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11

General Mach Discussion / spindle encoder, VFD, rigid tap, lathe

« on: October 29, 2009, 12:16:52 AM »

Hi All,

I am working on a lathe retro-fit and have a few questions about spindle feedback in Mach.  I currently have a little lathe running now on Mach with just a spindle index for feedback into Mach, one pulse/rev.  The spindle motor/drive is a cheap 3HP hitachi, no feedback into the drive.  It works amazingly well for cutting threads...

The big lathe I am working on now has a 15HP DuraPulse Vector drive with the encoder feedback option.  There is a quadrature encoder with an index pulse on the spindle that spins at the RPM of the chuck and there is an auto lo-high in front of that.  I was considering just running the spindle's encoder to the feedback card in the DuraPulse, and the index pulse to Mach3.  I have a few questions about the setup:

1- Is rigid taping on a lathe an option in Mach?
2- Can/should the encoder go to just Mach, just the drive, or both?
3- This is probably more of a question for automation direct, but how will the drive work with encoder feedback after a gear-shift?  I may need to change the way I command the spindle speed based on the ratio between the motor and the drive....  Anybody out there done this?

I am going to try to post some pictures of the machine in the "show'n tell" section if anyone is interested...
Thanks!
Dustin

12

General Mach Discussion / Lathe turret Tool Changer, PLC, VB Scripts

« on: October 28, 2009, 12:22:58 PM »

Hi All,

I am working on a Takisawa DTX-1 Turret lathe and am using Mach3 for the retrofit.  I have used Mach on 2 other machines, a small 9X24 lathe and a Bridgeport sized Gorton 1-22 knee mill, but have not needed extra IO.

On this machine there is an 8-position turret (see photo) that I need to get going.  There are at least 9 inputs (8 tool positions and lock/unlock state) and at least 4 outputs (lock/unlock, motor on/off, motor brake on/off, and forward/reverse), just for the turret and things need to happen at specific times.  For instance, the direction cannot change with the motor on, among other things...

I have talked with Peter Homann and he has graciously volunteered to write some custom software for his ModIO card, but I am considering using an Automation Direct PLC instead, mainly so all of the outputs are relay controlled and all of the logic is a nice robust 24V.

So, what I am looking for are some general guidelines on doing this.  I have watched the videos on VB scripting and the modbus, and that all seems fairly straightforward.  Here are specific questions:

1-Would one program all of the timing functions in VB, or would that be done in the PLC "ladder logic" and the VB would just do "something" via Modbus after the M6start?
2-Is Modbus a robust enough interface for a serious machine like this?  With a 15 HP spindle and 2KW servo motors I want this thing under control at all times :-)

Thanks for any help or suggestions!
Dustin
www.protoplant.com