Appel Electric Cruiser

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fechter   100 GW

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Re: Appel Electric Cruiser

Post by fechter » Sep 19 2018 12:36pm

APL wrote:
Sep 19 2018 12:05pm

In the meantime.
What do you think of the double bolt idea? Grade 8 bolts would go down into the axel a ways,
for a good anchor, and the torque would work against shear strength, which is extremely high.
9mm or 10mm bolt shafts would fit a dropout.
Perhaps the dual bolts could go through a torque arm strap on the outside face of the dropout?
Hmm..just an idea :)
If you used bolts like that, the plate could just have two holes and not need a slot since the bolts can be removed when you want to get the wheel off. We know roughly what kind of torque is on the axle so it should be easy enough to calculate what bolt size is needed.

If the dropout has a slot like your drawing, the holes could just be above and below the slot so you don't even need a plate.
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Chalo   100 GW

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Re: Appel Electric Cruiser

Post by Chalo » Sep 20 2018 12:01am

APL wrote:
Sep 19 2018 12:05pm
What do you think of the double bolt idea? Grade 8 bolts would go down into the axel a ways,
for a good anchor, and the torque would work against shear strength, which is extremely high.
9mm or 10mm bolt shafts would fit a dropout.
Perhaps the dual bolts could go through a torque arm strap on the outside face of the dropout?
3/8" socket head cap screws have much smaller heads than 10mm, but they can almost always use the same hex key. 5/16" SHCS have smaller heads than 8mm, but use a slightly bigger key, 1/4" versus 6mm. Smaller heads would give you more options for screw diameter and placement without the heads fouling each other.

It would make sense to make a two-hole washer with a raised rib to fit the dropout slot. Easier on both the bolts and the slot.
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APL   100 W

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Re: Appel Electric Cruiser

Post by APL » Sep 20 2018 1:00pm

Thanks for your input guys! Your opinions are valued, and well taken. I'm glad to here that you at least think
that the two bolt design has some merit. I wasn't sure.

This is a new version, using fetcher's plate, and Chalo's rib ideas. Plus it occurred to me that perhaps there
might be a shoulder bolt that would fit? The threads could be smaller, and the shoulder is precise, making a
tighter fit, and leaving more aluminum in the axle. I think most of them are tool steel though.

Also I thought, since the motor doesn't have to slide out of the rear of the dropout, it can be closed off, making
for a stronger dropout. I like the fact that the axle face is flat, which allows it to go in and out easier.
(up, and down)

The rib idea can be expanded out both sides as well, if more area is needed, (longer slot), and I thought maybe
even go down into the axle a little bit? :?: Maybe thats overkill...

Left, is a simple bent tab, plate. Right is a a solid rib.
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APL   100 W

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Re: Appel Electric Cruiser

Post by APL » Sep 20 2018 1:13pm

Also, I may have read fetcher's post wrong. I think he was saying that if the motor is going to be fixed,
in one place, then the dropout only needs two holes in it for the bolts, and no slot, which would be very solid.

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Chalo   100 GW

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Re: Appel Electric Cruiser

Post by Chalo » Sep 20 2018 1:41pm

APL wrote:
Sep 20 2018 1:13pm
Also, I may have read fetcher's post wrong. I think he was saying that if the motor is going to be fixed,
in one place, then the dropout only needs two holes in it for the bolts, and no slot, which would be very solid.
For a fixed motor location, that would work very well. If the motor must move for chain adjustment, you need a slot of course.

Amberwolf was mentioning before that the the diameter constraint on a hub motor axle is imposed only by the freewheel and brake rotor that must fit over it. That implies a 19mm right side axle end to fit through a multi-speed freewheel, but up to about 35mm on the left side if I remember correctly. Even at 30mm or so, the left side would be more than adequate for a two-bolt torque retention system such as you have designed. It wouldn't work with vertical dropouts, but all the same, I wish some motor manufacturer would make axles that way.

Putting the raised rib on the axle end instead of the washer would reduce the likelihood of user error in installation. It would also give the axle a definite position in the slot even if the bolts are undersized (e.g. 6mm).
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APL   100 W

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Re: Appel Electric Cruiser

Post by APL » Sep 20 2018 10:04pm

Well, the e-bike industry is having to evolve from the perfected road bike history. Having to make motors fit road bike dropouts is the problem. There needs to be a change at some point,.. to their own system. Much of the efforts I see on the ES have been to compensate for that dilemma. Vertical drops are a curse.

Luckily, since this is a 'mid drive specific' motor, we have a clean slate, to do justice. What ever you want.:D

It's unlikely that anyone would use a freewheel on the drive side, unless you turn it into a hub motor, however, if so, the axle can be made in two pieces, drive side being steel. But I was thinking more about single speed freewheels.
They have about 35mm as you have stated. My personal set up has a BB fixed cup on it as well, so I need 28mm for that ID clearance.

Thats why this drawing is using that right drive size, I plan to ride this dang thing! :shock:
But it could go up to 35mm like you said. Plenty solid axle!

Or you could go with dual 40mm ID bearings as well, and use the chainring bolt pattern drive cogs, or machine one, to get 40mm axles.
(back to wiring route)

Question becomes, whats big enough? Any engineers? Gut feeling says 28 - 30mm is going to be fine. :)

Raised rib on the axle would be nice. Much lighter, and easy to make. I guess I have questions about the ability to wollow or crush with the torque? 6061T is robust, and there are harder available. Theres a little over an inch of surface on both sides. I realize that the bolts going through the axle are just as susceptible, to wollow, but they have more contact area?
Hmm..what think?

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Chalo   100 GW

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Re: Appel Electric Cruiser

Post by Chalo » Sep 21 2018 12:13am

I'm no fan of vertical dropouts, but they control some variables that make derailleur shifting unpredictable. They have their place for mid drive e-bikes that use derailleurs. My beef lately is with through axle designs that add no advantages over vertical dropouts, but a few extra disadvantages. Those are surely a solution in search of a problem.

I think a 28mm long, 10mm wide, 5mm deep key on the axle end would be more than adequate to secure the axle against motor torque when the bolts are fully tightened. But if you're worried about its integrity, you could always use 7075-T6 aluminum, which is about twice as strong and hard as 6061-T6. It machines very nicely. Stiffness and density are about the same.

I made a torque arm for my girlfriend's e-bike out of 7050 aluminum, which is in between the strengths of the above mentioned alloys, but stronger than mild steel. It was a low powered motor (350W nominal, geared), but on the other hand it was only a 10x12mm threaded axle. I made the arm 9mm thick and very precisely fitted, to compensate for the small radius. It seems to work fine.
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spinningmagnets   100 GW

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Re: Appel Electric Cruiser

Post by spinningmagnets » Dec 22 2018 8:12pm

From the moderator: From this point forward, many of the existing were moved to a new thread where the original poster / OP began posting about developing a DIY motor.


"APL's DIY axial flux motor"
https://endless-sphere.com/forums/viewt ... 30&t=97860

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