compact drive unit attaches to a regular Nitto rack (convert the bike to electric and back in less than 30sec)
-automatic deployment/retract (with an elegant lockout feature when retracted)
-easy to attach and compact handlebar switch with plug-in wiring
-drive unit powers the front light, too
-bluetooth connectivity
-lots of room for different battery options + plenty of space left for transporting stuff

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Ecyclist   1 kW

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Re: Kepler Friction drive comes of age.

Post by Ecyclist » Jan 12 2022 1:53pm

This is a fantastic finished product. You should start you own thread.
Don't expect from life to be easy and then it will be.
My builds:
Avian with hypocycloidal drive https://endless-sphere.com/forums/viewt ... 2#p1318056
2016 GNG extreme drive https://endless-sphere.com/forums/viewt ... 28&t=82252

Lurkin   100 kW

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Re: Kepler Friction drive comes of age.

Post by Lurkin » Jan 21 2022 7:43am

Golly people still use this forum? all the others I used to frequent have long since died with the advent of social media.
Hope you are well John, this has certainly come a long way from mini Arduino discussions!
MarkForged3d were the apple of 3d printing last time I looked into it for automotive part purposes, capable of printing metal now and with a combination of printing and sintering to seal/finish/temper. Aluminium was definitely out (to hard for them to sinter correctly at the time, this may have changed by now).
Their demo units are located at Monash university (amongst other crazy machines - full engine block casting printings out and more) and they are using them to print titanium bike parts, cant remember the manufacturer they are for. Whilst titanium might be too expensive certainly printing steel or an alloy may be an option.
Could these be cut with a small CNC? Could be an affordable in house option without the need for redesign.
Look forward to see how you go with the PLA - I struggled with strength and longevity for my purposes. NB can also print carbon now - perhaps this is an option.
Anyway sometimes inspiration can come from seeing other new ideas/other ways of doing things - worth a look.
Could a nylon or plastic washer/thin spacer be used to dull the rattling now?
Guess its a solution to a problem you will no longer have shifting to 3d printing.

LewTwo   1 MW

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Re: Kepler Friction drive comes of age.

Post by LewTwo » Jan 21 2022 11:05am

Lurkin wrote:
Jan 21 2022 7:43am
Golly people still use this forum? all the others I used to frequent have long since died with the advent of social media.
social media ... what is that
The more I learn the more obvious the immensity of my ignorance becomes.
Weight Wennie E-Bike https://endless-sphere.com/forums/viewt ... 3#p1173723
Shaft Drive Grocery Getter https://endless-sphere.com/forums/viewt ... =6&t=90718
...and thanks to Justin!

calab   100 kW

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Re: Kepler Friction drive comes of age.

Post by calab » Jan 21 2022 12:40pm

Social media is the downfall of society with some outspoken crazy people on it.

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tomjasz   10 GW

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Re: Kepler Friction drive comes of age.

Post by tomjasz » Jan 22 2022 3:39am

calab wrote:
Jan 21 2022 12:40pm
Social media is the downfall of society with some outspoken crazy people on it.
No crazies here? Too funny.
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

massiveb   1 µW

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Re: Kepler Friction drive comes of age.

Post by massiveb » Feb 26 2022 11:49pm

Such a beautiful build :bigthumb:
Andre wrote:
Jan 04 2022 3:09pm
Hi all!

I'm back with another version of the friction drive...

Screen Shot 2022-01-03 at 6.29.58 PM.png
Screen Shot 2022-01-04 at 1.56.21 PM.png

Video here:
https://youtu.be/8FUkQn2LDEk

I kinda went all out this time :D

Features:
-integrated into a handlebar bag
-compact drive unit attaches to a regular Nitto rack (convert the bike to electric and back in less than 30sec)
-automatic deployment/retract (with an elegant lockout feature when retracted)
-easy to attach and compact handlebar switch with plug-in wiring
-drive unit powers the front light, too
-bluetooth connectivity
-lots of room for different battery options + plenty of space left for transporting stuff

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