Re: Step motor current

--- In CAD_CAM_EDM_DRO@onelist.com, Ron Ginger <ginger@s...> wrote:

> I have my Grizley MiniMill working. I've taken some photos, will

post

> them to my web site when I get a chance.
>
> For motors I used some NEMA 23 motors about 4" long that I found
> surplus- the only speck I have is that they cost $15. They have no

label

> or makers name. They are the same size as the ones usually listed at
> 150-180 oz-in. They are 200 steps/rotation, and measure 2.4 ohm per
> coil- ignoring the center tap.
>
> I have a slo-syn 430-th driver module, selected because it was $10

at

> the MIT flea market. It is capable of 3.5A, so I started runing the
> motors with it at full current, but the motors seem to get very hot-
> after 20-30 min they were to hot to hold onto. I lowered the

current to

> about 3 amps and the motors sounded smoother, still run as fast as

my

> program will drive them, but still get very warm.
>
> So, how do I select a current for a motor when I dont have a spec?
>
> I also note that at certain speeds, while the motor is rampning up

to a

> long move, the belts will vibrate a lot. They seem to steady out

when it

> reaches steady speed. I have measured and I am not loosing steps,

so I

> dont think its a motor resonance problem. Should I worry about this
> vibratiopn?
>
> ron

Ron,The docs that comes with dancam and dancad have some information
on how to figure out the courrent neccessary.I've being running my
step motors that are rated at 5v and 1amp max per fase, at
0.300amps/fase and there isn't much difference on the torque.
the motors are double stak and are rated at 120 0z/in at the
maximum volts and amps.They are made by pacific scientific and cost
only $40.00 double shaft.
try to add a tensioner on the belts a see what happens.
step motors run hot specialy when stoped,but not to hot or it will
desmagnatize.If you can't hold it with bare hands than lower the
courrent.
Hope it helps.
Fogassa.