Messages

221

General Mach Discussion / Re: Auto Tool Zero

« on: December 03, 2008, 11:16:55 PM »

Your little scenario was OK up to a point - but the computer would see a high signal  (the Bob reverses the signals) and would need to be active high.

I DO NOT understand the Ground from 5v supply to machine. If you are meanig a lead from the Bob 0v to your machine, then yes.

222

General Mach Discussion / Re: Auto Tool Zero

« on: December 03, 2008, 11:09:49 PM »

I take it what we are talking about here is the probe facility.

In the computer, whatever pin is allocated to your probe is normally kept high (5v) by the internal resistors in the computer. On the CNC4PC Bob board Arturo has seen fit to reverse these - so by the time you see the pin at the Bob, it is showing 0v.

Check that and see if I am correct - I think I am but I am not sure.

If you are using a copper clad pad, or similar as your touch plate (connected as you seem to say to pin 13) then what you need to do is put a +5v signal to it - not ground (0v) - why mess about with resistors.

Just try this with the diagnostics page on, and, if you touch your pad with a 5 volt lead, you should see the Digitise LED light up.
If it does, then all is working.If it is on then goes off, reverse the "Active Low"

You now have a dilema.
I personally would make an insulated probe of a fixed length that I can put in my chuck, with a +5v lead to it and use it that way.

However, what Arturo is saying is that you need to bring the plate up from it's 0v base to +5v (i.e. it is "on" all the time) then reverse the settings on Ports and Pins to active high - so the computer thinks it is off (because the computer sees it as low) . To do this he is suggesting putting the 5v to the plate through a 220ohm resistor. What would happen then is the tool comes down (and we must assume the tool is at 0v), touches the plate, pulls the plate down to 0v and gives a signal to the computer like that. It is one of the drawbacks of the CNC4PC board.

What I would do (which is even simpler) - and which I have done on mine - is take a lead from pin 13 BEFORE is goes into the Bob electronics, if you can get to it. Take this to a small socket on your electronics box.(a mini jack plug will do). Make up your plate with a wire and plug to fit the socket, so that when you want to use it, you can plug it into the socket  and put it in position on your machine. Bring the tool down (which is normally at 0v - although check there is a return path) touch the plate. This will register, then you can move the tool up and unplug the plate.

Using the socket ensures there are no loose wires floating around when not in use.

 Hope this helps.

Jim Pinder

223

General Mach Discussion / Re: A axis speed limiting in Tangential Mode

« on: December 03, 2008, 10:16:59 PM »

The motor on your A axis would seem to be the trouble.. When I was setting up my system, I wired my eight wire motors in series (I didn't know any different) and I could only get 4 inches per minute out of them before they missed steps (they didn't just miss steps, they stopped althogether).

I rewired them in parrallel and the difference was astounding - straight up to 40 inches per minute. I wound that right back for reliability but I can still get 20 inches per min out of them - reliably. Not up to your speed, perhaps, but this is a steel lathe I am talking about.

If your A motor is eight wire, in series, try it in parrallel, your Gecko will take it. My drivers were 2.5amp until I went onto Gecko, but even on that, performance was must better in parrallel than series.

My motors were rated at 2.5amps per coil (at 7.5v). With the Geckos  I have increased the current set to 4 amps,(feeding two coils in parrallel) and just lately put my voltage up from 24 to 36 volts. The motors will get hot (remember they are on all the time, even when not moving) - but if you can touch them, that's fine, if you can put a hand on and keep it there they are running cool. Reliability has improved tremendously.

224

General Mach Discussion / Re: plasma on off

« on: December 03, 2008, 09:59:26 PM »

To see if you have the thing configured correctly, turn your computer off and then run it back up. Check the voltage on the two pins. This is the signal at rest. Now switch the signal using the MDI line - just a single command M7.

Your M7 pin should alter status - if it was 0v it should be 5v - if it was 5v it should be 0v. If it has not moved, then your configuration is wrong.

Allocate M7 to an Output say #3, (Ports and Pins/Spindle setup) then allocate the output to a pin.(Ports and Pins/Output signals)
Do the same with M8 using #4

M7 should turn one on, M8 should turn the other on and M9 should turn both off.

225

General Mach Discussion / Re: Mach3 skips to subroutine, crashes Z, ruins part :(

« on: December 03, 2008, 09:49:08 PM »

I would also steer clear of using G54 in normal use - this is really a default.

Use G55 and G56 etc.

Did you check your offset table after these things had happened.

You seem to be saying, however, that everything has been working just fine for some time, but suddenly a fault has developed. Have you altered anything in the computer recently or altered the run of cables or anything similar.

226

General Mach Discussion / Re: what am I doing wrong?

« on: December 03, 2008, 09:38:47 PM »

If it is Feed you are talking about - i.e. F command, the only thing to check is that you have not set it, then changed units, because the Feed rate does NOT change. If you set at 100 in millimeters,(G21) then changed to inches,(G20) the feedrate would stay at 100 (inches) - and go 25 times faster.

I'm lucky - I am set up in inches, so if I forget to alter the rate, everything slows down

227

General Mach Discussion / Re: how to skip ahead on tool path? newb need's help

« on: December 03, 2008, 09:32:38 PM »

Yes - Unfortunately if you are using a program with a number of subroutine calls, the Code window does not show the Sub Routine until it is called, therefore the "Run from Here" is difficult to implement.

What you do not say is if the Sub-routine calls are all to the same sub-routine or not. I was running a program a few weeks ago that consisted of 10 calls to different subroutines, each subroutine being about 450 lines long, but they all started where the previous one left off.

If you are just calling a the same sub-routine then you should know what it is going to do - i.e. where it is going to start, and position your axis in an appropriate spot. What you need to do then is pick a line in the MAIN program just immediately before the call to the sub-routine, that positions the three axis (say a G0 move) and run from there. The difficulty will be if your program is just using positional information, rather than the full G0 or G1 instruction, because the machine must have a full line of code if it is to start reliably.

The machine will pick up it's position, then jump to the sub-routine. I suppose if it is a long sub-routine, rather than repeat it all, you could then stop (NOT an E-stop) with a controlled stop, and then advance through the sub-routine (the machine will have retained it's positional information) which will by now be showing on the window, to a more appropriate position and run again from there.

It seems a bit messy, but that is the only way I can think of.

228

General Mach Discussion / Re: plasma on off

« on: December 03, 2008, 09:12:23 PM »

M8 will not turn it off, unless you alter the program.

M9 is the turn off for M7 and M8

229

General Mach Discussion / Re: A axis speed limiting in Tangential Mode

« on: December 03, 2008, 05:42:02 AM »

The question is, why is it loosing steps.

Is it becasue you are indeed, trying to push the speed too fast, or is it the fact that at that speed, the pressure/drag is too much for the motor. Here is the dilema - because the answer to one is the opposite to the other.

If you want speed, but there is no appreciable pressure or drag, then you need to cut down your steps per unit. I don't know what drive is on the cutter, but can you change the gearing. I don't know what accuracy you are looking for, but the standard stepper motor is 1.8degree per step so a 2 to 1 gear would give you 0.9 degree - is this enough. A 3 to 1 would give you 0.6 degree and therefore the small changes would only require a few pulses.

If however, it is pressure and drag that is causing the problem, then the opposite is the case, and you need lower gearing to give greater torque to drag the whole cutter head round quickly.

Reading your post again - you say it looses steps over a large file run. I take it this is large number of the same pattern. Is it possible to incorporate a "return to zero" move either at the end or the start of a run, so that any missed steps would only be cumulative for the one cut.

Jim Pinder

230

General Mach Discussion / Re: PWM spindle control - Smithy 622 - Help Please.

« on: December 03, 2008, 05:20:40 AM »

Yes - you are making a mistake.

Firstly - does you motor control require a Pulse Wave Modulation signal, or Step and Direction signals. I do not know, but looking at your config, you have both set up.

Mach 3 can put out either. In the case of PWM it puts out the normal forward and reverse signals on the allocated M3 and M4 pins (off being M5). The PWM signal is put out on the "Step" pin of the spindle output. The PWM signal is converted by such a board as Digispeed, into a control voltage (usually 0 - 10v) and fed into your inverter.

The step and direction method is like an axis - and the spindle output pins are used.

On your ports and pins/engine configuration you are showing PWM selected, but you seem to be set up for step and direction on you spindle output page

If you are using PWM, you cannot have M3 (clockwise) and M4 (anticlockwise) allocated to the same pin because you will not get any change in direction. If you are using Step and Direction, leave the "disable spindle relays"ticked, you are not using them.