One Power Supply or Three?

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seal killer
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One Power Supply or Three?

Post by seal killer »

All--

Given a stepper motor scenario . . .

Does each axis (controller/stepper motor combination) require a separate power supply since a stepper motor consumes power when not turning? I am looking at the Gecko 203V and SOME motor from homeshopcnc, say, a 960 oz./in. device for the sake of argument/guesstimates. (I understand that each motor requires its own controller.)

Thanks.

--Bill
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jutz
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Post by jutz »

You don't necessarily need three power supplies but, if you use a single, it must be able to deliver full power to all three simultaneously unless you plan to make sure none of your programs ever try to drive all three at once. However, you have a lot more choices when shopping for small transformers than when shopping for large ones so it may be cheaper to use three small supplies.
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Vern2
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Post by Vern2 »

I started out figuring out the control stuff first. I'm working on Plasma CNC. The only problem with plasma is the center of table, has to be clear of everything. So I'll have dual motors and screws running down sides of table.

I wanted USB control board: This control board comes with free mcode software. The software can import your mcode. No dedicated PC.
http://www.stepperboard.com

Power supply from here:
http://www.applied-motion.com/?gclid=CO ... awod_RMb8w

Did get a separate 5v for control board.
Motor drivers from here:
http://www.geckodrive.com/[/url]

Stepper Motors from here:
http://www.probotix.com/stepper_motors

Vern
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Vern2
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Post by Vern2 »

Vern2 wrote:I started with figuring out the control stuff first. I'm working on Plasma CNC. The only problem with plasma is the center of table, has to be clear of everything. So I'll have dual motors and screws running down sides of table.

I wanted USB control board: This control board comes with free mcode software. The software can import your mcode. No dedicated PC.
http://www.stepperboard.com

Power supply from here:
http://www.applied-motion.com/?gclid=CO ... awod_RMb8w

Did get a separate 5v for control board.
Motor drivers from here:
http://www.geckodrive.com/[/url]

Stepper Motors from here:
http://www.probotix.com/stepper_motors

Vern
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Bill Shields
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power supplies

Post by Bill Shields »

I personally like 3 supplies - that way any problems with one will not affect the other(s).

but then I am old school..
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Vern2
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Post by Vern2 »

I don't think it's new or old school if any power supply goes down, everything stops. I don't think you build reliability with more power supplies. Thanks, you did make me think about it.
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seal killer
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Post by seal killer »

Vern--

Hey! Thanks for the links! I'm still reading them, but I wanted to say that I have some Peter Norberg stepper stuff I bought a few years ago (2?). Although it was low-end and inexpensive, everything worked well.

--Bill
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seal killer
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Post by seal killer »

Bill--

IF you were to use a single power supply, would it be necessary for it to be capable of providing enough current for all three steppers simultaneously?

Thanks!

--Bill
You are what you write.
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Vern2
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Post by Vern2 »

I'll be running 4 steppers. I'm running enough amps to run two motors full bore. The only time your running two motors is if your cutting a curve. 2 steps one way one another. Still one motor at a time.

A computer can only give one command at a time, period! But computer are fast. It only looks like multiple commands are given at a time. Computers can"t do it, anyway the ones you and I buy! Steppers take steps on, off, on, off, on, off. I'm not talking servos. The computers processor will go from one stepper to another giving it one command, them another, then go to another stepper.

There is no compilers widely used today that take advantage of todays dual, quad, and 8 processor computers. You might be running a 64 bit operating system. Sucker! There is no 64 bit compilers widely used today either. I don't even know any 64 bit software, except the operating system.

Vern
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Post by JimGlass »

IF you were to use a single power supply, would it be necessary for it to be capable of providing enough current for all three steppers simultaneously?
I'm fortunate to have a brother and a couple of good friends that are
Electrical engineers to help me with some of my projects.

They explain stepper power requirements like this. There is never a time
(They could think off) when more than one stepper motor would pull full power at the same time. Then the question comes up, "what about machining a 45 degree angle at full speed and full power?"
Answer: Because the two motors are working together to maintain speed and power they each use 50% of full power. The two motors combined will require the same power as one motor running alone at full power and speed.

When the steppers are powered up (lock up) but not running, are probably using about 1 amp or less depending on the motor size. No need to think when you power up a CNC machine the DC power supply will be under full load.

The steppers on my Bridgeport have current limits set at 5 or 6 amps per axis. I have the 63VDC-power supply fused at 10 amps and have yet to blow the fuse in four years. At the same time the steppers can snap off a 1/2" diameter endmill without loosing a step.

People get into trouble trying to run this hobby CNC stuff two fast. People see industrial grade CNC machines on TV or trade shows with rapid speeds that appear faster than lightning then go home and try running their hobby machine the same way. 8) Those industrial grade CNC controllers can be worth $30 grand and up. :shock: We can build a hobby grade CNC controller for under $1000 and I think they are great. But....don't try to run with big dogs if you have not paid your dues. :wink:

Jim
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JimGlass
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Post by JimGlass »

I wanted USB control board: This control board comes with free mcode software. The software can import your mcode. No dedicated PC.
http://www.stepperboard.com
Vern2: This sounds like something new. How does it work? Does it connect to a USB port on a computer?

Jim
Tool & Die Maker/Electrician, Retired 2007

So much to learn and so little time.

www.outbackmachineshop.com
John_Stevenson
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Post by John_Stevenson »

Rule of thumb is you need 60% of the total power of all 3 or 4 steppers.

John S.
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