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Author Topic: Wells Index CNC update  (Read 2214 times)

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Wells Index CNC update
« on: January 29, 2015, 08:37:45 PM »
I am currently trying to update a 1980 Wells Index 320 with a Heidenhain control - I have 3 phase power in my home shop and have powered machine up but it has lost its parameters and many keys are missing on the controls.  I would like to retain the DC server motors, west amplifiers, 24 volt relays and possibly the glass scales. I currently have a PC running windows 7 professional with a Galil DMC 1830 PCI card with cable connecting to an Opto 2900 module.  Has anyone run a similar system or am I better off starting with Windows XP - also I know the controller will run 3 axis - will Mach 3 control the spindle and coolant relays or should this be hard wired? from reading previous posts it looks like I will need version 7 Galil drivers and Galil plugin - does this sound right?  Any help you can give me is appreciated.  I will try to post some pictures of what I have so far later.
Re: Wells Index CNC update
« Reply #1 on: January 30, 2015, 02:30:59 AM »
Hi digman:
I retrofitted a similar mill some years ago with Mach3. It did not have glass scales, so I cannot advise you on that. 
The WestAmp drivers are analogue, +/- 10v signal; the Motors are most likely ElectroCraft, brush D.C. which are very long lived. You did not say if the motors had 5v. encoders, or the feedback is from the glass scales. The WestAmp drivers are directly connected to the limit switches, which cut the power for that direction when the switch is activated, so you can only jog off the switch, which is a nice feature. All the switches are 24v, and the original wires are still in place. The older machines (at least in my case) had excellent wiring, and shielded cables.  The reference switches are a separate circuit, and feedback to the controller. My controller is the "dspmc" from Vital Systems, and has worked flawlessly from the start. I had to change the digital encoders to differential type which have A+, A-, B+, B-, Z+,Z-, 5v+, and Ground. The original machine AC contactor's are the original, and still work perfectly, which were all Allen Bradley. The older machines had a huge amount of wires, and most all of that control wires must be stripped out, leaving the basic system. The newer controllers are so much more integrated than the old technology it is like night and day. The most difficult part was tracing out where all the basic control wires went, i.e. the relay banks, and the mag contactors, mag contactor for spindle etc. Once you have the basic layout schematic in hand, and label all the specific wires, connecting up to the controller is pretty straight forward. Also, using a LED panel for the screen, and a USB pendant, the control front end is quite simple. You will need to make a basic push button panel for Cycle Start, Feedhold, Stop, Emergency stop, but that is pretty simple 24v signal wiring, and add a couple of pots for Feed override, etc. Also, the old machines were very well made, with a lot of mass. 

John
 
Re: Wells Index CNC update
« Reply #2 on: January 30, 2015, 08:17:31 PM »
Thanks John - I'll do some research on the PSPMC controller. I had talked to someone a while ago on another site that had converted a wells index with a Galil 1830 controller and a 1900 module. hoping I can make the 1830 and the 2900 opto module as well as a USB pendant - all of which I already have - work. to your question the motors still have the original encoders and I have been told the glass scales also give position feedback.  Where are the reference switches you refer to - are these the encoders? Am I right that you are controlling your spindle with a separate switch not the mach 3 or the DSMPC - is that right? Are the limit switches on the table? I am confused what you mean by "jogging off limit switch".  I am working on my electrical and computer skills as they are pretty basic; however, I have an electrician friend helping me.  I also have a complete schematic for machine - yet the controller end is limited I believe due to the system being proprietary. I have been using an OHM meter chasing wires.
Re: Wells Index CNC update
« Reply #3 on: January 30, 2015, 08:31:09 PM »
here are some pictures.
Re: Wells Index CNC update
« Reply #4 on: January 30, 2015, 10:57:02 PM »
Hi digman:
With the WestAmp drivers, the axis limit switches connect to the drivers themselves. When either of the limits of a given axis are tripped, they cut the power to that direction of travel; then the axis comes to a stop, and you can only jog the opposite direction with that axis to come off the limit switch. The WestAmp driver manual has the schematics, and explains the action pretty well. This was an industrial standard at that time.

The analogue drivers are technically obsolete, given the newer digital AC drivers, and brushless AC motors, but if yours are still good, you can have a very useful machine that works. WestAmp has been out of business since the late 90's, but they can still be repaired, and used amps are available on the internet. It I had a big, high tech business with manufacturing deadlines, using old equipment would be a risky endeavor. We are talking home shop, or small business.

The reference switch is also a switch just like the limit, but is positioned to trip slightly before the limit, which is mounted at the right end of the X axis table. When you are referencing, from the Mach3 program control, the machine moves until the ref switch trips, then the machine reverses, and moves very slowly until the "Z" channel of the encoder is seen. The machine stops, and then backs off something like .050 or .100 and stops. The point the Z channel went active, is the machine "Zero". Since the encoder is connected directly to the motor, and the motor is directly connected to the Ball screw, this "ref" point is very accurate and repeatable. You can come back to a work zero position, after the machine has been turned off, and then restarted, to within tenths, .0001 or .0002. This is pretty useful, and is absolutely reliable; at least it has been for my machine, and setup. The "Z" channel on the encoder is only one digital pulse signal per encoder revolution.  The controller only see's the reference signal when you are in REF mode; in normal running the reference switch is ignored, and the machine can only see the limit switch.

Each axis has 3 micro switches, 2 limits, and 1 reference.

The spindle is controlled by Mach3. The 24v relay, tripped by the G-code reading an M3,  output signal of Mach3, in turn trips the spindle motor AC contactor. My machine has a 5hp AC motor, with a vari-speed pulley. I plan to install a VFD sometime in the future, but have not gotten around to it.

The controller box has inputs, and outputs.  In the case of the dspmc, they list each and every pin, and what the corresponding Mach3 I/O pin # is.

My machine originally had a bank of 8 24v relays, that actuated the various things, like the Driver power supply, spindle cw, spindle ccw contactors, coolant motor, mist solenoid, lube pump, etc. I did put in a new relay bank, but it connects to the same original AC wires in the AC cabinet. The original relay bank had some very obscure wires that were very difficult to trace, but I could discern what they controlled by tracing the AC wire side, going back into the AC Mag cabinet. This is where you have to get into the wire looms, and laboriously follow each little wire to make your schematic. I had some factory schematics for the 24v things, but nothing that showed the entire relay<>AC path. You have all the original factory drawings, which will be a big time saver.

The old controller end of things is going to be removed. The new controllers will have schematics showing all the inputs and outputs, so you just have to make the new connections. What you are doing is basically giving the machine a new "brain", which is far better, than the original collection of circuit boards. What used to take an entire circuit board, with 2 or 3 different voltages, and a big 50 pin edge connector, is now on a chip the size of a quarter. The computer will connect to the controller with a single ethernet cable, and a pendant will connect to the computer with a single USB cable. The dspmc controller is a small box, with 5 db25 plugs, an ethernet socket, and a 2 pin connector for the power.

Things really have improved, and made electronics doable by anybody with some time, patience, and a few bucks. In the 1980's CNC controls were proprietary, factory creations, with unique circuit boards that cost thousands of dollars, and failed frequently. Now, nearly the entire electronics in a CNC machine are "off the shelf" items. When you finish you mill, you will have a CNC machine that you can fix yourself, and make as good as you want.

John
Re: Wells Index CNC update
« Reply #5 on: January 30, 2015, 11:55:15 PM »
Thanks again John. I will try to find some schematics for the west amp drivers to get a better understanding. I have already removed the old controller and retrofitted the control cabinet to fit the pc and opto 2900 wiring module. Still lots of wires to chase/label. I was not sure the mach would put out enough voltage to trip the 24v relays. I thought in the main cabinet there is a 76v output transformer for the west amp. I will also look more closely for the micro switches and trace the wires from them. I will try again to post some picturs of project.
Re: Wells Index CNC update
« Reply #6 on: January 31, 2015, 06:31:48 PM »
Hi digman:
Regarding the 24 v relays, Mach does not put out the 24 volts. Mach puts out a digital signal, either a logic 1, or a logic 0 (zero).
In the case of a parallel port, the signal can be about 3.5 volts for a 1, and 0 to 1.5 v for a 0.

The typical breakout board using the old Parallel port input, takes that 3.5v signal, and  by means of a opto-isolated circuit, outputs a full 5v signal (logic 1)on a terminal connection, or 0v (logic 0). The typical stepping motor system uses 5v relays, and I/O signals for limit, home etc.
Some breakout boards are made to output a 24 volt on/off signal, but most don't. I believe the PMDX boards can output a 24v signal, and they are very highly regarded as to quality and function.

CNC4PC has a large variety of breakout boards, some of which can input a 5v TTL signal, and input or output a 12, or 24v signal.

However, these don't fully apply to your situation. You will be using a controller that plugs into your Win7, or Win XP computer either USB or Ethernet, and output the +/- 10 volt signal to the amps, and TTL signals for the relays etc. . This is the costly part of retrofitting an older mill.  You need to handle Analogue signals (amps and motors), as well as TTL logic signals (relays and reference switches). These are two separate parts of the machine control. The controller you choose will have the logic I/O built in, with terminals, including analog I/O (5 or 12v) for spindle speed and Feed rate override.

You will most likely need a new 24v power supply, and a 5v power supply for the separate circuits. These are control voltages only.

In my relay bank, I used a bank of DPDT relays from CNC4PC, with a 5v coil, and used a 1k resistor for the 24v signal coming into the relay coil. They have nice little relay boards with 2 relays per board, with LED's to visually see when it is getting an input signal. That is a big help when you are hooking things, up, to see what does what. The relays can be used with 5,12, or 24v input signals.

In the case of my dspmc controller, it has I/O boards that plug into the controller's db25 ports, and handle optically isolated 24v input and output signals. One of the dspmc I/O boards handles the analog +/- 10v signals, another I/O board handles the digital I/O for relays, etc., and another board handles the 5v digital encoder signals.

Basically, the 24 volts is much more noise immune than 5 volts due to the larger differential between the signal and ground, which is why the industrial controllers use 24 volt signals.

The big 76v transformer is for the amp power. You dont have to touch any of those DC power wires. There also should be a smaller transformer for 110v, single phase, from the 220 3 phase incoming main. The 110v power is on a separate buss bar, with AC hot, neutral, and ground. This will power your computer.

The WestAmp manual is 25 pages, 8-1/2 x 11. The title page reads, Instruction Manual, Westamp A651 Series, Rev. F. You should be able to locate one on the internet. If not, I can have it copied at Office Depot, I am guessing for about 10 or 15 dollars.

Once you get all your wires located, and labeled, you can make a drawing showing all the various pieces of the puzzle, and their connections. It will make a lot more sense, as you get further along in the project.

John