Motoman K6SB Retrofit

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18 Jul 2020 03:12 #175006 by thefabricator03
Does anyone have any advice on the type of grease I should use to replace the old?
I have done a bit of looking and cant find a definitive answer.

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18 Jul 2020 13:35 - 18 Jul 2020 13:38 #175033 by Roiki
Replied by Roiki on topic Motoman K6SB Retrofit


With the steppers I am going to be powering them with 80Vac with is nearly equivalent to 100VDC. They should be good for more than 1500 RPM at those voltages. But even so with the large gear reductions in the harmonic drives I do not think ultra high speeds will be necessary for my welding application so they should be fine I hope. We will see.


Steppers speed is not determined by the voltage but by the speed with which the driver can energize the coils. More voltage helps to overcome the inductance. Still I doubt you're going to get more than 1000rpm from nema 23 sized motors. Likely in the 800 range, also you have to Remember that at 1500 you'd have about 60% of the nominal torque. Higher speeds, even less. Driving the steppers faster will make the load of the robot go down, and at some point might reach a point where it can't overcome it's own mass. And because of the large reductions in the reducers the movements will we very slow at max torque speeds.

Cool to see you got those easycat modules. I've ordered one for tinkering myself.

Edit. I dont know specifically about cycloidals but I usually use just lithium grease for gearboxes. Has worked nicely so far.
Last edit: 18 Jul 2020 13:38 by Roiki.
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18 Jul 2020 13:52 #175035 by thefabricator03
The smaller motors are Nema 24's rated at 3N.m,


The larger motors are Nema 34's rated at 8N.m,


I understand that the torque decreases exponentially but given the starting torque is higher than the original motors torque, when it get to the working RPM it is still around the same torque if not just below.

The reason I brought these motors was not just because they are much cheaper than the DMM servos I was originally going to buy, but because I have used the non braked versions of the Nema 34's on my large industrial CNC plasma and I have not had a single issue performance wise with these motors. They FAR exceeded my expectations of what a stepper motor is capable of, and continue to everyday. I hope I have the same experience with these but only time will tell.
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18 Jul 2020 14:29 #175044 by tommylight
Replied by tommylight on topic Motoman K6SB Retrofit
Nema 24 looks good, the 34 is on the high inductance side, but still at 100V should be plenty fast. Should be a smidge above 2Mn at 1500 RPM.
The main deal breaker for fast stepper motors is inductance, the lower the inductance = the faster they can spin at a given voltage.
And i do have Nema 23 small motors that can do way over 3000RPM at decent torque with 72V and Lam Tehnologies drives.
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18 Jul 2020 17:57 #175058 by Roiki
Replied by Roiki on topic Motoman K6SB Retrofit

Nema 24 looks good, the 34 is on the high inductance side, but still at 100V should be plenty fast. Should be a smidge above 2Mn at 1500 RPM.
The main deal breaker for fast stepper motors is inductance, the lower the inductance = the faster they can spin at a given voltage.
And i do have Nema 23 small motors that can do way over 3000RPM at decent torque with 72V and Lam Tehnologies drives.


Can you tell me what drives those are? I could kinda maybe use those.

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18 Jul 2020 21:51 #175086 by rodw
Replied by rodw on topic Motoman K6SB Retrofit
I just checked. The New NEMA 34 motors I am using with the Lam DS1076a driver Tommy made me buy can do 2000 rpm which is rapids at 36 m/sec at 5 m/s^2 acceleration. Thats using 2 on the 30kg gantry with 5:1 belt reduction
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18 Jul 2020 22:23 #175087 by tommylight
Replied by tommylight on topic Motoman K6SB Retrofit

The New NEMA 34 motors I am using with the Lam DS1076a driver Tommy made me buy .......

Who? Me?
:evil:
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18 Jul 2020 23:40 - 18 Jul 2020 23:41 #175090 by thefabricator03
It works both ways Tom, I have a air drill sitting here I was coerced into buying by a certain Mr Rod.. Lol, I will set it up.. One day.. I think a RoboDrill would be a interesting project.
Last edit: 18 Jul 2020 23:41 by thefabricator03.
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24 Jul 2020 02:44 #175593 by thefabricator03
Got my toroidal transformer today,

Brought it from Tortech, I was going to get a custom wound unit that would output 80Vac but they found a old unit in their warehouse that will output 73Vac and they gave me a large discount on it.

1200VA - 73Vac output,

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