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Author Topic: VFD and pulley config observations  (Read 1348 times)

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VFD and pulley config observations
« on: January 09, 2013, 06:40:16 PM »
OK, I have a BP V2XT

which has a variable pulley that used to control the speeds.  I'm using it for the time being till I come across more $$$$ for a inverter grade motor and poly V belt pulleys.  What I am sticking with in this thing is


The back gear system.  It also has a sensor in there that tells the controller when it is in main gear and when it isn't.  Currently its a pushbutton, I burned out the NPN prox trying to hook it up to my C32.

Now, Hood wrote me a brain and a macro that selects the pulley according to S command in my G code.  The brain determines whether I am in backgear or not and that is used by the macro which replaced spindlespeed.m1s,  This macro figures out what S is and if it is in the range for back gear and I am not in back gear a message pops up telling me to engage back gear and then I hit OK ( wish cycle start could be used instead).  If the speed calls for main gear and I am engaged in back gear it requests main gear and I hit OK.  If it is in the right gear for that speed, I can just continue.   

Well, what is running this entire racket is a VFD.  Last couple of days I have been trying to get this thing to get up to 150 Hz.  I gave up on that, I am at around 130 Hz as shown on the display of the VFD.  Basically I set the VFD to the max speed I desired by playing with the max speed setting until my handheld tach gave me a reading I liked.  I also set the vari pulley so I got 2900 RPM at 60 Hz. 

After I was happy with my max RPM in main gear and noted that, I also set it to back gear, hit rev on the VFD and moved the potentiometer to total output ( how many Hz I don't care) and measured that and noted it.  Now I did set my VFD to 12Hz using the knob or you could use the button and I took note of my rpm in main and back gear.

                12Hz             around 130 Hz

Back gear      64.5 RPM              698

Main Gear      554                   6000

Now the max numbers from the chart I entered in the pulley configs and for Minimums I entered 0.
Under min PWM in spindle config I entered 20% (that macro ends up calling more than 20% so I am very safe there)

Basically the only math involved was averaging 554 and 698 .  626 RPM became my transition speed. Back gear is good from 70 rpm-625 rpm as per the macro and main gear is good for 626-6000 rpm in that macro.

So now it was time to test everything via the MDI screen using S commands and M3.  when I found out my speeds were too low, I just lowered the top speed in my spindle config for that pulley.  When I found that things were too high, I increased that number.  This in effect controls the analog 0-10 V bringing it up or down.

So far what I have learned is that the numbers in pulley config don't mean a thing, play with em as you need to.

Also, those pesky little message on the bottom of the screen of Min PWM or too fast for current pulley didn't mean a thing either.

I tested and I was within 50 RPM.  At this point I am wondering if I was to use that macro to call up "phantom pulley configs" so I can smooth out the PWM and get more accurate speeds, if that would work.  Say for ex, main gear = 626-6000 rpm say for 626-2000 rpm use config one and for 2000-6000 use config 2 and I could adjust those two separately.  Because I see that in each current pulley config the lower ends are below the called for speed and the higher end is above what is called for.

Anyone need that macro or Brain mail me.  You can have it.