KB45XL-1600kv dissassembly

[cogwheel1]

I have a KB45XL that I need to take apart. It has a bent shaft and I want to put it in the lathe and try to straighten it. I haven't ever pulled one of these apart before--how is it done? Do I use a puller on the shaft secured to the mounting holes on the endcap or a slide hammer mounted to the endcap? I assume it 's a press fit?
















xl

[FE Wannabe]

Here is what is listed from the Tips and Info section on the homepage.
It is supposedly the same disassembly instructions for the KB motors as the Feigao motors.

http://www.offshoreelectrics.com/inf...ao-bearing.php

I have just ordered new bearings for my Feigao XL so I will be attempting this soon myself.

Brad

[m4a1usr]

I have a KB45XL that I need to take apart. It has a bent shaft and I want to put it in the lathe and try to straighten it. I haven't ever pulled one of these apart before--how is it done? Do I use a puller on the shaft secured to the mounting holes on the endcap or a slide hammer mounted to the endcap? I assume it 's a press fit?

xl

No,... the front bearing plate screws into the shell. It spins off counter clockwise looking at the motor from the shaft end. The rear plate is glued in. Unless you are using a jewelers lathe I doubt you will be able to straighten the rotor shaft. Especialy if you plan on spinning it at high RPM's. I made a custom clamping fixture to be used in a vise for removing the front bearing plate. A word of advice to you should you decide to proceed. The magnets on the rotor are large and very powerful. When you get the bearing plate off you will need to be extremely careful not to scratch off the varnish insulation used in the windings pressed into the shell. The rotor will want to attach itself to one side once its free from the bearings as you pull it out. If you remove the wire insulation you stand a high chance causing a dead short and blowing your speedo should the sintered magnets on the rotor fail due to vibration problems now that you have a bent output shaft on that motor.

Thats a long about way of saying, get another motor. You may end up ruining more then just a cheap chi motor. Speedos usually cost more then a motor.

John

[cogwheel1]

Thats probably good advice, but the motor has never been run, and the shaft is barely bent. I thought I might try to turn the shaft down to 5mm as was suggested in my other post, 'Which props for twin motors in 43" Cat, to take the bend out. I have two lathes, however, neither is a jewelers lathe, but both are very high quality machinists lathes. Do you think I can pull this off? How do you chuck up the rotor without scratching the varnish off of it? Do you just chuck up the short tail shaft? If so, then I don't think it is possible.

[blackcat26]

I currently have this motor in my SW36 and have totally taken the whole motor apart. My bearings felt rough, though brand new and felt some drag like the rotor was scrubbing the windings or something. I popped the back plate off and unscrewed the front bell for inspection. The compressed windings are as you would expect for a cheap Chinese motor, waaay out of center with motor's can. I turned a piece of plastic down on a lathe. (as to not mar or be influenced by magnetism) I used a dial indicator to check the concentricity of the windings to the can. One side was about .015 out and the other end was about .045 out. I suspected the rotor was dragging on the windings so I marked it with a sharpie and confirmed it's contact. I decided since this thing was new and I was bored to go ahead and address these issues. I first drilled some holes for ventilation on the end bells since I have heard that these motors run hot. ( and they do trust me) I decided to re-machine the end bells to center the rotor as best as possible considering how far out of center the glob of windings were. I bored the bells out and pressing in new aluminum bushings and then installed bearings back. The bearings are now out of center with the O.D. of the can but are more centered with the windings now. Motor runs fine other than it gets pretty hot. Anyway after all my experience, I would recommend going with the Feigao and totally ditching this motor even though it's new. It's twice the price of KB but well worth it. Hope this helps.

[sailr]

Replace it with a Feigao 580L!

[m4a1usr]

Replace it with a Feigao 580L!

Amen to that. Or one of the many larger outrunners available, I was among the first herd of experimenters who ventured into cheap chi motors and speedos back in 2005 when the battle cry was cheaper and faster then domestic products while providing decent performance. So I know how you feel about having a new motor and its questionable on what to do. But so much can go wrong, damage many things when your motor, the power plant is going to be less then perfect. Vibration can damage your drive line/ strut/ rudder/ motor mount/ hull structure and of course steals power so there is more heat in both your motor and speedo.

On the other hand what better way to learn then to proceed with your repair attempt and see the results. That is truely what fuels us hobbyists. Make things better, overcome obsticles, go to the next level. I know I wouldnt have listened to junk the repair idea advice. And you have the tools, hopefully a V block and dial indicators. Maybe PM Peter Zicha or one of the other talented machinist guys here for recommendations/ suggestions.

But trust me on one thing, the stock rotor in a Keda 45 motor is far from balanced when they come off the assembly line. I spent something like $115 to have 3 rotors balance/ trued. And in the end I went to NEU's.


John

[cogwheel1]

By the way, This motor I'm talking about is a freebee because the have sent me a replacement. That's why I'm willing to mess with it. Since I'm running twins it's not bad to have a spare. The reason I like the idea of turning down the shaft to 5mm is that the collets that I got from G freak racing are huge abd heavy. They are also for 1/4" flex shaft which I think is overkill for this twin installation, although I like the idea of ball bearings in the stingers for this much RPM, which the 1/4" stinger drives have. I also like the 108mm length + drive dog prop and nut, rather than the 88mm. I like the idea of drilling cooling holes in the end caps--I had intended too, but wonder if it really does much without any source of airflow. One thing I always do, is run seperate cooling sources for each motor and each ESC, and I run 5mm line. If that doesn't do it, what will?
Russ

[m4a1usr]

I like the idea of drilling cooling holes in the end caps--I had intended too, but wonder if it really does much without any source of airflow. One thing I always do, is run seperate cooling sources for each motor and each ESC, and I run 5mm line. If that doesn't do it, what will?
Russ

Water cooling the windings or exterior of a motor is of little value. Water cooling of the motor face plate is of even less value. The open air circulation thru a motor allows at least convection cooling. I dont think enough folks are aware of where heat is actually generated. The bulk of the energy converted to heat is genuinely seen in the windings of a motor. The problem is its approximate to the rotor. Not the shell. So water cooling is of little significance. There is no way with current designs of water cooling you can remove enough heat to be effective. Remember that as heat increases in a Inrunner design motor its becomes worse at the rotor over time. As the rotor gets hotter it becomes less efficient so heat increases.

It self feeds the heat issue. No motor mount cooling or shell cooling can keep up. Circulation of air thru the gaps at least provides some heat removal at the source where the bulk of the heat is being generated. Thats basic science. Not opinion.

John

[Rumdog]

I do not believe this. Not to be rude at all. Simply run your setup with no cooling and take temps. Then install a nice water jacket, run it and take temps. Since the can is in direct contact with the windings wouldn't heat and therefore cool flowing water transfer through the can?

[blackcat26]

Yes as a matter a fact it would since the copper wire is an excellent thermal conductor and aluminum is not bad either. As long as the water temperature is cooler than the heat generated by the motor I can't see how it wouldn't cool it.

[m4a1usr]

You guys are missing the point. The greatest amount of heat being accumulated or building is INSIDE the motor! Not on the exterior where the heat removal tool is located. You know. Distance? A non conductive path? The rotors magnetic influence its what creates electrical energy to be converted to heat. The mass of the rotor? This is where the heat builds and destroys a motor. Not the darn windings. Take some time and understand the operation of an electrical motor. Get the windings hot and little happens if the insulation stays in place other then IR increases. Get the rotor hot and the magnets become less magnetic so they efficiencey goes down so amps go up and the heat continues to increase. So as you run the motor and heat goes nowhere. It increases. Such a basic lesson in physics.

John

[Rumdog]

So then, water cooling a brushless motor in a r/c boat is completely pointless? Since it is a non-conductive path, how does the outside of the can get hot?

[m4a1usr]

So then, water cooling a brushless motor in a r/c boat is completely pointless? Since it is a non-conductive path, how does the outside of the can get hot?

Water cooling isnt pointless. Its ineffective. Air or the gap between the rotor and the armeture is the best insulator known. The space shuttle tiles are almost entirely made up of air, yet they protect the crew from temps exceeding 3000 degrees. My point is that the heat that destroys an electrical motor is not from the windings. Its that which accumulates in the mass of the rotor. So shell cooling does little to nothing in removing this heat. Open the ends of your motor and allow convection or blow some air over the inside of the windings and over the surface of the rotor and cooling does become effective. Thats heat removal. Not waiting for conductive heat to dissipate thru several layers of mass.

I use shell cooling in most of my builds. A water jacket around the exterior. Its just not the most effective when you look at the mechanics of heat transfer. I do not advocate no shell cooling. But when you look at its effectiveness its of little value and can convince one that all that can be done is being done. Thats not true. There are better ways to cool a motor. Most motors in industrial applications are air cooled. Theres a reason for that and its not due to additional complicating factors such as a recirculating pumps. Its far more basic. Effectiveness. Efficiency.

John

[m4a1usr]

Since it is a non-conductive path, how does the outside of the can get hot?

It is a conductive path but from heat off the windings, where the heat damage to a motor is far less important. Where heat removal is most important is at the rotor. Not the caseing. As the rotor demagnetizes (due to heat increase) efficiency drops and amperage thru the windings increases. This adds heat to both the armeture and the rotor. The problem is shell cooling only removes the heat from the windings. More then half of the the heat being generated is not being removed by a shell cooler. Nor by a motor mount cooler.

You guys believe what you want. I didnt make this stuff up. Its basic science. And if you look at motor failures in general in our applications your going to find they are heat related due to ineffective cooling.

John