Messages

201

General Mach Discussion / Re: New Member Needs Help

« on: December 28, 2008, 05:33:29 AM »

Jim - I looked at this yesteday, but thought that I knew nothing about lasers ( the cutting/engraving type) so I would leave it alone - but nobody has answered.

Mach 3 is perfectly capable of controlling what you are doing. It can certainly move you table with the work on, in the correct manner, and there are many outputs avaiable to switch your laser on and off at the correct time.

There was a post a few weeks ago about delay on the M3 (spindle motor on command) which someone was using as a laser trigger, but that was resolved. You have a choice of already written on/off routines M3,M4,M7 and M8, which switch relays on and off, or you can write your own macro.

There are also a number of people engraving "circular" objects on rotary tables - Mach 3 can do it.

I don't really know, but I think it would be a simple job, if you can buy a commercial laser for engraving, then fit the business end to the spindle of your machine and away you go.

There are a number of programs ready written for engraving work, and I am sure there will be one for lasers.

202

General Mach Discussion / Re: Hall RPM sensor

« on: December 28, 2008, 05:21:20 AM »

Forget the welding and the cleaning - Happy New Year.

203

General Mach Discussion / Re: 2 Questions

« on: December 28, 2008, 05:14:10 AM »

Ray - Yes you are right, and I could not think of circumstances where you would use offsets., but never-the-less I feel it is a good idea to understand the relationship between machine and program co-ordinates, when it comes to using them.

You could, of course, make your own "home" without having  switches fitted - i.e. a place where you can put the table with some repeatable accuracy - and then zero the machine co-ordinates.

I must admit, I am in a quandry on the lathe. I home my machine - but where then to move to. x axis is down the centre - that is easy, but the z axis

Do I have 0 position at the chuck - (if so is it right at the chuck, or about 10 mm off, so a parting tool can get in behind), or is it at the opposite end of the workpiece. That one I will have to ponder.

At least the X axis is fine, and my centre drilling fixture works a treat.

Dom't worry Bob, just an old man ruminating at Christmas - and the best to you all in the New Year.

204

General Mach Discussion / Re: 2 Questions

« on: December 27, 2008, 03:36:55 AM »

Bob -

The machine needs to know where it is before it starts. It keeps it's position in Program Co-ordinates which are displayed when the program co-ordinates led is lit. To this it adds all the various offsets for programs and tools etc, so the tool arrives at the right place at the right time.

On commercial machines, the first job of the day is to "home" the machine - done in Mach by selecting the various home switches. The machine will move to a position that it knows is 0.0.0 in machine co-ordinates and set the DRO's accordingley. It is now "home" . The home position is probably not any good for machining from, and will certainly not bear any relationship to the 0.0.0 position the program is written from - so each program then has an "offset" written into it, which brings the machine to the correct position to start work on that program.

If you do not have home switches fitted and activated, Mach has been written so that your machine co-ordinates will zero at any position.

You should, therefore, move your machine to a suitable position to start your program, and this is normally (but not necesarily) the 0.0.0 position of the program you are about to run.

The safest way to proceed is then to press "machine co-ordinates"  so the button is lit. The machine is now displaying "machine co-ordinates" and then press "RefAllHome" This will zero the machine co-ordinates. Then press the "machine co-ordinates" again, the led should go out. The DRO will display "program co-ordinates" This could be 0.0.0 or could be a random set of numbers from your last job.

Zero each DRO using the zeroX, zeroY and zeroZ - the DROshould again display all zero.

You now have the Machine Co-ordinates and the Program Co-ordinates all singing from the same hymn sheet, and you can start your program run.

Why so much fuss - if you do not have both sets of co-ordinates in a fixed relationship to each other (here they are identical - which is the simplest relationship - i.e. the offset is 0.0.0) then any offsets in your program will not necessarily work correcty, and you will be left wondering why.

There is nothing wrong with starting like this, I have home switches on my lathe, but for some "one-off" jobs, it is easier just to get on with it rather that worry about all the offsets using the homing switches. Fitting home switches is something you can tackle later - if you feel then need to do so.

If you look under Config/Fixtures you will see a fixture table. This has from G54 to G58 then another 250 or so from G59P7 upwards, which allows you write a lot of programs, each with it's own start point. If you were in a long run, and closed overnight, when you came in the morning you would zero your machine and press "GO". The machine would pcik up the offset from the fixture table, move to the correct position for that program and get on with it, without further ado. Some porgrams have the same series of instructions, working from different "offsets" if cutting say, patterns out of a large area of material.

These offsets mgiht change during the day, so when Mach shuts down, it saves all the current fixture list, so it is ready for the next day.







 

205

General Mach Discussion / Re: Hall RPM sensor

« on: December 27, 2008, 02:53:43 AM »

Nice job.

Christmas job for me - ball screws.

Cross slide is done - speed up from 20 in per min to 1000mm per min without effort, will probably go higher. Since I only have about 10 inches total movement, thats fine.  No measurable backlash I can detect - I'm having another look at that today. (Now in mm, please note Hood)

Just the lead screw to do - but I can't turn it because my lathe is in bits - will have to wait for a friend to recover from Christmas.
Huh - some people !!!

206

General Mach Discussion / Re: Tool numbers and lengths

« on: December 20, 2008, 04:05:16 AM »

Sorry - I didn't read the GCode before replying - and so missed the fact that new co-ordinates are given for each spindle. If you include the spindle offsets in the tool table, the machine will take these up as well, and save you having to write them.

I have a drilling feature on my lathe. The offsets and lengths in the tool table are such that the tool ends up on the centre line of the lathe, with the tip of the tool 2mm short of the chuck (which is my Z0 position)

T0101 (or any tool number)
G0 X0 Z0

would bring the tool to that position. The only thing I have to alter is my Z position to allow for the length of the job.

207

General Mach Discussion / Re: Spindle revs out of control

« on: December 20, 2008, 03:52:35 AM »

As KTM says, you do not say what system of control your machne uses. I had trouble with mine, which uses the PWM signal through a digispeed - giving a 0 - 10v signal to an Omron Inverter.

The trouble is each part of the system depends on the one before being spot on. I managed to buy an oscilloscope - which ran through my PC. This was extremely cheap - about £30. It will monitor two channels, on a range of 0 - 15 volts input.

With it, I could trace the signal coming out of the PC (PWM) and right through the system up to the Digispeed. I don't have a breakout board as such, but the changes in polarity going through some breakout boards are difficult to trace.

With an oscilloscope, you can see the waveform change as you put in S commands. I eventually found the PWM signal was inverted when it reached the Inverter. This meant that when the spindle switched on it went to full speed, instead of staying still, and never did get to the proper speed.

I soon got it sorted out, and it works fine now. (Apologies to our friend in Australia if I gave the idea there was something wrong with the Digispeed.)  

208

General Mach Discussion / Re: Tool numbers and lengths

« on: December 19, 2008, 01:46:57 PM »

If you look on General Config, you will see that you can alter what action Mach3 takes on a tool change.

The default is "Ignore Tool Change". If you type in the M6 followed by T*** and alter the config - in your case I think I would use the "auto tool changer" option, becasue the other alternative stops the machine to let you change tools.

If, on your tool table, you put in accurate offsets for the three spindles, along with the tool lengths, the machine should then move to the new spindle.

209

General Mach Discussion / Re: Screen 4 - What am I doing wrong

« on: December 13, 2008, 01:48:31 AM »

Thanks for all the suggestions - I will persevere.

210

General Mach Discussion / Re: Help Getting Started

« on: December 10, 2008, 07:57:21 AM »

Bobby Don - you are not saying a lot  apart from something abot a 30 yr old lettering machine.

You say you have a CNC. From that do you mean you have bought a lathe or mill fitted with gear to run as a CNC machine. If so what is it, and what is the laptop you are trying to run it with

We take it that you are trying to run this machine using Mach 3 on a laptop P.C. Is the lathe/mill already hooked up to your PC, if so, how. Is it using the LPT1 port, or a Smooth Stepper or what. Or is it a system that comes with the lathe/mill and just uses Mach 3 as the software.

As has been said some laptops are poor. This is becasue, to keep down costs, manufacturers have certain functions shared, and Mach 3 needs a substantial amount of basic processing to generate the drive pulses for a system (which have to be correct and in real time). A good laptop - such as my Toshiba - which was fully functioning - will run Mach3, and mine only finally baulked when I tried to rig up a video camera through it as well. I now use it to run an oscilloscope program, and use a tower for the lathe/mill.
The video camera (which has software in Mach 3 for positioning) works fine through my tower, showing the additional capability.

You would probably be able to run a laptop, and use a Smooth Stepper interface (through a USB port). Smooth Stepper generates many of the timing and driving pulses required by Mach 3 (as well as giving additional input and output ports) and leaves the laptop for basic control and computing functions.

Give us a bit more information, and we can advise you what to try next.