Converting a hubmotor to a middrivemotor

Discussions related to motors other than hub motors.
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Re: Converting a hubmotor to a middrivemotor

Postby John in CR » Sun Dec 02, 2012 9:47 pm

Sorry about the repeat posting. I should have looked thru the whole thread first.

FWIW, it turns out that sealed is probably worse for corrosion. Justin proved there's no way to keep the moisture out, so you might as well let it dry out. Sealed motors will even suck water in through the wiring like a straw. Get your motor up to running temps and then hit it with some rain, and it slurps the stuff in. I've seen sealed hubbies locked up from the buildup of rust in the magnetic gap. We haven't seen any of that with ventilated motors. Even the guys who didn't put their exhaust at the perimeter, so grit and sand has no way out haven't had issues. Zappy had the only failure I know of and that was a couple of computer fans that got killed running through a muddy stream.

With the rpm of those little motors you can easily pull enough pressure to use a filter of some sort. It will impact flow, but getting fresh air in far better than roasting it in a sealed housing.

It's a good idea to put some rust prevention coating

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Re: Converting a hubmotor to a middrivemotor

Postby mr.electric » Sun Dec 02, 2012 10:05 pm

ImageUploadedByTapatalk1354503723.864081.jpg
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Started making the heat bridge for my BMC. Since there is no cover plate in the center of the stator like the Mac I found this old threaded hub - disc adapter that fits closely to the flange of the BMC stator. Now I will drill some holes and add screws. This heat bridge may prove to be too thick. I will mill it down with a grinder if needed once the holes are drilled.
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Re: Converting a hubmotor to a middrivemotor

Postby mr.electric » Sun Dec 02, 2012 10:06 pm

ImageUploadedByTapatalk1354503926.078262.jpg

Heat bridge in place. I had to file the id of the adapter to make it drop down over the shoulder on the stator
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Re: Converting a hubmotor to a middrivemotor

Postby mr.electric » Mon Dec 03, 2012 12:32 am

ImageUploadedByTapatalk1354512652.924467.jpg
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Threaded on another adapter to help drill through the cover.
ImageUploadedByTapatalk1354512688.324571.jpg
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Holes seem accurate enough for my purposes.
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Re: Converting a hubmotor to a middrivemotor

Postby crossbreak » Mon Dec 03, 2012 6:03 am

Looks great! As we know now these holes do not have to be drilled that accurate like the ones in my bafang due a different bearing config (more conversion friendly) in the MAC/BMC. But working that accurate does not harm the final product :)

BUT you should try taking out the shaft before going further. I guess that relieving the axle axially (bad english sorry) will not be as easy as with the MAC. Keep that advance in mind, it may slip on the axle in the end.

Hey John, I saw the video about deposits in hubmotors a year ago. A small hole to let water/steam out at the bottom of the housing should be all it has to take. Works also with CroMo frames. Car alternators also work for years in the dust and they are even brushed. All i'm talking of is keeping the dust out of the gears. A more sophisticated drive would separate motor and gears further. Like some RC-drives we see on the sphere from time to time. Not only miles and me dream of things like that :D
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Re: Converting a hubmotor to a middrivemotor

Postby Whiplash » Mon Dec 03, 2012 9:22 am

I would imagine it would be fairly simple to divide the geared portion from the motor portion in the MAC with a simple dust plate is something out of rigid plastic or fiberglass no? Then you could vent via side cover just like a DD hub..
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Re: Converting a hubmotor to a middrivemotor

Postby crossbreak » Mon Dec 03, 2012 9:28 am

where exactly would you place this plate?
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Re: Converting a hubmotor to a middrivemotor

Postby bØb » Tue Dec 04, 2012 12:22 am

Just a little teaser about what I did after supper
Image

Image

A friend brought me a heatsink today. Modified it some, but still need to mill out clearance around six bolts that hold the heat bridge and stator carrier.
Anybody got in their junk box an old 1-3/8" - 24 lock nut for an old cup and cone loose bearing bottom bracket. I want one to screw on the freewheel mount of the MAC motor case. Gonna call it quits for the night.
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Re: Converting a hubmotor to a middrivemotor

Postby John in CR » Tue Dec 04, 2012 12:55 am

Bob,

Nice. Now you have me wanting to put oil in a hubbie. Mount it with the stator oriented with the hall board up, somewhat less likely to create problems. If small drips of oil leak out it's just automatic lube of the chain instead of getting on tire or brake disk. Not only does the oil conduct heat to the shell rapidly where your extra surface area dissipates it better, but it should help repel water. It all seems perfect for a beach and rainy day bike. :mrgreen:
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Re: Converting a hubmotor to a middrivemotor

Postby bØb » Tue Dec 04, 2012 1:10 pm

There will be very little oil in the housing. Maybe an inch or less when the motor is not running. Just enough to dip the edge of the rotor in while the motor is running. The main heat path out of the motor will be from the stator to the aluminum carrier that the stator is pressed on, to a header/ heat bridge, that holds the stator in position, to the motor cover, to the heatsink, to the air :P There is hopefully some lube and corrosion advantages also.

I am going to mill slots in the back of the heatsint to run the phase and hall effect wires through to holes in the cover. Seal the wires and the covers with silicone. The case will vent through the hollow shaft where the wires originally ran. The hole in the shaft comes out in a quiet place, for oil splash, in the motor.

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Re: Converting a hubmotor to a middrivemotor

Postby Whiplash » Tue Dec 04, 2012 4:12 pm

Good point about the wire hole! I never thought of it but its dead center and should almost never see any oil especially since its spinning! Centrifugal force is on your side!
Power is a fascinating thing, the more you have, the more you want, but the real power is having the restraint not to use it all at once...............Um...Yeah..

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Re: Converting a hubmotor to a middrivemotor

Postby Whiplash » Tue Dec 04, 2012 4:18 pm

crossbreak wrote:where exactly would you place this plate?



I was thinking between the gear portion and the motor, you could maybe seal it with silicone around the perimiter?
Power is a fascinating thing, the more you have, the more you want, but the real power is having the restraint not to use it all at once...............Um...Yeah..

The harder you work.....The luckier you get!!

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Re: Converting a hubmotor to a middrivemotor

Postby crossbreak » Tue Dec 04, 2012 6:15 pm

This heatsink fits awesome! Good luck when milling it. Keen to see if you use a hand tool (dremel) or a machine. I always try to get better in hand milling.

the hollow shaft is fine for venting. nice idea! This steam will still get in and condensate during cool down. it would be easy to push in a steam barrier that keeps steam out, but stil letting it out (just like GoreTex).

I can only sign what bob says about inserting oil. This will do best.

Using ScotchWeld for mounts and sprockets is a cool thing i did not know yet :idea: i'll try. Thx to Doctorbass for this great video!

@ whiplash: Sounds like a nice idea. But there is so little space. I can imagine using a thin sheet between motor and planetary carrier. But that might slip on the rotor bell doing friction. But doing a conversion to the hub might have the option to get some space here, by giving it more space. You will have to take a look into details, but this sounds like it will be worth it. You can give distance by adding washers between planet carrier and motor, but this will make the whole hub wider :? this might somehow work since you only need 1mm.
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Re: Converting a hubmotor to a middrivemotor

Postby Whiplash » Tue Dec 04, 2012 10:58 pm

Yes I won't know till I have it apart...
Power is a fascinating thing, the more you have, the more you want, but the real power is having the restraint not to use it all at once...............Um...Yeah..

The harder you work.....The luckier you get!!

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Re: Converting a hubmotor to a middrivemotor

Postby bØb » Wed Dec 05, 2012 12:38 am

Finished the heatsink after supper:
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Re: Converting a hubmotor to a middrivemotor

Postby mr.electric » Wed Dec 05, 2012 4:00 pm

Nice work! Heat sink looks awesome.
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Re: Converting a hubmotor to a middrivemotor

Postby kfong » Wed Dec 05, 2012 6:54 pm

Nice conversion, I might be doing something similar this winter.
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Re: Converting a hubmotor to a middrivemotor

Postby mr.electric » Thu Dec 06, 2012 9:39 am

My heat bridge is coming along. I pulled the axle out completely. It rides in a bearing pressed into the rotor. Does the shaft need to be locked to the rotor or planetary carrier. As it sits now it seem that the shaft would just spin freely disconnected from everything. The sun gear is part of the rotor on my BMC.
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Re: Converting a hubmotor to a middrivemotor

Postby bØb » Thu Dec 06, 2012 11:05 am

mr.electric wrote:My heat bridge is coming along. I pulled the axle out completely. It rides in a bearing pressed into the rotor. Does the shaft need to be locked to the rotor or planetary carrier. As it sits now it seem that the shaft would just spin freely disconnected from everything. The sun gear is part of the rotor on my BMC.


mr.electric,
yes, the shaft must be locked to the the planet carrier. In a MAC, and I would assume in a BMC, just put the key back in shaft for the clutch. The clutch will then be a freewheel for the shaft. The clutch will engage and turn the shaft. The shaft will turn in the opposite direction from the way the housing turned. You must mount the housing in the frame in the opposite direction from the way it was used as a hub. Your output shaft, what use to be the axle, will turn in the proper direction for chain or belt drives.

I hope I have explained this so somebody can understand it. Planetary gearing can be very hard to get your head wrapped around. These little motors use the simplest of planetary gear drives. There should be some some examples of planetary or epicyclic gearing on the web or you could borrow a Machinery's Handbook. There are examples that will blow your mind for hours analyzing the outputs.

Just remember: Lock the stator to the case and the planet carrier to the axle (new output shaft), turn the motor around in the bicycle frame. :roll:
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Re: Converting a hubmotor to a middrivemotor

Postby Miles » Thu Dec 06, 2012 11:25 am

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Re: Converting a hubmotor to a middrivemotor

Postby crossbreak » Thu Dec 06, 2012 1:45 pm

bØb wrote:yes, the shaft must be locked to the the planet carrier. In a MAC, and I would assume in a BMC, just put the key back in shaft for the clutch. The clutch will then be a freewheel for the shaft. The clutch will engage and turn the shaft. The shaft will turn in the opposite direction from the way the housing turned. You must mount the housing in the frame in the opposite direction from the way it was used as a hub. Your output shaft, what use to be the axle, will turn in the proper direction for chain or belt drives.
...
Just remember: Lock the stator to the case and the planet carrier to the axle (new output shaft), turn the motor around in the bicycle frame. :roll:


That's a good abstract of what I wrote the past 10 pages :D thanks for that, maybe you should write a wiki page or HowTo ;)
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Re: Converting a hubmotor to a middrivemotor

Postby bØb » Thu Dec 06, 2012 2:52 pm

crossbreak,

Thanks for the complement. I should have mentioned to make holes in cover to get wires out though.
Yesterday I order some 2.75"Ø aluminum rod to make the header/heatbridge. It will probably come in next week. That will be the last big operation to complete the motor. After that it should just be wiring and assembly. I have been saving pictures and will probably try to start a new MAC specific to How To soon. I didn't really want to start it until I had the motor completed. You were really the inspiration that got me started on this. I'm not really a bicycle person :oops: I bought the bicycle that the motor will go in >30 years ago. It was used then and I still have not worn out the half used up tires that were on it. I did buy the bike new tires, rear wheel, freewheel cluster, pedal cranks and chain rings for the project tough 8)

Sorry about the thread jacking,
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Re: Converting a hubmotor to a middrivemotor

Postby spinningmagnets » Thu Dec 06, 2012 3:34 pm

I think I now understand what you are doing. As I now understand it, I am very impressed and I now feel this is a very important development. I have been pondering the various options for the "ES BB-drive" thread http://endless-sphere.com/forums/viewtopic.php?f=28&t=45313 (similar to the GNG, but capable of double the continuous power). My concern over using the MAC 12T was how wide the axle had to be, even after trimming a small amount to make it slightly narrower.

In this configuration, The BB bracket will attach to the fixed shell, and the hub axle can be trimmed even narrower. The fact that the planetary ratio is improved to 6:1 from the stock 5:1 is an additional benefit. I believe the BMC and Bafang geared hubs both have two winding choices available, but the five windings from cell-man (including the very hard to find elsewhere 12T) would make the MAC my first choice to try out.
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Re: Converting a hubmotor to a middrivemotor

Postby crossbreak » Thu Dec 06, 2012 6:15 pm

I think I now understand what you are doing.

ok... now you blame me :? was it really so confusing what I told all the time? Maybe you should have told me. I thought that most people here know how a planetary works, mabye I was wrong :? I just wanted to motivate other people to do the same as i did, cause I see some benefit, and wanna get the necessary feedback to get on further. Wanted to give back what I got from the sphere, the half bakery, just as half baked as I am. I spend almost spend $200 for this project (of course this was my fault), just to have a look if it might work. I really should have split both topics in the first place.

I think this topic is done... it's time for two new ones, the first one called "converting a MAC to middrive - -making the axle rotate" If this is said first, most people will get it in the first place I hope.

And another one called the "through the jackshaft drive" which is about having the crank sprocket on the left and only one final output drive sprocket on the motor (on the right). It could be called the "ANTI freewheel crank" topic - cause I'm a resistance fighter here :evil: really hope I wont stay the outcast, seeing so many drives going to trash after weeks of use, can you image where I get my €30 250W bafangs?

Seeing the GNG Gen2 which still runs through the cranks using a tiny 9T drive sprocket shows that this topic is completely off any sence at all. Seeing all those guys here buying something which lasts a few weeks like 1200W cyclone and 1000W GNG just makes me sad :(

No excuses plz about thread jacking, it was meant to be an enlightening in the first place. I have no time to answer all questions, neither for a good Middrive Wiki, that I started no one will ever further develope, I guess. There is no need to chew the hole story to a perfect HowTo, getting through the mess is something educating for noobs, and it's always fun and encouraging like bob can tell now i hope ;) Bob, just start a new thread with the above topic. This thread is really done now. People may read this one if they really wanna know how this all came up, if they dont (like most), they can just stick to the two new ones.
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Re: Converting a hubmotor to a middrivemotor

Postby bØb » Thu Dec 06, 2012 9:05 pm

I was kind of thing along the lines of "Problems in Paradise,How To Solve Them. Get the Hub Motor Between the Pedals" :lol:

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