Messages

71

Show"N"Tell ( Your Machines) / Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion

« on: June 20, 2012, 04:42:46 PM »

The ATC covers are back on and the half of the inside is painted with 2 coats.   I removed the Z and the back Y way covers as these will need to be bent back into shape for smooth operation, plus it made it easier to paint.  The outside has the first coat of paint, hoping to get the second one on soon.

Also, the large electronic enclosure is sanded and prepped for paint.

72

Show"N"Tell ( Your Machines) / Prep and Paint

« on: June 14, 2012, 11:56:57 AM »

Getting some time back on the BIG MILL, this tool is big and I have parts all over the shop….. cant take the mess any longer!

The inside and outside of the large enclosure has been degreased, welded and sanded as well as several other large parts.  The ATC covers have been painted and are ready to be installed back into the VMC.   Been doing some work on the way covers too to ensure proper movement and chip protection.

Thanks
JH

73

Show"N"Tell ( Your Machines) / Re: 9x20 Chinese Lathe Conversion

« on: June 14, 2012, 11:17:40 AM »

Looks great !  Cant wait to see it moving.

JH

74

Show"N"Tell ( Your Machines) / Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion

« on: May 07, 2012, 03:45:18 PM »

Engineering Article on VFDs

http://www.edn.com/article/521522-Teardown_The_nuances_of_variable_frequency_drives.php

75

Show"N"Tell ( Your Machines) / Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion

« 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

76

Show"N"Tell ( Your Machines) / Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion

« 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

77

Show"N"Tell ( Your Machines) / Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion

« on: May 02, 2012, 10:23:42 AM »

It looks like your servo amplifier is the same as mine, just maybe a lower power version.  I thinks its the 3 AXIS Integrated version that was not easy to interface with Step and Dir. 

All Manuals can be found here:
http://www.meau.com/eprise/main/sites/public/Downloads/Manuals/default

78

Show"N"Tell ( Your Machines) / Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion

« on: May 01, 2012, 08:53:51 PM »

8 foot door for sure.  If your drives are 3 separate units, I think they can be configured for step dir.  This would save you a ton of time an money.

Find the specs on drivers, I'll help you find the data sheets.  I did hours and hours of research on all Mitsubishi drives.

79

Show"N"Tell ( Your Machines) / Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion

« on: May 01, 2012, 08:16:37 PM »

JH, how tall is the 4800 with the head all the way down? Will it fit through a 7' door?

On the 4800, the Z Servo needs to be removed after the head is lowered.  Then it will fit under an 8 foot door.  Its BIG....  12,000 lbs too

80

Show"N"Tell ( Your Machines) / Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion

« on: April 30, 2012, 06:47:00 PM »

Ok, looks like they are unusual then and likely no use for Marty to reuse. Did they only accept commands via that bus ?
Hood

His could be very different.  On the 4800 it used 2000W Servos, Meldas had other models that looked like they would work with Mach when I was looking/digging into my drivers.