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Author Topic: Mach problem or hardware problem?  (Read 13064 times)

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Re: Mach problem or hardware problem?
« Reply #20 on: October 08, 2010, 09:31:39 AM »
Well, I thought I had this thing licked after copying over the other config but it appears to be resurfacing now.  One thing I noticed is that it doesn't normally stall when I have one axis moving and then just start another one moving.  It really tends to stall when I have one axis moving (e.g. Z), start another (e.g. X), then change the direction on the X.  I wonder if it has to do with the higher speeds that this mill runs and if it is not decelerating (the X) fast enough before going the opposite direction?
Re: Mach problem or hardware problem?
« Reply #21 on: October 09, 2010, 02:18:53 PM »
Just to add to this - it seems the reason it resurfaced once I thought it was gone was because I enabled backlash compensation.  I have between .0005 and .002 backlash between the 3 axes.  I have tried it with accel of between 10% and 100% and only turning it off makes the stalling go away.

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Re: Mach problem or hardware problem?
« Reply #22 on: October 09, 2010, 07:31:51 PM »
Do a search for backlash comp and the user name Rich and you should come up with info on setting it up. Afraid I have never used backlash comp so dont know what the settings are that work.
Hood

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Re: Mach problem or hardware problem?
« Reply #23 on: October 09, 2010, 07:32:55 PM »

Offline RICH

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Re: Mach problem or hardware problem?
« Reply #24 on: October 09, 2010, 09:10:49 PM »
Why not just cut your velocity down and get rid of the problem. Speed is not impressive if the result is a machine you can't have faith in.
Play around with the backlash settings. Start with "slow" settings so you can see how each setting affects how the backlash is implemented.
Makes no sense to me to see a machine rapid at 200 IPM only to cut at 20 IPM or even slower. Ya beat the poop out of the machine to save a few minutes of time .........sorry ....I just don't get the reasoning when at a hobbiest level of machining.

RICH
« Last Edit: October 10, 2010, 03:42:18 PM by RICH »
Re: Mach problem or hardware problem?
« Reply #25 on: October 10, 2010, 09:56:16 AM »
I could live at a slower velocity.  The nice thing about the higher rapids IMO is at the end of a job when I move the head and table to clear the part so I can remove it - especially if I am making multiple ones. 


The thing that bugs me is that it just seems like the machine functions fine one axis at a time, so why shouldn't it function fine with 2 axes? 
Re: Mach problem or hardware problem?
« Reply #26 on: October 10, 2010, 10:59:40 AM »
Rich,

Could it be that the breakout board is underpowered.  A C11 is an optoisolated board, it requires two power supplies.  The main power supply must be rated at least at 1.5Amps.  The other side of the circuit can be powered with the provided USB cable.

Arturo Duncan
http://cnc4pc.com

Offline RICH

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Re: Mach problem or hardware problem?
« Reply #27 on: October 10, 2010, 05:56:50 PM »
Arturo,
Could be, but i would bypass the BOB if the drives are optoisolated and see if there is a different axis behavior.

nucular,
Do you get the same affect when using the X & Y axis?


Acceleration setting is different than velocity. First you find the max velocity at a low acceleration and then increase the acceleration to find the max acceleration  relative to the max velocity and you don't use either at the max. You reduce them. You want reliable motion over a variety of conditions.
Actualy what you want is power, so the velocity setting may be much lower as that puts the max velocity / speed  setting at the highest torgue relative to motor speed / rpm. All somewhat of a trade off i may add.

RICH

Re: Mach problem or hardware problem?
« Reply #28 on: October 11, 2010, 10:46:19 AM »
I get the same effect when I try any combination of 2 axes.  X/Y, X/Z, Y/Z, etc.

Also, I am running the 115V in to a 5VDC/2A power supply and am running that to both sides of the board.  Should I be running a separate power supply to the other side instead of using the same for both?

Offline RICH

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Re: Mach problem or hardware problem?
« Reply #29 on: October 11, 2010, 06:04:10 PM »
nucular,
I can't duplicate on the lathe what you are experiencing. Didn't try the mill. I run my lathe and mill at max 100 IPM and the acceleration is set at
10 to 15% of the velcocity. By the time i press the reverse key ( 1/2 second maybe ) for the axis the axis has stopped. At an accel of 30% things get
unreliable ( the motors will skip). You really can't directly compare two different machnes but it gives you an a very rough idea / flavor of someone elses. A few seconds are not worth much if it creates aggrevation....... ;)
FWIW,
RICH