Messages

951

General Mach Discussion / Re: Spindle Control

« on: January 06, 2008, 03:44:48 PM »

I have just googled this VFD and come up with this link to a forum. There is a chap on there who seems to know quite a lot about it.The link is at http://www.cnczone.com/forums/archive/index.php/t-24107.html.

The connections to your VFD bear no comparrison to those on a modern VFD

We now appear to have, as standard 6 pins.
1. M3 connection 2. M4 connection 3. 0v M3/M4   4.V+ connection 5. Speed voltage reference 6. 0v speed regulator
Pins 1 and 2 connected to ground (via a relay) give forward or reverse drive - both cannot be "on" together
Pins 4.5 and 6. which are electrically seperate from 1,2 and 3 give a +v and 0v reference to attach to a potentiometer and pin 5 is the return from the pot wiper, which sets the speed.

The connections shown for the Oracle VFD are nothing like that. You require momentary contacts on the forward or reverse pins (not on/off switches) and the speed sensing seems to be somehow all intertwined with it .

Unless you are a competant electrical guy, I would suggest, in all honesty,that you get yourself a more modern VFD that has standard connections. On the standard set up, Mach 3 has the relevant outputs - M3, M4 and PWM (to run a digispeed controller to control your VFD) - and THEY WORK.

I have had M3 and M4 going for some time, but I also fitted a Digispeed two weeks ago, and now I can control the spindle speed to 1 r.p.m from the computer. It is marvellous.

Without being a pessimist, I think you will spend a lot of time with your old Orac, and all you will manage is  to get forward and reverse going satisfactorily - and that will still leave the speed control up in the air.

Anyway - have a look at the link and see what you think

952

General Mach Discussion / Re: Spindle Control

« on: January 06, 2008, 03:15:58 PM »

We will have to get this bit out of the way, before we go forward -

Your VFD has two connections - Yes !
Is one connection for M3 and the other for M4 - OR - is one connection for Go/Stop and the other for forward/reverse. It does not matter which it is, but it is essential we find out which one it is.

Mach 3 simply puts out a signal on one pin for M3 (forward) and another signal on another pin for M4 (reverse). The pins are not on simultaneously (and should not be). My VFD shows a fault if both pins are on simultaneously. This is relatively easy to connect - and it sounds like you are along that road already.

If your VFD requires one signal to tell it to turn on/off and a second signal to tell it to go in forward/reverse direction, this can be simply achieved with a couple of diodes.

If you say you have retrofitted this lathe - is there a book or data for the VFD

953

General Mach Discussion / Re: So Close to it working!

« on: January 05, 2008, 05:49:34 AM »

You are trying the big bang approach - and getting a big bang.

Turn off two of the homes on your Ports and Pins/Inputs and concentrate on one axis at once.

The two axis you have turned off will not move but the DROs will go to zero

The live one should be set up in order.

If you are going to use soft limits, and it looks as though you are, then these limits must a a little outside those set for your referencing. If you manuall watch your axis when it homes it pushes the switch until it clicks - mine then carry on a little because there is over-run on the motors (I don't know why) They then reverse and back off until the switch clicks again. If you are using the same switch as a limit switch, then this is taken care of in the computer program, in that, if you are homing the limmit switch part is disabled until the homing is finished

The limit switch and homing switch should obviously be set up on the same pin number.

So, ensure the inputs are correct under Ports and Pins/Input signals. Are your switches wired so they are normally open - i.e. positive until activated - Active Low, or normally closed - Active High - ensure the appropriate tick in Active Low if needed.

Try it out - jog the axis to the middle of its run, and press the ref all switch. If the axis is moving the wrong way stop it and alter the homing direction on Config/Homing/Limits. The axis should run down to the switch, press it, reverse and stop. The DRO should zero if you have ticked auto zero.

When you have that correct, turn it off (all the other settings will stay) and turn on another axis and set that up until you have each individual axis working correctly.

Then try the big bang !!!

954

General Mach Discussion / Re: Spindle Control

« on: January 05, 2008, 05:04:51 AM »

I am a little puzzled. From what you are saying, your spindle motor on your lathe is controlled by a variable frequency drive. Is the direction hard wired on the drive or a switch or push button ?? A single relay on your breakout board controls the motor on/off.

If the above is correct then the fault cannot lie with Mach 3 becasue it does not have control over direction. The fault must lie with your VFD.

I am puzzled by the VFD - mine has two inputs, one for M3 (forward) and another for M4 (reverse). Either one can be switched at any time, BUT NOT BOTH together. there is no forward/reverse switch as such. How does your VFD switch to reverse.

What I would try is rewire the leads between the VFD and motor so you are effectively driving it in reverse, and then reverse the VFD and see if the fault repeats itself in the reverse direction. It could be that the electronics/ relay/ or whatever that controls the forward reverse is a little sluggish.

955

General Mach Discussion / Re: Tribute to Art

« on: January 05, 2008, 04:48:05 AM »

Yes - thanks for all the knowledge and experience I've gained in so short a time.

One word of warning. I have retired. I work harder now than I did when I was working !!!

There's always something to do or something else to find out about.

956

General Mach Discussion / Re: Macros and how todo them

« on: January 03, 2008, 01:37:25 PM »

I am competant enough at writing the logic of Macros, but the actual syntax of Mach 3 Vis Basic is a bit of a mystery, and I don't know where to get it from. There is a starter video under "scripting". A "brain" might be the answer. Perhaps the big boys can help.

I cannot see why you want to press a key on a keyboard from somewhere else - surely it is the function behind the keypress you want to activate

957

General Mach Discussion / Re: Spindle Speed setup

« on: January 03, 2008, 01:30:18 PM »

My machine is a lathe with a milling head, run off the same motor. I have no pulleys on the lathe drive - that is more or less direct. There are a couple of pulleys on the mill head, but I have only bothered with one yet.

The way the automatic configuration seems to work is that the computer puts out a PWM signal to your driver board, starting at a low speed and ramping up, and then compares the speed it thinks it has set with the actual speed as per your spindle inde. Mine spindle seemed to be about 10% too fast. I would have thought then you would do it again and the computer would gradually adjust itself until it was correct, and announce itself.

It doesn't seem to matter how many times you calibrate, it always goes through the same procedure, but when you save, shut down and then restart the speed setting appears spot on (It is on mine anyway)

958

General Mach Discussion / Re: Spindle Speed setup

« on: January 02, 2008, 09:39:41 PM »

Got my board and fitted it up, and after a bit of fiddling with the settings, it worked.

I used the automatic calibration. If you do this manuall, you never seem to get anywhere. The machine says successful run, store data, or something similar. So I stored the data. Then I manually  put in an M3 S600 command - and the speed was nowhere near. Did the automatic set-up about 4 times - no better.

I closed Mach3 Turn and opened Mach 3 Mill and tried again - same result.

I went back to Mach 3 Turn and put in a speed and it came out spot on with the requested speed. Back to Mill - same thing.

You must have to close down and restart for the data to have effect.

959

General Mach Discussion / Re: Tribute to Art

« on: January 02, 2008, 09:26:47 PM »

I think it says - I don't know what all the fuss is about, we did it 2000 years ago. And ours are bigger than yours!!!

960

General Mach Discussion / Re: gcodes

« on: January 02, 2008, 09:24:40 PM »

Back to the Bat in question

I take it you start at the larger diameter, then as you traverse, the diameter gets smaller, and you want to increase the feed rate - for what purpose -  to get an even finish??   I take it these are aluminium bats, perhaps ( maybe showing my ignorance)

I think Overloaded has the answer. I take it the spindle speed of your machine is automatically variable.

If not you might consider a Macro written is Visual Basic
Something like                While Is moving
                                     Feedrate is proportional to X axis distance
                                     Code F etc
                                     Wend

(That is not the syntax - but you get the idea - While is moving is in the syntax - usually to STOP anything else happening. You can adjust the feedrate  by getting the present readout from the DRO (either X or Y I suppose) apply a multplier, and have the macro pump out the new feedrate.

You might prefer to do a Macro like this, because you can control all the various parameters. The is a Macro Tutorial (Scripting) which gives you the idea of how to do one.