Dynomotion

Group: DynoMotion Message: 10257 From: Wcarrothers Yahoo Date: 10/6/2014
Subject: Steppers
Ok. I'll admit it. I don't like steppers. Would never build a machine with them. How ever. I have gotten a
Couple vanguard 7000 series new Hermes units. And well they are a complete engraver and basically a tank when it comes to construction. And they have steppers. The first one I found had a simple logic gate chip ahead of the stepper control chips. So interfacing to its existing controller was easy. Took about a day wiring and it is up

The second unit has a more complex driver. Leaves me thinking I would be better off selling that control as a complete unit and fitting this with. Gulp a stepper controller. Anyway
My question is

The servos are Sanyo step sync motors. And the tag says 5.4v 1.5a. So stupid question. Does that mean the driver gets a 5v supply to run these and that is it?

Thanks.

B
Group: DynoMotion Message: 10263 From: Tom Kerekes Date: 10/7/2014
Subject: Re: Steppers
Hi Bill,

The voltage marked on most steppers is the DC voltage that will provide the normal maximum allowed coil current.  It is really another way of telling the coil resistance.  In your case the coil resistance is:

R = V / R = 5.4 / 1.5 =  3.6 ohms

If a supply of only 5.4V was used it would work but only for very slow operation because it would take a long time to get the current to flow because of the coil inductance and back emf voltage.  So usually a supply 10-15X higher is used so much higher voltage can be applied to ramp the current up more quickly, and then when the desired current is obtained the supply is "chopped" (switched on and off) in order to regulate the desired current.

Those low current, high resistance steppers are not likely to have much performance.  They will probably have decent holding torque but the torque will drop off quickly with any speed.

HTH
Regards
TK

Group: DynoMotion Message: 10264 From: Wcarrothers Yahoo Date: 10/7/2014
Subject: Re: Steppers
It is on an older engraving machine.  So does not over all have to push that hard.  And you are correct I have found on the other unit I already have running interfaced to their controller which had a simple logic input chip for step and direction signal it is good to about 100ipm   Was running at 150ipm at first but every so often it would flake out which costs material so slowed it down

Ended up finding the logic chip on this other control (different model) and ends up looking like the same ship but nxp ship rather then and ST part so didn't find it right off

Thanks for the info

B

On by Oct 7, 2014, at 4:22 PM, "Tom Kerekes tk@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

 

Hi Bill,

The voltage marked on most steppers is the DC voltage that will provide the normal maximum allowed coil current.  It is really another way of telling the coil resistance.  In your case the coil resistance is:

R = V / R = 5.4 / 1.5 =  3.6 ohms

If a supply of only 5.4V was used it would work but only for very slow operation because it would take a long time to get the current to flow because of the coil inductance and back emf voltage.  So usually a supply 10-15X higher is used so much higher voltage can be applied to ramp the current up more quickly, and then when the desired current is obtained the supply is "chopped" (switched on and off) in order to regulate the desired current.

Those low current, high resistance steppers are not likely to have much performance.  They will probably have decent holding torque but the torque will drop off quickly with any speed.

HTH
Regards
TK