Help finding a solution to Bafang gear stripping

[voicecoils]

Ok, sounds good fetcher.

Shock loading is a worry. I'd rather wear the gears planetary gears then bust the freewheel if something has to give.

With a cad drawing of the gear, a mold could be laser cut out and stacked to give the desired thickness. I could pour molten solder into a mold but that's about all I've got the in-house ability to melt

I think if some one more mechanically minded then I and with shop access, had a hack at this problem a few workable solutions could come out pretty fast.

{EDIT EDIT} I just realised I've been saying "sun gear" when what I meant to say was "ring gear". My terminology in previous posts is therefore incorrect. Sorry to anyone for the confusion. A bit of a "doh" moment, now that its dawned upon me.

[Knuckles]

SSAY1_25-28.dwg

SSAY1_25-28.dwg

(11.39 KiB) Downloaded 79 times

I just plotted the dwg to scale at it appears to be a dead on match.
This gear is (of course) discontinued! Go figure!
http://www.khkgears.co.jp/en/khk_produc ... lition.pdf

I also assume the inner bore of the bearing is exactly 8mm.

SSAY1.25-28.jpg

(133.29 KiB) Downloaded 35 times

SSAY.pdf

(313.77 KiB) Downloaded 72 times

This may have potential ...
This is located very close to me ... http://www.qtcgears.com/

I may have to pay them a visit!

[TPA]

Hi,

I am a machinist. I work in a fully equipped machine shop. We might be able to work out a little barter if you are interested.

There is a good chance I can make that gear, unfortunately only small quantities though.

My proposal:

1. you need gears (aluminum, stainless, chromoly...), I might be able to make them.

2. I need a hub motor...you sell them.

If you sent me a single new gear and the mating bearing, I would make you a set of three gears out of the material of your choice identical to the one you sent me. I send the set to you and you test it out. If it works, I make you about 10 sets in exchange for a complete wheel kit. I would offer you any plans and drawings, but I'm not likely to make any. If the gears do not work, then you do not have to send me the kit.

This should save you a considerable amount of money, and helps me out at the same time.

The might part of it depends on the possible need of special tools and how expensive they might be.

I can't make large quantities at one time because it is not my shop.

[dnmun]

'sun gear' is the correct term. a ring gear is a hypoid bevel gear where angular rotation is turned 90 degrees as in the rear axle diferential. teeth are on the outside of the flywheel ring gear. sun gear is the classic term for the gear when used for overdrive in a tranny.

it would be interesting to see if the new composite gears for the BMC are the same size. maybe there is some way to convince bafang to manufacture with the composite gears from the start.

EDIT: thanks miles, i stand corrected. so the other uses of ring gear are just by similar position?

ps: with respect to whether it is possible that bafang would use composite gears, i suspect they also are already economically developed enuff to start using planned obsolesence in the motor, and every dead motor to them is just a possible new sale. if it were possible to find the manufacturer of the composite gears for BMC, they might consider developing a replacement composite gear for the bafang. was it mark at team hybrid who originally started the push towards steel gears for the puma? that may be the way to go too since it got BMC to actually change their manufacturing process. chalk another one up to our fav silent member.

[Miles]

Sun gear is the one in the centre.

Planet gears are arranged around it on the planet carrier.

Ring gear is the outermost one, with teeth facing inwards to engage with the planets.

[fechter]

'
it would be interesting to see if the new composite gears for the BMC are the same size. maybe there is some way to convince bafang to manufacture with the composite gears from the start.

Not likely the BMC gears will fit. I have a set of metal gears for a Puma, which I believe are the same size as the BMC. They are quite a bit larger in diameter.

[TPA]

A gear made out of aluminum or brass would meet the load requirements and not damage steel components in the hub because brass and alum. is softer.

If nylon can make it as far as it has been described here, then non anodized 6011-t6 can handle it with no problem. It would wear over time because it is softer than steel, but still last a while.

[voicecoils]

A gear made out of aluminum or brass would meet the load requirements and not damage steel components in the hub because brass and alum. is softer.

If nylon can make it as far as it has been described here, then non anodized 6011-t6 can handle it with no problem. It would wear over time because it is softer than steel, but still last a while.

Awesome TPA I was hoping someone on this forum would have the skills in-house.

Brass sounds good. If no one state side can send you a gear, I'll send you one of mine from Sydney, Australia.

Hopefully a more local offer offer will come through.

[voicecoils]

appropriate bearings:
http://www.vxb.com/page/bearings/PROD/SkateboardBearings/sk8zz
http://www.vxb.com/page/bearings/PROD/Scooter/608ZZ10




608ZZ Dimensions:8mm x22mm x7mm
Quantity 10 Bearings 608ZZ
$4.95

[johnrobholmes]

Ok, Ok, I spent an hour today sourcing gears. Found a match that would just need boring, and found a company that makes spur gear stock.

Want to measure the width of the gear for me? 10mm work fine? Are we positive it is 20* pressure angle?

[Knuckles]

Metal gear installed and ready for testing.

Heavy_Metal.jpg (24.13 KiB) Viewed 1080 times

http://98.131.176.65/endless-sphere/GEDC0828.JPG
http://98.131.176.65/endless-sphere/GEDC0827.JPG
http://98.131.176.65/endless-sphere/GEDC0826.JPG
http://98.131.176.65/endless-sphere/Metal_Gears.jpg

Knuckles

[dnmun]

before you grease it why not paint the faces with prussian blue and see where the wear faces are on the gears? excellent find!

[snowranger]

The 826.jpg shows the steel gear barely engaging the ring gear. Is it just the photo?

[Knuckles]

Gravity. When I rotated the assembly the nylon did the same.

Original_Gears.jpg (47.64 KiB) Viewed 1057 times

And of course no racer bearing on the "non-available" gear.

I got the last two in stock at the local "Gear Store"

WTF!

But the gear dude said he can get more as "special order"
He was blown away about e bikes ... never heard of them ...

But only torture testing will tell ...

[lawsonuw]

Nice!

No bearing but it should work just fine for a while. Hadn't heard of KHK before, added them to my list of stock gear companies.

Marty

[johnrobholmes]

So the metal gear will be riding direct on the planet gear post?

[Knuckles]

So the metal gear will be riding direct on the planet gear post?

YUP!

[voicecoils]

:D Metal gear installed and ready for testing.

Heavy_Metal.jpg

http://71.18.69.167/endless-sphere/GEDC0828.JPG
Knuckles

Well done! Can the metal gear spin freely on the post? Obviously a bearing would be better but... you might still be able to test it.

Can you pop the metal gear on top of the nylon one and comment on whether the tooth profile / pressure angles are identical? What are the specs from the shop?

[Knuckles]

It's tight but spins free as birdie! But of course this is really just a test of M 1.25 28 teeth gears.
(Dead on Identical VC! Dead on!)

I showed the peanut butter to "Mr. Gear Dude" (Brian) and I know these guys can make anything.
Very cool shop. Making gears likes SOB's they were! NY cost I would think (of course) for custom gears.
This shop is located very close to me ... http://www.qtcgears.com/
The "discontinued" KHK gear is made in Japan btw.
Part Number KSSAY1.25-28

Makes me feel great hope for 'lil' Bafang.

72V 30A off road time!

[zibbby]

What about if the gear is made of BRONZE?
The bronze is self lubricated and would work great with steel and my be little quiter then steel. It may also not need bearing.

[Kurt]

If you want it to last get some one to bore out the gears ID on a lathe so you can press in a bearing. It would be a 5 min job for anyone 1/2 decant. It will last for ever then.Running the motor under load with the gear naked on the post could chew up the post then even if you want to fit a bearing later it will be a bad fit on the chewed out post.
Kurt.

[voicecoils]

If you want it to last get some one to bore out the gears ID on a lathe so you can press in a bearing. It would be a 5 min job for anyone 1/2 decant. It will last for ever then.Running the motor under load with the gear naked on the post could chew up the post then even if you want to fit a bearing later it will be a bad fit on the chewed out post.
Kurt.

It's hard to argue with doing the right job the first time around. I totally agree.

Knuckles however has some stock to play with, as well as replacements. If he wants to try it out, I say go for it! It's not a good long term solution. I'm curious to hear how well the meshing with the ring gear goes.

I also would like to know what happens if metal bits grind off and fly into the motor

[Knuckles]

F-N-A!

[dazzassj6]

i cant wait until knuckle comes back with the test results lol will it work?!

if it does work, maybe knuckles can stock a few of these for all of us hehe.

maybe bafang would start supplying them too if this works.

i totally agree with kurt, im worried knuckles might wear the post out.

[voicecoils]

F-N-A!

spill it!

I need a "you so crazy factor" on a scale of 1 - 10