Messages

291

General Mach Discussion / Re: Mach 3 Questions

« on: October 01, 2008, 02:31:56 AM »

I prefer a non-powered breakout board, i.e. one that is just an easy way to access the wires from the LPT1 socket. However, the latest thing is the smooth stepper, which I have not used, but many swear by them.

This is a USB driven breakout board, (you just plug it into the USB port on your computer) and it provides all the signals for the axis, plus input and output lines for switches, spindle control etc (far moroe that you would get on an LPT1 port - which only has 4 outs and 5 ins)

Yes - I was new to CNC when I started with Mach 3, and I found it easy to use. It appears very flexible ( i.e. it con be configured many different ways for different application) Therein lies the rub - more flexibility means it is more complicated than a plug and play system - but if you take it bit by bit, it's easy enough.

AND you've got this forum   

292

General Mach Discussion / Re: MACHINE "Zero" with Button

« on: October 01, 2008, 02:19:55 AM »

The only way you should be able to "zero" machine co-ordinates is if you have the home switches in the off position on the Posts and Pins page. Are we sure they are all properly labelled.

293

General Mach Discussion / Re: Mach 3 Stepper motor Settings, Little help needed please!!

« on: October 01, 2008, 02:13:04 AM »

The workbench is as good a place as any to get the bugs ironed out.
The first thing to do is make sure your drivers do not deliver more current than your motors can take. Check to find out the ratings for your motors, and then see if your driver cards can be limited to a fraction under the rating.

The voltage does not matter (and 40 volts is not excessive). My Geckos can be limited - 7 amps max, I have mine limited to 4 amps to drive my motors ( 2.5amps per coil - wired in parrallel). My third driver is a Routout CNC driver (from UK) which I had originally. This is a 2.5 amp driver on the Z axis and I have also noticed, when idle, that it hisses. I put it down to being slightly faulty (although it works well enough) but it may be that it is working up near it's maximum and this is the current limiting noise.

As far as speed is concerned ( and I take it you mean velocity in Config/Motor Tuning) then you can set this up fairly accurately if you know your gearing, and leadscrew pitch - you must have some idea.

Set the steps per inch first, and I am not going into that scenario again, there are enough posts on here. Your default driver card setting is standard - 200 pulses for the motor, and a microstepping setting of 8 = 1,600 per rev. If you are connecting the motors direct to your leadscrew then multiply by the number of turns the leadscrew requires to move the table 1 inch, and you are done. Mine is 10 so my answer would be 16,000 steps per inch. (I also have a 3 to 1 reduction so my real anwer is 48,000, but reduction depends on whether you are looking for speed or accuracy)

Once you have set you steps per, then you can set up the speed, and you must have a target that you want to reach. Yes, without load the motors should get there well enough, but it is nice to see them working at the correct speed, and it may be that there is some other reason that they don't - so try it. Acceleration is the other setting and leave this at 1 for the moment.

If the motors work well at your required speed, then increase it gradually until you get to the point when they start stalling. This is your maximum (well a little below that) - and you can increase the acceleration as well in a similar way.

At least when you put the motors on you will have something to aim at.

To listen to the music,  do a g2 or g3 over a 4 inch radius and it is facinating to watch the motors accelerate and decelerate in turn.

As has been said, motors get hot under load, and remember, unlike ordinary motors, they still have current going through them even when idle. Some driver cards reduce this to stop the motors getting too hot, which is why I said check your current output. As has been said 85 degrees is acceptable, and that is too hot to touch, so if you can put your hand on and keep it there you are OK.

294

General Mach Discussion / Re: Arc problem ?

« on: September 28, 2008, 02:08:39 PM »

This might not be the right answer - BUT - on G3 and G4, I thought I and K were offsets from where you were - therefore they will be a different position on every cut, because in your program they are all the same offset. They are not, as far as I know, the centre of rotation, which is what you seem to have programed them as.

I don't know, because I always use the "R" parameter with G3 and G4.

295

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: September 28, 2008, 01:58:19 PM »

Well, I suppose 6 thou is pretty good!

296

General Mach Discussion / Re: program quits at 5K line every time

« on: September 27, 2008, 02:13:41 PM »

Are there any premier golf courses near Carnoustie 

297

General Mach Discussion / Re: program quits at 5K line every time

« on: September 27, 2008, 02:12:23 PM »

Mike - I have this problem when using my download version to run some copper clad etching programs which often go to several thousand lines. When I download them, they only load to the 500th line - you can see that in the download window. Another dead giveaway is that the toolpath diagram does not show the whole cut, (only the first 500 lines).

If you say you have purchased a copy of Mach 3 this should now open up to do the complete number of lines.

You can, if you wish, test this by cutting 450 line chunks out of the program using notepad and adding M99 at the end.
If you just do a couple say, using "save as" name them p1 and p2 and file then in the "subroutines" folder. In your main program, where you cut them out, type in M98(p1.txt) and M98(p2.txt) and load that.

You should find that your Toolpath display now displays about 1400 lines of the code - two 450 line subroutines and the 480 or so lines after that. I am not suggesting that you do all the program like that, it would be far to taxing, put it will point to where the problem is.

298

General Mach Discussion / Re: AXYZ CNC router conversion

« on: September 27, 2008, 01:57:30 PM »

What you need to do is find out what controls the axis motors (you mention a "step" motor, but you don't say what it is one) and what controls the spindle motor.

Mach 3 puts out step/dir pulses on two wires to each axis. These normally control driver cards e.g. Gecko, which convert the step and direction pulses into on/off signals for each phase of the motor. If this machine already uses stepper motors for the axis, then (providing they are CMOS/TTL compatible, you can probably control the driver cards directly from a computer output.

The spindle is different, in that Mach 3 can output two different signals - one is step/dir as above - but acting on the spindle controller, the other method is a PWM (pulse wave modulation) waveform which can be converted into a speed signal voltage to drive an inverter or similar, and the reversing is taken care of by outputs on the spare outputs wires (one wire is "on" for forward, one wire is "on" for reverse)

What you do not mention is what computer the client will be using, and what outputs it has. Probably the best way to go these days is with a cheap laptop, and a Smooth Stepper output board, which plugs into a USB port - and provides all the outputs/inputs for the various mach 3 functions.

299

General Mach Discussion / Re: Auto tool zero - touch probe - please help

« on: September 27, 2008, 01:45:02 PM »

The probe function on Mach 3 is fairly straight forward.

The tool is earthed, and when the function is called, the Z axis moves down until the tool contacts a pad, (connected to the "probe" input) and then it stops.

Tool change facility, and the system for writing scripts to control it is subject of a video - see "scripting" . This shows you how to write your own script to make the tool do what you want when you call a tool change.

What you clearly need is to write a script that moves the tool to a position for you to change it, then wait til you change, then move to the pad and drop the tool to get a reading, then change the DRO to a set figure, and move back to where you were.

It sounds a lot, but when you get into it , it is relatively simple. The problem is that everybody 's tool change is different so it is a problem to write one to suit all.

300

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: September 27, 2008, 01:11:37 PM »

This is a lovely post - you can have some time off - and it is still going when you come back 

N2airz - John - you must understand what constant velocity is - here the next line starts to accelerate as the last line decelerates to a stop, so yes - they will stop short - every line will stop short (except the last one).

Yes - the only way to stop this is to use Exact Stop. Here the previous line is completed and one (or both or all three) axis come to a stop before the next line begins, therefore all axis complete their exact travel.

Jon Messenger - If you are doing 1000 ipm, then what is your pulses per inch set at. The problem is your pulses per inch count for accuracy and if you miss some, then quite clearly the fewer pulses per inch you have, the greater the error. Similarly, when you are running two (or three) axis simultaneously, all three axis are related, in that the axis moving furthest moves at the set speed, and the other axis move at a slower speed so thry all complete in the same time, the pulses being calculated on the fly/ It stands to reason the the pulses on the slower axis will be truncated more often than not, unless the divisor is a whole number. Again if your pulse count is low, there is the chance that your motors will loose steps.If you are doing one long cut, then this might not be a problem, becasue only one calculation will be made per line, and if that line is 12 inches long, then the error, if there is any over that distance will be minimal.

If your V carve or whatever is made up of many many little straight lines, then the possibility of one or the other axis being truncated is very real. My normal programs are about 100 - 200 lines long for milling or turning steel. Imagine my suprise when I found a program I was using to cut copper clad electronic boards was generating 20,000. I am experimenting and judicious use of the parameters has cut this to 6 - 7000. This means that even on a short cut, the program is truncating one or the other axis many times.

My steps per unit is 60,000 so I have 60 steps (including microsteps) per thousanth of an inch - so I do not see accuracy as a problem.