Transcript for How To Do Relief Engraving and Air Assist
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The Concise RDWorks Learning Lab with Russ Sadler.
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Session 20 Relief Engraving Air Assist.
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I just hope you guys don’t skip any of these programs, because although what we’re gonna do today is more or less the same as what we did last time.
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Every session that I do builds and builds and builds,
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you’re going to get new information today that you didn’t have last time and if you missed today’s session,
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you’re going to miss out some bricks in the house that I asked you to build.
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Now, you’re not going to be able to put the roof on if you don’t put bricks underneath the window, are you?
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So make sure you learn as you go and keep referring back.
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I’m going to keep reminding you as well of some of the things that we are talking about that you should have remembered from a long time ago.
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So today as well is just reversing incised engraving.
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We’re going to be learning quite a few more things about the machine and the technology associated with the machine.
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We’re going to build on what we’ve had so far. OK, here we are at RDWorks, and I’ve got five circles drawn on there.
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What I’m going to do is to just show you a little trick that you may or may not know. If I
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put a handle around those and then I put my shift key down and I add this one to the group.
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The last one I added to the group was this one. So now if I go up here and I use these tools, which are basically horizontal and vertical align.
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If I do the horizontal one to start with, watch where these four circles finish up.
Transcript for How To Do Relief Engraving and Air Assist (Cont…)
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They finish up in line with the last circle that I selected and now we’ll do the same for the vertical selection.
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And there we go. So what I’ve done,
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the very last object that I selected becomes the focus of all the other items and they will all congregate around the last item that I selected.
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Now, those circles are not bitmaps.
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Those are lines that are called vector lines.
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They’re mathematically drawn on that page. And if I zoom in, the lines do not get thicker.
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They always remain the same thickness because they’re drawn onto that screen mathematically.
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Now, that’s not the case with a bitmap, as you will find out later on when we zoom in on a bitmap,
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there are little things called pixels and those pixels will get bigger and bigger and bigger.
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Whereas the lines did not get bigger and bigger and bigger. This is an example of a vector graphic.
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Well, here’s our target. And we’ll just open up the parameters and we see at the moment those parameters say cut.
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OK, now I’m going to change this to scan. Doesn’t matter about the parameters at the moment, just the scan and say, OK, nothing has happened.
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Well, nothing has happened because up here in config we’ve got something called Graph Hatch. If you put Graph Hatch on – tick.
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All of a sudden, what it will do, it will show you the area that will be engraved.
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It’s obviously the black area that will be engraved, this is a very important lesson that you must understand,
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and that is the order in which things will be scanned.
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If you have a closed boundary with a vector graphic like a circle, which is fully closed,
Transcript for How To Do Relief Engraving and Air Assist (Cont…)
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it will fill in that circle for you, but it will only fill in that circle until it comes to another boundary.
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And so it’s filled in the first circle because starting from the outside, we’ve got a closed boundary.
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So it’s filled in that closed boundary until it hits the second boundary.
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And when it hits the second boundary, it finishes its engraving and then it jumps across until it finds another boundary.
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Well, it’s not this boundary because this is the boundary that finished the engraving off.
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So it jumps across to this boundary, which is another new boundary.
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And it fills that in until it hits another boundary and that boundary is the finish boundary, not the start boundary.
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So it then moves across to here and it finds another boundary which it can then fill in.
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So those are the basic rules for scanning or engraving.
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It will fill from the outside first and it will only fill in totally closed boundaries.
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And there we go.
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Now, at the moment, that’s filled in because it’s come to a boundary and it’s filled, everything inside that boundary, then it’s come to nothing.
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You can follow the rules here, it’s just filled in solid boundaries,
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I could probably break this text up by going to ungroup up there, and that means that this letter is now a character on its own.
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And I could possibly choose to put that character there on a blue layer, for example, and the blue layer is set to cut.
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So it automatically becomes a cut rather than an engraved character.
Transcript for How To Do Relief Engraving and Air Assist (Cont…)
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This is a vector graphic that is not filled because it’s cut.
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This is a vector character that has been filled because we’ve asked it to scan.
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So now you can begin to understand how scanning rules operate.
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Relieved text. This is not supposed to be a session on how to use RDWorks.
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But I will just let you know that all of this text is one layer.
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If I click on any one of these texts, it will bring the whole, it’ll put a hand around the whole lot.
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So if I use that handle that’s around the whole lot and I do ungroup, what it’s done is ungroup those into individual letters
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now, as you see, OK? Now what we want to do as we would like to have that text nicely centred, justified underneath the word relieved.
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And the way that we do that, is we mark that group and we put it back into a group, and then we use this group here, we put that into a group.
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So now I’ve got the word relieved, which if I click on that will all be live.
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I’ll click on the T and that will all become live.
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So now I’ve got two separate groups of letters there.
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What I can now do, we could use the, the text here and then we’ll hold down the shift key and select the second group of text.
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Now remember what I showed you a few seconds ago. The second group will become the target for the first group.
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So let’s take a look up here at what we want we want to centre it in the vertical direction.
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So we need to do that. And there we go.
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So we’ve now produced relieved text as two separate groups.
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OK, now what we can do is put them all back into one group again.
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So now if I click on that, they’re all one group again.
Transcript for How To Do Relief Engraving and Air Assist (Cont…)
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Let’s now just set this to scan. Doesn’t matter about the layer
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colour at the moment, or the values. And there we go, look, we’ve got scanned text.
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That’s not what we want. We don’t want scanned text. We want the background scanned and we want to leave the text alone.
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Well, the only way that we can do that, and we can put a rectangle around there.
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Now, look what’s happened.
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Remember the first boundary that it comes to, it will fill in until it comes to another boundary, well every letter is another boundary.
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So now we’ve got a lasered background and no effect on the text.
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Let’s just set some parameters for that. Let’s just use 30 percent.
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And I think we did use 100 mm a second. I think those are the parameters that we used last time.
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And I seem to think that we finished up with setting at naught point two line spacing.
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If you remember back to the last session, several things, first of all. We’ve got a very small amount of air flow through there,
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and we set the focus four millimeters above the surface, is 24, 10 and 14 is 24 because that’s a 10 mm spacer.
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OK, so I’ve stopped it because it’s not doing what we expected.
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Why not? Not only has it relieved the text to start with, which it shouldn’t do! It’s then gone on to relieve the background, which it should do.
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So what has gone wrong?
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First of all, always use the little blue screen, the little blue monitor screen up there to preview what the machine is going to do.
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So if we click on that, ahh, that’s a bit of a mess, isn’t it?
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Look, it’s not a clean, relieved text, so it’s scanning the text first and then the background.
Transcript for How To Do Relief Engraving and Air Assist (Cont…)
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Remember, the rules for scanning it will scan the outside shape until it comes to a boundary.
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But we created the whole of this piece of relief text, as one group so, the software has become very confused about where the boundaries are.
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So what we’ve got to do is ungroup it. So every single one of those letters is a separate letter, as I showed you previously.
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Now, if we go to our preview screen. Ah ha!
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Relieved background and text left alone.
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Very nice, clean, not brown text with a relief background.
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Now, that’s the sort of thing that you would use, maybe if you want to do, a wood cut
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block, for example. You’d obviously reverse the letters around, but that’s how you’d make a print block.
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OK, so we happen to be using nice soft wood here.
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Obviously you can’t do this sort of thing with slate, glass or any other material that doesn’t cut. Wood cuts, plastic cuts, acrylic cuts.
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So you can do this sort of thing on those softish cuttable materials.
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There’s another material that you can use, which is a machinable or a laserable rubber material, which you can use for making rubber stamps with.
Transcript for How To Do Relief Engraving and Air Assist (Cont…)
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And you use exactly this technique.
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But the problem is, if you want really, really small letters, those edges which are used for printing are very, very weak and unsupported.
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So we can actually put little slope’s or buttresses to support these letters so that they’re thin letters is at the top,
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but they’re thick letters at the bottom. Let’s go and have a look at that and I’ll show you what’s involved.
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OK, so how do we get these buttresses on the side of the letters to make them stronger?
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Now, something we haven’t tackled yet is the use of this minimum power.
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Now, that’s really going to pop up in the next session. But we have an application here where we need to use minimum power.
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So, first of all, let’s set this tick here to ramp effect and then we’re going to set the ramp to well,
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I don’t know how much room we need at the bottom of the letters, but let’s just say we’re going to put it one millimeter.
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So we’re going to have the width of the letter with one millimetre at the bottom on either side all round,
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so it’s going to be well supported because it’s only about a millimetre deep
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these letters. So it’s going to have about a 45 degree ramp on it, but it cannot have a 45 degree ramp on it unless the machine can change the power.
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So at the top of the ramp, it’s got to be zero. And at the bottom of the ramp, it’s got to be 30 percent.
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So we get the full depth of cut at the bottom, but we get no cutting just at the top here.
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Now, bear in mind, we’ve got this out of focus as well.
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So we’re not going to get exactly the effect that we would otherwise expect if we had it perfectly in focus. Now,
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we can take a look on the preview screen and see what effect we’ve had.
Transcript for How To Do Relief Engraving and Air Assist (Cont…)
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There it is. We’ve got the ramp all the way around the letters.
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You can see that we’ve got, definitely some buttressing along the side of the T there. But the thing is, we’ve closed off
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the V and the E there. Now I’m being very critical because I need to point these things out to you.
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That means that probably we haven’t got the minimum power set right. We’ll change the minimum power back to say,
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10%, OK, and we’ll try it again and see whether or not we can get the separation between the V and the E.
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I think you can see nicely now how all these letters have got relief on the side.
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And we got a little space between the V and the E this time.
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So we’ve now got our minimum power set about right. Because we’re getting such nice, clean text.
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It makes me wonder whether we can help get a little bit more depth,
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a little bit more crispness by bringing the focus back down from, say, four millimetre clear to maybe two millimetres clear.
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So we’ll drop it down to 12mm. We’ll start exactly the same job again and we’ll turn the air assist on full.
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I think it’s no longer exploding sideways. It’s been blown back down onto the job by the force of the air assist that’s coming out of the nozzle.
Transcript for How To Do Relief Engraving and Air Assist (Cont…)
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It’s made a right mess of it by having the air assist blowing directly down on the job,
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as I said to you, you want that smoke to go up away from the job and stay away from the job?
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We need enough flow coming out of there to protect the lens.
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We’re now going to talk a little bit more about the nozzle and why this has, this air flow has such an impact on the job. We’ve got
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a very, very small amount of air that I can feel. When I put my finger on the end there,
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I can feel the pressure building up. OK, but it’s not enough air flow to blow down onto the work.
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And I will explain why in a moment. Let’s just run that same job again with only minimal airflow.
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We still got the same amount of brown smoke. The difference is it’s being allowed to drift up.
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You see, it’s not being forced out sideways as it was before.
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It’s not being carried away cleanly, because I’ve got the front door open, but as you can see, it’s not actually going straight back up into the nozzle.
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You can see how rapidly that smoke is now being pulled backwards. It doesn’t get a chance to get anywhere near the nozzle, because the explosive
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effect of this little volcano is not sufficient to blow it right up to the nozzle.
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So this, as I said before, is air flow management. And there’s the difference between the two results.
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So the air is going into the nozzle just here below the lens, which is up where my fingers are.
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And it’s blowing out of this very large hole that’s in the bottom here, six millimetre diameter hole.
Transcript for How To Do Relief Engraving and Air Assist (Cont…)
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Now, if I close this top up, it’s the same as having the lens in and the air that’s coming out of there is very, very low flow.
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Now, not only is it low flow, but because it’s over such a large area, it doesn’t get a chance to form into a jet.
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It comes out of here and it’s spreading out. Now here,
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I’ve got a very shallow tray of water. I’ve got the machine,
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lights reflecting in here for a good reason. If I put that about 20 millimetres above the surface, which is roughly where it was. About there.
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You can see the disturbance of the surface there. Let me now wind the air assist on fully.
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Now you can see it’s a completely different disturbance pattern. This is an engraving nozzle, where we do not need much air assist. Now here,
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I’ve got a cutting nozzle.
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A cutting nozzle is a completely different sort of animal. First of all, it’s got something like about a two or two and a half millimetre hole in the end.
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The same amount of flow is going to direct a jet of air at the surface, rather than a gentle protection of the lens and no effect on the surface.
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So let’s just plug this nozzle in and see what happens. Here’s the same minimal flow at 20 millimeters away from the surface.
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You can see, first of all, not only is it disturbing the general surface, but if you look closely,
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you’ll see there’s a hole in the middle of the water where it’s depressing the water.
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If I close this down to an even smaller gap, you see the effect of distance that, that is making, and that is the minimum air flow protection that’s required when
Transcript for How To Do Relief Engraving and Air Assist (Cont…)
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we’re using this nozzle. If I now, turn the airflow up, nearly 60 millimetres above the water surface.
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Look, what I’m doing to it, look what the air is doing to it. Now, as I bring it down closer, you’ll notice something has happened.
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The hole in the middle is getting smaller, but I’m getting a lot of disturbance around the outside.
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It’s actually trying to undercut the water and blow it out here.
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Here you can clearly see the effect of air assist on the engraving. Here,
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a nice clean set of engraving. Here we’ve used a cutting nozzle, exactly the same as this, with minimal air assist,
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and again, look what’s happened. We’ve got brown painted text because we’ve got a jet of air firing the fumes back onto the surface of the work.
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We must let the fumes drift up and be pulled away by the managed cross flow to produce this nice, clean text.
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Remember when I introduced you to engraving, I said the requirements for cutting and engraving are diametrically opposite.
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And that’s what I mean.
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You need a big gap between the work and the nozzle, which this shorter nozzle helps to produce. Just enough air through here to protect the lens.
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And because it’s a large hole, it drifts out gently.
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But if you put too much airflow in, it will produce turbulent flow on the surface and you will get, again, a brown painting of your product.
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And with a cutting nozzle, well, you’ve got a very small hole.
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That same amount of air, here, is directed into a jet.
Transcript for How To Do Relief Engraving and Air Assist (Cont…)
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And that’s not good. So this is a cutting nozzle with a small hole and a small gap between the work and the job.
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And this one’s an engraving nozzle with a big hole in it and a large gap between the work and the job.
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If you’ve got a job that requires cutting and engraving, do you use this one or do you use this one?
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That’s a decision you will have to make a little bit later. When you understand more about cutting, if you need it deeper, just run it twice.
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Don’t try and force a deeper cut with more power, less speed.
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You need to remember the basic principle of converting solid material into gas.
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If you convert that solid material into gas too quickly. It will become explosive and uncontrollable.
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Do it gently and if you’ve got enough gap between the work and your nozzle the fumes will drift up and get carried away by the managed airflow.
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Oh.
Transcript for How To Do Relief Engraving and Air Assist (Cont…)
