Messages

541

General Mach Discussion / Re: Homing all axis Help!!

« on: June 11, 2008, 02:40:24 AM »

If you are using three switches in series (no problem) ALL THREE switches must be shown on Ports and Pins identically.i.e. Xhome YHome and ZHome should all be enabled, all Port 1, all the same pin, and all active hign or low.

If you test these manually, then each switch when pressed should light up ALL THREE led's in the Diagnostices page simultaneously. Mach 3 will sort out which one it wants to look at.

As Chip says - when homing, the axis do not stop immediately, they carry on past the switch slightly, then back off.
I was going to say try just wiring one - but if your diagnostics show all the switches coming in simultaneously, there is not much point.

Have you wired these switches on Make or Break - if you have wired them on Make, then if there is a break elsewhere all three will become inactive.

Running over switches is a hazard - would you try and stop a car by standing in front of it. My switches are now lasers, shining on detectors, to allow for any over-run.

542

General Mach Discussion / Re: Fried 2nd Computer (Newbie)

« on: June 11, 2008, 01:56:05 AM »

You should have tried that with the 240 volts across here. All electrical work over here (at mains voltage) now has to be certificated. Having done most of my own electrical work over the years, I was upset when this regulation came in - but I can see why !!

543

General Mach Discussion / Re: Having trouble using and understanding Mach3

« on: June 10, 2008, 09:34:13 AM »

I must admit, I didn't expect such a simple answer.  If you are "up and running" try writing some GCode to make a program.

Again forget all the bells and whistles. There are two commands (4 to be really truthful, but start with two)

G0 is the command to move from where you are to another specified point. The axis are split into inches. We will assume you are starting in the bottom left hand corner of your table. There are two co-ordinate systems running simultaneously on your machine. One is machine co-ordinates and the other is program co-ordinates (or work co-ordinates). These are displayed on the same DRO's. If the Machine Co-ordinates button is lit, the machine is displaying machine co-ordinates, if the button is not lit you can see the program co-ordinates. (Click the button to toggle between the two).

We will use program co-ordinates - becasue this is how you write your programs.  Change the display to program co-ordinates, and then zero the axis DRO's. This now says the place where my cutter is in 0.0.0. Normally when milling, this is the bottom left hand corner of the work, with the cutter just resting on the top of the work.

If you now type in directly on the MDI page ( page 2) G0X1 (return) the machine will move the cutter to position X1 Y0. You could have repeated the Y position in the instruction it would have made no difference. Iy you type G0X0 the cutter will return to 0.0.0

If you type in two co-ordinates e.g. G0X3Y5 then the cutter will move positioin to X3Y5 simultaneously moving each axis i.e. a diagonal move (not strictly diagonal but) Note the y axis will move more slowly than the x axis so as to reach it's position at the same time. If you also typed in in a z co-ordinate then the z axis would move simultaneously as well.

The axis with the longest movement moves at the speed set in motor tuning, the other axis move accordingly.

G1 is the same command, but this is the cutting move and you can add a further parameter F which is the feed rate. i.e. it does not move at G0 (warp speed) F is in inches per minute.

You can now cut some thing - start the spindle, drop the z axis to cutting height, and move from here to there
three commands  - M3     G0 Z-1  G1F2X6
We will cover M3, M4 and M5 later, which start and stop the spindle.

G2 and G3 are cutting moves (F parameter if required) but these deal in arcs of a circle - G2 is clockwise, G3 is counter clockwise.
There are other parameters to add in, and I tend to use the R parameter which is the radius of the circle (or arc) (You can use I,J or K which are offsets for the centre of the arc, but R is a lot easier). R can be plus or minus - and if you use the wrong one you will get rabbits ears - try it and see.

The beauty about Mach 3 is that you can make up GCode programs and when you enter them , your movement will be shown in the toolpath window, wich gives you an idea if you have done it right or not. You can also run it on Mach 3, without your machine being connected. I have Mach3 on this computer which is in my office/study/front room and I write most of my programs here and then transfer them to the workshop on the wireless connection to run them in the workshop - but most of the testing is done here in comfort.

Have a crack at it, and you will find that it is great fun, and you can soon get quite proficient at it.

I forgot to say that that is all there is to GCode. Those four commands cover all the moves. All the other commands are to do with positioning,  and incidentals - yes there are a lot of them, but you don't need them.

544

General Mach Discussion / Re: Having trouble using and understanding Mach3

« on: June 10, 2008, 02:04:33 AM »

Unfortunately America is BIG. - and I am stuck on the other side of the pond.

Stick at it - if you read some of the posts there are those much worse than you. How far have you got and what is your problem.

You can get Mach 3 running, with very little effort or expenditure, and produce some worthwhile stuff, without all the bells and whistles, limits and homing of a commercial set up.

I think most people try to get it all up and running at once, which is a mistake (because there is a lot more to go wrong). I am also in a theatre organ forum - again based on a PC and on that if you get one note to sound you have mastered the basics - only several thousand to go before you get the full organ.

From your other posts, it seems that you are a fair way into it, I know I have just answered a post about acceleration from you. If it is the principles you are not sure about, that I can answer on the forum (and benefit other people).

If you have your three axis working (dont worry if it is at optimum speed yet) then you are ready to try cutting one or two things on your machine. If you are already confident with machines manually, then converting to a CNC is no problem.

545

General Mach Discussion / Re: Fried 2nd Computer (Newbie)

« on: June 10, 2008, 01:44:29 AM »

I am getting a bit upset that we are giving you advice which you are not heeding. Either that, or there is too much advice and you are getting confused.

It seems to me that your knowledge is a little lacking, and you will have to, therefore take things step by step. You will insist in connecting everything up and switching on and hoping for the best. This is not a scientific way of doing it.

You had better give your computer the once over first and see if signals are still coming out of the LPY1 port. . Is this a standard shop bought computer, or one you have put together yourself. Is the chassis earthed.
Connect a cable to the LPT1 port and turn on the computer. Do not connect anything else. If you have Mach 3 on the screen then fine. Has Mach 3 properly loaded onto your computer, with the drivers running. Have you run a driver test. Do all this before going any further.

With Mac 3 running check with a volt meter, or a logic probe, the signals coming out of your printer port. What voltage are they at. Check each wire 1 to 17 against one of the signal return wires 18 to 25. The pin numbers are stamped on the plug (somewhere).
What voltage is the sheathing showing

The sheathing should be at 0v and pins 18 to 25 should show 0v to each other and the sheathing. No other pin shoud have a voltage on it greater than 5 volts. If there is anything wrong - particularly stray voltage on the sheathing, FIND OUT WHERE IT IS COMING FROM  before you do anything else.

Moving to your Bob board - it sounds like you have now bought one of the opto-isolated variety. WHY DO YOU INSIST ON CONNECTING 12 VOLTS FROM YOUR FAVOURITE VOLTAGE REGULATOR TO IT. This is a recipe for disaster. The opto isolated board - if it is from the same stable as your last board has a simple connector - a USB connector, which you plug into your computer and into the Bob board. This provides power to the Bob. Since it is from the computer, then all voltages must be the same.

If you LPT1 cable checks out, then plug it in, fasten up the USB link and the Bob should now work. I cannot percieve anything more simple than that. DO NOT CONNECT ANYTHING ELSE TO THE BOB UNTIL YOU HAVE TESTED IT.

That is enough diatribe - if you get that far (and live) and want some more, come back.

546

General Mach Discussion / Re: Motor Tuning

« on: June 10, 2008, 01:06:39 AM »

Speed and Acceleration of axis are usually different for everybody. because the physical weights and resistamces of your machine are different, as also is the power exerted by the stepper motors.

If you have a table 3 feet long - say 40 inches - then you might be satisfied witha speed of 80 ins per minute from your axis - if the table was very large, you might be looking at something a lot faster..

In motor tuning you can set the speed of the axis for G0 movements (rapids) so decide what you would like your speed to be and set the speed at that. Keep the acceleration low say at 1 for now. Test the axis by jogging. Either the table will travel at that speed or not. If not the motor will stall and give off a loud whine as the pulses keep going through it, but the motor is stuck (it does not damage them). If all is well try increasing the speed by 10% and try again, until you get the whine, then back off by 10% and set that as the maximum speed. Be particularly careful in checking that this speed can be used all over the table, not just the central area where things are worn in and move more freely.

Now set the acceleration (and braking). From your 1, increase this until you get the dreaded whine, which means the motors do not have the power to accelerate the table at the rate you want it. Back off to get a reliable setting.

It is mostly trial and error - before you start make sure everything is clean and oiled up for best performance, then get to it.

547

General Mach Discussion / Re: Calibrating Issues

« on: June 09, 2008, 01:17:14 PM »

I don't want to pour cold water over your excitement, but if you are referring to the steps per unit (as in your old post), then unless your steps are very highly geared, you should get better than 1.3 thou.

As a matter of interest, what is you number of steps per thou. Mine, for example is 60,000 per inch, giving me a resolution better than 0.1 of a thou. Steps per inch is a fixed number which can be calculated, and not open to adjustment.

548

General Mach Discussion / Re: CV Mode .. thought I understood, but ..

« on: June 08, 2008, 05:13:24 AM »

I am a little at a loss here. CV mode should not be jerky, unless you have the parameters wound up so as to more or less cancel it out.

1. Absolute Stop mode means that the axis - as they change direction (or speed) to give an apparent change in direction - come to an absolute stop - before setting off on their new setting.

2. CV mode means that the acceleration required for the new setting is computed and mixed in with the deceleration of the old setting, so the axis never comes to a stop.

C.V. mode should be smooth - Absolute stop is often jerky is, for example a curve is made up of many little straight lines.

549

General Mach Discussion / Re: Fried 2nd Computer (Newbie)

« on: June 08, 2008, 04:09:26 AM »

I have tried to fraw a wiring diagram for you. It is schematic - in that it does not put everything in its place as you have tried to do.It is however essentially similar to yours, but, I think, easier to follow.

However - there are a few things to note.

1. Your power leads to the driver cards must be a seperate pair to each card - NOT daisy chained from one to the other
2. Note the inclusion of a second power supply to provide 5 volts to your BoB. This will ensure there is no chance of any fault developing on the regulator side that allows 24 volts into your computer system.
3. I do not understand why you need 12 volt supply to your Bob - (I dont know which Bob yu are on now) - most work on 5 volts, and again cut out the possibility of voltage getting back to your computer. You wre on the Probotix board - I think that board has a 5 volt regulator on board - so all you need is a low voltage supply
4. You MAY derive a 12 volt supply for your fan from the 24 volt supply
5. As someone has already said - your voltages around your 25 lead cable to your computer are suspect - where is the stray voltage coming from. The outer sheathing and pins 18 to 25 should be at 0v.
6. The leads from your Bob to your drivers cards should be seperate to each driver. The "common" lead (green) could be 5 volts, or 0v depending on your driver board requirements.

550

General Mach Discussion / Re: Fried 2nd Computer (Newbie)

« on: June 07, 2008, 03:16:12 AM »

THIS IS GETTING TOTALLY *********

Have you got a wiring diagram for all this, or are you making it up as you go along. You keep quoting chip numbers to us when talking voltages - yes, alright, these are regulator chips - but why so many.

Have you designed this in three easy stages as I suggested, or are you still trying to just fasten it on one board and connect all the wires together.

You must get some system. You must have a diagram for each stage of the system - and you must stick to the diagram.

Try Drawing a diagram of the Bob board, and the power supplies you have connected to it first. Post that on this post and we will look at it and give you an opinion.

No, it is doubtful that you have bought 3 faulty boards - but you never keep the same board long enough to learn where your mistakes are.

I put in a previous post - there are three parts to the system Computer, Bob board, Driver boards. Lets do one thing at once !!!