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Author Topic: Step losses in specific displacement  (Read 11041 times)

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Offline jimpinder

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Re: Step losses in specific displacement
« Reply #10 on: August 02, 2007, 04:30:16 AM »
I don't know a lot about power supplies, but the reason I use batteries is that the voltage stays constant, both when the motors are on ( and if all three are on together they could pull 7.5 amps) but also when they are off, the voltage does not rise above24 volts ( as I have found with a lot of transformer based power supplies, unless properly regulated).

My stepper motor boards  by Stepmaster says specifically that supply voltage should not rise above 30 volts (against a working voltage of 24)
Not me driving the engine - I'm better looking.
Re: Step losses in specific displacement
« Reply #11 on: August 02, 2007, 12:10:32 PM »
http://www.kelinginc.net/SwitchingPowerSupply.html

That is where I get my Power from ;)
http://www.kelinginc.net/SwitchingPowerSupply.html

The prices are actually very good. Unfortunately 120 Vac imput voltage is not suitable for French network.
I checked different solutions and I will finally do my own supply. It will cost about 60 Euros.
The output voltage will be rated about 25 Vdc while the stepper motor board can accept up to 35 Vdc so if the voltage is slightly higher when the motors are not running, it should remain within the driver board limits.

Thanks everybody for your help
Jean-Louis
Jean-Louis
Re: Step losses in specific displacement
« Reply #12 on: August 04, 2007, 10:39:41 AM »
I think they will also take in 220V (The last one that I worked one would).

Thanks
Brian
Fixing problems one post at a time ;)

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Re: Step losses in specific displacement
« Reply #13 on: August 05, 2007, 05:50:20 AM »
I've ordered the components to make a new power supply but I'll keep think link and contact them if necessarry
I'll confirm you if the problem has been definitely solved by changing the power supply

Thanks
Jean-Louis
Jean-Louis
Re: Step losses in specific displacement
« Reply #14 on: August 07, 2007, 07:55:07 PM »
Hi everybody,

I made new test today with my new power supply and despite a voltage drop that is now limited to 1 V maximum, the problem still occurred.
The "sound" of the machine on this particular segment (about 45° angle, positive X move and positive Y move) was really like a vibration so I slightly modified the fixing of the Y motor (I actually added one fixing point) and since I made this modification, I ran about 10 or 15 times the same program without any problem (I previously had it about once every 3 attempts). The sound is now different and I think that it is definitely linked with a resonance frequency, and this frequency has probably been changed by modifying the motor assembly. I have to run several other programs, hoping the resonance frequency has been moved out of the range I meet on my machine.

Jean-Louis
Jean-Louis

Offline jimpinder

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Re: Step losses in specific displacement
« Reply #15 on: August 08, 2007, 11:57:33 AM »
I still think this might be a power supply problem.

If you are running say G0 X10 Y10 from a position of 0,0 then as you say this is 45 degrees. Yours motors will be taking the maximum current exactly simultaneously. THEY ARE INSTANTANEOUS MACHINES AND REQUIRE MAXIMUM CURRENT IMMEDIATELY FOR A SHORT PULSE THEN STOP, then the start again, and stop etc etc.

I assume they are both set up for the same number of steps per rev or per inch, or millimeter, whatever, so the will perform simultaneously, and (of course) since they are controlled via a parrallel port it will be simultaneous. Even if you can only detect a 1 volt drop on a multimeter, your actual voltage drop will be greater.

Try your power supply running a large motor or something,  and try stalling the spindle and see if the voltage drops when you get to say 10 amps. It must a a big **** power supply to give 7.5 to 10 amps without loosing voltage.

Jim
Not me driving the engine - I'm better looking.
Re: Step losses in specific displacement
« Reply #16 on: August 08, 2007, 12:35:12 PM »
Hi Jim,

You're probably right when you say that the voltage may drop more than what I see on the voltmeter (even though I used an analog voltmeter that is better than a digital one for such a measurement), but I clearly get a more stable voltage since I made this new power supply (the previous one dropped down to 15 V when running the same program).
However everytime I had these step losses, it occured after having reached the rated G0 speed. It means that the motors were not accelerating anymore (you actually made me realise that :)), and that's why I finally don't think that it was due to a power supply problem, even if I actually really had one.

Jean-Louis
Jean-Louis
Re: Step losses in specific displacement
« Reply #17 on: August 08, 2007, 09:15:37 PM »
Can we see a pic of the axis that is giving you trouble ?
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vmax549

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Re: Step losses in specific displacement
« Reply #18 on: August 14, 2007, 09:02:23 PM »
DRstein, have you tried to swap the yand x axis after the drives. You will need to rotate the workpiece 90 deg but this should tell you if it is a mechanical issue or a drive/computer related issue.  If the error still ocurs on the Y axis then it is mechanical related, if it moves to the x then swap the drives themselves and retest. At least you will eliminated things  one at a time as you test. (;-) TP
Re: Step losses in specific displacement
« Reply #19 on: August 15, 2007, 08:27:26 AM »
I have no clue what your issues are but when I read about vibration it made me think of this thread.  Check out the videos.

http://www.cnczone.com/forums/showthread.php?t=32284