Messages

71

General Mach Discussion / Re: mach3 and hobbycnc board

« on: April 26, 2009, 12:43:53 PM »

You are less that clear in you explanation. I will assume that your hobbycnc board is a driver board for stepper motors. I do not understand what you mean when you say "turn on the box"

Stepper motors are such that they are live (i.e. drawing current) even when they are still. The coils are wired so that current through them pulls the armature into line and holds it there. Movement is obtained electronically by then switching a different set of coils so that the armature is pulled to the next "step".

When you turn on your driver card, therefore, the motors are locked, by the drivers, to a certain position, and cannot be moved without effort. Is this what you mean.

If it is, then this a a normal situation.

If you have wired the outputs from Mach correctly - i.e. step and direction wires to each driver (plus a signal return wire) then pulses are translated by the driver to move the armature the specified number of steps.

IF you have wired everything correctly, then you will probably find that the board contains some "enable" line, or "axis disable" line which stops the Mach 3 communicating with the relevant driver.

The simple way of "unlocking" this is to put a jumper wire to the relevant terminal (usually 0v or 5v) to enable it. Do not bother trying to wire it through Mach at this time, until you get everything working.

72

General Mach Discussion / Re: Help with Mach3 config.

« on: April 26, 2009, 12:30:42 PM »

I think you have your ****** in a twist. You must decide BEFORE you do anything else whether you are a metric or imperial user. This does not mean you cannot work in the other dicipline if you want to, it means that mm or ins is the unit in which your whole system is set up. I work in steel, and if your move G0X1 resulted in a 25 mm move, then I would be in trouble - an inch is 25.4mm. It may not mean anything when you are routing wood, but if you were in steel it is the difference between a fit or not, by a wide margin (16 thou to be precise)

What you must do is set up your units first. Then set up your motor tuning - i.e. the steps per unit. Since I do not know your machine, I must assume that your calculation of 500 is correct. On my steel lathe, it is 1200 but I have a 3 to 1 reduction, so your 500 sounds about right.

The speed and acceleration are for setting when you are satisfied your steps per unit is correct, but for now, something like a speed of 250 per min (very conservative) and acceleration of 50 will do, and will not lead to any missed steps.

If you now check your machine, input g21 - (metric), then G0X1 and your axis should move 1 mm. If you enter G0X25 it should move 25. If you enter G20 (imperial) then G0X1 it should move 25.4mm (not 25).

If you are not correct with your movements ( and make sure you always measure in the same direction ) i.e. move the axis right, zero the DROs then move right again and measure - (to avoid backlash) then you must check your steps per unit calculation. I don't think you are so far off.

Do not try to adjust the steps per unit figure to make the movement correct - it is a finite figure that depends on the geometry of your machine, and cannot alter. If you are getting wrong figures, the fault must lie elsewhere.

73

General Mach Discussion / Re: True Spindle Speed RPM

« on: April 26, 2009, 12:09:35 PM »

As Hood said, pick a free input pin number (10 - 13, or 15) and connect to that. Go to Ports and Pins / Inputs and assign your selected pin to Index. As with a lot of CNC4PC stuff, you may have to show it active low, or active high to get it to work.

I cannot understand where you are getting the 5 volt supply from, however. Do you have a break out board, or not. If you  have a breakout board, you will find a 5 volt supply on that - but then if you have a BOB you will be inputing the signal through that, surely.

If you do not have a BOB, you will have to make up a small 5 volt supply.  A small plug/transformer will do - like the phone chargers or similar, with a 5 volt voltage regulator. Connect the 0v side to the common return of your parrallel port (pins 18 to 25) and the 5 volt to the CNC4PNC board. There is no 5 volt supply on the printer port cable. I assume the 0v side of the CNC4PC card is already shown as connected to the 0v side of the printer port.

74

General Mach Discussion / Re: input signal for TOOL CHANGE

« on: April 16, 2009, 04:14:51 AM »

Are you saying that  you have an auto tool change mechanism, that you are trying to adapt to Mach 3.

I do not understand where your line of code comes from - my M6start does not have that line in - is this a VB script that you have got from somewhere.

Does this mean there is a switch on your tool change mechanism that closes when the tool is in pace and it is safe to proceed - in which case you will need to program an input pin for that function - perhaps an OEM function. There are a couple of tool change function leds in the list at 806 and 6, but I have no idea what they do.

Can you post the full script to have a look at.

75

General Mach Discussion / Re: block some parameter

« on: April 16, 2009, 03:56:16 AM »

I do not fully understand what you are saying BUT you can have different "versions" of Mach 3 for different applications, each with it's own set of parameters.

76

General Mach Discussion / Re: Homing Slave Estops system

« on: April 15, 2009, 07:19:07 AM »

We had a few months ago, exactly this query. The way the "homes" work is each axis moves singly, and, yes, Mach is only looking for a signal from that axis, It then does the other axis. The problems then start, becasue if one of the switches is tripped out of sequence, the switches act like limits and stop all movement.

I did not follow the post to it's conclusion, but seem to think that there is a way to "slave" both axis together and have the "home" acting together. Another search is called for, unless the "poster" points the way to it.

77

General Mach Discussion / Re: 4 Axis Waterjet Cutting In Mach3

« on: April 15, 2009, 07:12:40 AM »

I had got off on the wrong foot in my first reply, thinking that what you were wanting to do was hold the cutting head at a constant height above the target, much as I understand they have to do in plasma cutting. What you seem to be indicating is that what you are wanting to do is alter the X or Y position so that when the jet is pointing at an angle, the same spot is targeted, as when the jet is vertically above.

The amount of offset is clearly dependent on the mean height of the cutter above the target, and the angle at which it is shooting.

I am trying to think of the easiest way to implement this. Becasue I am used to macros my first thought is a macro.  e.g. M1001.
The macro would take in the present position and height of the jet, and the angle at which it is, and if it is not vertical, compute the offset and apply it to X or Y as required. This would mean adding the M1001 (or whatever you use) to your GCode, whenever you want the offset to take place. That I could see working, although how practical it would be to implement would have to be seen.You could, as below, use B or C in your code, and a simple "replace" task would insert the Macro which would then write the GCode.

The alternative may be a brain, but I have very little experience of them. You may, for example be able to program the plan of the cut say as though it were a B or C axis, and then the brain instantaneously translates this into offsets for X and Y dependent on the angle of A. Perhaps some "brainy" people might comment.

All in all, a "post processor" might be the answer, where you run your raw GCode through the computer, and it looks at it and applies offsets where required, and rewrites the GCode before you apply it to your machine.

Sorry I can't be much more help - but someone out there must know.

78

General Mach Discussion / Re: 4 Axis Waterjet Cutting In Mach3

« on: April 14, 2009, 03:58:01 AM »

I have no experience of water jet cutting, but I understand the problem. Clearly (if you are going, shall we say, for an angled shot) yes, as the head rotates, the Z axis could drop as the distance to the target increases. To keep the nozzle the same distance from the target, Z would have to drop as the cosine of the angle. This would be alright for small values of angle, but the distannce (nozzle to target) would increase rapidly as the angle got greater - so much so that you could not make up by dropping Z.

What sort of distances and clearance are we talking about.

79

General Mach Discussion / Re: M01 Optional Stop

« on: April 14, 2009, 03:44:12 AM »

Ray -

You could try -

If Not GetOEM(65) Then DoOEMButton(177)

and

If GetOEM(65) Then DoOEMButton(177)

I think the led's are bolean - and the "on" is not necessarily a "1", but it is a non-zero value

80

General Mach Discussion / Re: Hurco proximity style limit switch problems

« on: April 14, 2009, 03:05:36 AM »

The diagram (on which I can only see the X axis limit, appears to have four wires to it. Yellow and black for the power, and the return is via the black and brown. I assume the second black wire is also at Ov potential as a reference for the brown wire. You do, however need some reference across to your breakout board for this to "spot" the voltages coming out.Unless you are using the rest of the board for some other purpose, I would do away with it. Power the switches directly from your 5 vlt/0v supply on your nreak out board, and take the return directly in.