Messages

231

General Mach Discussion / Re: Parallel port trouble!

« on: December 03, 2008, 05:01:55 AM »

The Mach 3 you download is identical to the one you buy, and will operate a fully functioning CNC system. I am still using the downloaded version. There are restrictions, of course, for example, only 500 lines of code at a time can be run, and I think there are other shortcomings with threading. All that happens when you buy a licence is that these restrictions are taken off. I don't think you even have to diisturbe the downloaded version.

Download Mach 3 with the driver and install in as per the instructions. There is no restriction in XP and if the driver installs properly it should work fully. I would use the latest lockdown version.

I did come across a couple of weeks ago a restriction in the Bios of my particular computer, where the LPT1 port had for some reason, become disabled. I switched it back on and everything was fine again. I would try the computer with an old fashioned LPT1 printer (if anyone still has one). If the printer works, there is no reason why Mach3 will not.

The leaning at the moment is towards a Smooth Stepper, which has a USB connection to your PC, and controls your machine. I suppose this brings us into the modern era - but - no - the old system still does work.

232

General Mach Discussion / Re: plasma on off

« on: December 03, 2008, 04:45:24 AM »

Spatch - Nobody seems to have asked what turns your plasma on, and what delay you need  - or - indeed, what system you are using.
If you are using the output from a PC - via your printer port, then Mach 3 can put out on/off signals on various pins to turn thngs on and off.
The standard printer port is three ports in one. Pins 2 to 9 are an eight pin output, Pins 1,14,16 and 17 are outputs and Pins 10 - 13, and 15 are inputs. If you are using a different interface, such as a smooth stepper, these will differ, but you should have the documentation for that.

Is is normal (but not necessary) to use the outputs 2 - 9 to control the axis - each axis requiring 2 wires. If you are only using 6 of the wires, you can use the other two for something else. We can consider than you might have pins 8,9,1,14,16 and 17 spare as outputs. These can be allocated on Mach 3 to various functions.

If you go into Config/Ports and Pins/Spindle Setup you will see, on the left hand column reference to M3,M4,M7 and M8. These can be indirectly allocated to pins, so that when GCode M3 is used, the pin for M3 goes high (or low) and similarly for all the others. To turn off M3 and M4, an M5 command is used To turn off M7 and M8 an M9 command is used. These outputs are allocated to outputs #1 to #6.

If you now turn to Config/Ports and Pins/Output signals your outputs can be allocated to pin numbers on your output port.
The signal from this output pin should then drive a relay, which in turn can drive whatever application you want. I have four outputs, all driving 5 volt relays via a Darlington array. From these relays I drive my spindle inverter, and (if I ever get it going) my coolant system.

The use of the M3, M4, M7 and M8 are not compulsory, there are other ways of driving outputs, but they are well know Gcodes - you are merely using then for a different purpose to that intended.

If you can identify from you GCode what signal you CAM program is putting out to turn on your plasma, then you can configure the appropriate output on Mach 3, and wire a relay into the system to turn your plasma on. Bear in mind it is a different Code to turn off.

I don't know if this is what you were wanting.









 

233

General Mach Discussion / Re: Limit switches

« on: November 29, 2008, 06:03:08 AM »

You don't say what switches you are using, but to get over this bounce problem, try replacing them with optical switches of some sort. Mine are laser detectors, fixed at the limits. I have two lasers on the carriage, and when they shine on a detector the detector sends a Ov signal to the computer. The lasers were £10 each and the detectors were in the order of £1 each (possibly less, I can't remember) The beauty about it, there is no big mechanical obstruction on your lathe bed to get wiped out, and you can, if you wish have both homing and limit detectors run by each laser.

The detectors are schmidt trigger types, which give an instantaneous signal (no bounce), and I find the accuracy very good, even with cheap non-focused lasers (to less than 1 thou).

I had some pictures, but have lost them - if you would like to see the idea, I will post them again.

234

General Mach Discussion / Re: making parts to size on customer prints

« on: November 27, 2008, 03:15:07 AM »

Rich - yes - that is what I anticipated I would get, but, as I say, I kept getting the original without the comp. I notice you are using  a Px.********* command after the G41/42. Does G41/42 not pick up the cutter diameter from the tool table, or do we have to add this each time.

I was trying to use the tool table.

235

General Mach Discussion / Re: making parts to size on customer prints

« on: November 24, 2008, 02:52:27 PM »

I will put my hand up and admit, that after I wrote my last post, I went into the workshop to try it, with a pen in the spindle chuck. No matter what I put in, in what order, I was still getting the pen to describe the arc, circle, or line, without any compensation. I am at a loss.

If you look on the GCode tag on the milling 1024.set, there is now a description of many of the  codes, including 41 and 42

Rich - gives us a clue in what order to put the code in. Does it only work in a GCode program, or can you access it from the MDI line. The codes at the top of the display change as you enter them.

Are there any settings in Config that I am missing.

236

General Mach Discussion / Re: making parts to size on customer prints

« on: November 24, 2008, 04:12:24 AM »

If you are experimenting, you must remember that Mach 3 must run into cutter compensation, In other words, it is no good lining up your work, then switching on cutter compensation and expecting Mach 3 to jump to one side or the other to apply the compensation.

If you are cutting, say, a circle in a plate, then start at the circumference of the circle (without cutter comp). Your first move should be to apply cutter comp - G41 or G42. The second move is move round the circumference of the circle a short distance - say a quarter turn G2 or G3. This is the move that Mach uses to apply the compensation. The third move should be then to cut the circle, drop z, then   - G2 or G3 Bear in mind that the tool table must have the cutter diameter, and the correct tool must be selected.

G41 and G42 depends on whether you are using G2 or G3 (which direction your tool is travelling) and whether your tool is inside or outside the circle.

Try replacing your cutter with a felt tip pen, and drawing it out on a sheet of paper, you will be able to see the different paths, particularly if you try doing the circle first, then using compensation. The way Graham drew it, I am quite sure he has it in his head as a fixture, but to us lesser mortals, it could be a good reminder to then pin the diagram on the workshop wall.

237

General Mach Discussion / Re: making parts to size on customer prints

« on: November 24, 2008, 03:59:18 AM »

Cutter compensation is one of those subjects that comes up very regularly.

Yes, you are quite right. Using cutter compensation yOu should be able to program the machine to cut as per the drawing, and the machine should then make allowance for the width of the cutter, according to the tool table.

If you search this forum, a complete explanation with diagrams was given by Graham Waterworth as to how it should be applied, i.e. left or right hand, depending on what result you wanted to achieve.

Having said that - and I am sure someone will tell me - HAVE WE LOST THAT WHEN WE UPGRADED THE FORUM - ANYBODY??

238

General Mach Discussion / Re: centering cross hairs on video camera

« on: November 23, 2008, 04:07:19 AM »

Thanks gents, I've got it all sorted now. As Ray said, it was off so I moved it by hand until the crosshairs lined up with my target, and it was spot on, even when turned round as Zarzul says.

My vertical movement is limited (a milling attachment on a lathe), so I simply mixed some araldite, and glued the camera into the housing - (adjusting for centre before it set) - with the camera at it's highest point (about 2.5 inches).

It certainly makes it easy (and much quicker) to centre the spindle at the start (0,0) position of programs - put in the camera, jog to the start position, zero the DROs and away we go.

Thanks for the help - Jim.

239

General Mach Discussion / Re: centering cross hairs on video camera

« on: November 20, 2008, 02:39:23 PM »

Yes - thanks Ray - now you have said that, I've had another think   

240

General Mach Discussion / Re: centering cross hairs on video camera

« on: November 20, 2008, 10:23:14 AM »

Rich -
 Yes - I've thought about this - AND - as far as I see it, the problem in machining the housing is that you could be off centre with it. My housing fits in the milling/drill chuck. So > I put a small drill in first, and drilled a target hole in the workpiece, then swapped the drill for the camera.

The picture I get is the target hole, but the cross hairs on the screen are  off to the left  (not a long way - but say 5mm - it is a bit hard to tell becasue I don't know the magnification).

If I spin the chuck manually with the camera in, the picture turns - not about the cross hairs - but about my target hole. Therefore my camera seems to be aligned with the spindle, but the cross hairs are not. If I move the camera, it won't be aligned with the spindle, it seems to me that it is the cross hairs I need to move - but how.

Jim