Cool vid. If you can get your second bearing mounted below your motor it will have higher torsional stiffness in the shaft and smaller loads on the bearings. This is due to a larger moment arm from the pivot point (the top bearing) to where the second bearing is mounted. This will make it so that your bearings and shaft experience a smaller load when the weapon strikes something.
i was going to say the biggest risk of a direct drive would be the centre shaft, then got to the second half of the video. Interesting videos as always (from someone outside the hobby of combat robots)
This was the vídeo i needed, i think it’s the next step in combat robot. Well implemented hub motors like Daedalus simply don’t stop. Thanks for sharing this video ;)
The air gap between the stator and magnets seems larger in the cheap hobbyking motors I’ve used. A hit in electrical efficiency might be worth the extra clearance.
That's very neat! 'Elegant' in engineering terms. :-) The two-point mounting to prevent spindle wobble is ideal for home workshop manufacture, but your video got me thinking about other possibilities. I imagine there are plenty of industrial single-point bearings - such as what's used on the nose-wheel of some light aircraft - but the cost would be astronomical for a hobbyist. I've seen a few fancy carbon-fibre racing bicycles with one-sided 'mono blade' front wheel mountings. Very high load, but relatively low speed. And no doubt ludicrously expensive. A lot of lawnmowers use a single-point mount for the blade. That's a horizontal metal bar spinning at high speed, but it's only hitting grass and daisies. The bearings would be easy to source from junked mowers, but I don't suppose they'd last long smashing against hardox in a combat robot. I think the only common single-point bearing most people would encounter day to day would be the main bearing holding the drum in a washing machine. Just one back mount to support a metal drum full of wet laundry, spin-drying at 1,600 rpm. Hmm. Those bearings can certainly take a beating. [I think Clive Sinclair might have used something similar on his C5 three-wheeler.] The one in my old washer is 17 years old and still totally slop-free. Far too big for anything but a heavyweight bot, though. Maybe you could just use the whole machine as a walking bot. With an unbalanced load mine can really move across the floor...
None of those bearings you mentioned require tight tolerances. They can all have radial play to them without causing issues. This application doesn't have room for any side play, so those bearings would not work. Plus they are all way too big. Also most of the ones that you mentioned are going to be some sort of dual bearings in the housing, or a dual race bearing, or maybe just a single tapered roller bearing, so basically the same things he has talked about here. Having dual bearings is the best way, because you get a little more leverage on the shaft because the points of contact are further apart. You could use a single tapered roller bearing as he said, but then you are relying on mounting bolt tension to prevent radial play, and the tighter you go the higher your friction loss and bearing heating gets, plus any loosening of the mounting bolt, metal deforming etc, and you lose your stability and the motor eats itself up. So while you could get double race bearings for not much more money, you don't gain anything really.
Thanks for this really nice demo of the pros and cons of hub motors. Another con I might add, for say an RC car, is that the motor is un-sprung weight.
@@RobertCowanDIY I mean that if the motor is in the wheel itself, it will not benefit from the suspension providing it cushioning on rough terrain. It will bear the full force of every pothole that the wheel hits.
@@RobertCowanDIY yes, that lip keeps the outer races apart, and that is why there should be a spacer with the same thickness as that lip between the inner races :)
I'm working on a hub motor drum spinner design right now. When altering your motor can, do you just stick it in a lathe and use a cutoff tool to get it to just a ring? Do you think this would be possible with just a dremmel with a cut off tool and a bit of finishing?
A helpful video, as I've come to expect. I do wonder if that second piece to hold the upper bearing in place was really necessary (I know you doubted its need as well). Perhaps one or two tapped holes near the holding diameter of that bearing would allow you to ensure the bearing stays in place with the head of a screw or two. That would save the trouble of a second part. You also don't talk much about the mounting of the magnet ring - I assume that's basically a press fit with some epoxy to hold it in place. Cool video and I'll be considering your recommendations if/when I make a hub motor. Thanks as always for taking time to share your knowledge.
Hey Chris. Yeah, the top piece is just extra and isn't absolutely necessary. The bearing already sits in a pocket, so as long as the shaft is snug it's not going anywhere. But, I guess it kinda protects the bearing? Plus it looks nicer. For the magnet ring, you can just press it in there, it's not really going to slip. A bit of superglue or epoxy would hold it in there, but that's not absolutely necessary, it usually won't slide around much, there's not enough torque to do that.
@@RobertCowanDIY Good to know. I'm curious - what have you seen fail on hub motors? On Blue Screen I keyed the weapon disk directly to the motor and ultimately ended up deforming the motor bell itself with enough hard impacts. That wouldn't seem to be likely here. Is the idea that the hub motor structure is so strong that the "weak leak" is the magnet force between the two motor halves, and that essentially the magnetism serves as a "clutch" to prevent damage to any of the motor components? Seems like it would take incredible force to damage the 10mm shoulder bolt. Do you worry about anything failing on your hub motor and, if so, what?
@@chrismiksovsky5871 I don;t have a ton of hub motor experience, but I don't really expect anything to fail. I will probably be surprised, but I'm not sure what the weakest link is, beyond maybe the magnets shattering (even after being epoxied). The 10mm shaft probably won't bend, maybe the bearings will give out? It's a very heavy design, but should be robust. On Sgt. Cuddles, the magnet ring could slip a tiny bit, it wasn't really tight. So that served as a clutch and in theory it could spin during a huge hit. I never really tested that theory, but it was a pretty reliable weapon in general.
What are your thoughts on using a single roller bearing instead of 2 ball bearings? It would be substantially robust (heavy) but nearly indestructible.
I specifically cover this topic. Unless the inner and outer races can remain perfectly concentric and they have zero play, you will need two bearings. Roller bearings typically have quite a bit of play in them.
@@RobertCowanDIY oh sorry, I may have missed that dialog. Good to know. We use angled roller bearings for motorcycle steering and they're the biggest most robust bearings I've ever seen.
I assume 'brg' means bearing? You aren't wrong, but we're not talking about loads, it's more about centering the stator and the magnets. Two bearings are required for that.
I have my own CNC. They're not TOO difficult to make, but if you don't have a CNC, you can outsource them. Ask around the robot groups, or check out my combat robot resource guide, you can find machinists from various places. There are a few Chinese machine shops that can make these parts for pretty cheap. The good news is if you design them correctly, you can use them for awhile, they don't tend to fail.
I clicked for the title in researching my bot idea, with no idea you are a bot builder! thanks for sharing the info we want.
Ha! Be sure to check all my other videos, I have a lot of information. Welcome!
Cool vid. If you can get your second bearing mounted below your motor it will have higher torsional stiffness in the shaft and smaller loads on the bearings. This is due to a larger moment arm from the pivot point (the top bearing) to where the second bearing is mounted. This will make it so that your bearings and shaft experience a smaller load when the weapon strikes something.
i was going to say the biggest risk of a direct drive would be the centre shaft, then got to the second half of the video. Interesting videos as always (from someone outside the hobby of combat robots)
You r a true great inspiration sir!!!! One who guides and shares his knowledge...
Thankyou very much for all ✌️✌️✌️✌️
This was the vídeo i needed, i think it’s the next step in combat robot. Well implemented hub motors like Daedalus simply don’t stop. Thanks for sharing this video ;)
great video! Very informative, I will be using some of this information in my journey to create my own DIY electric skateboard
This is a great introduction to hub motors and exactly what I was looking for, thank you.
Tapered bearings would be the ultimate version of this :)
I like the way he explained it hope I can make my own hub out this learning
The air gap between the stator and magnets seems larger in the cheap hobbyking motors I’ve used. A hit in electrical efficiency might be worth the extra clearance.
Yeah, it's VERY tiny in these.
That's very neat! 'Elegant' in engineering terms. :-) The two-point mounting to prevent spindle wobble is ideal for home workshop manufacture, but your video got me thinking about other possibilities. I imagine there are plenty of industrial single-point bearings - such as what's used on the nose-wheel of some light aircraft - but the cost would be astronomical for a hobbyist.
I've seen a few fancy carbon-fibre racing bicycles with one-sided 'mono blade' front wheel mountings. Very high load, but relatively low speed. And no doubt ludicrously expensive.
A lot of lawnmowers use a single-point mount for the blade. That's a horizontal metal bar spinning at high speed, but it's only hitting grass and daisies. The bearings would be easy to source from junked mowers, but I don't suppose they'd last long smashing against hardox in a combat robot.
I think the only common single-point bearing most people would encounter day to day would be the main bearing holding the drum in a washing machine.
Just one back mount to support a metal drum full of wet laundry, spin-drying at 1,600 rpm. Hmm. Those bearings can certainly take a beating. [I think Clive Sinclair might have used something similar on his C5 three-wheeler.] The one in my old washer is 17 years old and still totally slop-free. Far too big for anything but a heavyweight bot, though.
Maybe you could just use the whole machine as a walking bot. With an unbalanced load mine can really move across the floor...
None of those bearings you mentioned require tight tolerances. They can all have radial play to them without causing issues.
This application doesn't have room for any side play, so those bearings would not work.
Plus they are all way too big.
Also most of the ones that you mentioned are going to be some sort of dual bearings in the housing, or a dual race bearing, or maybe just a single tapered roller bearing, so basically the same things he has talked about here.
Having dual bearings is the best way, because you get a little more leverage on the shaft because the points of contact are further apart.
You could use a single tapered roller bearing as he said, but then you are relying on mounting bolt tension to prevent radial play, and the tighter you go the higher your friction loss and bearing heating gets, plus any loosening of the mounting bolt, metal deforming etc, and you lose your stability and the motor eats itself up.
So while you could get double race bearings for not much more money, you don't gain anything really.
@@ke6gwf This. Nicely said.
Thanks for this really nice demo of the pros and cons of hub motors. Another con I might add, for say an RC car, is that the motor is un-sprung weight.
How do you mean?
@@RobertCowanDIY I mean that if the motor is in the wheel itself, it will not benefit from the suspension providing it cushioning on rough terrain. It will bear the full force of every pothole that the wheel hits.
Good idea with the tapped holes to get the magnet ring out.
Awesome. Great video. Thanks for sharing
it will bully all in the field.....can't wait for fight video good luck
The new version of the ML-4008-620KV, is the ML-4108-620KV, and it can be found on Aliexpress
Cool, good to know!
Bldc
Should there not be a spacer between the bearings on the inner race so that the bearings don't get squished?
there is a lip in the housing that keeps them apart.
@@RobertCowanDIY yes, that lip keeps the outer races apart, and that is why there should be a spacer with the same thickness as that lip between the inner races :)
@@MrAlekoy Good point, I should put some spacers between the races.
With 3D printer use flexible filament to put between ouster race and inside if cover. Provide some shock resistance?
I'm working on a hub motor drum spinner design right now. When altering your motor can, do you just stick it in a lathe and use a cutoff tool to get it to just a ring? Do you think this would be possible with just a dremmel with a cut off tool and a bit of finishing?
Better if channel for wires?
A helpful video, as I've come to expect. I do wonder if that second piece to hold the upper bearing in place was really necessary (I know you doubted its need as well). Perhaps one or two tapped holes near the holding diameter of that bearing would allow you to ensure the bearing stays in place with the head of a screw or two. That would save the trouble of a second part. You also don't talk much about the mounting of the magnet ring - I assume that's basically a press fit with some epoxy to hold it in place. Cool video and I'll be considering your recommendations if/when I make a hub motor. Thanks as always for taking time to share your knowledge.
Hey Chris. Yeah, the top piece is just extra and isn't absolutely necessary. The bearing already sits in a pocket, so as long as the shaft is snug it's not going anywhere. But, I guess it kinda protects the bearing? Plus it looks nicer. For the magnet ring, you can just press it in there, it's not really going to slip. A bit of superglue or epoxy would hold it in there, but that's not absolutely necessary, it usually won't slide around much, there's not enough torque to do that.
@@RobertCowanDIY Good to know. I'm curious - what have you seen fail on hub motors? On Blue Screen I keyed the weapon disk directly to the motor and ultimately ended up deforming the motor bell itself with enough hard impacts. That wouldn't seem to be likely here. Is the idea that the hub motor structure is so strong that the "weak leak" is the magnet force between the two motor halves, and that essentially the magnetism serves as a "clutch" to prevent damage to any of the motor components? Seems like it would take incredible force to damage the 10mm shoulder bolt. Do you worry about anything failing on your hub motor and, if so, what?
@@chrismiksovsky5871 I don;t have a ton of hub motor experience, but I don't really expect anything to fail. I will probably be surprised, but I'm not sure what the weakest link is, beyond maybe the magnets shattering (even after being epoxied). The 10mm shaft probably won't bend, maybe the bearings will give out? It's a very heavy design, but should be robust. On Sgt. Cuddles, the magnet ring could slip a tiny bit, it wasn't really tight. So that served as a clutch and in theory it could spin during a huge hit. I never really tested that theory, but it was a pretty reliable weapon in general.
Psychotic Break V Daedalus please :-)
One of them would have to board a plane for that sadly, but it would be an epic fight!
I'm literally watching this as I'm designing a hub motor weapon, we'll see how it goes.
So I have an outrunner motor, can I turn it into a hub motor?
Yep.
What are your thoughts on using a single roller bearing instead of 2 ball bearings? It would be substantially robust (heavy) but nearly indestructible.
I specifically cover this topic. Unless the inner and outer races can remain perfectly concentric and they have zero play, you will need two bearings. Roller bearings typically have quite a bit of play in them.
@@RobertCowanDIY oh sorry, I may have missed that dialog. Good to know. We use angled roller bearings for motorcycle steering and they're the biggest most robust bearings I've ever seen.
I love electric motors!
only 1 brg is needed to control thrust loads. with that mind ... a caged need brg + a single ball brg might provide additional shaft position control
I assume 'brg' means bearing? You aren't wrong, but we're not talking about loads, it's more about centering the stator and the magnets. Two bearings are required for that.
what ever
@@MIGuy lol very mature
Nice
Sergeant cuddles sounds like the name of a pet cat.
It was actually the name of a pet tarantula before it became a robot. So you're close.
@@RobertCowanDIY
Oh god noooooo thank you I'll just keep my distance thanks 😅😅😅
how do you machine the main metal part? do you have your own mill or is there a cheap way to get them custom made?
I have my own CNC. They're not TOO difficult to make, but if you don't have a CNC, you can outsource them. Ask around the robot groups, or check out my combat robot resource guide, you can find machinists from various places. There are a few Chinese machine shops that can make these parts for pretty cheap. The good news is if you design them correctly, you can use them for awhile, they don't tend to fail.
Who loves bearings?? 🙋
Jonathan Ransom oil lite bushings for larger bots are noice
this video was clickbait. all you talked about was rotor alignment. you did not introduce hub motors at all. what a waste of time.
Stop whining
4:30 dont refer to units by their letters, refer to them by their names when speaking. AND, you said RPMs, with an s. oy vey. you [expletive].