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first test but singing step motors any ideas?

Posted by Dave in Spain 
first test but singing step motors any ideas?
November 14, 2013 04:05PM
I have been working on my own stainless steel reprap its looking good nearly all together now but the motors dont want to do as they are told by the pronterface panel, if I press 0.1 they will move the small amount but if I press higher eg the 10 to try and calabrate it the motors will just sing at me for the duration of around 10 seconds and not move just seem to be fighting forward and reverce together and just locking, frustrating me any ideas please.

Thanks Dave
Re: first test but singing step motors any ideas?
November 15, 2013 04:23AM
I can think of a few issues that can provoke that sort of effect ( I've had it several times )

A) Something's jamming the axis, check for any obstructions and make sure it moves freely when drivers are off
cool smiley Linear shafts or leadscrews need lubrication
C) Current setting on the drivers is too low or too high
D) An incorrect frequency setting in the Firmware is resulting a wrong motor drive frequency
E) Feedrate is too high resulting a wrong motor drive frequency, try specifying a very low feedrate and see if it still does it
F) Wrong bootloader selected for the hardware used resulting a wrong motor drive frequency
G) Bad connection on the circuitboard somewhere on MS or Step pins

Hope that helps

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Re: first test but singing step motors any ideas?
November 17, 2013 12:14PM
This has happened to me several times also.

As Azrael mentioned, the feedrate is likely too high in the firmware settings. Also, try adjusting the max acceleration in the firmware. The steppers may be capable of a higher velocity, but they can't accelerate to that speed as quickly as the firmware thinks.
Re: first test but singing step motors any ideas?
November 18, 2013 12:44PM
FYI - the feedrate in the firmware is a maximum feedrate. It doesn't come into play unless you try to exceed it. If, as I am thinking, you are using the pronterface interface, the feed rate is right there on the screen near the movement control expressed in mm/min. Change that value to a lower value and see what happens.

Of all of the options in post 2 above, the 2 front runners in my mind are A and C.

Regarding A, you can temporarily detach a motor from its belt/screw so there is no mechanical load on it to see if it will turn when so instructed. If it moves, then you know you have some kind of mechanical binding.

Regarding C, the stepper drivers usually have some kind of trimmer potentiometer on them. Have you adjusted them? The build instructions say to turn them all the way down and then back up - I think it was a quarter of a turn. These really should be calibrated using a voltmeter or ammeter, but most people just do it by observation. If you turn the pot down too low, the motor will buzz and not move. If you turn them up too high, the motor will get very hot.
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