FrictionFast Bike project

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McDesign   100 W

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FrictionFast Bike project

Post by McDesign » Jan 10 2011 6:56pm

I'm starting this little project, since I've got all the pieces. The goal is to make a legal, bolt-on addition to a kid's bike - in this case my daughters 26" wheel mountain bike. Georgia allows 500 W and still calls it a bike - so twin 250W permanant magnet brushed motors.
FrictionFast.jpg
FrictionFast concept
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The thought is to pick up the rack mounts for the main mounts. The mechanical approach is to pivot the motor plate (green) on a different center than the rear wheel axle. This way, drive torque from the motors tries to push the motor toward the rear of the bike, and it presses more tightly into the tire - ideally, the more torque the more pressure.
FrictionFast 3.jpg
FrictionFast "Engaged"
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Pull the motor mount forward, against the seat stays, and the drive rollers lift clear of the tire.
FrictionFast 2.jpg
FrictionFast - "Idle"
FrictionFast 2.jpg (47.91 KiB) Viewed 4791 times
The motors I'll run at 48 volts, and max out at 6000 rpm - that's what I have them doing on scooters now - no, I know they won't be running at 250 Watts - but that's what the labels say

I'll use 35-durometer urethane "cushion" rollers (they have teardrop shaped voids through the roller) from Fairlane to start.

1.5" diameter gives me 27 MPH at that max motor speed.
1.75" gives me 31 MPH
2 gives me 36 MPH

Such is my plan at this moment

Forrest

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Re: FrictionFast Bike project

Post by Hillhater » Jan 10 2011 7:36pm

Interesting ?
Why 2 motors ? ..you could get a single 500W motor for $50.
Will you run a single controller or dual ?
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McDesign   100 W

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Re: FrictionFast Bike project

Post by McDesign » Jan 10 2011 7:58pm

I have a lot of 250W motors . . . and controllers . . .
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Stuff
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Forrest

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Re: FrictionFast Bike project

Post by LI-ghtcycle » Jan 10 2011 9:25pm

I'm very interested in hearing more about those urethane rollers, are they textured or just smooth? If I understand correctly, they are designed to deform and take the shape of the wheel under power? How well do you expect they will grip the tire if things get wet?

Thanks! :)
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Re: FrictionFast Bike project

Post by gogo » Jan 10 2011 9:40pm

Signed up for this thread! :D
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McDesign   100 W

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Re: FrictionFast Bike project

Post by McDesign » Jan 17 2011 5:28pm

Lightcycle -

Here are the rollers I just ordered to try, from McMaster-Carr- (soft-ish urethane; not cushioned)

http://www.mcmaster.com/#catalog/117/1108/=amucrc
Urethane Drive Roller 35A Durometer, 1-1/2" Dia, 1.25" W, 1/2" ID Bore (Same as 2475K62)

http://www.mcmaster.com/#catalog/117/1108/=amud0t
Urethane Drive Roller 35A Durometer, 2" Dia, 1.94" Width, 3/4" ID Bore (Same as 2475K65)

Here's the cushioned one from Fairlane I didn't get - yet - it's 2.5" diameter; not enough reduction to spin the over-volted motors fast enough (6000 rpm), at a reasonable road speed (under 30 MPH)
http://www.fairlaneproducts.com/techshe ... soft-EX625

Forrest

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Re: FrictionFast Bike project

Post by McDesign » Jan 29 2011 7:19pm

Okay - finally got back on this project - Past two weekends were too busy!

Here's the Swing Plate, rod ends, roller and motors - I still need to machine the roller axle.
IMG_0148.JPG
Arrangement on Swing Plate
IMG_0148.JPG (53.05 KiB) Viewed 4580 times
Here's the pivot point - I welded a 5/16-18 flanged nut to each dropout -
IMG_0144.JPG
Pivot mount detail
IMG_0144.JPG (72.51 KiB) Viewed 4583 times
Here's the Swing Plate assembled onto the pivots -
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Pivot detail
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Here's the plate swung forward - note that the arch is off the tire -
IMG_0138.JPG
Plate swung forward
IMG_0138.JPG (78.18 KiB) Viewed 4580 times
Here's the plate swung backward - note the arch is against the tire -
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Plate swung back
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Here's the Swing Plate ground and ready for paint -
IMG_0151.JPG
Swing plate smoothed
IMG_0151.JPG (41.82 KiB) Viewed 4583 times
Here's the battery stack and shape I'll use, (80) 1.2V / 7 AH NiCads. I'll wire them as 48V / 14 Ah. Behind it, the bike's dropped top tube can be seen - this is where the battery pack will mount -
IMG_0152.JPG
Battery stack
IMG_0152.JPG (66.68 KiB) Viewed 4583 times
More to come - will make a cardboard battery box mock-up to see how it feels between my legs.

Forrest

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Re: FrictionFast Bike project

Post by spinningmagnets » Jan 29 2011 7:35pm

When the roller is resting forward and off of the tire, how will it engage? Its my understanding that the Kepler/Adrian style wants to jerk backwards when turned on (a phenomenon I noticed when operating a hand-drill), and of course, only a tiny movement is needed to get the roller to touch the tire, and then begin pulling itself deeper into the tread.

The thought occurred to me that if the roller was resting on top of a stationary plate (both not touching the tire), turning on the motor would impart some movement, and as stated before, only a small amount of momentum is needed to get the assembly moving towards tire-engagement. This looks like a fun project, and I wish you the best of luck with whatever you decide.

edit: I think that this is a very clever design, and once you factor in that a variety of motors could be easily optioned-in (brushless, higher power if desired), this style has a lot going for it. Since it doesn't require one-way clutch-bearings, that is one less part, one less possible failure/wear concern, and the roller choices are much better.

Have you seen the posts about "stippling" metal? A simple shaft union (soft steel) could connect the two motor shafts and form not only the connection, but an affordable steel roller. Stipple the roller skin to give it a rough surface, then heat it and roll in sugar (Jeremy's suggestion) to harden the skin. The roller skin could also be cheaply knurled by a shop (rather than stippled), and most local fab shops have knurling jigs. I look forward to hearing how the urethane holds up. That may prove to be a great roller solution...
Last edited by spinningmagnets on Jan 29 2011 7:50pm, edited 1 time in total.

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McDesign   100 W

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Re: FrictionFast Bike project

Post by McDesign » Jan 29 2011 7:47pm

At this point, I don't know what will make it engage - have to see if the "jerk" will do it - it seems like it would kick the swing plate forward, but maybe it could bounce of a cushion and back into the tire? If not, maybe some sort of lever thingy - Or hey - just had an idea - what about a little tab just under the roller at rest position, but clearing the tire? It could serve as the "launch platform".

Hmmmmmmmm.



Forrest

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Re: FrictionFast Bike project

Post by McDesign » Jan 29 2011 9:52pm

Battery box cardboard model - this fit the battteries correctly, but not the bike (hits the stem).
IMG_0155.JPG
First battery box model
IMG_0155.JPG (82.96 KiB) Viewed 4559 times
I'll fudge the next model to fit the frame angles exactly, and think the batteries will fit fine. That cardboard is BCC flute, or 1/4" thick, while the actual battery box will be .063 steel, so that will save me almost 1/2" all around.

Forrest

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adrian_sm   10 MW

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Re: FrictionFast Bike project

Post by adrian_sm » Jan 29 2011 11:35pm

:shock:

Ahhhh.... How tall are you? Can you still stand in front of the seat without endangering any future kids you may have?
Build #1 ~28kg ~ 700w Avanti Hardtail Crystalyte 408, 48V10Ah Headway. ~5500 kms to date. (retired)
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Build #3 ~13kg ~2000w Commuter Booster <1kg Friction Drive in Beta testing (www.commuterbooster.com)
Build #??? ~21kg ~1500w Adrian's Bafang BPM Hardtail MTB Bafang BPM code12, 15s LiPo, ~40kph, ~30kms

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Re: FrictionFast Bike project

Post by Bluefang » Jan 30 2011 3:03am

Wow, thats a awefully large battery case for a low power friction drive. But your concept will work and you might want to look into some way of dampening the engagement and disengagement of the drive as with Kelpers drive, the commuter friction drive Adrian is doing, both mounting from above the wheel and the one i built(similar to yours mounting from below) all the drives have a dampening system in them to stop the kick back.
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McDesign   100 W

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Re: FrictionFast Bike project

Post by McDesign » Jan 30 2011 9:51am

Yep, all those things I've got to do. The bike (a kid's frame) is pretty short, so I can straddle the battery box fine.

In regards to the battery box size, I really don't know what capacity I need - four 12V packs seemed not enough, eight does look big, but 48 Volts is what I'm using on the kids' scooters. If 36 V would work, I could use six packs.

Power-wise, I'll probably use a 40 or 60 A controller, just because I've got some. Max power should be about 2KW, just based on my experience so far with this stuff. I have ordered a couple of those $30 wattmeters from Asia, so hopefully I'll know for real what's happening with the electrons.

This is all sort of an experiment to learn, using all the material I have.

Forrest - gonna go make another battery box this morning

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Re: FrictionFast Bike project

Post by friedwires » Jan 30 2011 10:36am

its looking good Forrest. whats your gameplan for charging the nicd's

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Re: FrictionFast Bike project

Post by McDesign » Jan 30 2011 11:57am

Don't know about charging - need to investigate.

Here's this mornings work - the Swing Plate is painted to sorta' match -
IMG_0159.JPG
Swing Plate
IMG_0159.JPG (57.22 KiB) Viewed 4484 times
Here's a better-fitting battery pack -
IMG_0157.JPG
2nd cut battery pack
IMG_0157.JPG (70.53 KiB) Viewed 4484 times
Forrest - thinking that space under the BB looks promising for a batterypack - Hmmmmm.

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McDesign   100 W

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Re: FrictionFast Bike project

Post by McDesign » Jan 30 2011 12:06pm

Charging - maybe this? It will do (40) cells, so maybe two of these?
http://www.powerstream.com/NiCad-NiMH-Catalog.htm

Forrest

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Re: FrictionFast Bike project

Post by McDesign » Jan 30 2011 6:08pm

Hmm - had to address that battery pack. I had the thought that maybe it would fit under. Actually was able to add a ninth pack, so I'm contemplating 36V at 21 Ah with this configuration.

First attempt - (100) cells
IMG_0166.JPG
Pack noodling
IMG_0166.JPG (77.4 KiB) Viewed 3047 times
Second attempt - (90) cells and space for a controller by the head tube
IMG_0172.JPG
Pack refined
IMG_0172.JPG (72.31 KiB) Viewed 3047 times
Goofy looking, but possible - 3" ground clearance -
IMG_0171.JPG
Pack model hung from frame
IMG_0171.JPG (94.54 KiB) Viewed 3047 times
Forrest - need to make a CAD model for the sheetmetal pattern

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rearengine   100 W

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Re: FrictionFast Bike project

Post by rearengine » Jan 30 2011 9:19pm

Forrest... I'm interested in your drive ,as it is very much like my drive in the way it contacts the tire ..( Hill Helper thread ) I just want to say I have been experimenting with what I call a park ramp to get the roller off the tire .. As mentioned above by Spinner.. I found that it works , but when not calling for more torque, or when coasting, you end up on the edge of the ramp :( Needless to say not good for the roller ... Thats been my experence with my drive .. Yours could be different , because it is working on top of the wheel ,and mine has to go up the tire in front .. Good luck with your build, It's looking good ...

Very nice trikes , Kids are cute to... Bill

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Re: FrictionFast Bike project

Post by Hillhater » Jan 30 2011 10:17pm

McDesign wrote:
Power-wise, I'll probably use a 40 or 60 A controller, just because I've got some. Max power should be about 2KW,
This is all sort of an experiment to learn, using all the material I have.
I would recommend that you invest a little time & money in a brake up-grade before you experiment too much.
..Those calipers are going to work overtime holding back 2kw and all those batteries ! :wink:
Minimum of a front V brake, though a disc may be easier.
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McDesign   100 W

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Re: FrictionFast Bike project

Post by McDesign » Jan 31 2011 3:03pm

Some work on the battery box - it's 3.75" wide, clears everything, and has room for the batteries and a bit more.

Forrest
Attachments
Battery Case.jpg
Battery Case 36V / 21 Ah
Battery Case.jpg (38.16 KiB) Viewed 3011 times
Battery Pack detail.jpg
Battery Case detail
Battery Pack detail.jpg (76.2 KiB) Viewed 3011 times

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McDesign   100 W

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Re: FrictionFast Bike project

Post by McDesign » Feb 09 2011 7:17pm

Got my little axles made that join the two motors and onto which the roller mounts. I sent a perfectly fine piece of mild steel 7/8" rod to my way-back-from-college buddy Bruce - http://www.boonerings.com/ , but he didn't like it - seemed "crude". He made these out of ring-quality Titanium, 'cuz that's what he's set up for!
IMG_0196.JPG
Titanium axles
IMG_0196.JPG (82.62 KiB) Viewed 2860 times
Y'all need a ring of any type for any thing, he's your man - goal is a week turn-around, always - check out his site. He made lots of Ti bike parts, long ago, and some great HPVs - I think still 83rd fastest in the world, ever, in about 1988.

<edit> found the listing - http://www.recumbents.com/wisil/fastest ... est&ID=553


Forrest

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McDesign   100 W

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Re: FrictionFast Bike project

Post by McDesign » Feb 10 2011 9:26pm

Hey - had to play tonight after work! Everything fit very nicely together - so tightly that I had to polish a bit - no runout at all.
IMG_0211.JPG
IMG_0211.JPG (54.75 KiB) Viewed 750 times
The inner setscrew on each end of the titanium axle engages the normal flat on the 8mm motor shafts, the outer is a backup. the two setscrews on the roller hub just engage the axle - I'll mark the places, and file a small flat for the setscrew to engage.
IMG_0213.JPG
IMG_0213.JPG (44.67 KiB) Viewed 2936 times
Forrest

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Re: FrictionFast Bike project

Post by amberwolf » Feb 11 2011 3:04am

Don't file a flat, drill a dimple instead. ;)

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McDesign   100 W

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Re: FrictionFast Bike project

Post by McDesign » Feb 11 2011 5:58am

I'll try, but it's darned tough stuff!

Forrest

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spinningmagnets   100 GW

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Re: FrictionFast Bike project

Post by spinningmagnets » Feb 11 2011 7:38am

Use one of the new drill bits from McMaster-Carr, where the tips aren't carbide or diamond, they're made from the skulls of teenagers...the hardest substance known to man.

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