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incresing speed on stepper motors
« on: January 23, 2011, 12:27:55 AM »
I understand speed of the motors are controlled by velocity and acceleration. How do I make my motors go faster without them stalling on me? I see other machines cut really fast and mine seems slow in comparison when I see machines in videos.

Offline Hood

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Re: incresing speed on stepper motors
« Reply #1 on: January 23, 2011, 03:23:27 AM »
Lots of ways and all will depend on what you have but bigger motors, higher voltage if your drives allow, less gearing between motor and screw, bigger pitch screws are a few of the ways. Servos however may be the only way to get real speed, depends on what machine you have whether it would be justified.

Hood

Offline Dan13

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Re: incresing speed on stepper motors
« Reply #2 on: January 23, 2011, 06:59:08 AM »
Hood,

Think you meant to say smaller motors ;)

Dan

Offline RICH

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Re: incresing speed on stepper motors
« Reply #3 on: January 23, 2011, 08:08:19 AM »
Have a look at the motor curve....if one is available for your  particular motor. It will provide a torque to motor pulse /rpm curve based on some voltage and also for different wiring of the stepper.
From that you pick where you will have the most power or where you will be on the curve. That tells what can be expected in terms of  torque to motor rpm. You need to relate that to your intended use of the machine. You have what you have and cannot compare to someone elses machine and can only do so much. Speed is useless if there is no reliability.

Now if you were starting from scatch, you define the intended use of the machine and design accordingly.
IE; - define the desired axis feedrate / IPM
     - define the desired resolution
     - define the cutting that will be done
     - find a motor which can provide for the above ( a stepper may not work and you need to go to a servo )
     - based on the above, check that the other parts of the system ie; computer, power supply and drive are correct for the application
All the above may not work so it becomes a compromise of them all.

Have a look at this for a flavor of the above:
http://www.machsupport.com/forum/index.php/topic,12484.msg80824.html#msg80824

There is nothing wrong with duplicating someone's machine that is very similar to yours but one needs to understand any differences between the machines and how it
may affect your outcome.

RICH





« Last Edit: January 23, 2011, 08:20:09 AM by RICH »

Offline ger21

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Re: incresing speed on stepper motors
« Reply #4 on: January 23, 2011, 08:21:15 AM »
Quote
How do I make my motors go faster without them stalling on me?

As Hood says, the only way to make the motors spin faster is to use a higher voltage.

But, to get the machine to move faster, the drive system needs to be designed so the motor spins SLOWER, where it will have more torque.

Can you tell us what pitch screws your using, as well as drives. power supply, motors, and maybe a pic of the machine?
Gerry

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Offline Hood

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Re: incresing speed on stepper motors
« Reply #5 on: January 23, 2011, 08:29:49 AM »
Hood,

Think you meant to say smaller motors ;)

Dan


Not at all Daniel, could be either just depends on the machine and the motor now. Smaller motors will rotate faster but they may need more gearing, larger motors will rotate slower but may not need any gearing.

The question asked is really meaningless without knowing the setup and type of machine.
Hood

Offline RICH

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Re: incresing speed on stepper motors
« Reply #6 on: January 23, 2011, 08:46:49 AM »

Offline RICH

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Re: incresing speed on stepper motors
« Reply #7 on: January 23, 2011, 08:56:13 AM »
Attached is info on the motor but no curve that i could find.
RICH

Offline ger21

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Re: incresing speed on stepper motors
« Reply #8 on: January 23, 2011, 09:44:56 AM »
Doesn't say what drives he's using, but the real killer is the 1/2-10 acme. Switching to 1/2-8 2 start or 1/2-10 5 start will give much greater speeds. I can get 190ipm with 1/2-8 2 start and 24V with a Xylotex, with slightly smaller motors, on a bigger machine.
Gerry

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JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html

Offline stirling

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Re: incresing speed on stepper motors
« Reply #9 on: January 23, 2011, 10:36:59 AM »
how are the motors wired?, what's the drive current set to?, what motor voltage are you using?

T curves for your motors attached.

Ian