Stepper Choice

[lum]

Aloha

I'm about to buy a stepper kit from http://kelinginc.net but have some issues deciding on witch motors to get. The motors will be used for a fixed gantry design and be driven by a g540.

For the Z-axis I'm thinking one :KL23H284-35-4B but for the fixed x and y I'm undecided.

Trying to keep to NEMA 23 sized motors I'm looking for the type with the most torque once they go up in speed a bit. Naturally I thought bipolar parallel but the biggest at kelinginc.net are hybrids. I get the hunch that hybrids are not as good when it comes to torque at higher speeds as true(?) bipolars.

F.x. the KL23H2100-50-4B is 570 oz-in has four leads and I see no torque curve.

The KL23H286-20-8B is 425 oz-in but has eight leads and still no torque curve. Seems like this one is the strongest with eight leads?

So will the possibility to run the later in parallel result in higher torque once you go up in RPM?

[Dorsal]

Read this page, about 1/2 way down - it will give you a method of determining exactly what TYPE of motor you need. http://www.geckodrive.com/support.aspx?n=42801
Then read this one: http://www.geckodrive.com/support.aspx?q=10005 and at the bottom it explains how to appropriately SIZE your motors.

The torque curve for that motor is on the Keling site, at http://kelinginc.net/KL23H286-20-8BT.pdf

[Crevice Reamer]

Don't overthink it. Hybrids are best. You will get best speed at 50V or closest to it. Speed max determines how much torque the motor will have at high speed. (Or even how fast a speed it will run without stalling.)

The motor that will give you most torque and speed with the G540 is the 50V Keling 570 KL23H2100-50-4B. At 3.5A its torque will detune to 399oz. Second best is the 54V Keling 381 oz KL23H2100-35-4B. (Frankly, I would use this one and save the extra money, as you really won't miss 18 oz much.) The 65V K387 comes in third with max speed somewhat slower. Loss of RPM will wipe out the 9 oz it has over the 381. The 85V K425 will run much slower, so it will actually provide LESS torque at a lower speed than 381.

You only need a 7.3A 48V PSU to run 4 3.5A motors.

Torque speed graphs are driver/PSU dependent, so cannot really be used for comparison unless using exact same components. They are often rigged to make the motor look better than it will actually perform.

CR.

[lum]

So you think I should get 3x KL23H2100-35-4B with the g540 and a 7.3A 48V PSU?

[Crevice Reamer]

Yep! That's what I recommend:

Page 57

CR.

[lum]

Another quick one.

Are the couplings from Keling any good? I would likely use them with ball screws from linearmotionbearings2008.