What time does it take to a stepper to reach 600 rpm ?

[cnc2]

Hi everybody !

I'm planning to build a drum plotter and to implement the soft to control it, as implementing acceleration would make it harder on the soft side, i want to have an idea about the hardware limits (full speed all the time...no accel).

My main problem is on the print head... i need it to go 1.8 m/s the plotter is 600mm wide so the print head will have to make three passes of 600mm in one second (tell me if you think i'm crasy...i've some doubts on myself).

So, what time would it take to the stepper(200step/rev) to reach 600 rpm with no load and with the print head ?(making the print head to reach approx 6.5 kph, it's a light weight print head friction is small...ball carriage).

what would it take to the stepper to achive three passes in one second ?...if it is possible to achive without ramping the motor (no accel)


Waiting for your help & comments !

Thanks !

cnc2.

[H.O]

It depends a lot on the motor, the drive and at what voltage you run it. But honestly, my gut feeling says that 600rpm without acceleration is probably not going to happen...

I don't think you could expect to be a able to start it instantly above a couple of 100Hz at most. Hopefully someone else will give you some real-life data, or try/test it yourself.

/Henrik.

[cnc2]

It depends a lot on the motor, the drive and at what voltage you run it. But honestly, my gut feeling says that 600rpm without acceleration is probably not going to happen...

I don't think you could expect to be a able to start it instantly above a couple of 100Hz at most. Hopefully someone else will give you some real-life data, or try/test it yourself.

/Henrik.

Thanks for your reply Henrik, i was expecting such a reply since it was too good to be true, the motor is from an old printer it's approx 4.6Kg/cm of torque & has 17.5 ohm coils.

By the way congratulations for the Rencos you've solved the misterious problem, & thanks for the vid on youtube where you compare'em to the amt102, wonderful i couldn't ask for more !

Thanks !

cnc2.

[cnc2]

:UP:up

[jschmitt]

If you don't need resolution, how a belt drive like they use on printers, with a bigger timing gear so that you don't need rpm. just a thought

[bdahmet]

Have a look at this thread.
Best belt drive ever! (If I do say so myself)

and the clips on the website.... I think its better than what you need...

http://www.bell-everman.com/ServoBelt.wmv

[kreutz]

Take a look at this video:



During the tests the stepper motor is made to turn suddenly in reverse, while turning forward at high speed, several times. No stalls and no steps are lost.

[bdahmet]

Hello Kreutz,
impressive work you have. (Have read also your other posts...)
On the video you seem to have a quite big (in diameter) and heavy wheel on the stepper. So theres quite a bit of flywheel effect there. So the actual transversion would be much better I guess...

[kreutz]

Hello Kreutz,
impressive work you have. (Have read also your other posts...)
On the video you seem to have a quite big (in diameter) and heavy wheel on the stepper. So theres quite a bit of flywheel effect there. So the actual transversion would be much better I guess...

The device is actually a flywheel, it has 3.5" diameter, weights about 1 lb; It was the only load around. The motor is a Nema 23 6.8 mH, 425 oz-in.

Best regards,

Kreutz.

[cnc2]

Hi guys, Happy new year !

Thanks for your replys & tips, I've been offline for a while due to phone line problems & couldn't follow the thread, sorry !

jschmitt, if i consider the 200Hz advised by Henrik i'll need a timming pulley of ~19 cm dia. Too big... but if the motor can start at say 600Hz i'll need a pulley of ~6 cm dia. wich is more doable.

bdahmet, the bell-everman design you've shown is magic but it uses a servo motor & i don't know how it will perform with a stepper like mine.

Kreutz, you convinced people like me to go the servo way & now you design a stepper drive that's even better, after Henrik finished pulling out his hair to solve the encoder problem on his servo drive you show us this propaganda video...Shame on you ! just kidding! but watch out don't you make it closed loop, or i'll , closed loop i's the last argument of servo users!

Kreutz, what speed you think is reachable without accel on a small stepper (200 step/rev 4.6kg/cm unipolar) and not loosing steps ?
How did you drive the motor in your test ? (half step, full step...)

Did your test program include a kind of breaking cycle to lock the motor just before it reverses to (help) prevent it from loosing steps ?

Keep up the GREAT work !

Thanks !

cnc2.

[kreutz]

Hi guys, Happy new year !

Thanks for your replys & tips, I've been offline for a while due to phone line problems & couldn't follow the thread, sorry !

jschmitt, if i consider the 200Hz advised by Henrik i'll need a timming pulley of ~19 cm dia. Too big... but if the motor can start at say 600Hz i'll need a pulley of ~6 cm dia. wich is more doable.

bdahmet, the bell-everman design you've shown is magic but it uses a servo motor & i don't know how it will perform with a stepper like mine.

Kreutz, you convinced people like me to go the servo way & now you design a stepper drive that's even better, after Henrik finished pulling out his hair to solve the encoder problem on his servo drive you show us this propaganda video...Shame on you ! just kidding! but watch out don't you make it closed loop, or i'll , closed loop i's the last argument of servo users!

Kreutz, what speed you think is reachable without accel on a small stepper (200 step/rev 4.6kg/cm unipolar) and not loosing steps ?
How did you drive the motor in your test ? (half step, full step...)

Did your test program include a kind of breaking cycle to lock the motor just before it reverses to (help) prevent it from loosing steps ?

Keep up the GREAT work !

Thanks !

cnc2.

The motor on the tests was driven by Mach3, and there is a ramp for up and down speed, you can make the acceleration as fas as possible without upsetting your motor. It really depends on the motor characteristics (L/R constant), power supply voltage and available torque at that speed. A fast ramp (in fractions of a second) appear as a sudden change in speed. I think that the test was done at 1/10 micro-step, it should specify that at the beginning of the video.

Beware of Mach3 speed display, the real pulse rate could be different than the kernel speed chosen, which will introduce an error in speed. I measured the motor speed with a tachometer.

[kreutz]

..........

Kreutz, what speed you think is reachable without accel on a small stepper (200 step/rev 4.6kg/cm unipolar) and not loosing steps ?..............

cnc2.

4.6Kg-cm = 64 Oz-in you are not going to go too far with that motor once you have it loaded. The motor on my video is a 425 Oz-in.