I will buy one for $60 plus shipping. These are aluminum, yes?
Converting a hubmotor to a middrivemotor
- Thread starter crossbreak
- Start date
crossbreak
1 MW
That's great Spinningmagnets!
Still i'd like it cheaper before I order. But indeed, I'd like to order this week. If there are only us that are interested at that price, I'll order four and take the rest as spares.
As the price of the higly intergrated V3 Adapter would be quite high, I try to lower cost by separating it into more and simpler parts, that can be machined much faster. This way it's also higher value, since it can be used in other drives that differ from mine. The final distances and sprocket interfaces can be simply swapped using a different assembly. Using a common interface, there can be a construction kit for sprocket adapters for different freewheels, sprockets and shafts.
The interface I chose is four M4 screws, 10mm offset from the center. What do you think?
The shaft interface will fit MAC, BMC and all Bafang Motors as far as I know.
Still i'd like it cheaper before I order. But indeed, I'd like to order this week. If there are only us that are interested at that price, I'll order four and take the rest as spares.
As the price of the higly intergrated V3 Adapter would be quite high, I try to lower cost by separating it into more and simpler parts, that can be machined much faster. This way it's also higher value, since it can be used in other drives that differ from mine. The final distances and sprocket interfaces can be simply swapped using a different assembly. Using a common interface, there can be a construction kit for sprocket adapters for different freewheels, sprockets and shafts.
The interface I chose is four M4 screws, 10mm offset from the center. What do you think?
The shaft interface will fit MAC, BMC and all Bafang Motors as far as I know.
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speedmd
10 MW
M5 screws would be much better IMO. Larger hex / torqx key opening, much stronger and lots more styles available.
crossbreak
1 MW
M5 does not fit well, walls/ material gets too week/thin then.
I had 3 M4 screws in my Gen2 adapter. We should go for four M4 screws to make it bullet proof. There can be corrosion etc that would weaken the interface.
Using my torque wrench, I need about 65-80 Nm to break one screw. If we devide that by two (safety factor) and use 4 of them, we should be able to pass at least 120Nm through that interface after the screw got rusty. Which is unlikely to happen if we use stainless. I Guess even the MAC could not break them. Also, the main torque will not be passed through the screws, but through the clamping forces between the sprocket adapter components
I had 3 M4 screws in my Gen2 adapter. We should go for four M4 screws to make it bullet proof. There can be corrosion etc that would weaken the interface.
Using my torque wrench, I need about 65-80 Nm to break one screw. If we devide that by two (safety factor) and use 4 of them, we should be able to pass at least 120Nm through that interface after the screw got rusty. Which is unlikely to happen if we use stainless. I Guess even the MAC could not break them. Also, the main torque will not be passed through the screws, but through the clamping forces between the sprocket adapter components
crossbreak
1 MW
I like the multi-piece design best (but I will take whatever you order). The major assemblies can be the easily-machined aluminum, and the section under the 3-tab IGH sprocket can be water-jetted STEEL for maximum strength.
Would it be strong enough with three M5 bolts, rotated 30 degrees away from the three IGH tabs, in-between them?
Would it be strong enough with three M5 bolts, rotated 30 degrees away from the three IGH tabs, in-between them?
crossbreak
1 MW
3 M5 can not produce the same consistent contact pressure as 4 M4 screws :?
I'd even take stainless
My first one made of St37 did still fail with my SWXB at 45amps and 12s lipo 
The screw interface was fine, but the pockets for the Nexus sprocket failed almost. The nexus IGH sprockets are made of very durable steel
Sad that there at no 8mm head dia M5 screws :x
I'd even take stainless
My first one made of St37 did still fail with my SWXB at 45amps and 12s lipo The screw interface was fine, but the pockets for the Nexus sprocket failed almost. The nexus IGH sprockets are made of very durable steelSad that there at no 8mm head dia M5 screws :x
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speedmd
10 MW
I just measured a bunch. They range from just under 8 to just under 8.5mm for the 4mm socket / hex key head industrial style. The 10.9 low profile head ones are at 8.43-8.45 mm and common in your part of the world. Tons of small head headed ones used in handle bar stems but you will need to search a bit. Regardless, I would try to squeeze them in so your not stuck using a 3mm hex key which are not at all gorilla proof.
crossbreak
1 MW
Did you measure M5? 8.5mm can be the holes for the head, so 8.2mm head would still works I guess 
Measure some myself... 8.5mm holes would be very close but worth a try.
Measure some myself... 8.5mm holes would be very close but worth a try.
Since the section under the large sprocket is separate than the 1.38 X 24 threaded section, is it possible to have Shimano splines? They could be water-jetted, and this is a perfect application to let the machine do the difficult-to-cut parts.
crossbreak
1 MW
OK just testet 8.5mm heads... would look like this :x
I dont wanna use another proprietary system... still the splines are something worth to talk about: There are almost no non-hyperglide sprockets available. Hyperglide sprockets cant be used as output sprockets. That's why I went for the IGH Nexus 1/2 x 3/32", they are compatible with many 9 speed chains.
I dont wanna use another proprietary system... still the splines are something worth to talk about: There are almost no non-hyperglide sprockets available. Hyperglide sprockets cant be used as output sprockets. That's why I went for the IGH Nexus 1/2 x 3/32", they are compatible with many 9 speed chains.
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crossbreak
1 MW
Is that one shimano standard?
speedmd
10 MW
Yes, I measured a bunch of different M5 screws. Some have a head diameter less than 8mm. They are plated /unmarked so I can not tell the hardness, but assume them to be 8.8. A smaller diameter nut spacer washer would give you the head clearance. When I get to my bike parts later today I will measure some of the stock heads from a few stems which if I remember correctly are on the smaller side.
crossbreak
1 MW
We could of course use a bolt head likes this one, but it wont get shorter :?
@speedmd: I have to now a source for them :? I searched the net but didn't find any yet. 8mm is still a bit too large... I'll design a bolt head version with 12mm distance. I'll call it V5
How about 6 M4 screws? Would be best IMO... M5 is just impossible with that same all-over length... of course it is when using the large 16T freewheels, but that restricts the overdrive ratio possibilities way too much! I would never use a 16T ... makes no sense for me, since there are 14T available.
@speedmd: I have to now a source for them :? I searched the net but didn't find any yet. 8mm is still a bit too large... I'll design a bolt head version with 12mm distance. I'll call it V5
How about 6 M4 screws? Would be best IMO... M5 is just impossible with that same all-over length... of course it is when using the large 16T freewheels, but that restricts the overdrive ratio possibilities way too much! I would never use a 16T ... makes no sense for me, since there are 14T available.
six M4 screws sounds good to me. Are Shimano splines impossible? This spider has the smallest chainring of 28T, and the track-cogs largest is 22T.
And this Shimano spline adapter for 74-BCD chainrings can hold 24T to 32T chainrings
And this Shimano spline adapter for 74-BCD chainrings can hold 24T to 32T chainrings
speedmd
10 MW
If the 4 fits, you need to go with it. I use both the m4 and the m5 screws almost daily, and I rarely if ever round out a M5. The M4 rounds out all the time with the hex key or the key gets stripped. Torx head is much better, but the heads grow on them also to the size of the M5 heads.
crossbreak
1 MW
Yeah, that interface is possible. I'll try to make both IGH and Shimano spline for a good price. I'll use 6 M4 torx stainless then As said, I use 3 M4 screws now and it lasted for over 1000km without any problem, so 6 should really be fine.
The adapter is then also compatible for both left-hand hand right-hand drives. I'll redesign it so that it fit's both an gets even more simple. I'll post that new version... later Thx for your help!
As said, I use 3 M4 screws now and it lasted for over 1000km without any problem, so 6 should really be fine.The adapter is then also compatible for both left-hand hand right-hand drives. I'll redesign it so that it fit's both an gets even more simple. I'll post that new version... later
Thx for your help!
waynebergman
100 kW
Crossbreak, I see how the adapter fits nice onto the 10mm flats of a stock axle but what about if a person is making a new axle for a mac conversion that is solid not hollow. On my axle on my first conversion I ended up going with an adapter that used key slots and a 5/8" axle end to fit as the adapter was not originally intended for the 10mm flats on an electric motor axle. For my next conversion that may be early fall do you think I would be best to make the 10mm flats on the solid 17mm axle for your adapter to fit or would there be any options on the mounting of your design to fit a 17mm or 5/8" round shaft with key ways?
Thanks Wayne
Thanks Wayne
crossbreak
1 MW
sorry wayne, you'd have to drill out the 10mm flats hole and make a keyway. Can't make an adapter that fits anything
The Bafangs have their hollow end on the left when converted (motor is turned around due conversion). If you use the adapter on a Bafang, you can have a left side only drive and so you can just cut the left side hollow shaft
Sadly the MAC has the cable exit on the right, so it makes sense to make a new shaft. As I see, a MAC conversion is harder than I thought? Why the hell do you all want the MAC? The QBPM isnt smaller, it costs half and it must be easier to convert? Ok I can talk much, didn't get myself a QBPM in the meantime... but I will order... soon
The Bafangs have their hollow end on the left when converted (motor is turned around due conversion). If you use the adapter on a Bafang, you can have a left side only drive and so you can just cut the left side hollow shaft
Sadly the MAC has the cable exit on the right, so it makes sense to make a new shaft. As I see, a MAC conversion is harder than I thought? Why the hell do you all want the MAC? The QBPM isnt smaller, it costs half and it must be easier to convert? Ok I can talk much, didn't get myself a QBPM in the meantime... but I will order... soon
crossbreak
1 MW
waynebergman
100 kW
HI Crossbreak..............The main reason I converted the mac was I already had the mac sitting in my spare parts area as last year I got the phase wires too hot, also sheared the key stock and to further damage this poor motor I dug into the phase and hall sensor wires right at the axle opening with my gear puller. It was a murderous attempt at best to fix this motor on a road trip. Later when I saw your "Converting a hubmotor to a middrivemoter" thread here I thought to myself my broken mac could not be more perfect to test out this conversion. And now that I am happy with how it turned out and familiar with this motor I will most likely just stick with the same motor again for the next conversion. So there you have it why I went with the mac. I look at it as just dumb luck.
speedmd
10 MW
Good one. I was going to ask about that, but ruled it out as you would need to remove adapter to get at screws. As log as the fit on shaft is not too tight, it should be workable.
cheers
cheers
I want both!
crossbreak
1 MW
Just saw these 12T freewheels: They would also be an option. Shaft dia is 15.9mm or 5/8". But: The smaller the sprocket, the smaller the chainwheel. So, to higher the chain force, so the higher the axle load. With the Pedal freewheel 10mm further away from the motor, the shaft loads raise anyway, i wonder if this would be a good idea :?
Tomorrow I'll post both the versions for right hand drive and shimano splined sprockets. So with this construction set at least 4 different versions are possible. Two additional versions can be with BSA threads instead of the 30mm x 1mm threads I use ATM for the 13T ,14T and 15T freewheel sprockets
Tomorrow I'll post both the versions for right hand drive and shimano splined sprockets. So with this construction set at least 4 different versions are possible. Two additional versions can be with BSA threads instead of the 30mm x 1mm threads I use ATM for the 13T ,14T and 15T freewheel sprockets
crossbreak
1 MW
speedmd said:
My beta version 2 adapter already looked like that. I had a hard time to disassemble it after the first test. I use thin 2mm sheets when I tried that. Now we've got 16mm of alloy holding the flattened shaft. I have no doubt that is will be quite simple ti remove the adapter even after years. I used a puller which destroyed it :? I should have turned it backwards first... but the 2mm thin sheet really ate into the shaft....I'll lhave a look if I still got pictures from that try.....but that is why I talk with you and run a small production run of only four. The first who wants one will also be a beta tester, since I've still got one to sell
I'm waiting keen to ask what the redesigned version will cost....but I doubt it will be much cheaper :?
EDIT: I dont have pics anymore... but this was one of said sheets:
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