district9prawn wrote: ↑
Mar 21 2019 1:15am
ElectricGod wrote: ↑
Mar 18 2019 8:47pm
In conversing with Revolt, they won't tell me anything other than what they post on their web site. I think they really dislike me scrutinizing their motors, but won't say anything. You'd think they would want to brag about their motors...at least the Pro and E...nothing. They get annoyed when I tell them what I have found in the motors. They think their motors are perfect or something as is.
I find their attitude just as concerning as the problems you've found in their motors.
In practice would the single key holding the shaft to the rotor be that big a problem.
Aluminum is a soft metal. It deforms relatively easily. Even 6061 like these motor parts are made from is just a harder aluminum alloy,
1. 100% of the motors torque will be transferred from the aluminum bell top, through the key/keys, to the shaft and then to a sprocket.
2. T8f is all steel chain and capable of holding about 2kw reliably.
3. The amount of energy transfer area one 4mm key like found in the RV-100E is similar to that of t8F chain.
4. By comparison the key and key way in the RV-100E ought to hold about 2kw as well...maybe a bit more.
5. To make aluminum not deform under loading, you give it a lot of surface area to spread out the loading.
You have several mechanical things playing against each other in any motor:
1. 50-80kv motor RPM's translate to wheel RPM's fairly easily with a single stage of gearing.
2. The closer to 1:1 gearing you get, the more stress on the mechanical linkages (keys, keyways, chain, sprockets, etc) there is.
3. Further from 1:1 reduces the loading stresses on the mechanical linkages.
4. Using a 120-200 KV motor significantly reduces the stresses on the shaft to bell keys and keyways, but it means gearing is now 2 stages to get motor RPM's to a usable wheel RPM.
5. Simple, single stage, 3-4:1 gear reduction is compact, reliable, has low frictional losses and easy to maintain.
6. This means that probably most people will be using inrunners and outrunners in the 50-80kv range where the mechanical linkages deal with the highest stress levels and therefore need to be robust.
Revolt says the RV-100E is a 6-11kw outrunner. From Revolt, it has enough metal at the shaft to bell to reliably hold about 2kw. The keyway in the aluminum bell top will be the weak spot and over time will deform and fail. If Revolt used 20mm of the 24mm of length they have available in the bell top, they could have increased that measly 2kw to more like 2500 watts. That extra 5mm would have been zero cost to add. What's more there's a single key and keyway in a place that at a dead minimum needs 2 of them. IMHO, dual 20mm long by 4mm keys would hold up fairly well to 6kw.
I have 2 HLD inrunners good for about 6kw. They use a single 25mm by 4mm key. The shaft, key and sprocket adapter are all hardened steel parts. One of my HLD's has about 5000 miles on it and the other maybe 300 miles. The one with 5000 miles, they keyways are now about 4.5mm wide. The hardened steel has deformed and now there is about .5mm of slop in the keyways. This translates to about 1mm of rotational play between the shaft and sprocket in hardened steel parts. Imagine what similar wattage on a smaller key into soft aluminum will be like in 5000 miles. I bet that keyway in the aluminum bell top will have stretched considerably more than .5mm! I bet it will fail completely well before 5000 miles. As a rock bottom minimum Revolt should have made them 20mm long and used 2 keys.
In none of the Revolt or Alien Power motors I have looked at is the bell to shaft union adequate. In the Alien Power motors 2 4mm set screws on flats on the 12mm shafts will work very short term. I bet on the C80100, you'll get 50-100 miles before this mechanical linkage fails. In the 12090, if it lasts 5 miles, I'd be surprised! In the Revolt motors I have, I bet you will get a few hundred miles before the shaft to bell unions start giving way. In motors from either source, this mechanical union is insufficient for long term reliable use.
I still stand by what I have said many times before. Revolt motors are better than Alien Power motors.
The AP C80100 is a fairly close comparison with the RV-100-regular. Realistic wattage numbers are similar. The C80100 has 2 M4 set screws holding the bell to the shaft. The RV-100-regular has 2 3mm x 8mm keys. Both are inadequate for long term and reliable transfer of power. However, the dual keys in the Revolt motor will easily handle 2X the power of those 2 tiny set screws in the C80100 and do so for far longer time frames. The RV-100 has larger magnets and better copper fill too.
The AP 12090 is similar to the RV-120-regular. They both deliver similar power to their shafts. The Revolt motor has 2 4mm x 8mm keys between the bell and shaft. The 12090 has 2 4mm set screws just like the much smaller C80100. The Revolt motor has a 15mm shaft and the 12090 has a 12mm shaft. Every aspect of this is a win for Revolt over what AP has in their motors. Never mind better copper fill and bigger magnets.
Bigger bearings, larger shafts and other things make the Revolt motors mechanically better than similar AP motors. Better copper fill and bigger magnets help make the Revolt motors better too. The big advantage AP motors have is .3mm lams in all their motors. Revolt in the Regular motors use .5mm lams, but in the current Pro and E series use .3mm lams. In every way that I can see and measure so far, it looks like Revolt is the better option. Perfect...no not at all, but compared to Alien Power, definitely better products.
So despite the languid and complete inability for Revolt to fix anything in any of their motor product lines, I'll continue to use them instead of the Chinese made AP motors. The Chinese manufacturer of AP motors doesn't take feedback either!