Author Topic: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion  (Read 93238 times)

0 Members and 1 Guest are viewing this topic.

Offline JHChoppers

  • Active Member
  • Posts: 367
    • View Profile
    • JHCHOPPERS
Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion
« Reply #120 on: May 02, 2012, 03:51:36 PM »

The current plan is to use the built-in encoder on the spindle motor with the stock FREQROL-SF VFD Drive.   

The original FREQROL-SF VFD had a SF-DA (Speed Reference and Magnesensor Card) to interface with stock MELSAS CNC Controller and stock Magnesensor.  Since the MELDAS CNC controller is being replaced with a Mach3 PC, this SF-DA interface card has been removed from the FREQROL-SF VFD SF-CA mother board and the Magnesensor will not be used. 

To date I have successfully removed the SF-DA card and updated the jumper settings and parameters on the SF-CA mother board to test the unit in a Stand-Alone Mode.  Using simple dip switches to test and interfaced to an old wire-harness, I can take the unit out of eStop to charge up the DC Bus and turn on the spindle fan, enable to unit, run forward/reverse, and adjust the speed with a 10K potentiometer. 

The same wire-harness has connections for spindle orientate switches and its position location is configurable with parameters on the FREQROL-SF VFD mother board.  I have not prototyped up the connections or studied the parameters to test.  I am hopeful that this will work…   I need to get a large block of time allocated to fully study this and test at one time.

Thanks
JH


Marty,

I used my lathe to generate the 3rd leg to test FREQROL-SF VFD, running it on rotary should be fine.  You will have to reconfig it as I did above for stand alone mode.

The servos are AC Brushless.

When are you starting your thread ?  Now that you committed !!!

JH

Offline cnc-it

  • Active Member
  • Posts: 153
    • View Profile
Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion
« Reply #121 on: May 03, 2012, 02:35:37 AM »
Not being well up on rotary phase converters could you run the whole machine off one? Would save doing a retrofit..

Offline Marty_Escarcega

  • Active Member
  • Posts: 65
    • View Profile
Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion
« Reply #122 on: May 04, 2012, 06:51:09 AM »
Not being well up on rotary phase converters could you run the whole machine off one? Would save doing a retrofit..

Yes, I imagine you could provided the Rotary is fairly well balanced.

Offline Marty_Escarcega

  • Active Member
  • Posts: 65
    • View Profile
Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion
« Reply #123 on: May 04, 2012, 06:53:18 AM »

The current plan is to use the built-in encoder on the spindle motor with the stock FREQROL-SF VFD Drive.   

The original FREQROL-SF VFD had a SF-DA (Speed Reference and Magnesensor Card) to interface with stock MELSAS CNC Controller and stock Magnesensor.  Since the MELDAS CNC controller is being replaced with a Mach3 PC, this SF-DA interface card has been removed from the FREQROL-SF VFD SF-CA mother board and the Magnesensor will not be used. 

To date I have successfully removed the SF-DA card and updated the jumper settings and parameters on the SF-CA mother board to test the unit in a Stand-Alone Mode.  Using simple dip switches to test and interfaced to an old wire-harness, I can take the unit out of eStop to charge up the DC Bus and turn on the spindle fan, enable to unit, run forward/reverse, and adjust the speed with a 10K potentiometer. 

The same wire-harness has connections for spindle orientate switches and its position location is configurable with parameters on the FREQROL-SF VFD mother board.  I have not prototyped up the connections or studied the parameters to test.  I am hopeful that this will work…   I need to get a large block of time allocated to fully study this and test at one time.

Thanks
JH


Marty,

I used my lathe to generate the 3rd leg to test FREQROL-SF VFD, running it on rotary should be fine.  You will have to reconfig it as I did above for stand alone mode.

The servos are AC Brushless.

When are you starting your thread ?  Now that you committed !!!

JH

Not committed quite yet. I have to go measure the machine and see if I can get it in the garage opening. Can only hope.

What are you running your machines off of. I know you did a Bridgeport VMC. Rotary? I was concerned about feeding the Frequol from a rotary because of voltage imbalances. I supposed I could tune the rotary.
Marty

Offline Hood

  • Mach4 Alpha
  • Posts: 25,773
  • Carnoustie, Scotland
    • View Profile
Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion
« Reply #124 on: May 04, 2012, 06:58:45 AM »
Are rotary converters not usually pretty well balanced? Thought that was the idea of having the motor so it put out true 3 phase rather than the two that a static will.
Hood

Offline Marty_Escarcega

  • Active Member
  • Posts: 65
    • View Profile
Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion
« Reply #125 on: May 04, 2012, 07:07:09 AM »
Are rotary converters not usually pretty well balanced? Thought that was the idea of having the motor so it put out true 3 phase rather than the two that a static will.
Hood

No, they are not. You usually add oil filled capacitors of varying values across the legs and measure the voltage until they get closer. Ive done this once many years ago. And it seems to vary with the load so best to balance on the machine it runs on. 3 phase motors generally tolerate the imbalance. But I'm concerned about feeding an electronic spindle drive like the Frequol imbalanced AC voltage. That's why I am asking JH what he plans or does run his machines on. Looks like he has shop in his home garage.

Offline Hood

  • Mach4 Alpha
  • Posts: 25,773
  • Carnoustie, Scotland
    • View Profile
Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion
« Reply #126 on: May 04, 2012, 07:11:40 AM »
I must have just been lucky then when years ago I had a static and a 10HP motor connected to it to make it a rotary, each phase was within a volt or so of each other even when I had two machines running off it.


Hood

Offline JHChoppers

  • Active Member
  • Posts: 367
    • View Profile
    • JHCHOPPERS
Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion
« Reply #127 on: May 04, 2012, 10:19:23 AM »
Your input line voltage doesn't have completely balanced for the FREQROL VFD to work.  I have successfully run this spindle from 100 RPM to 6000 RPM using 220VAC Single Phase.  This was done by simply faking out the since circuit on the VFD using a small cap and resister to create a phase shift on the since circuit, not on the power side.  I would not recommend this for long term, but it proves the point.

The FREQROL, just like any other VFD, converts the input AC Voltage into DC.  If you get a change to look at it, there is a large bank of caps and bus bars that stores this DC voltage.  When I measured mine, it was 385-410VDC depending on the RPM.  Then the inverter circuit will use large SCRs to switch on and off the DC voltage to create the precision AC 3 Phase and Target Frequency needed to drive the 3 Phase AC Spindle at the correct RPM.  When the Spindle slows down, it acts like a generator and will drive up the DC bus voltages, thus you need to control how fast you decelerate the spindle or you will create a DC B bus voltage higher than the system can handle.  Mine tripped out at 465VDC when decelerating to fast.  Braking resisters circuits can help with this.  They are simply switch onto the DC Bus when the voltage gets to high to absorb the voltage/energy allowing the system to decelerate the spindle faster, as the voltage is decreased the resisters are removed from the bus.

Since my shop only has single phase, short-term I am using my lathe (5 HP 3 Phase using a static converter) and its 3 leg for the 3 rd input into the FREQROL VFD.  Long-term, because I don’t want the lathe running just to run the spindle, I plan to add a 5 HP Rotary just for the 3 rd leg needed to make the FREQROL VFD rectifier circuit happy.

Thanks
JH

Offline Marty_Escarcega

  • Active Member
  • Posts: 65
    • View Profile
Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion
« Reply #128 on: May 04, 2012, 10:38:41 AM »
Cool. What size is your spindle motor? I understand you should size your rotary converter a bit larger than the motor. Say 7.5hp spindle motor, 10hp rotary converter?

Its good to know the Frequol is not that sensitive. I got some news this morning after Dave Design measured his 2016 which is the newer machine to the 4500. He says 83" with some disassembly, maybe more by dropping the Z axis entirely (unbolting the ball screw assembly)

I will go see the machine today to inspected and measure once more. Then I have to sell of my woodworking machinery to fit in the VMC and an EMCOTURN I am getting next week!

Thanks JH
Marty

Offline JHChoppers

  • Active Member
  • Posts: 367
    • View Profile
    • JHCHOPPERS