Help finding a solution to Bafang gear stripping

[Knuckles]

Metal gear installed and ready for testing.

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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.

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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

[John in CR]

Knuckles,

Don't forget who asked first for metal gears back in July...That is once you have any to share.

John

[fechter]

F-N-A!

spill it!

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

You get at least a 9 for scoring metal gears. Walk-in no less.
Let Mr. Gear Dude ride the F'N bike around (like with 72volts) and then talk special order. How many gears can you get in trade for a motor? Hey if it's a special order, then they make'em with the right size bore for the bearings.

[johnrobholmes]

Alright, I have three sources that can get gears for me, and one machine shop that will call me back about obtaining gear stock. Another machine shop can cut the gears in brass, but it may be expensive since they wouldn't start with gear stock.


So we have a choice of stainless, delrin, Steel 9 SMn 28K, and brass construction. The Delrin will be very affordable, next is stainless, and the brass may be most expensive.


I am leaning to using the delrin first to see if it works. I bet it would hold up much better than the stock nylon and still be very quiet. My next choice is the stainless, since it is decently soft.


Expected price points would be $20 each delrin with bearing, and $35 each stainless with bearing-but this is low quantity pricing. Brass I haven't gotten a quote yet. I will run my bike on 72v and ruin the gears to see where the limit is once I get replacements.

[Miles]

I am leaning to using the delrin first to see if it works. I bet it would hold up much better than the stock nylon and still be very quiet.

It would wear better but there's not much difference between them strength wise - impact strength of Delrin is a bit better. I would go for metal, I think.

[Knuckles]

First test run of metal gear is success.

So it is now firmly established that the gear size is M1.25-28 w/ 8mm bore ...
The original nylon gear has a 10mm face.
My steel test gear has an 8mm face.

I replaced the existing washer with a thinner washer to make up the difference.
Just added a few drops of oil as lubricant.

Only a slight increase in noise level and a very solid feel.
Time will tell if the gear post wears out.

Of course a metal gear with bearing is the way to go.
(These test gears cost me $10 ea btw and can still be special ordered).

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[Knuckles]

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.

So far the gear is working fine. Sounds good and feels great. But just one day of local riding.
This is more a "proof of concept" endeavor. But I do like the one steel gear combined with the two
original nylon.

I can either buy more of these 8mm face gears or I can go back to the gear dudes and ask for a version at 10mm with bearing.
But knowing Dr. Holmes I am sure he is already on it. (Go John Go!)

Of course it would be nice if CHINA (A hem) would just do this so that the Western World could buy it.

[lawsonuw]

@johnrobholmes: I'm going to agree with Miles on this, and say skip delrin as it will perform about the same as the nylon gears. If you want to stay with plastic, Torlon or a graphite fiber filled Nylon/Delrin is my guess at the best bet. Of the metal choices brass will be most tolerant of running dry, though bronze would be better. Any of the steel options should work just fine though. My two cents says go with whatever metal gear is cheapest.

Marty

[johnrobholmes]

I have some 10mm face gearblanks with 4-6 week lead time available, and the rest would be custom machining (if we are just considering metal). $10 is cheaper than I have found for the blanks, but the ones I found were USA made. Add in machine time and bearing cost on top of blank cost.

[johnrobholmes]

Blam Ba Lam! Just got an email from a company that will make 10ft of spur stock for me (200ish gears), but only in steel. 8-9 week lead time, and totally worth it. Gonna go for this one! I will probably have to get another company to part and bore each one.

[voicecoils]

Blam Ba Lam! Just got an email from a company that will make 10ft of spur stock for me (200ish gears), but only in steel. 8-9 week lead time, and totally worth it. Gonna go for this one! I will probably have to get another company to part and bore each one.

Cool, only downside is I want to be blasting around NOW

Seriously though, the bearings are $0.50 each so that is just a small concern. To bore and press the bearings will certainly cost more, but hopefully less then the cost of the sliced up spur stock.

It's looking good