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Author Topic: Can not increase motor velocity (65mm/min). Why?  (Read 2572 times)

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Can not increase motor velocity (65mm/min). Why?
« on: October 10, 2016, 06:29:34 AM »
I am using 10mm lead with 1.50mm pitch, 200-steps per revolution and so 1.50mm per revolution. I tested the velocity, it can not be increased more than 65mm/min. If I increase, the motor stops after a JERK, and the motor power supply turns off automatically (thanks God, if it would not then it may harm).

The motor tuning setting is attached to show how I set the parameters.

Note:
Using full-step mode
Kernal speed = 35000Hz
Using computer ATX power supply.
Driving stepper with 5V
Using L297 & L298 driver.
« Last Edit: October 10, 2016, 06:32:32 AM by musicworld1 »

Offline Tweakie.CNC

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Re: Can not increase motor velocity (65mm/min). Why?
« Reply #1 on: October 10, 2016, 07:18:23 AM »
I think all the information you need to know about stepper motors and their drivers is contained in the Gecko documentation here; http://www.geckodrive.com/support.html

(Basically, Torque is a function of motor Current and Speed is a function of motor Voltage. 5 volts is unlikely to produce a reasonable speed performance).

Try reducing your Acceleration in motor tuning and see if that enables more motor speed before the stall. Also reduce your Kernel speed to 25kHz (35kHz is not helping you).

Tweakie.
KEEP SAFE !
Re: Can not increase motor velocity (65mm/min). Why?
« Reply #2 on: October 10, 2016, 07:24:49 AM »
Sorry, I forget to post Motor Tuning setting image

Offline Davek0974

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Re: Can not increase motor velocity (65mm/min). Why?
« Reply #3 on: October 10, 2016, 08:27:00 AM »
As Tweakie has said 5v is not going to do you any help here, what motors? Nema17, Nema23 ??

Even little Nema17's would need 12 or 24v minimum to get them moving with any load.

Nema23's maybe 24, 26, 48v depending on drive capability - it looks like the L298 can take up to 46v so i would go to 36v max to allow some headroom for overvolatge during deceleration.

Also try using the 1/10 idea for acceleration to start on - speed 65 acceleration 6.5 and so on, acceleration is the bit that takes its toll on current/voltage.
« Last Edit: October 10, 2016, 08:29:13 AM by Davek0974 »
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Offline stirling

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Re: Can not increase motor velocity (65mm/min). Why?
« Reply #4 on: October 10, 2016, 10:46:15 AM »
it looks like the L298 can take up to 46v so i would go to 36v max to allow some headroom for overvolatge during deceleration.

....and the L297? ...and current limiting?

Offline Davek0974

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Re: Can not increase motor velocity (65mm/min). Why?
« Reply #5 on: October 10, 2016, 01:58:35 PM »
....and the L297? ...and current limiting?

Well i presumed if the OP was smart enough to be using discrete drivers and other i.c's he would know the limits no?

Looks like 2A on the motor and the logic uses 5v as normal.

Data...
http://www.st.com/content/ccc/resource/technical/document/application_note/0a/84/39/6c/ae/9a/42/0a/CD00003803.pdf/files/CD00003803.pdf/jcr:content/translations/en.CD00003803.pdf

The ATX supply has a 12V output too, using that would help but will need different limit resistors etc.
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Offline stirling

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Re: Can not increase motor velocity (65mm/min). Why?
« Reply #6 on: October 11, 2016, 04:03:31 AM »
You may be right - just raising a note of caution.

@musicworld1 - have you implemented current control on the L297?
Re: Can not increase motor velocity (65mm/min). Why?
« Reply #7 on: October 11, 2016, 11:39:04 AM »
I am using L298 L297 in a way as attached image.

Now I have completed the test with 12V from ATX power-supply. NOW the maximum velocity I found is 175mm/min, still very low. I think I should try with MORE THAN 12V increase velocity.

The results are:

It all depends on veriable-resistor (V.Resistor), however to use it.

Note: When I say Tzzzzzzzzzz sound in motor-winding, it is when motor is in STILL condition but its screw does not vibrate.

(V.Resistor)---value zero --------   motor not move with step pulse   

(V.Resistor) more increase ------- motor not move with step pulse but screw vibrates showing step pulse

(V.Resistor) more increase ------- motor moves with step pulse but a little Tzzzzzzzz sound in motor and L298 heat-sink does not heat up during work

(V.Resistor) more increase ------- motor moves with step pulse but MORE Tzzzzzzzz sound in motor and L298 heat-sink does not heat up during work

(V.Resistor) more increase ------- motor moves with step pulse but MORE MORE Tzzzzzzzz sound in motor and L298 heat-sink does not heat up during work

(V.Resistor) more increase ------- motor moves with step pulse but MORE MORE MORE Tzzzzzzzz sound in motor and L298 heat-sink does not heat up during work

(V.Resistor) more increase ------- motor moves with step pulse, NO Tzzzzzzzzzz sound but L298 heat-sink gets very much HOT in just 10 sec WITHOUT step pulse (it is dangerous point to stay)

« Last Edit: October 11, 2016, 11:52:05 AM by musicworld1 »
Re: Can not increase motor velocity (65mm/min). Why?
« Reply #8 on: October 11, 2016, 11:50:01 AM »
What mean by Tzzzzzzzzzz sound of motor in STILL position here?

Why L298 heat-sink heats up a lot dangerously after increase V.R to a specific higher value?

Offline Davek0974

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Re: Can not increase motor velocity (65mm/min). Why?
« Reply #9 on: October 11, 2016, 01:53:03 PM »
I think it looks like the Vref VR is used to set the motor current - you need to get a meter in there to see exactly what it is setting as you could easily over-drive the 298 which won't end happily ;)

Should it have a heat-sink? 2A is a fair bit of power to be sinking without one i think.

Steppers are always drawing power and can make noises, any chance of a video clip?
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives.
Plasma table, Mach3 V062, Step motors, C&CNC THC.