Session 21 – Line Drawing with a CO2 Laser

Transcript for Line Drawing with a CO2 Laser

1
00:00:06,070 –> 00:00:10,940
The Concise RDWorks Learning Lab with Russ Sadler.

2
00:00:10,940 –> 00:00:27,410
Session 21: Line drawing. This is today’s session, it’s all about using the machine for drawing.

3
00:00:27,410 –> 00:00:34,520
Now, many people think that this is the easy part of using the laser machine.

4
00:00:34,520 –> 00:00:44,060
I beg to differ. There is a lot of understanding that you have to have to get good quality drawings out of this machine.

5
00:00:44,060 –> 00:00:51,750
Now, as I’ve said, for many other engraving processes, you can just throw some numbers into this machine and it will produce a result.

6
00:00:51,750 –> 00:00:55,970
Will it be a good result? Well, that’s up to you to judge.

7
00:00:55,970 –> 00:01:03,830
You might be lucky first time, but there’s quite a lot more to vector drawing than meets the eye.

8
00:01:03,830 –> 00:01:09,260
And I’m going to show you some of the tricks and secrets today to getting a good result.

9
00:01:09,260 –> 00:01:12,920
You will note how the smoke is pulling away towards the back.

10
00:01:12,920 –> 00:01:19,130
We’re using all the same sort of tricks that we’ve used in previous sessions, we’re using the engraving nozzle.

11
00:01:19,130 –> 00:01:22,190
And we’re using very, very low air assist.

12
00:01:22,190 –> 00:01:31,700
And we’re drawing the fumes away very quickly, so that they don’t make the job brown, because this is cardboard

13
00:01:31,700 –> 00:01:38,390
after all, a type of wood. This is producing nasty brown fumes exactly the same as wood.

14
00:01:38,390 –> 00:01:42,500
OK, can you see any hint of brown on there, apart from the lines?

15
00:01:42,500 –> 00:01:47,000
So we’re going to start off again, as we always do with the sessions at square one.

16
00:01:47,000 –> 00:01:53,420
We’re going to break the problem down into its simplest elements and gradually work towards doing this sort of work. Although

17
00:01:53,420 –> 00:02:00,020
you can do this on wood. Birch plywood is very good because it’s got a fairly uniform texture.

Transcript for Line Drawing with a CO2 Laser (Cont…)

18
00:02:00,020 –> 00:02:05,870
Certainly, I wouldn’t be trying to do this on something like bamboo.

19
00:02:05,870 –> 00:02:10,490
There are just too many different woods in this thing called bamboo.

20
00:02:10,490 –> 00:02:17,360
Bamboo might be classed as a wood, but within bamboo there’s around about a thousand other woods.

21
00:02:17,360 –> 00:02:23,600
And we’ll take a look at that later on and I’ll explain what I mean.

22
00:02:23,600 –> 00:02:34,340
This is basically a one millimetre thick piece of beer mat card, the sort of thing that’s used in pubs that soaks up your beer if you spill it.

23
00:02:34,340 –> 00:02:38,390
So this is basically pretty raw wood.

24
00:02:38,390 –> 00:02:43,970
It’s uniform wood because it’s just wood pulp that’s been reconstituted.

25
00:02:43,970 –> 00:02:47,900
There’s no other chemicals or materials in here.

26
00:02:47,900 –> 00:02:52,130
So it is as I said, this is basically grainless wood.

27
00:02:52,130 –> 00:02:59,840
I’m using this because it’s a very good material to demonstrate the sort of principles, that I need to show you. As I pointed out to you just now.

28
00:02:59,840 –> 00:03:02,990
We’re using the short nozzle because we are engraving.

29
00:03:02,990 –> 00:03:11,660
We want the maximum distance we can possibly get between the work and the nozzle. For the small amount of material that we’re going to be burning,

30
00:03:11,660 –> 00:03:17,370
it’s still going to explode upwards and get drawn away, as you saw in the opening shots. We’re

31
00:03:17,370 –> 00:03:23,090
using your two inch lens with the flat side down at the moment.

32
00:03:23,090 –> 00:03:32,840
We experiment with that a little bit later on. Well, one of the first things we’re going to talk about today is my Ferrari, that I don’t have.

33
00:03:32,840 –> 00:03:39,720
But there is an effect on this machine that I like to describe as the Ferrari effect.

34
00:03:39,720 –> 00:03:46,640
It’s just a piece of ordinary physics. But if I relate it to a Ferrari, I’m sure you will remember what we’re talking about.

35
00:03:46,640 –> 00:03:54,080
So if I had this wonderful machine that was capable of doing 200 miles an hour, I could take it out onto the road.

36
00:03:54,080 –> 00:04:02,270
And if nobody caught me, I could travel in a straight line 200 miles an hour.

Transcript for Line Drawing with a CO2 Laser (Cont…)

37
00:04:02,270 –> 00:04:09,620
Right now, the question is, if I started off from the traffic lights, what distance would it take?

38
00:04:09,620 –> 00:04:18,290
The chances are it would be something like maybe a quarter of a mile, maybe to get up to 200 miles an hour.

39
00:04:18,290 –> 00:04:23,310
And then, of course, I could carry on at 200 miles an hour. Let’s change the scenario

40
00:04:23,310 –> 00:04:28,040
now. I haven’t got a straight road and I haven’t got a set of traffic lights.

41
00:04:28,040 –> 00:04:35,340
What I’ve got. Is the block where I live, which might have six houses on it,

42
00:04:35,340 –> 00:04:44,510
and it’s probably about 200 meters by 200 meters, and there’s a road that runs around the block like this.

43
00:04:44,510 –> 00:04:56,780
OK? Now, if I start here with my Ferrari, how fast will I be going when I get to this corner? or

44
00:04:56,780 –> 00:05:06,020
put it another way. How fast will I be able to get to before I have to put the brakes on to go round the corner?

45
00:05:06,020 –> 00:05:12,590
The chances are I will only probably be able to get up to about 60 mph because by the time I get to 60,

46
00:05:12,590 –> 00:05:21,530
I’ve got a jam on the brakes to get round the corner. So there isn’t a lot of point in having a 200 mile an hour car.

47
00:05:21,530 –> 00:05:25,760
If you’re on a very short, small sharp road.

48
00:05:25,760 –> 00:05:34,910
The only time you can benefit from that 200 miles an hour, is if you’ve got a long, straight road or a very gentle curve.

49
00:05:34,910 –> 00:05:44,930
Here is the Ferrari of my machine. It’s the head. It cannot instantly go from zero to two hundred millimetres a second.

50
00:05:44,930 –> 00:05:47,090
It’s the same problem as my Ferrari.

51
00:05:47,090 –> 00:05:57,800
It takes a physical amount of time before it can get to 200 millimetres a second and then it can carry on at 200 millimetres a second.

Transcript for Line Drawing with a CO2 Laser (Cont…)

52
00:05:57,800 –> 00:06:06,020
But equally, it takes time to to slow down from 200 millimeters a second to zero.

53
00:06:06,020 –> 00:06:14,840
So there is an acceleration and a deceleration period, which depends upon the speed at which the head is moving.

54
00:06:14,840 –> 00:06:22,250
So the faster you move the head, the greater the distance it will take for it to reach the speed that you want

55
00:06:22,250 –> 00:06:27,650
to travel at, 200 miles an hour or on this machine 200 millimetres a second.

56
00:06:27,650 –> 00:06:44,420
So every time I approach a corner, I’ve got to slow down to zero in Y, and then I’ve got to start from zero in X.

57
00:06:44,420 –> 00:06:53,450
So at that point, there the speed is zero zero X and Y, it comes to a dead halt on the corner.

58
00:06:53,450 –> 00:07:00,380
Now, the problem with this machine is the power is on all the time.

59
00:07:00,380 –> 00:07:11,250
As we slow down, the cut will get deeper and deeper and deeper to the point where when the beam is stopped, it will be very deep.

60
00:07:11,250 –> 00:07:13,010
And then when the beam starts off again,

61
00:07:13,010 –> 00:07:20,680
it will get shallower and shallower and shallower and then it’ll get deep again on this corner and this corner and this corner.

62
00:07:20,680 –> 00:07:38,880
Hey now, I’m just going to give you a little demonstration of the Ferrari effect.

63
00:07:38,880 –> 00:07:46,890
OK, so here is that 200 meter race track around the block, that I was just describing to you.

64
00:07:46,890 –> 00:07:52,260
We go flying down here, we have to put the brakes on and we have to stop at the corner.

65
00:07:52,260 –> 00:07:57,540
But because the power hasn’t stopped, here’s what happens at the corner.

66
00:07:57,540 –> 00:08:03,720
Look, you can clearly see the brakes being applied here as it slows down.

Transcript for Line Drawing with a CO2 Laser (Cont…)

67
00:08:03,720 –> 00:08:12,220
Look, so here we are. We’re running from zero up to and we’re an accelerating up to 100 millimetres a second.

68
00:08:12,220 –> 00:08:17,140
We’re then running along here with a shallow cut at 100 millimetres a second and then all of a sudden,

69
00:08:17,140 –> 00:08:21,360
whoa, we’re going to hit the corner, too fast, jam on the brakes.

70
00:08:21,360 –> 00:08:28,560
So we jam on the brakes and eventually we stop at the corner and look how deep the cut is right at the corner.

71
00:08:28,560 –> 00:08:32,880
So here’s our original hundred millimetres a second and you can see it accelerating.

72
00:08:32,880 –> 00:08:39,600
It reaches 100 millimetres a second and then it decelerates. Now we change to 400 millimeters a second.

73
00:08:39,600 –> 00:08:45,420
And look, first of all, it takes a lot longer to get to 400 millimeters a second.

74
00:08:45,420 –> 00:08:49,830
It just about makes 400 millimeters a second in the middle here.

75
00:08:49,830 –> 00:08:53,980
Look. And then it has to jam on the anchors here.

76
00:08:53,980 –> 00:08:59,100
Now, there’s no difference in the depth of cut because we’ve still got exactly the same power.

77
00:08:59,100 –> 00:09:05,040
So when it stops, it stops. So the depth of cut will be the same.

78
00:09:05,040 –> 00:09:11,490
The only thing that will be different is that because we’ve asked it to run at 400 millimetres a second,

79
00:09:11,490 –> 00:09:16,740
it takes longer to accelerate up to the correct speed.

80
00:09:16,740 –> 00:09:23,490
The point I’m making here is you can set a drawing speed to anything you like.

81
00:09:23,490 –> 00:09:33,240
It could be a thousand millimetres a second, but if the distance is not long enough, it will never make a thousand millimetres a second.

82
00:09:33,240 –> 00:09:41,580
If you’ve only got a two millimetre long cut at 100 millimetres a second, it’s still going to not make 100 millimetres a second.

83
00:09:41,580 –> 00:09:45,090
It’s only going to make maybe 40 or 50 millimetres a second.

84
00:09:45,090 –> 00:09:49,620
And that’s your burning capability, 50 millimetres a second.

85
00:09:49,620 –> 00:09:57,240
Speed and power are related to the depth of cut or to the damage you can do.

Transcript for Line Drawing with a CO2 Laser (Cont…)

86
00:09:57,240 –> 00:10:04,890
So we’ve got two physics problems here. Number one, we want to cut and draw as fast as we can do.

87
00:10:04,890 –> 00:10:11,910
And when you’ve got fairly smooth, straight lines, you can run pretty fast.

88
00:10:11,910 –> 00:10:20,460
But when you’ve got sharp corners, you have to slow down and as you slow down, so your line thickness will change and you’ll burn

89
00:10:20,460 –> 00:10:29,310
depth will change. I’ve changed my material to MDF because it’s a nice, easy material to see the effect that I want to show you.

90
00:10:29,310 –> 00:10:36,270
Now, I’m going to run exactly that same 400 millimetres a second Test square again.

91
00:10:36,270 –> 00:10:39,960
I think you can see on these corners here,

92
00:10:39,960 –> 00:10:45,150
the line is getting thicker and it’s getting browner on these corners, because

93
00:10:45,150 –> 00:10:52,920
of the slowing down effect. Let’s change that to 100 millimeters a second.

94
00:10:52,920 –> 00:11:00,870
OK, so those are the two for comparison. When the beam stops, penetration is the same for both in the corners.

95
00:11:00,870 –> 00:11:09,870
And we can see that because if I turn it over, look, it’s come through by exactly the same amount on both of them. Because this is a fairly hard material.

96
00:11:09,870 –> 00:11:15,870
You can’t really see that change very much. Here’s my beer mat card.

97
00:11:15,870 –> 00:11:23,670
And you can see the effect very, very clearly on here, how it’s running into the corners, making the lines thicker and blacker.

98
00:11:23,670 –> 00:11:31,320
And then when we turn it over and have a look what’s on the back, you can see how far the effect is coming into the corners.

99
00:11:31,320 –> 00:11:36,930
So what I’m going to do now is to show you how we get rid of this effect.

100
00:11:36,930 –> 00:11:46,710
So here’s my little program. And I had it running at 400 millimetres a second and I was using 20 percent power for both Max and Min.

101
00:11:46,710 –> 00:11:50,520
This is one of the occasions when you can use minimum power.

102
00:11:50,520 –> 00:11:55,320
Most of the time you would always have your max and min power set the same,

103
00:11:55,320 –> 00:12:01,980
especially if you’re cutting. Mainly it’s for engraving that you might want to change this minimum power.

Transcript for Line Drawing with a CO2 Laser (Cont…)

104
00:12:01,980 –> 00:12:10,980
And what I’m going to do is I’m going to change that minimum power to five percent at the moment, leave everything else, the same.

105
00:12:10,980 –> 00:12:15,240
Now, bear in mind, the only thing that I’ve changed is minimum power.

106
00:12:15,240 –> 00:12:22,860
We’re going to change the power up to eight percent minimum power.

107
00:12:22,860 –> 00:12:26,160
We’ve just about got the corners to join up.

108
00:12:26,160 –> 00:12:34,200
Let me go back to seven per cent and I’ll show you that it doesn’t take very much to make the corners separate.

109
00:12:34,200 –> 00:12:41,520
So this is minimum of seven percent. And as you can see, at seven percent power,

110
00:12:41,520 –> 00:12:45,060
the corner is missing. We haven’t. What we’ve done,

111
00:12:45,060 –> 00:12:52,590
we basically put the brakes on and we stopped before the corner. There is something built into the machine, which I’m not going to explain,

112
00:12:52,590 –> 00:13:03,410
but basically it is a proportional power control that happens in relation to the speed that you are running.

113
00:13:03,410 –> 00:13:10,920
And in fact, at nine percent, we’ve overdone it. Look, it’s got a little bit of burning in the corners.

114
00:13:10,920 –> 00:13:16,800
And let’s look underneath, and look we’re just coming through with the power.

115
00:13:16,800 –> 00:13:20,970
So we applied the brakes to late at nine percent.

116
00:13:20,970 –> 00:13:26,040
So it looks as though eight percent is the right value that we should be choosing.

117
00:13:26,040 –> 00:13:32,250
So let’s try eight percent, and there we go at eight percent, we’ve got nice clean corners.

118
00:13:32,250 –> 00:13:38,940
And if we look underneath, we have no burning through. Let’s change that to 100 millimetres a second.

119
00:13:38,940 –> 00:13:43,310
Well, we got a darker result. Corners not too bad.

120
00:13:43,310 –> 00:13:48,240
It was four hundred millimetres a second here and now it’s 100 millimetres a second,

121
00:13:48,240 –> 00:13:52,070
the line thickness doesn’t look a lot different, but the colour is.

122
00:13:52,070 –> 00:13:59,250
But I think I’ve described to you in one of the previous sessions, how colour is nothing to do with the burning effect.

Transcript for Line Drawing with a CO2 Laser (Cont…)

123
00:13:59,250 –> 00:14:04,610
It’s all to do with the depth of the cut, and it’s the depth of the cut, the blackness,

124
00:14:04,610 –> 00:14:12,860
the occlusion of light that’s causing this apparent blackening of the line. As the line gets towards the surface,

125
00:14:12,860 –> 00:14:18,530
shallow here, it looks brown, but as you put it in deeper, it gets black.

126
00:14:18,530 –> 00:14:24,740
That’s the key thing, that I wanted to explain to you; the Ferrari effect and the fact that you can get rid of the

127
00:14:24,740 –> 00:14:33,590
Ferrari effect by changing the minimum power. We’ll just do our Ferrari test square again,

128
00:14:33,590 –> 00:14:48,080
using the same minimum power number. We’ve got rid of that corner penetration because we’ve stopped the power exactly at the corner?

129
00:14:48,080 –> 00:14:54,920
OK, so I’ve just draw a little program here and we’ll use exactly the same parameters.

130
00:14:54,920 –> 00:15:03,630
Hundred millimetres a second and eight percent and 20 percent min and max power.

131
00:15:03,630 –> 00:15:12,120
And we’ll see what results we get this time, should we? We’re going to run that program again,

132
00:15:12,120 –> 00:15:18,150
and I’ve made one small change. Nothing to do with the speed or the power.

133
00:15:18,150 –> 00:15:30,800
I’ve just added another feature. Listen, can you hear how that’s hissy? The cut, and again as it goes around the outside.

134
00:15:30,800 –> 00:15:45,210
Listen to how hissy that cut is. That tells me we’re in pre-ionisation mode. Let’s just change the power very slightly to something like 30 percent.

135
00:15:45,210 –> 00:15:55,070
I don’t know whether you’ll be able to say that, but with the naked eye, this one is definitely blacker than this one.

136
00:15:55,070 –> 00:15:59,240
This one’s got a slightly brown hue, a dark brown hue to it.

Transcript for Line Drawing with a CO2 Laser (Cont…)

137
00:15:59,240 –> 00:16:08,000
And this one is blacker, and it’s also crisper, because changed the speed from 100 to 400 millimetres a second.

138
00:16:08,000 –> 00:16:10,190
The line has got thinner.

139
00:16:10,190 –> 00:16:18,560
These little pieces will never get up 400 millimetres a second in the same way that these will never get up to 100mm/s.

140
00:16:18,560 –> 00:16:25,820
So I think these are both looking the same because they are limited by the speed they can actually reach.

141
00:16:25,820 –> 00:16:42,540
Now, let’s just run this last sample that I did, on different materials to see what the effect is.

142
00:16:42,540 –> 00:16:51,930
Did you hear that last rip around that the speed and the noise that tells me we’re still operating in pre-ionisation mode?

143
00:16:51,930 –> 00:17:05,370
Let’s try a piece of my soft poplar plywood. And a piece of Baltic birch plywood.

144
00:17:05,370 –> 00:17:14,530
And now a piece of interesting thin white card, which I’ll explain in a minute what it is.

145
00:17:14,530 –> 00:17:22,820
As you can see, these settings work for a whole range of materials. That’s just about to come through the back of that card.

146
00:17:22,820 –> 00:17:30,080
Now, if we hold this last one up to the light, it’s full of perforations.

147
00:17:30,080 –> 00:17:35,990
That perforation is what I was describing to you in an earlier session.

148
00:17:35,990 –> 00:17:41,390
That’s what pre-ionisation does. You heard it making a very hissy noise.

149
00:17:41,390 –> 00:17:51,500
That’s high frequency pulses. And that’s why those pieces haven’t fallen out, because it’s a perforated cut, not a continuous cut.

150
00:17:51,500 –> 00:17:57,230
And pre-ionization tends to give you a very nice, clean smoke free cut.

Transcript for Line Drawing with a CO2 Laser (Cont…)

151
00:17:57,230 –> 00:18:03,830
There’s no smoke damage on any of these. So there will be instances when you want thicker lines.

152
00:18:03,830 –> 00:18:08,810
So the way you get thicker lines is you don’t mess around with the power or anything like that.

153
00:18:08,810 –> 00:18:16,280
You just put it out of focus slightly. So I’m going to lift that focus up by two millimetres for your two inch lens.

154
00:18:16,280 –> 00:18:24,030
You’ll notice how much darker that is. It’s not because I’ve increased the power.

155
00:18:24,030 –> 00:18:36,860
It’s because I’ve basically softened the intensity. I’m basically doing more scorching and less deep cutting.

156
00:18:36,860 –> 00:18:51,140
OK, the lines are slightly thicker as well. So look at the range of colours that we’ve achieved just by messing around with the focus.

157
00:18:51,140 –> 00:18:56,660
We haven’t seriously compromised the thickness of the lines or the quality of the shape.

158
00:18:56,660 –> 00:19:06,880
We’ve made the lines slightly thicker, much darker, and we’ve done that just by increasing the focal distance.

159
00:19:06,880 –> 00:19:13,150
Didn’t we have an amazing effect when we changed the focal distance, when we were deep engraving?

160
00:19:13,150 –> 00:19:19,480
It’s very underused facility on this machine, changing the focus.

161
00:19:19,480 –> 00:19:23,110
Everybody wants to keep things perfectly in focus.

162
00:19:23,110 –> 00:19:34,760
Perfectly in focus isn’t always the right way, as I hope I’m demonstrating to you. Let’s see what out of focus does on this card.

163
00:19:34,760 –> 00:19:44,630
Now, with this thin card, you can clearly see that we are not cutting in as deep. As I said, when we’re running with it in focus,

164
00:19:44,630 –> 00:19:49,860
we’ve got good penetration into the material. When we defocus,

165
00:19:49,860 –> 00:19:54,350
we’ve got exactly the same amount of power there, but we’ve softened the power and

166
00:19:54,350 –> 00:20:00,260
we’ve spread it out. So that it can’t go in as deeply. It doesn’t go in as deeply,

Transcript for Line Drawing with a CO2 Laser (Cont…)

167
00:20:00,260 –> 00:20:08,480
and it actually scorches the material more than cut the material, which is why we’ve got a darker and a thicker line cut.

168
00:20:08,480 –> 00:20:17,000
And if we look on the back, you’ll see we’ve got nothing coming through, whereas previously we had cuts that went right the way through.

169
00:20:17,000 –> 00:20:26,660
OK, now I’ve taken the two inch lens and I’ve physically turned it from flat side down where we had fifty point eight,

170
00:20:26,660 –> 00:20:39,080
exactly where we expected it to be. And I’ve turned it flat side up and now the focal point is no longer where we expect it to be,

171
00:20:39,080 –> 00:20:45,270
just there. The focal point has come down here to fifty two point eight. In other words,

172
00:20:45,270 –> 00:20:51,570
we’ve got a bigger gap. Now, you can’t really see it,

173
00:20:51,570 –> 00:21:00,570
probably on this picture, but these two lines here are pretty close to the same, but that I judge to being the thinner line of the two.

174
00:21:00,570 –> 00:21:09,930
But when I compare that line to this line here, this line is slightly thinner than that line there.

175
00:21:09,930 –> 00:21:19,740
So the focal point is different and it’s also generating a slightly thicker line when we use it this way up.

176
00:21:19,740 –> 00:21:22,110
Now, that may be to our advantage,

177
00:21:22,110 –> 00:21:33,060
because now I’m going to move away from; everything that we’ve been doing up to now has been done at low power, 20, 30 percent power.

178
00:21:33,060 –> 00:21:40,980
Now, if I want to do big letters, I should be able to run very fast because remember the Ferrari effect.

179
00:21:40,980 –> 00:21:50,310
If we get big letters, we shall get large expanses of curves and long straight lines, we should be able to run very fast.

180
00:21:50,310 –> 00:21:58,870
But of course, if we run very fast, we’ll run out of puff because we shan’t have enough power at 20 percent.

181
00:21:58,870 –> 00:22:04,740
So we shall have to put the power right the way up, which is the opposite end of the spectrum.

Transcript for Line Drawing with a CO2 Laser (Cont…)

182
00:22:04,740 –> 00:22:10,230
The problem with understanding how the machine works is it sometimes can get in the way.

183
00:22:10,230 –> 00:22:18,570
We’ve been working with powers down at the blunt end of my beam, because this is what the intensity looks like

184
00:22:18,570 –> 00:22:21,270
at round about 20 percent.

185
00:22:21,270 –> 00:22:33,450
I probably exaggerate that slightly because, as I said, when we’re using the pre-ionisation zone, we artificially probably jump up to here or here.

186
00:22:33,450 –> 00:22:38,780
Even though technically we would expect to be right the way down here. Because of the high,

187
00:22:38,780 –> 00:22:44,310
high frequency pulses, we get a much sharper beam than we would normally expect.

188
00:22:44,310 –> 00:22:49,980
But now we’re going to go right to this end of the spectrum and we’re going to use full power.

189
00:22:49,980 –> 00:22:54,150
Now, full power means that we’re going to get a much sharper beam.

190
00:22:54,150 –> 00:23:01,680
Does that mean to say we’re going to be able to get thicker lines if we pull it out of focus? Hmm.

191
00:23:01,680 –> 00:23:06,900
That’s an interesting question you see. If we want to run fast to do drawing.

192
00:23:06,900 –> 00:23:15,360
What about running into the corners with the Ferrari effect? And then we’ve got this effect here where we might get a sharp beam rather than a blunt beam.

193
00:23:15,360 –> 00:23:23,010
Now, I’ve got the lens the wrong way round. Curved side down remember. And we said that it was around about fifty two point eight,

194
00:23:23,010 –> 00:23:27,930
which is a two millimetre bigger gap than previously.

195
00:23:27,930 –> 00:23:34,920
So fifty two would mean this would normally be set at 22.

196
00:23:34,920 –> 00:23:44,790
So if I want to add 4 to that, I’ve got to set this at twenty six. So we’re four millimetres above the focal point and we’re going to run this with

197
00:23:44,790 –> 00:23:50,010
the standard parameters that we’ve been using up to now, 200 millimetres

198
00:23:50,010 –> 00:24:02,870
a second, 30 percent power for maximum and eight percent minimum.

Transcript for Line Drawing with a CO2 Laser (Cont…)

199
00:24:02,870 –> 00:24:14,700
As I think you can see, hmm, it’s not all that dark. And what we have got is where it’s running along very fast here, 200 millimetres a second.

200
00:24:14,700 –> 00:24:21,450
And up here, it’s slightly lighter than it is where it’s going slower round these corners.

201
00:24:21,450 –> 00:24:24,840
The same applies here. Look, we’ve got dark and light.

202
00:24:24,840 –> 00:24:29,970
The whole of that centre section is darker because it never gets up to 200 millimetres a second.

203
00:24:29,970 –> 00:24:35,110
The first thing we’ll do is we’ll raise the power up to 95 percent.

204
00:24:35,110 –> 00:24:50,580
Now, trust me, 95 percent on my machine is perfectly OK because I’ve got an underpowered power supply on here, which I can drive to it’s limit.

205
00:24:50,580 –> 00:24:57,420
You see, that’s pretty good. I’m going to push this up to 400 millimetres a second.

206
00:24:57,420 –> 00:25:04,020
Think about it for a minute. Remember the Ferrari effect? OK, so I’ve set the speed to 400 millimetres a second.

207
00:25:04,020 –> 00:25:12,660
Will it ever reach 400 millimetres a second? Because some of these corners here, it cannot go round these corners at 400 millimetres a second.

208
00:25:12,660 –> 00:25:22,260
So by running faster, I’m likely to bring this difference in thickness and density back into the equation, because

209
00:25:22,260 –> 00:25:28,140
in places it will be running very slowly and in other places like round here or down here,

210
00:25:28,140 –> 00:25:35,980
it will make it to 400 millimetres a second. And these lines will be a lot lighter.

211
00:25:35,980 –> 00:25:49,590
Well, there’s no doubt about it, it’s definitely lighter.

212
00:25:49,590 –> 00:25:54,360
OK, so if I want these lines to be thicker. I can I can feel in there

213
00:25:54,360 –> 00:25:58,500
at the moment they are quite deep, with my fingernail.

Transcript for Line Drawing with a CO2 Laser (Cont…)

214
00:25:58,500 –> 00:26:07,050
So I could get those lines thicker and darker by lifting the focus up at 200 millimetres a second.

215
00:26:07,050 –> 00:26:14,700
And that was four millimetres above the focal point, five, six, seven millimetres above the focal point now.

216
00:26:14,700 –> 00:26:30,740
So we’re running this at 200 millimetres a second, full power.

217
00:26:30,740 –> 00:26:38,870
Quite nice, thick lines that are proportionate to the size of font that we’re using, we’ve been able to run quite fast and we’ve got it quite dark.

218
00:26:38,870 –> 00:26:49,070
What I’m saying to you is there is a whole range of power, speed and focus that you can use with drawing.

219
00:26:49,070 –> 00:26:56,700
But do not overlook the Ferrari effect, which we don’t have here because look, we’ve got no sharp corners on this font.

220
00:26:56,700 –> 00:27:16,220
Let me change the font and see what effect this setting has on a different font.

221
00:27:16,220 –> 00:27:26,000
I mean, I can see that just here, for example, on the Serifs, we’ve got a little bit of darkening here, and on the short lines.

222
00:27:26,000 –> 00:27:34,940
We still got quite a good depth of cut in there. But we’re losing a little bit of colour just here,

223
00:27:34,940 –> 00:27:43,770
where it gets up to speed. Look, it’s darker down at the bottom and at the top and lighter down these gentle curves. The same applies here

224
00:27:43,770 –> 00:27:46,890
look, we’re going up the N and then when we get up to here.

225
00:27:46,890 –> 00:27:57,990
It gets very dark, very dark, and then it moves away from dark to quite light here, back to dark, light, and then you get darker on the top of these serifs.

Transcript for Line Drawing with a CO2 Laser (Cont…)

226
00:27:57,990 –> 00:28:06,040
So, yes, there are differences if you’re critical. But if you just look at that, generally, that’s not bad.

227
00:28:06,040 –> 00:28:14,510
What I’m basically trying to show you is, you can get thick lines and thin lines with drawing, you’re not limited to just thin lines at

228
00:28:14,510 –> 00:29:10,840
the focal point. A little demonstration to finish off with. So as you can see, we’re using all the tricks of engraving here.

229
00:29:10,840 –> 00:29:20,910
You can clearly see that the smoke is not really reaching the nozzle, and the explosive effect on the surface is obvious,

230
00:29:20,910 –> 00:29:27,050
but we are not sending it up so high that it’s trying to force its way into the nozzle. It’s

231
00:29:27,050 –> 00:29:38,570
being drawn away by the crossflow of air, before it has a chance to get up there.

232
00:29:38,570 –> 00:30:05,480
We’ve turned the lens flat down again and we’re using this four millimetres above the focal point, so that we get a nice dark burn and a slightly thicker line.

Transcript for Line Drawing with a CO2 Laser (Cont…)

233
00:30:05,480 –> 00:30:15,490
Now I put the outside shape on a different layer because I want to cut it, and the problem is, I want to cut it

234
00:30:15,490 –> 00:30:22,470
at 20 mm. So I’ve got to stop the program, reset the focus,

235
00:30:22,470 –> 00:30:45,090
and run just the outside of the job. Just take those little magnets off there.

236
00:30:45,090 –> 00:30:53,850
And there we have a beautiful table mat, if you want such a table mat. And we haven’t talked about cutting yet, but hey, I cut that with an engraving

237
00:30:53,850 –> 00:30:56,620
nozzle. Not the best thing to do,

238
00:30:56,620 –> 00:31:03,880
but it’s always possible, because I’ve just got this one shape to go around the outside here and I can make some compromises.

239
00:31:03,880 –> 00:31:08,360
But hey, that’s as much as we need to do about drawing

240
00:31:08,360 –> 00:31:11,680
with your laser, you can see what is possible.

241
00:31:11,680 –> 00:31:23,264
The rest is all down to your imagination and remembering some of the things that we’ve done with this machine today.

Transcript for Line Drawing with a CO2 Laser