Topics

1

General Mach Discussion / Skipping movements intermettently, & work offsets

« on: September 27, 2011, 05:22:38 PM »

When engraving identification letters on various components the machine is sometimes missing part of the movements, giving rise to various problems. Here is the latest programme to give problems:

G90
G0  X121.0 Y-75.0 Z0.0 M3
    Z-32.5
F   200
G91
G0  x -1.75
G51 X0.7 Y0.7
M98 P066

G50
G90
G0  Z0.0
G0  X0.0 Y0.0 Z0.0
M30

O066  (upper case B)
G91
G0  Y0.500
G1  Z-2.00
    X2.50
G3  X0.00 Y4.00  I0.00 J2.00
G1  X-2.5
    Y-9.00
    X2.50
G3  X0.00 Y5.00 I0.00 J2.50
G0  Z2.00
    X5.50 Y-0.5
M99

The sub-routine is from a library of alphabetic characters used with different engraving jobs. The G51 scales it from 10 mm high to 7 mm.

The B starts with the middle bar, then the upper curve, horizontal to the left, down the main upright, horizontally across the base then up with the lower curve to complete the letter in one continuous cut.

Today, two times out of four, the first curve of the B was not completed so the remaining lines were out of position, maybe 1.5 mm right and 0.5 mm down, so the upright is displaced to the right and the end of the line does not meet the middle bar as it should. This has wrecked the job at the last operation, which is very annoying.

At an earlier stage in developing the interface to this machine I got crosstalk between the watchdog signal and the X axis drive in a short section of ribbon cable used to extend the parallel cable into the machine. This gave rise to un-programmed moves on the X axis. Getting rid of the ribbon cable and taking the printer lead direct to the interface board seems to have solved that one, but it might be relevant. I still suspect the quality of printer cables when used for machine control.

Another programme on the same machine but using a different setup profile resulted on one occasion in the last character being out of position, showing that one rapid move had missed the X Y moves, and a second time the last character was overwritten on the second last, and the cutter dug in deep indicating an entire rapid move had been missed. Programme (without all the subroutines) below:

G90
G0  X1.0 Y-75.0 Z0.0 A-121.0 M3
    Z-32.5
F   200
G91
G0  Y2.50
G51 X0.3 Y0.3
M98 P050
M98 P046
M98 P048
M98 P032
M98 P109
M98 P109
M98 P032
M98 P083
M98 P084
M98 P065
M98 P073
M98 P078
M98 P076
M98 P069
M98 P083
M98 P083
M98 P032
M98 P083
M98 P084
M98 P069
M98 P069
M98 P076
M98 P032
M98 P040
M98 P051
M98 P049
M98 P054
M98 P041
M98 P032
M98 P067
M98 P069
M98 P082
M98 P084
M98 P046
M98 P032
M98 P050
M98 P056
M98 P051
M98 P051
M98 P052
M98 P054



G90
G50

G0  X0.0 Y-78.0 Z0.0 A-121.0
    Z-32.5
G91
G51 X0.3 Y0.30
M98 P083
M98 P078
M98 P066
M98 P032
M98 P069
M98 P108
M98 P101
M98 P099
M98 P116
M98 P114
M98 P111
M98 P110
M98 P105
M98 P099
M98 P032
M98 P083
M98 P101
M98 P114
M98 P118
M98 P105
M98 P099
M98 P101
M98 P115
M98 P032
M98 P050
M98 P052
M98 P072
M98 P114
M98 P032
M98 P084
M98 P101
M98 P108
M98 P032
M98 P048
M98 P055
M98 P055
M98 P049
M98 P048
M98 P056
M98 P052
M98 P048
M98 P051
M98 P054
M98 P049


G50
G90
G0  Z0.0
G0  X0.0 Y0.0 Z0.0
M30

O049  (numeral 1)
G91
G0  Y2.50
G1  Z-2.0
    X2.00 Y2.00
    Y-9.0
G0  Z2.00
    X5.00 Y4.50
M99

O054  (numeral 6)
G91
G0  X3.00 Y4.50
G1  Z-2.0
G3  X-3.0 Y-4.0 I1.1667 J-4.0
G1  Y-3.0
G3  X4.00 Y0.00 I2.00 J0.00
G1  Y1.25
G3  X-1.75 Y1.75 I-1.75 J0.00
G1  X-2.25
G0  Z2.0
    X7.00 Y-0.5
M99

Two lines of text are written using X Y scaling to set the character height, with a non-scaled move between lines to set the line spacing and centring.

I've only included the last two character subs - 61 - as that's where the problems occurred. Most of the subs have been used successfully in various combinations, so I don't think there is anything wrong with them in principle, although one or two may have errors in them. I would say the last G0 in sub 049 was being missed.

The only hint I can find, and it may not be relevant, is that I can't get the axes to zero when I issue G28.1. The initialising code at switch on is G28.1 X0 Y0 Z0 A0. This usually leaves X at 3.44, Y at 2.55, not at zero. If I look at the offsets, G54 Is also at X 3.44, Y at 2.55. If I zero them in G54, then the Machine Coordinates change from all zero to X3.44, Y 2.55. If I zero the machine coordinates the values reappear in the G54 offsets.

How do I, once and for all, make all coordinates zero when the machine has homed and (officially) zeroed all axes? My suspicion is that this discrepancy is giving rise to movement errors, but I can't prove it.

The computer is a VIA ITX running windows XP, configured by Les Caine as "Mach in a box", using Mach R3.042.020, and with his interface card. Motor drivers are IM483.

Can anyone shed any light on the missing movements, the zeroing problem, and any possible link between them?

2

G-Code, CAD, and CAM discussions / G73 parameters

« on: November 04, 2010, 08:15:52 PM »

I'm trying to use G73 for a row of deep drilled holes, and I can't see any guidance in the manual for the use of the parameters. I gather from other discussions that X & Y are the start position, that Z is the hole depth, R is the final retract position (maybe), L is the number of repeats (only useful in incremental mode) and Q is the retract increment. So what do A, B & C do? And have I got ANY of them right?

In other discussions F is brought in as a feed rate, but it's not mentioned in the G73 description. If F is a valid parameter for G73 shouldn't it be mentioned along with the others?

Can anyone clarify what the parameters are? Simple examples in absolute and incremental modes would be useful.

And if you did the same for the other canned cycles I suspect you'd be doing everyone a favour!


Keith

(not involved in previous G73 discussions)

3

Mach Screens / "Load G-Code" button - file locations

« on: June 29, 2010, 07:35:56 PM »

I'm setting up a screen for use with an engraver handling a large number of simple jobs. The G-Code programmes for these will be stored in a number of directories sorted by customer name, type of job, and so on. When I use the "Load G-Code" button it takes me to the last directory used. What I want is to have a number of buttons, each opening a specific directory, so the operator can go more directly to the required file.

Is there a way to do this? Bear in mind I have not tried Macros or VB Script yet, but if you can give me pointers I'll have a go - got to start one day!

4

Mach Screens / FRO Slider

« on: June 29, 2010, 07:26:22 PM »

I'm having trouble with a feed rate override slider. I copied it from the usual Mill screens, but the green bar is narrower than the allocated space.

An earlier thread included:

The trick is the format string, tab group, and the "skined" (should be spelled "skinned") should be checked as well.

I've found the format string, but where is the Tab Group and how is the DRO Skined (Skinned)? I see no space for a graphics file to be defined, nor any "Tab Group" in the definition box for this DRO.

The width and height of the slider are 25, 200 but the bar looks more like 12 pixels wide, and so is the DRO text at the top.

I'm working in Mach3screen, but Machscreen doesn't give any more clues. Can anyone clarify this for me?

5

Screen designer tips and tutorials / Removing Jog Controls flyout

« on: June 06, 2010, 09:19:42 PM »

I'm designing a very simple screen which will include the various Jog buttons, so I won't need the Jog Controls flyout, normally brought up using TAB. How do I remove it and make sure TAB does nothing to my new screen?

For more complex projects I might want to add other screens on flyouts like Jog. The Jog Controls are on screen 50 - how many screens can I have, and how do I add new ones with numbers above 15? And then how do I make them toggle with TAB, or some other key?

6

Forum suggestions and report forum problems. / Where is the wisdom accumulating?

« on: May 18, 2010, 08:24:53 PM »

When I search for various topics I get huge lists of threads, many of which have nothing to do with the subject I have in mind, and it takes ages to search through them. Usually I give up after the first hundred without finding anything relevant to my problem. Cryptic and irrelevant headings don't help, and some threads never reach any definite conclusion.

Where can we put the important information once all the discussion has come to a conclusion? I'm thinking of a growing online manual which would include everything known so far about, for instance, each G code command. This would be the first place to look for information, and would save the same questions being asked over and over again. Should the Wiki pages be used for this? There doesn't seem to be a space for G codes.  I'd like to see at least one page for each G, M or F code. For example, I have only written a few simple programmes but I feel I could improve the descriptions of G90 & G91 and G51, having had to use them intensively, and would aim to do the same for any other codes I have to use.

The hope would be to distil out the best descriptions of programming techniques, together with simple examples, and put them somewhere where they will be found easily. Eventually this could replace the printed (printable) manual, or be incorporated into it.

7

General Mach Discussion / Invisible Mach-3

« on: September 10, 2008, 11:11:40 PM »

Hi all,

I am new to all this, so I may be dealing with something which is old hat to the regulars - please be patient!

I hope to use Mach 3 to control an existing engraver, which I'm sure it can do. The jobs are all similar, and there will be about 20 standard components, each needing one line of text. I want the operator to load the component into a fixture, select the component type, and then input the line of text. They then press the GO button (in some form) and the job starts. No programming, no G codes, nothing like that bothering the operator. So all the generation of G codes and so on happens automatically.

The big question is - can this be done?

The second question is - can anyone give me a clue as to how?

Thanks in advance,

Keith