my Stepper just Buuzzz's

[BentRods]

Hi All
I've lurked around these forums with interest in CNC for some time, recently I finally got around to building one of the Driver's for a small XY Table that I got... so I guess I'm fresh meat here :-)

What I've got is ...
Mach2 V6.11N release
2x Steppers are from JDK Dynasyn 2SH-04A6S (Also looking for the Data Sheet if anyone has one or even a link)

The Driver I built is from PMinMO
This is the Schematic...
http://www.pminmo.com/l297-8/L297_8HVschematic.pdf
as well as the pdf's for the Copper and Board to make the boards.

my problem is this,
1- The stepper seems to BUUUZZZ a lot, I mean its making all the sounds like its moving all over the place but really its not moving very far at all just a couple of mm's back and forth at best. I have for almost 2 Days been messing with the Tune of the motor in Mach2 and tried all the settings from one extreme to the other ... its still the same !

Current is limited to approx 0.5A I've increased up and down no changes here either.
I also have an O-Scope if anyone cares to offer suggestion to trouble shoot this further I have already probed the IO's of the 74HC14.

Appreciate any Idea's

Regards
BentRods

[Clyde Crashkop]

If it just jiggles back and forth you may have the motor coil wiring step sequence wrong.
If it just sits there vibrating, you may be sending signals faster than the motor can start or turn.
Try sending steps one at a time to see if the sequence is right.

[pminmo]

I wasn't able to find any info on your motors. How many wires are they? What does the name plate say in reference to coil values? Do the buzz when not stepping?

[BentRods]

In between Blackouts here gggrrhh
Clyde
excuse my ignorance but how do I change the step sequence ?
for a Bipolar motor does it matter what way each of the 2 wires for each phase's are wired ? I've tried swapping them round on one of the phase's with no change that I could see.

It will move but only when there is a a long distance to travel thats not requiring a lot of acceleration or velocity, I'm also certain its not moving the correct distance but that can be addressed later I think, I've tried changing the Steps per Unit from 2000 to 3000 and lower to see if there was any noticeable change ... only to make it worse or no real change.

I did try increasing the Kernal speed to 35kHz and that made it worse so it was back to 25kHz is there a way to slow it down further ?

Using the "Step" option using the Jog appears to step ok at the smaller settings however at .100 and 1" its not moving more like twitching as I use the keyboard arrows.

Phil
I too have been looking nothing yet tho,
there are 4 wires,
on the name plate :
4.3 V/ Phase
0.85/0.27 A/Phase
When you say Buzz, if I pause the program there is no Buzzing as such, its almost as if it cant keep up with the Step when its running, you hear the tone of the stepper Wow it sounds impressive ! only to occasionally start moving back and forth. If I insert a screwdriver into the slot on the shaft it feels like its trying to run in both directions, looking at the O-Scope the Step and Dir are steady so I dont feel its the Program/ PC, I've used a Signal Generator to step this Driver but that shows similar results.

2AM, reckon it's time for sleep

Bentrods

[pminmo]

OK, couple of things. It kind of sounds like a setup issue.
1. Did you setup you acceleration and velocity settings appropriately? If your way to fast, the motor will twitch rather than step. Try starting at a low velocity and acceleration.
2. Did you set the pulse width to 5us or greater?
3. When you say pause, do you mean pause a G-code sequence? or get out of mach, or.....?
4. With the motors enabled, bot nut stepping are they locked up? (difficult to turn by hand, when not enabled they should rotate by hand fairly easily.)

[BentRods]

1, I have tried both Accel & Velocity adjustments at both ends of the Range, there results are better with a low Accel and velocity.

2, I did Try the PW at 5uS, but not greater than this I will give it a go.

3, I mean Pause the G-Code Sequence.

4, With the motor enabled and not stepping its locked up and its difficult to turn by hand, when not enabled they do rotate by hand fairly easily.

[BentRods]

Could someone explain to me about the 2 ratings stamped on the name plate of the stepper,
its marked as the following..

[0.65/0.27] A/Phase

Thanks

[pminmo]

I can't say that I know what the two numbers are. Are they small motors, like could be used in a computer disk drive? I wonder if they are .27A motors and you are overdriving, if you set your current limit to .27A do they respond differently? Do you have any mechanical load on the motors? what are your specific settings in mach for velocity, acceleration, units....?

[BentRods]

The OD of the motor is 55mm and the 4 mounting holes are spaced at 48mm, the Body length is 46mm.
This Table was salvaged from an old Wire Cutting Machine.
I just set the Amps to .27 ... no change's.

The only mechanical load is the Table itself, its free enough to turn by Hand without a lot of effort however I will check it out further for tight spots etc, I did have just a Stepper motor hooked up initially and it was the same so I don't feel its the XY Table.

Current Settings are in Inch's have also tried mm
Accel 23 units/sec^2
Vel 2.3 Units/sec
Steps/Unit 2000
Min Pulse Width 5 uS
Direction Per Change 5 uS

Thanks

[BentRods]

I'm a happy camper now
After several hours probing with the Scope I found the problem, there was some un-etched copper thats close to the track that was effectively joining pins 1&2 of the L298 ... hehe now I know why its was getting kinda warm to start with
anyway it all works sweet now
Thanks for all your help