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Author Topic: Octimising Mach settings, help needed  (Read 2270 times)

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Octimising Mach settings, help needed
« on: April 28, 2013, 02:58:41 AM »
 Hi.
I have a Wabeco cnc bench mill
  I have upgraded the controller to GeckoG540 in a bid to running faster feed speeds. The best I can reliably get is 400mm per min. Which I am a little disappointed with.

Here is the spec and settings.

Power supply. 48v switching 7.3A.
New Stepper motors.     350Ncm, 1.8 degree, 4.2A, rated voltage 3.36V.

Motor tuning.

1000 steps per.  Velocity 400.  Acceleration 90.  step pulse 3.   Dir pulse 3.
kernel speed 25000HZ.
Are there any settings that I should change that would help me achieve faster feed speeds without loosing steps. Any advice would be appreciated.  Thanks
John.

Offline Tweakie.CNC

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Re: Octimising Mach settings, help needed
« Reply #1 on: April 28, 2013, 05:16:56 AM »
Hi John,

If your machine has ball screws then yes you should be able to increase your velocity (in motor tuning) to 1000 and achieve faster rapids without loosing steps. However, if you have the gibs set too tight or any other binding in the drive train then this may be causing your problem.

It may just be worth connecting an analogue voltmeter across your 48V PSU output and checking that there is no voltage drop when jogging X and Y at the same time.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Octimising Mach settings, help needed
« Reply #2 on: April 28, 2013, 01:59:49 PM »
Tweakie.

Thanks for your quick reply. I will check voltage drop, also gib adjustment. Yes I do have ballscrews fitted
Re: Octimising Mach settings, help needed
« Reply #3 on: April 29, 2013, 03:08:44 PM »


I think we have found the problem with low feed speeds. We had the steppers wired in series rather than in parallel.  We have to run some tests to check out the best reliable speed setting.

Gibs seem to be adjusted correctly. Have not checked yet so see if there is any voltage drop when 2 axis are running.

Are the steppers more likely to loose steps at a given speed when wired in series rather than in parallel ?

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Re: Octimising Mach settings, help needed
« Reply #4 on: April 30, 2013, 02:07:36 AM »
Quote
Are the steppers more likely to loose steps at a given speed when wired in series rather than in parallel ?

As stepper rotational speed increases so available torque reduces. Parallel wired motors tend to have more torque at higher speed than series wired motors. There is also the mid-band resonance issue to be considered.

Probably the best information is here http://www.geckodrive.com/support.html

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.