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Welcome to this session of Lightblade learning lab, today we’re going to show you just
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how to make sense of the profusion of Zeros, datum’s and origins associated with this
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software and the machine.
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In the first session, we talked about setting up at the top right hand corner here, the
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datum position 0,0 datum for the machine itself and then down at this bottom right-hand corner
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we’ve got this little floating green square which parks itself when there’s nothing on
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the page, down at this bottom left hand corner.
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None of this will make sense unless you’ve got a basic understanding of something called
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Cartesian geometry, now this does not mean you have to be a mathematician so don’t for
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goodness sake get turned off.
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This is all very simple stuff because I’m sure that most of you when you were at school
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got involved with graphs and when you looked at graphs there was always a y axis that went
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upwards, and there was always an x axis that went out to the right, that’s probably as
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much as you ever learn if you didn’t go very far into mathematics.
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Now in the bottom corner there is a point there which was zero for the Y-axis and zero
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for the X-axis, and then it went from zero to X+ and then it went from zero to Y+ and
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that was the pattern of events that you expected to see on a page.
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If you go beyond those zero points the X becomes X minus and the Y becomes Y minus, this Cartesian
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coordinate system is basically nothing more than whenever you put a point somewhere, and
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lets just put my cursor just there, basically that point is defined by a Y plus dimension
Transcript For Laser Machine Datum, Zeros and Origins (Cont….)
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and then a X minus dimension, that would define where that point was in space.
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The guy that invented this, a guy called Rene Descartes, as you can probably tell from his
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name he was French and well, he didn’t like to make things too simple. I mean wouldn’t
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life be easy if everything worked the same way. Everybody understands that 12 o’clock
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is at top and then we go three o’clock, 6 o’clock and 9 o’clock, wouldn’t it be very
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convenient if we had zero degrees at the top 90, 180, 270 note this guy was a Frenchman
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he decided to confuse people, so he started off at 3 o’clock with the Zeros and so that’s
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zero degrees there, and then we work backwards to 90 degrees and backwards to 180 and backwards
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to 270 and eventually we get round for a full circle with 360 degrees.
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Note this is all very simple stuff for most you guys but there be one or two people that
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need just a little bit of help with their maths so persevere with me please. So we go
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to use one tool up here, which is basically this rotation tool and as you can see the
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Chinese have shown a very nice little symbol up there which shows it going clockwise. Now
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that’s not particularly helpful, now we want to place this arrow in the correct direction
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so that it goes Y plus now we’re going to rotate that because we’ve got handles round
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it now, we can come up here, we can click in this box and we can change that zero to
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another number. Now which number do you think we should change that to? We want it to point
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up there at 90 degrees should we point it up there at 90 degrees? Let’s do it. It points
Transcript For Laser Machine Datum, Zeros and Origins (Cont….)
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up at 90 degrees but did it rotate the way that the arrow was showing? No, so what about
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this one here if you want to get to 180 that’s pretty easy because whether we go clockwise
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or anticlockwise we going to ask for it to go to 180 degrees, so I can now move that
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to this axis here. Now this last one we want to point downwards, now I know that it says
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270 down there and that’s a clue to say that we could actually write 270 degrees up
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in here, but equally well, look this is zero plus 90, if we go from zero to minus 90 we
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get to 270 as well so instead of writing 270 in there, perhaps we can write -90, so – 90
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works as well, so why have I bothered to show you all this?
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When we set our machine up, it’s the same corner as this corner here. So when it said
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we wanted to mirror something, the something that we were going to mirror was X plus and
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of course when you mirror X plus it becomes X Minus and when you mirror Y plus it becomes
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Y minus – that’s why we had to tick the mirror boxes, we had the mirror the X and we had
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the mirror the Y. So we had to make them both the opposite to a standard X and Y pattern,
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so that’s the definition of our first 0,0 which is the machine 0,0 which is tucked up
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that corner there and it’s moving in an X minus and a Y minus coordinate system. So
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our work table is in the third quadrant, that’s enough of that mathematical stuff.
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Let’s go back to doing a simple drawing and we’ll put a circle in again because it’s
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a very convenient form that allows us to see the handles on the corners. So we hold down
Transcript For Laser Machine Datum, Zeros and Origins (Cont….)
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our ctrl key and then we’ll put handles on the corners. Let’s go back to the config and
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we’ll change the system setting. If I change it to this bottom left corner there’s not
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a little man in the background with a calculator that works out how you’re going to get this
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is your machine. There’s a very set, very complicated set of Mathematics that goes on,
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every object on this page is a mathematical object and it can be defined in mathematical
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terms.
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You don’t have to worry about that at all, because the programming system hides it all
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away from you, but the essence of the program is that it will be written from this green
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dot so this circle will be defined in terms of X plus and Y plus coordinate points.
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Now, if we change the coordinate system with the config system setting to that one, which
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is where we’ve got our datum over in that corner. It’ll be written in X minus and Y
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minus numbers, so I think for convenience purposes we will leave the green dot at the
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top right hand corner of all the geometry that we’re going to use. Because that way
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we will know that basically we’re trying to always generally set things over here at the
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top right hand corner of the work table, and then everything will grow out to the left
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and downwards. So that’s what the green dot is, the green dot is the 0,0 point for the
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program that’s going to be written.
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Now there are ways of moving this around accurately on the page, let’s just take a look at these
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little windows, this window here has got little arrows pointing up and down and left and right
Transcript For Laser Machine Datum, Zeros and Origins (Cont….)
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and I think it’s probably fairly reasonable to assume that they’re something to do with
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the dimensions of this object. So if we set, first of all unlock the lock and I will set
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this dimension here to 100 so you can see that I’ve actually changed the X dimension
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to 100 and it’s no longer a circle.
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Let’s just undo that, and now what we want to do, is we want to set them to exactly the
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same dimensions and the way that we change the dimensions and keep them proportionately
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the same is to put the padlock on. If I change that dimension to 100, I have now got 100
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millimetre circle. Now what I would like to do is move this corner here which is the green
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corner and the reference point if you remember, to a position somewhere. This can be rather
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confusing, now what I am going to do initially is move this object to a known position in
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this coordinate grid.
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And I am going to move it with these first two windows, to a position of 100,100. Now
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where do you think the object is going to finish up?
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Well if you look, the clue is in the scaling at the top here. Because the scaling of this
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drawing is working away as I said from 0,0 so it’s running backwards it’s not running
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from this corner as you might have expected it’s running away from this 0,0 point and
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it’s running down the page from that zero point at the top. So this is truly machine
Transcript For Laser Machine Datum, Zeros and Origins (Cont….)
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0,0 and this is a coordinate although we’ve defined as 50,50 in real terms it’s -50,-50
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but that’s only for the programming purposes, but hang on, we didn’t set that corner at
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50,50 we told that corner to go to 100,100 didn’t we?
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Ah, that’s because it hasn’t moved in accordance with that green Dot, this object
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here on the drawing has moved in accordance with this little pattern here. Now if we take
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a look at this, if we click on this little icon next to the padlock, we get something
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called at Select position this is a feature that only here in the drawing package, it’s
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not on the machine itself, and that is, what we’ve done, if you look we’ve got centre point
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marked here. Now if we check where the centre point of this object is, that has gone to
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100,100 so when we defined this dimension up here of 100,100 for the position of X and
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Y it wasn’t for the green dot it was for the centre of the object.
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So if I choose to move that to there now, and I say ok. Watch what happens up here to
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X and Y, what do you think is going to happen? Yep, now we’ve got the green dot and the positional
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location the same, so although we’ve still got a Centre Point for the object, that’s
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no longer the handle for moving the object around on the page.
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That basically is the centre of gravity of whatever shape is there, let’s for example
Transcript For Laser Machine Datum, Zeros and Origins (Cont….)
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just add to the situation with this square, and we’ll put a box around it. You can see
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what I mean, this has now moved so that the diagonal between this corner and this corner,
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and at this corner and this corner, intercept at that mid-point there. That’s no longer
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the centre of an object it’s the centre of the box the enclosing rectangle. So yet another
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confusion about how you locate things in space. At the moment we’ve got it set on the corner
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and that generally is probably a good place to keep it, because then you’ll know that
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your green screen and your positional location, if you want to use these numbers at the top
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here will be in accordance with each other.
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Now there is one other place where datum’s and zeros can be a bit confusing, and if we
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move to the bottom right-hand corner here, we shall find that we’ve got something called
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position, and at the moment it’s set to current position but there are some other options
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down here, one of them is absolute coordinate, that’s a very useful features sometimes.
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If I save my program with this saved Ufile with the drawing like this, then I shall not
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get the option on the machine to move the datum around and press the origin button.
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You specified absolute coordinates, so what that means is, the Circle will get drawn there
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and only there in relation to 0,0 you won’t have any chance of moving around on the workpiece.
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So in general terms, unless you want to very accurately position something in relation
Transcript For Laser Machine Datum, Zeros and Origins (Cont….)
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to a datum point on the machine itself, and we can talk about that the location purposes
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later on, in general terms stay down here with this thing called current position which
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allows you to be totally flexible with where you place the origin point or the head on
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the machine. So bear in mind that the head, the Machine Head is actually going to sit
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at this green point here. Most people will grab hold of the head and will drive the arrow
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key so that the head sits there, and their immediate reaction is � ok, my first circle
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is going to be here. You can clearly see that isn’t going to be, you’re going to be cutting
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off of the work area and you’re going to get an error on your keyboard, it says “Slot
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error” basically I think Slot in Chinese is probably meaning idiot.
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So that’s one of the dangers of having a system which is not intuitive, driving the head to
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the top right hand corner is far less intuitive as far as positioning you work then it is
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if it’s on the top left hand corner which is where everybody conventional works from,
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reads from, writes from. To try and overcome this problem, what I would generally say is
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try and get your mind around the idea that your first object will be sat there and you
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work right to left and down the page and you work right to left and down the page rather
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than left to right across the page
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Now although it seems like a lot more, in reality that’s only four datum points, 0,0
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positions and Origins that you’ve got to think about, so it’s not too bad. But the problem
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is trying to make sure you understand them in relation to each other and the work area,
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so we have been near the machine in this session and it’s possible that we might not go near
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the machine in the next one or two sessions. So we’ve really got to look at all the tools
Transcript For Laser Machine Datum, Zeros and Origins (Cont….)
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that we can use before we start drawing anything or before we start programming seriously any
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objects.
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So today has all been about the relationship between this drawing page and the work area,
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but that’s an important set of fundamentals that you really must try and master. Well
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thanks for your attention and I will see you next time.
