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Messages - jimpinder

1041
General Mach Discussion / Re: How do I configure Mach3
« on: November 11, 2007, 02:18:49 PM »
If you go to the configure menu it is all there - how to configure Mach3. You can configure your axis, your backlash, -  indeed all the machine.

Specifically for the axis Mach 3 needs to know how many pulses per inch or mm your steppers needs. This depends on how you have set up your machine in the "Set Native Units"...

You must then set up your "Ports and Pins" - to tell Mach3 which wire from your Printer port runs which axis for step and direction

Finally - you must "tune" your axis motors. Enter the number of pulses your motor must have to move your axis by one ??.
Some steppers cards are on 1/8 step drivers - and each step moves 1.8 degrees - so your could be on 1600 just to turn you motor by 1 revolution. If that is geared down to your axis - mine are 3 to 1 - then you are up to 4800 - and if each leadscrew has to turn 10 times to move say 1 inch, then you are on 48,000.

You can then set the speed at which your axis can move per minute - this depends on your machine - start low and gradually increase it until your motors start to stutter and miss steps. You can increase and decrease the acceleration as well, to get the best performance.
This is the speed for your G0 moves. Your jogging can also be at that speed. Remember what speeds up must also slow down, so do not run to the end of the axis and hope that it will stop from full speed to zero instantaneously.

You cannot really damage a stepper motor. They are designed to stall with power attached - indeed that is how they work. If you put too much load on them they will miss steps instead of turning. You can overheat them , apparently by using too low a voltage as well as too high a voltage - so stick to the voltage recommended on your driver cards, and set the current limit accurately.

1042
General Mach Discussion / Re: Lathe Threading
« on: November 11, 2007, 01:52:45 PM »
I agree this is probably the backlash - because Mach3 does pause as it adds backlash.
However - even with backlash disabled, there will still be backlash in the system and therefore you would still have a delay in the movement of the tool as it pulled out.

How do you run into your thread. Really as you set your tool, you need to move in to a point past the depth by an amount equal to the backlash, and then draw back by an amount equal to the backlash - the tool is then set to come straight out of the thread when you need it to,

1043
General Mach Discussion / Re: Making a GO TO button
« on: November 11, 2007, 01:43:25 PM »
Wayne - If you look at the introduction to scripting tutorial this sort of thing is covered there.

A tool change location is specifically mentioned, and it is also clear enough how to write, or amend, scripts to do what you want.

You can basically add a button to any of your screens and then write a script to have the machine dance a jig, if you want to???

1044
General Mach Discussion / Re: Almost Home!
« on: November 11, 2007, 01:30:54 PM »
Wayne - It is a bit difficult to tell you - and a bit simplistic to say that you need to do A B or C.

The thing that Mach 3 needs to know is where it is in relation to the G code program.

Some G code is written from the work table upwards - i.e. Z0 is the work table level - so you can touch your tool tip on the work table and zero the DRO and away you go.
Some G code is written from the top of the work downwards - so you touch you tip on the worktop and then zero your DRO and away you go.

What you need to tell Mach 3 is - where is the tool tip in relation to what the program is expecting - how you do that is up to you. You can touch the tool tip where you like - as long as you know what height it is and then set the DRO accordingly.

On my lathe, for example, I take a cut across the face of the job - and then tell Mach 3 that point is Z0 (because that is how I write my programs). I then touch the tool tip on the side of the work. I measure the thickness of the work, half it, and then tell Mach 3 that is X?? - X0 being an imaginary line down the lathe centre.

You, I assume, do the same for x and y - setting the tool at a point - and telling the mill that is X0 Y0 - i.e. where your program starts - and you must do the same with the Z - i.e. tell Mach 3 where Z0 is - either by moving it to Z0, or moving it to some other place and telling it what height it is at.

1045
General Mach Discussion / Re: Cutting Circles
« on: November 08, 2007, 08:17:31 AM »
Normally when operating a lathe/milling machine etc, one always tries to move the axis in the same direction, the problem being that the screws that move the tables have play in them, so when you reverse, the first part of the turn of the screw is lost by the thread moving across the gear to the opposite tooth, to move the table the opposite way.

This is not a problem in manual operation, because you do not tend to make such complcated moves - i.e. straight lines generally.
If you try and cut a circle using CNC, the table changes direction on both the x and y axis. You might start by moving the table from x0 to x1, but when you move back to x0, although your DRO's will say you have moved back by 1 unit, you may have only moved back by 0.995 i.e. 5 thousanths short. You can test this as outlined above - move from x0 to x1 - to make sure that any backlash is taken up in the positive direction.  (I use a G0 X1 command rather than jogging) and measure the distance you have moved. I use digital calipers to measure, and now zero them. Move from x1 to x2, then x2 to x1 and measure again. The calipers should read 0, but will not - they will read the "backlash" figure. Repeat for the Y axis. Repeat for the Z axis. (Actually repeat on the same axis several times to check your figures - if you are not getting the same figures consistantly (and it is difficult to accurately measure small distances) take a mean average.

It doesn't matter in which direction you actually do this - you could go 2 - 1 - 0 - 1 if you wanted, because , in theory, at any rate, backlash should be the same in both directions.

Under Config/Backlash enter the measurements and tick "backlash enabled". If you restart Mach3 these figures will be remembered.

This means that when Mach3 is traversing - if it hase to change direction on any axis, it will insert the extra pulses at the change of direction of the move to take up the "loose" movement of the screws, so that you maintain accuracy.

My lathe, when cutting a ball shape in the middle of a rod will traverse, then cut the G2 or G3 curve up to the crown of the ball and stop. Backlash is taken up (You can see the motors moving, but the table doesn't) and then it cuts down the other side of the ball. It leaves a faint mark on the work where it has changed direction. If the backlash was not enabled, there would be a flat area on the ball, where the Z axis (the main traverse) was still moving (because that has not changed direction) but the x axis was not moving because the backlash in the gearing was being taken up.

1046
General Mach Discussion / Re: completley of the topic!
« on: November 07, 2007, 03:55:31 AM »
Dont get excited - this happens in the UK too.

Things advertised in America for say $50 come to England where we have to pay £50 - and the £ to $ rate is 2 to 1.

It happens the world over. Find a friend in America who will buy one and post it to you.

My son (with Special Forces in Iraq) wanted a telescopic sight for his rifle. I tried to get one in the UK (from an internet site in America) and was refused - saying this was not permitted by US law. My son's friend (on leave from Iraq) bought one over the counter in America, and took it out to him. What a farce!!!

Where there is a will there is a way !!

1047
All I can say to the Administrators is

 ;D KEEP UP THE GOOD WORK  :D ;D

1048
General Mach Discussion / Re: units/min drop with backlash comp on
« on: November 07, 2007, 03:37:33 AM »
Changing the shuttle acceleration cuts down the time the axis travels after (reversing) before stopping, before applying backlash, and changing the backlash speed helps cut down the time the machine takes to apply the backlash. I would NOT however, on my own machine, like to take the backlash speed above 100% in case I missed steps - (but that is on MY machine)

On a shuttle setting of 0.1 and 100% backlash speed, although the machine hesitates, it is certainly much quicker off the blocks.

Whether that is going to answer Sheperd's difficulties - I await to find out.

1049
General Mach Discussion / Re: units/min drop with backlash comp on
« on: November 06, 2007, 07:00:12 AM »
I think we could do with some help from the team on this one.

I have just done a short program - g0 x1,g0 x.3, g0x.5
Run without backlash - perfect
Run with backlash (set at 20%) - runs to x1, runs back to 0.9215, long delay, runs to 0.3, runs back to 0.3795, long delay, runs to 0.5
and this is only on one axis. The delay was several seconds and seemed to be standard, regardless of the distance setting for backlash.
I had wondered if your problem was on small incremental movements, if your backlash exceeded the move, would the machine be able to calculate.
I must admit this has me beat. The backlash - which I have set up on my lathe works perfectly, and is accurate. It will, for instance stop if cutting a ball shape, pause on the crown, apply the backlash, then cut down from the crown, with perhaps the faintest of marks where it has paused. The backlash on the mill needs some expanation, I think. In the scenario above, why in one direction does it run 0.0215 and in the other 0.0205 - before applying backlash. If this is part of the backlash the two should be equal. I have tried with backlash greater than and less than this figure.  If your backlash is less, then the delay is short, but if the backlash exceeds this figure then backlash can be some seconds delay.

I can see if you are contouring a complcated profile, where all axis have to stop and apply backlash compensation, that the machine must seem to grind to a halt.

All my observations are on Mach3 program alone - the machine here in the office is not connected to a machine.

Anybody got any observations on this, please ???

Jim






1050
General Mach Discussion / Re: Lt's get digi with it! Digitizing a Guitar
« on: November 05, 2007, 10:45:51 AM »
You guitar lads really are going the hard way about it.

A soundcard, and SF2 file with your guitar sounds, and you could make your computer play the guitar while you cut it out !!!

Jim