OK everyone. My name's Zach and I'm a Manufacturing Engineering student at the Pennsylvania College of Technology in Williamsport, PA. I have a decent electronics background as well. My school is about to throw away 2, count'em, 2 1992 Bridgeport Discovery 308 VMC's. They run the very awkward SX-16 control, made by Bridgeport. Mechanically, the machines are in decent shape. Electrically, well, they're broken. The controls are bad in both and parts aren't available. I have all but completely convinced the school to let me retrofit a control onto one of them as a project. I'm thinking very seriously about using Mach3 as my control software but am also looking at FlashCut. Any opinions on their software would be appreciated. Here go machine specs:

TRAVELS................................: 18" X, 12.5" Y & 16.1" Z
SPINDLE SPEEDS.........................: 60 to 6000 RPM
SPINDLE TAPER..........................: BT 30
FEED RATE RANGE X & Y AXIS.............: 1 to 472 IPM
FEED RATE RANGE Z AXIS.................: 1 to 295 IPM
SPINDLE DRIVE..........................: 5 or 7 HP (i'm not quite sure yet)
EQUIPPED WITH:
8 STATION TOOL CHANGER
FLOOD COOLANT
BIJUR AUTOLUBE

Tomorrow after my first class, I'll take some pics and throw em up here for you guys all to see. I've already done a little investigating on the servos. Here's what i got.
All three axis are SEM brand DC Brushed Servomotors MN:MT30U4-31
CStall Torque: 35lb/in 13.5A
Max Speed 4000rpm 125V 86A
Tacho 9.5V/1000rpm IP44 IC40
Made in January of 1992
I'm gonna call SEM tomorrow and get the manuals on them for the rest of the specs. They dont make the 31 model anymore, but they make a 26 and a 36 with specs up online.

I haven't got the lowdown on the spindle motor itself yet, but i do know this. Currently the spindle is controlled by a V400 Flux Vector AC Motor Control 4.0kW max which is made by either SECO, Danaher Motion, or Control Techniques. I'm not sure who owned who when it was made, but i'm gonna make calls tomorrow. I'm also gonna look into the types of encoders currently on the machine.

Now for my list of questions:
What kind of hardware am i looking at needing here?
Do I need to buy a PLC, if so i've used allen bradley and DIRECTLogic. Opinions?
Servo Drives? Can i use the ones already in there..as far as i know they work. Would Gecko Drives be sufficient? Any other recommendations?
I want to still be able to use the tool changer and flood coolant. What do i need to take into consideration? I have the wiring diagrams and currently there is a little PCB designated "Spindle orientation board" sitting right by the big AC motor drive. I assume i have to keep that?

After i do an initial cost report on this and present it to my school, i can start buying equipment and get this rolling. Any input you guys can give would be greatly appreciated.

Here's some pics i have of these machines from last year...when they still worked. My buddy kevin is making something on one of them. I'll get more and better pix tomorrow

If you are going to do a control like that you need to look at the Galil cards.. you could keep all the old amps in the machine (that are not all that old).

You should be able to get a 4 axis version for about 1200 and you will have a full closed loop controle.

hope that helps
Brian

What part of my plan makes me have to go to Galil? Is it the spindle/tool changer/coolant control?

Trying to get all my ducks in a row here i need to control this much stuff:
X-axis servo, encoder, and limit switches
Y-axis servo, encoder, and limit switches
Z-axis servo, encoder, and limit switches
Spindle on/off, direction, speed, and somehow orient
tool changer engage/disengage, and index
coolant on/off

This sound about right? So this would be 3-axis, and how many input/outputs, and digital or analog? or both?

The type of amps that you have in the machine. they are analog torque amplifiers and will not run from the P Port. BUt will run from the Galil or you at the S&D to analog cards (Never used them)

Ok now i'm somewhat more confused. If i'm completely off base tell me, but it shouldnt matter what kind of amperage i'm dealing with in my machine. As long as i have good servo drives and spindle drive, i can choose from a bunch of controllers. What prevents me from using the same hardware everyone else uses if i have the drives to run these servos and spindle? Also, could you clarify what you meant when you said S&D to analog cards?

Most of us are using small motors with homemade power supplies and Gecko drives for the motors. This will not accomadate the requirements of you motors. The S&D to analog convertors would take the step and direction pulses produced by Mach and convert them to an analog signal. This would allow you to use the drives you have now. Don't take my word for law, let someone verify this before you proceed.

Brett

engineeringpunk,

Sounds like a very energetic project.

S&D is short for step and direction.   If you use the same amps (refering to the amplifiers - or - servo motor drivers) they are probably analogue input, not the step/direction input type.

 Most cost effective would to use as much of the hardware that you have and still is functional,  but that will not be the simplest way. 
It will require interfacing mach3, which does step & direction outputs via the parallel port to your analogue cards (the biggest hurdle), there are some interfaces that do this but I can't help you there.

The simplest way would be to purchase servo drivers with step & direction inputs, if a Gecko is large enough to handle the power requirements of your existing servos (they are pretty good drives).  Then the next hurdle is all the other IO you have for limits, tool changer, coolant etc.  You will quickly run out of points on your parallel port, even if you put in an additional parallel port card.  With your knowledge of PLC's you would probably want to put the less time sensitive IO on a PLC and communicate via ModBus with it. There will be a time lag between sending and receiving these ModBus points due to scan cycle time and how often Mach looks at the modbus.
Things like e-stop, limits & spindle index(1 pulse/rev index signal) you will want to keep on the parallel port for timing reasons.   Tool changer, coolant, maybe spindle start, stop, direction could probably all be done on the PLC.   Spindle speed, I am guessing you probably have an analogue input to the VFD,  you can use a mach to output a pwm signal on the parallel port - convert that to analogue and feed it to your VFD.

Lots of info in these forums, you should have a good time with this, looks like a very worth while project where you will learn a lot.

Arnie

I have had good luck with the pixies (http://www.skyko.com). They convert step/dir to analog out using the encoder on the motor for feedback.

Hello EngPunk,
I think you need to have a look at what is in the machine now and what you can save. You will find that it is not as simple as loading new software But it is doable and it is a ton of fun to make it work with new software. You need to have a very good understanding before you start taking parts out of the mill.

Posta  pic of what is in the boxes on the mill and we can tell you what you have

Thanks
Brian