Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: Fred_evans on April 10, 2016, 08:17:12 AM

Title: is this stepper big enough?
Post by: Fred_evans on April 10, 2016, 08:17:12 AM

Hello Chaps --
I am not in the least accomplished in electronics and electrical stuff

Firstly -I have heard that steppers have there most torque when running very slowly?
Is this correct.
Therfore am i right to assume that a direct connected drive will be the most powerful way of
connecting the stepper to the leadscrew??

I am attaching a picture of a stepper motor ( no names or labels on it ) and a picture of
my benck milldrill. Can anyone tell me if the stepper shown will be OK for connecting to the
mill drill shown by a direct drive onto a 5mm pitch ball screw?
the drive will be powering the left to right feed and the front to back feed
Would it be better to use a toothed belt and gear the motor speed down ? small pulley on
motor bigger pulley on lead screw??
All comments will be appreciated
And many thanks
Fred Evans

Title: Re: is this stepper big enough?
Post by: Davek0974 on April 10, 2016, 09:47:04 AM

Can't see the motor ;)

Can you also post the dimensions of said motor?

;)

Title: Re: is this stepper big enough?
Post by: Fred_evans on April 10, 2016, 11:27:30 AM

sorr something went wrong?
the motor is  55mm X 55mm X 75 long ( excluding shaft which protrudes about 20 mm
I attached the motor picture to this mail

rergards

fred

Title: Re: is this stepper big enough?
Post by: Davek0974 on April 10, 2016, 11:46:47 AM

Looks like a Nema23 3Nm motor with those dimensions.

A direct drive to 5mm ball-screw would likely work.

Title: Re: is this stepper big enough?
Post by: RICH on April 10, 2016, 07:13:33 PM

Quote

Firstly -I have heard that steppers have there most torque when running very slowly?
Is this correct.

The torque is max at the slowest rpm of the stepper and degreases as the rpm increases. So yes, BUT,
you also want to have a decent axis resolution by micro stepping, adding gearing increases delivered torque.
Without any motor model / make you know nothing of that motor. You could mount it such that you turn the shaft and see max generated voltage.
Also can measure resistance, capacitance/ inductance of the windings. All a trade off of speed, torque, axis resolution.

Suggest you go to the Gecko Site as they have a lot of info on steppers to increase your understanding

RICH

BTW, Steppers are rather cheap these days and worth buying new and thus you know what to expect when installed.

Title: Re: is this stepper big enough?
Post by: Fred_evans on April 12, 2016, 06:37:18 AM

Thanks chaps-- Hmm yes i didnt think of the microstepping bit
I will look at the gecko page and try and glean as much as possible

How many steps per rev would be typical for a stepper like this??
 Then i can work out the resolution that i am likely to get

Just an aside-- Yes the steppers are very inexpensive now- but you know
the South African Rand has devalued so dramatically that everything has
become unaffordablly expensive. I remember when our currency was
R1.40 to a pound sterling. It is now usually over R20.00 to a pound.

Thanks for the advice anyway

fred

Title: Re: is this stepper big enough?
Post by: Davek0974 on April 12, 2016, 06:56:46 AM

Usually 200 steps per rev, but there are other flavours but my guess is 200.

Title: Re: is this stepper big enough?
Post by: RICH on April 12, 2016, 07:06:05 AM

fred,
You will find info in Members Doc's on how to calculate steps per unit. There is a spread sheet
which makes it easy. If you have a torque wrench you could test to see how much holding torque is available.


RICH

Title: Re: is this stepper big enough?
Post by: Fred_evans on April 12, 2016, 07:31:50 AM

thanks all-
regards
from
south africa