Messages

401

General Mach Discussion / Re: How can I use subprograms in the subroutines folder?

« on: July 26, 2008, 03:05:37 PM »

M98 (nameofsubroutine.tap) - where the subroutine is in the folder.

402

General Mach Discussion / Re: Wiring motors

« on: July 25, 2008, 01:53:10 AM »

I use exactly the same motors.

The stepper motors have 8 wires - this means that they have 4 coils - two North/South and two East/West.

Your stepper motor driver boards only have four wires, so you must wire the coils together, the North/South together and the East/West tpgether.

You can do this by wiring them in series or in parrallel.
In series the motors will use less current - but not be as powerful. (Wire up as Kirsten says)
In parrallel they will be more powerful, but use more current. (see below)

These motors are rated at 2.5 amps at 7.5 volts - but that is for one coil. I use(d) 24 volts  to drive them, and wired them in series. The drives I used were rated at 2.5 amps. This got me going - but I later found that the motors would not give me enough speed.

I connected them in parrallel AC - A#C#  and BD - B#D#. The only trouble was that this method required about 4 amps to drive it and the drives were only 2.5amps. I changed to Gheko drives. The difference is fantastic - my speed before was about 4 ins per minute (steel cutting lathe), now I could get up to 40" per minute - a 10 times increase. I have settled in the high 20's for accuracy. I have now increased the drive voltage to 36 volts.

Just a quick word of warning - reading your post - the drives you have chosen seem to say they are PWM drive. Mach 3 does not use PWM control - it uses step and direction pulses to control the axis motors.
Before you buy them just check that they have a step/direction input to them - not a direction/PWM

403

General Mach Discussion / Re: G2/G3 codes and CV.

« on: July 25, 2008, 01:11:30 AM »

Now I have read the post, I'm not sure what you are after - whether you want Constant Velocity on or off.

With Constant Velocity ON as a line is coming to the end of a move, the next line is calculated, and is started before the old line is finished - and the net output combined to give a position that suits both (or suits neither). This leads to rounding of corners etc. I tried this on my lathe/mill and on an acute angle, the table was stopping nearly 30thou short of the line end.
Exact Stop is, as described, an exact stop, where the line is completed and the axis stops BEFORE starting the next line. In many applications, particularly complicated patterns where arcs are made up from many, many little lines, this gives a jerky movement. It is, however, exactly accurate.

There are several moves where constant velocity does not function - and G2 and G3 is one - becasue the axis co-ordinates for these moves are continually generated in Mach3 as the move progresses. I could see also where having constant velocity on would ruin a cut, and I would have thought that threading is one of them, since accuracy is called for.

If you want to make your lathe/mill smoother, then ramp down the acceleration on the motors. You can keep the max speed, but cut back on the gas - and make for a smoother run.

I have not adjusted my CV - I have left it at the default values. You may have adjusted it so that it is almost like exact stop.

I think the problam is with your basic motor acceleration.

404

General Mach Discussion / Re: Opto Isolation Inhibits Pulse Stream ?

« on: July 24, 2008, 12:46:46 PM »

You do not say what speed you are expecting these to work at. The Opto isolation is just another switch in the path of the current, and has a finite time to operate. The Dir is a relative slow pulse, whereas the Step pulse varies as to the speed of the axis. It may be that the opto chip has a fault on that particular path.

What happens with the other pins, you can configure Mach 3 to use any of the output pins. Is this the only one faulty, or is it more widespread.

405

General Mach Discussion / Re: input diagnostics

« on: July 24, 2008, 12:39:41 PM »

I'll do my explaining the DRO's blurb - it might make it a biy clearer.

The Digital Radouts show two positions for Mach 3.
If you click the Machine Co-ordinates button, the button surround will light. The DRO's are now showing Machine Co-ordinates. This is the system by which Mach 3 keeps track of where everything is. You cannot alter Machine Co-ordinates. The only way to change these is by the "RefAllHome" buttpn. If you have "Home" switches installed on your machine - and they have been activated - then the machine will visit each switch in turn, and stop at it. It will zero each axis DRO in turn as it does so. The machine now knows exactly where it is. If your Home switches are not connected up (and not activated) then you can press "RefAllHome" and the DRO's will zero where-ever the machine happens to be, but it is meaningless.

It is unlikely that this position will be of any use to you for machining purposes, and will almost certainly NOT be the position from which your GCode program has been written. This, for a mill, is usually (but not always) to the bottom left of the workpiece, with the cutter resting on the top of the workpiece.

If you click the "Machine Co-ordinates" button, so the light goes out, the DRO's are now displaying "Program Co-ordinates". These you can zero and if you do so, they will display 0,0,0, the same as the Machine Co-ordinates.

If you now jog your machine to where your program starts, you will see the Program Co-ordinates move, and when you get to the correct position, you can zero them again. The machine now knows where your program starts.

If you look again at the Machine Co-ordinates you will see that these have not changed - and they display the "offset" between your Machine Co-ordinates ad your Program Co-ordinates. If you look at the list in Config/Fixtures you will see that G54 has the same co-ordinates in it.

If you switch back to Program Co-ordinates, you can run your program, and the DRO's will show the position as it is written in the program - this is not how the machine keeps track of it's own position (which is a combination of Machine Co-ordinates plus offset).

What is the purpose of this -
In a professional machine shop, each day (perhaps more often), the machines are zero'ed with "RefAllHome or the equivelant.  The machines now know where they are. All obstructions, and fixtures are mapped in them to avoid collisions etc. When starting a program, the program will have in it an "offset" code G54 to G58, and G59P7 to G59P255, written in near the beginning. The machine then moves to this "offset" code and therefore sets itself for the particular job - and away it goes. As you can see - each job can start on a different "offset" depending where the workpiece is put.

You need not bother with all that. By all means "RefAllHome" but as I said, the DRO's will just zero, where-ever you are, unless your switches are set up. You need to be in Program Co-ordinates. To start with all you have to do is jog to the right starting position, zero the DRO's and press "cycle start" - and away you go.

To use Machine Co-ordinates and "offsets" you need to be very disciplined, and always work the same way. If you are writing programs and running them, they are not necessary. I use them on my machine, becasue I have a drilling fixture on the cross-slide that needs to know where it is, but other than that, I don't need them.

Hope this sheds a bit of light.

406

General Mach Discussion / Re: Mach3 Wave form??

« on: July 24, 2008, 05:09:40 AM »

Again - you are not giving much away -

what driver cards  are you using - are they stepper motors etc - are you using a three in one board, with a built in break-out board.

Many commercial cards have an "switchon/off" pin on them - make sure that is grounded or whatever. If you are still at the workbench stage, just connect up one motor to one driver card to your computer and do all your testing with that (the others are just more of the same). You can set up all of Mach 3 with just one motor - it is that flexible.

Things to watch for - Config/Ports and Pins/Motor Outputs - make sure the motor is activated, with the PORT and the pins correctly configured - port = 1 (Do not both about active/low/high at this stage. Set the "jog" keys for this axis. You should be able to jog the motor backwards and forwards.

Your frequency seems OK, I trust there are not too many noise spikes on your test. The led's you refer to seem to light up whatever you do. Stick at it.

407

G-Code, CAD, and CAM discussions / Re: Lathe Gcode

« on: July 23, 2008, 03:12:52 PM »

No, there is an on screen list. Look for the boxes "GCode" and "MCode" and click on them.

Most are self explanatory, but to get a better explanation, trying "googling" GCode and see what it comes up with. There are one or two articles for free that you can read. It usually gives the syntax for the more complicated ones.

THESE ARE SHOWN ON THE "MILL" SCREENS - NOT THE "LATHE" SCREENS  1024.SET. YOU COULD USE SCREEN 4 AND COPY THEM ACROSS

408

General Mach Discussion / Re: Tool height input and probe input together

« on: July 23, 2008, 03:06:17 PM »

All the probe, or your tool height plate do is send a signal to the computer - so you can set them up anywhere you like. The thing that makes the difference is what happens next.

If you are using the same program to measure your tool height as you are for your probe then there could be a clash if both use the same input. If the probe is just a switch, and the tool height fixture is just a switch, then there will be no problem - since both are open then one closes when it touches, then there is no feedback to the other.

If there are some electronics in the probe or the tool height fixture, there might be some feedback and in that case,I, personally, would use a Nand or an Or CMOS chip to combine the two signals - the cost is a few pence. The chips have numerous inputs, but only one output, and all you do is lead the inputs to the chip, and the output to the breakout board. The chip isolates the inputs, but as it's name implies if one input OR the other signals then it passes the signal to the computer. (The Namd chip is the same, but inverts the signal)

If you are using a seperate program for your two sensors, then use seperate pins as inputs and configure accordingly.

409

General Mach Discussion / Re: Z axis home/limit problem

« on: July 23, 2008, 04:05:26 AM »

The way the switches work is different when it is used as a limit or as a home switch,

Whe it is a limit switch, the switch closes (or opens, depending how you have them wired) and triggers the "limit", and as you say, activates the e-stop.

On a home movement, what is supposed to happen is that the switch closes, then the axis reverses and the switch opens again - which triggers the "home" .

What is happening is that your switch is noisy - i.e. it is making a poor contact - and when the axis reverses, the switch appears (to the computer) to open - completing the move> this only takes a millisecond. In actual fact, what has happened is that your switch has opened for a fraction of a second and then closed again - and when the computer reverts to checking the ";imit" switches it finds this one still closed and triggers the limit.

As Hood says try adjusting the de-bounce on the switches (this is a "repeat" time the computer looks at the switches to make sure they are where it thought they were), and another thing to try is the speed at which the "home" movement takes place. This is set as a percentage of max speed. If you are having trouble, set it a little higher and the switch moves a little further "open" so avoiding re-triggering the "limit"

Another thing to check is - is there any spring return on your Z axis. I had a very strong one on mine, and had to "derate" it to get the movement working to the satisfaction of the computer.

410

General Mach Discussion / Re: input diagnostics

« on: July 23, 2008, 03:46:34 AM »

As Hood says - you don't give a lot away.

I assume you have your home/limit switches wired up on your machine.

If you do not have the switches wired up, all that will happen when you RefAllHome is that the DRO's will go to zero (if they are activated)

I f you have the switches wired up, it depends what signal they are sending back to the computer when they are "activated". If the signal is +5v then they are "Active High" , if it is 0v, they are active low. The configuration of the switches on Config/Ports and Pins/Input signals must correspond, otherwise they show active when they should be off, and vica versa.

The diagnostic page (or the LEDs on the front panel) only show the sate of the switch - i.e. whether the computer considers it "active" or not. If they are lit all the time then you have them configured wrongly.