Mag Max: compact 2-stage drive /w mag clutch brake regen

[j3tch1u]

The goal of this project is to mate a magnetic clutch (for brake regen) with a compact planetary drive--two 75 series Matex gears (total 12:1 reduction) powered by a 10-turn Astro 3210. The mid-drive system is mounted on the swing-arm and uses a dual freewheel threaded onto the clutch hub that drives a Nuvinci CVP dev kit servo controlled gear hub. The Nuvinci lets you store 5 shift maps selectable by push-button for various pedal or motor configurations. I plan to run: 1-pedal only, 2-pedal assist, 3-hill climb, 4-high torque, 5-high speed. The first prototype was a no-go--holding power of the clutch wasn't strong enough for the torque of the motor. Now modifying my design to use a wet type multi-plate clutch that should be good for 25 Nm. There is still much more in the works including complete frame redesign to integrate the batteries. More details to follow.

Prototype /w compact drive and Nuvinci dev kit, HV110, throttlizer, elogger, bike-cam and monitor with On Screen Display (CNC mill and lathe in the background).

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Holding power of the 12V clutch on this drive is inadequate--back to the drawing board. Section-view of Solidworks model on the right.

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Swapped out the clutch for now. Made a new finned housing to help air-cool the motor.

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Next candidate: wet type multi-plate electromagnetic clutch good for 25 Nm.

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[kfong]

That's an unusual front suspension. Did you make it yourself?

[Ypedal]

Looks awsome !!!

I'm very curious to know what you get for efficiency wh/km, and also no load amps. I'm looking for a 3 speed hub to replace my NuVinci for testing.

Going to run full voltage ?

[j3tch1u]

That's an unusual front suspension. Did you make it yourself?

no. it is an old-school Girvin parallel link suspension fork. i added the wings to stiffen/jazz it up not sure if it really works aesthetically. they are originally for 26" mtb wheels. i cut the springs and reduced the travel for the smaller 24" wheels i'm using. i plan on building my own linkage fork using the Girvin as a reference. they will have integrated cree mc-e lamps and carbon fibre arms. conceptually something like this:

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[j3tch1u]

Looks awsome !!!

I'm very curious to know what you get for efficiency wh/km, and also no load amps. I'm looking for a 3 speed hub to replace my NuVinci for testing.

Going to run full voltage ?

ypedal--thank you! i'm a big fan of your builds--i came across your website early on before i found es. do you have anything new in the works?

i'll take some tests after i put the bike back together. don't have any wh/km numbers on the nuvinci and probably won't even bother--after all, the hub is 4kg, my bike is 75 lbs and i'm running a 3" tyre on the back just don't burn out your controller on a big hill like i did. i ditched my manual nuvinci--can't shift under power and don't want to shift all the time. the devkit on the other hand shows promise. the devkit devs are cool and cut me a great deal at Interbike. really the only change to the hub is a square shift rod and more turns for mechanical advantage (ie. servo shifts under power). not sure if it is geared (haven't opened it up) but i'd like to bump the ratio so that it shifts through the 350% range faster (btw you lose a bit of range because the rod is protected from hitting the hard limits).

if i can get the mag clutch working, i'll be using an S3X which is practically begging for motor braking (and only 990g to boot).

Nuvinci vs S3X
weight: 4.1kg vs 990g
flange diameter: 148mm vs 67mm

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9-spline pattern equally spaced. Each spline is 6mm wide but one spline is only 3mm. Some sort of Sturmey thing?

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Standard ISO 1.375" x 24 TPI. Fixie sprocket and ENO freewheel threads directly onto S3X

S3X_ENO.jpg (106.95 KiB) Viewed 8228 times

[j3tch1u]

Going to run full voltage ?

for the time being, i'm running 12s3p A123 in a CamelBak(Buster). i will try to fit 16s1p 15aH A123 prismatic into the new frame. blew a gate driver on my fechter/goodrum 2.3 bms so temporarily using cell log 8s atm.

[j3tch1u]

Here's a brief summary on the CNC mill and lathe in my bike workshop. They are bench-top machines adequate for prototyping ebike sized parts but not nearly heavy-duty or fast enough for production use. Their small size makes them a good learning platform--not as fatal if you make mistakes. CNCZone Forums has a nice machinist community with their own superstars like LFP (in a Bizzarro ES Universe sort of way).

Taig CNC Mill:
- Gecko G540 step motor drive
- SmoothStepper motion control interface
- MACH3 with VistaCNC iMach3 screen
- Macbook Pro 17 running Windows 7
- HTS 4th axis rotary/trunnion table
- 5" screwless toolmakers vise
- Craftsman Quickrout adapters converted to quick change tool holders
- MeanWell SP-320-48 power supply /w PFC
- polycarb enclosure on steel table reinforced /w pressure treated wood
- relay/timer/solenoid controlled intermittent mist coolant system
- 3-flute solid carbide end-mills (perfect for 6160-T6 aluminum)
- xyz limit/home switches
- jog pendant using ShuttlePro2 controller

taig_cnc_mill.jpg

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Taig Micro Lathe II:
- pretty much stock except for digital scales on x-y axis
- A2Z quick change tool post
- powerfeed retrofit kit (on the way)
- steel table reinforced /w 4mm stainless steel plate
- indexable carbide turning bits
- IKEA knife holder modded with N42 magnets

taig_micro_lathe2.jpg

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[Miles]

File comment: 9-spline pattern equally spaced. Each spline is 6mm wide but one spline is only 3mm. Some sort of Sturmey thing?

No, this is how the normal Shimano/SRAM drivers are - it's for Hyperglide cog alignment.

[kfong]

Nice setup j3tch1u, I like how you have enclosed the mill. We wanted to do that as well with our micromill so we could use coolant, but eventually decided it was too messy. We found we could do without the coolant if we kept our cuts light. We mainly cut copper, brass and aluminum. We use a vacuum to keep the bit clear while it’s cutting. Our metal shop.
http://www.embeddedtronics.com/metalworking.html

Could you show pics or views of the cad work of the Matex gear and parts you CNC for it. Looks like I’m going to have similar problems with the currie gears I have. I’ll have to come up with a design to encase them, but it sounds like the ones you have are being torn up with your current setup.

[Miles]

File comment: Standard ISO 1.375" x 24 TPI. Fixie sprocket and ENO freewheel threads directly onto S3X

Yes, great for a regen. set-up. I want to try out my fixed-free switching freewheel on the S3X hub

[j3tch1u]

File comment: 9-spline pattern equally spaced. Each spline is 6mm wide but one spline is only 3mm. Some sort of Sturmey thing?

No, this is how the normal Shimano/SRAM drivers are - it's for cog alignment.

aha so luke's broached ENOs should fit this puppy too. great!

[j3tch1u]

File comment: Standard ISO 1.375" x 24 TPI. Fixie sprocket and ENO freewheel threads directly onto S3X

Yes, great for a regen. set-up. I want to try out my fix-free switching freewheel on the S3X hub

like an acs freecoaster but with xbee receivers controlling magnetic coils to actuate the engagement pawls? i've got a freecoaster on my Redline RL20 sitting in my basement in Toronto!

itswoodyitson!

woodyitsonacsfreecoaste.jpg (221.45 KiB) Viewed 9530 times

[Miles]

I hadn't come across the Freecoaster - interesting.....

[j3tch1u]

that looks really neat. how does it work? and will it hold up to 21,120ft-lbs of torque @ 1rpm?

[Miles]

If the pins are in they lock the pawls. As it's a screw on freewheel, at the moment, the back-drive torque capacity is somewhat limited

[j3tch1u]

Nice setup j3tch1u, I like how you have enclosed the mill. We wanted to do that as well with our micromill so we could use coolant, but eventually decided it was too messy. We found we could do without the coolant if we kept our cuts light. We mainly cut copper, brass and aluminum. We use a vacuum to keep the bit clear while it’s cutting. Our metal shop.
http://www.embeddedtronics.com/metalworking.html

Could you show pics or views of the cad work of the Matex gear and parts you CNC for it. Looks like I’m going to have similar problems with the currie gears I have. I’ll have to come up with a design to encase them, but it sounds like the ones you have are being torn up with your current setup.

that's a cute mill--it should be able to handle the gear parts just fine. first time i've seen a loc-line used on a vacuum. just curious, how much backlash were you able to get it down to?

i'll take some more pics. it's a pretty simple/straightforward gearhead design--motor faceplate, gear1, spacer, gear2, cylindrical housing, cover plate/drive mount, M4 hex bolts, output shaft, support hub with big radial bearings, a couple needle thrust bearings, a fixed sprocket and freewheel, 1-way clutch bearing press fit onto a freewheel adapter.

i haven't torn up the gearbox (yet). just a broken 12mm clutch bearing caused by the keyway on the output shaft. if your d-cut connection is tiighhht you'd probably wheelie before snapping off the shaft.

[kfong]

There is a bit of play, I think the backlash was .01; it's been a while since I checked it. But it’s easily handled by the software. We are still using the original threaded stock. There have been a lot of mods to the mill along the way. The gibs were redone in brass to tighten up any slack. The only shortfall is the thin column design. A mini mill would have been a better choice. Only the Z axis has a ball screw. The main thing is I'm still able to get tolerances to within +-.001, which is fine for most of the things I do. I've milled a 1/8th stainless plate with it, needed some for my torque arm on the BMC build. I had to convert it over to servo motors to do this. It has been a pretty useful mill. Eventually we will CNC the X3 mill. That should handle steel easily.

Any photos or info on your gear box will help since I will need to model one up as well and need to make it robust as possible.

[j3tch1u]

Astro 3210 10-turn motor. Lapped the face for better thermal conductivity and tapped 4 additional #6-32 holes for the faceplate. This is important as the entire gearhead assembly acts like a giant heatsink. Turned the 3/8" shaft nub down to 8mm and milled a 1mm deep flat. Tolerances are held close for tight slip fit.

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[j3tch1u]

Applied a thin layer of thermal compound.

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[j3tch1u]

Faceplate bolted to the motor.

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[j3tch1u]

First stage 3:1 planetary gearbox Matex part #75-3MAD.

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[j3tch1u]

Gearbox spacer Matex part #U75-903.

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[j3tch1u]

Second stage 4:1 planetary gearbox Matex part #75-4MLD.

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[j3tch1u]

Gearhead housing. Fins were cut for better heat dissipation.

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[j3tch1u]

Gearhead faceplate with integrated drive mount.

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