The Concise RDWorks Learning Lab Series
Welcome to Module 3 of the new Concise RDWorks Learning Lab Series with Russ Sadler. Module 3 will build on the information learned in the previous modules and will be targeted on the differing types of laser engraving methods and the techniques needed to consistently achieve great engraving results. We’re about to learn how to laser engrave!
In this Session, Russ starts the “Doing Process” and starts us off with an overview of engraving. The 9 processes of laser engraving explained. Surface, Deep Cut, Relief, Line, 3D, Greyscale, Photo, Laser Origami & Lace Work. What materials can be engraved?
Release Date: 5th November 2021 (Bonfire Night in the UK)
Over the last 6 years, Russ has built up a formidable YouTube following for his RDWorks Learning Lab series which currently has over 200 videos.
The original RDWorks Learning Lab series on his “Sarbar Multimedia” YouTube Channel, follows Russ as he tries to make sense of his new Chinese laser machine and to sort out the truths, half truths and outright misleading information that is available on the web.
Six years later with over 3 million YouTube Views under his belt, Russ has become the go to resource for everything related to the Chinese CO2 laser machine user or wannabe user.

In this new series, Russ has condensed his knowledge and experience of the last 6 years to provide valuable information and insights into the purchasing, understanding, use, repair and maintenance of the Chinese CO2 laser machines and their key component parts.
Watch Session 17 – How to Laser Engrave – An Overview, through the Panopto Viewer;
Watch this video through the Panopto Viewer (free sign-up required for full functionality) for a more interactive viewing experience. The viewer will allow you to:
- Change the Captions to show translated subtitles if English is not your first language.
- Currently available languages include: Chinese (Simplified), Danish, Finnish, French, German, Hungarian, Italian, Japanese, Korean, Norwegian, Polish, Portuguese, Spanish, Swedish and Thai . These are Google translations, so if you spot any errors, please let us know.
- You can search the video for specific keywords and jump to the relevant section.
- This can work both within an individual video, across all videos and across all translated languages.
- Post public comments on the video as well as private comments to the moderators.
- Add your own notes, synchronised to what you are watching
- Add bookmarks to remind you of important items.
Podcast Download for How to Laser Engrave – An Overview
You can download the audio file for this video here, just click on the three dots to the right of the player:
Video Resource Files for How to Laser Engrave – An Overview
There are no resource files associated with this video.

External Resource Links for How to Laser Engrave – An Overview
There are no external resource links associated with this video.

Transcript for How to Laser Engrave – An Overview
Click the “Show More” button to reveal the transcript, and use your browsers Find function to search for specific sections of interest.
Transcript for How to Laser Engrave – An Overview
1
00:00:05,870 –> 00:00:15,820
The Concise RDWorks Learning Lab with Russ Sadler. Session 17 Engraving – An Overview.
2
00:00:15,820 –> 00:00:19,980
Well, here we are, I think we are in session 16.
3
00:00:19,980 –> 00:00:29,190
Now, we’ve done nothing with this machine up to now except trying to understand the technology and the various parts of the machine,
4
00:00:29,190 –> 00:00:35,820
because first of all, you are the only one that’s going to be responsible for servicing and looking after the machine when it goes wrong.
5
00:00:35,820 –> 00:00:42,000
But I hope what we’ve done so far by taking you through the various elements of the machine would take some of the instant fear away.
6
00:00:42,000 –> 00:00:45,030
When something goes wrong, it will hopefully make you stop,
7
00:00:45,030 –> 00:00:52,840
think, look at the various things that may have gone wrong in the chain and work your way back to find out what the problem is.
8
00:00:52,840 –> 00:01:02,630
Now, the mechanics of the machine are not really an issue because they’re just bits of metal screws, wire, etc.
9
00:01:02,630 –> 00:01:07,130
The real problem comes in doing something with the machine.
10
00:01:07,130 –> 00:01:21,110
And today we’re going to start the doing process. Now, you bought this machine for two reasons, one, to cut materials, and two, to engrave materials.
11
00:01:21,110 –> 00:01:27,500
I don’t think you really understood just how big the subject is. So, I’ve got to make a decision,
12
00:01:27,500 –> 00:01:32,780
now do I start you off with engraving or do I start you off with cutting?
13
00:01:32,780 –> 00:01:39,430
Now that’s a big decision for me because they are two completely different subjects.
14
00:01:39,430 –> 00:01:43,770
They are absolutely diametrically opposite in every respect.
15
00:01:43,770 –> 00:01:51,460
Now sometimes you’ll have to find some compromise parameters because you’re going to do some cutting and some engraving on the same job.
16
00:01:51,460 –> 00:01:56,170
That’s where your skill will come in making a judgment as to what parameters you should use,
Transcript for How to Laser Engrave – An Overview (Cont…)
17
00:01:56,170 –> 00:02:03,810
what lenses you use, how much power you should use, what material you should use. Oh dear, the problems are endless.
18
00:02:03,810 –> 00:02:13,740
Now, I’ve made the decision, after all, that you’re going to start off with engraving now, engraving is a huge subject.
19
00:02:13,740 –> 00:02:19,830
You’re going to have to go back to that first or second session and start remembering some of the science that we spoke about,
20
00:02:19,830 –> 00:02:25,020
because now that science of both the laser,
21
00:02:25,020 –> 00:02:31,410
and the material is going to be very, very important to you. Yes, you can sit down at this machine,
22
00:02:31,410 –> 00:02:38,520
you can put a few parameters into the program, chuck a bit of wood under the laser head and you’ll get a result.
23
00:02:38,520 –> 00:02:42,810
It might look like a barbecued piece of wood, but hey, it’s a result and you’ll be very,
24
00:02:42,810 –> 00:02:49,080
very pleased with it until you get a bit more proficient and you look back at it in a couple of years time and you think,
25
00:02:49,080 –> 00:02:53,700
how did I manage to produce something that bad? It is practice,
26
00:02:53,700 –> 00:03:04,470
but hopefully I’m going to teach you some of the tricks and essential lessons that I learned that will stop you making too much barbecued wood.
27
00:03:04,470 –> 00:03:11,700
I’m not sure that even this list fully covers all the opportunities for laser engraving.
28
00:03:11,700 –> 00:03:18,990
The thing that you first imagined is probably number one. That’s the only thing that you think about when you normally see engraving.
29
00:03:18,990 –> 00:03:24,810
This is the sort of thing that you’d think about doing some text burnt into a piece of wood.
30
00:03:24,810 –> 00:03:31,590
Okay, well, that is just basic laser surface engraving. Now, here is Laser deep cut engraving.
31
00:03:31,590 –> 00:03:38,190
It’s called incised text, because what we’ve done, we’ve cut deeply into this wood.
32
00:03:38,190 –> 00:03:42,420
And I don’t think it takes a genius to work out what Laser relief engraving is.
33
00:03:42,420 –> 00:03:48,330
The text has been allowed to come up to the surface and we’ve taken away all the background.
34
00:03:48,330 –> 00:03:54,960
So it’s the opposite of this incised text. This is laser line engraving.
35
00:03:54,960 –> 00:04:02,970
Now, all the lines on here are different thicknesses and I’ve achieved the different thicknesses of lines on here.
Transcript for How to Laser Engrave – An Overview (Cont…)
36
00:04:02,970 –> 00:04:08,940
By virtue of changing the distance of the focus, it’s the same lens,
37
00:04:08,940 –> 00:04:14,720
but different focal distances produce different thicknesses of lines for different parts of the job.
38
00:04:14,720 –> 00:04:19,520
So you can see these lines down here are completely different thicknesses to these very,
39
00:04:19,520 –> 00:04:30,150
very thin lines here for the cables and then here’s something that you didn’t probably know that the machine could do, laser 3-D engraving.
40
00:04:30,150 –> 00:04:41,750
Wood and acrylic.
41
00:04:41,750 –> 00:04:45,890
Was that a surprise? I’m not going to go too much into laser grayscale engraving.
42
00:04:45,890 –> 00:04:52,670
That’s a rather specialist subject, which you have actually been using laser grayscale engraving to do laser 3D engraving.
43
00:04:52,670 –> 00:04:58,440
But there is a subject of laser grayscale engraving that we can deal with separately on its own.
44
00:04:58,440 –> 00:05:04,860
Because you can actually do sort of try and do laser photo engraving with laser grayscale engraving.
45
00:05:04,860 –> 00:05:11,580
The next subject, laser photo engraving is fascinating and a huge subject on its own.
46
00:05:11,580 –> 00:05:18,030
There’s a rather handsome guy there on a piece of slate, a lovely image there on a piece of card.
47
00:05:18,030 –> 00:05:21,930
So there’s a white photographic image on a piece of black acrylic. Here
48
00:05:21,930 –> 00:05:26,610
we’ve got an amazing photograph on a ceramic white tile.
49
00:05:26,610 –> 00:05:33,870
There’s my favorite fox again on a white tile. Sometimes you come across a subject using what on earth am I going to do with laser origami?
50
00:05:33,870 –> 00:05:38,190
Sure, laser origami, is bending and folding things.
51
00:05:38,190 –> 00:05:44,520
Yes. And here I had a need recently to do some laser origami work.
52
00:05:44,520 –> 00:05:52,110
This is five millimeter thick acrylic and I put a 90 degree bend in it using the laser machine.
53
00:05:52,110 –> 00:05:58,500
Basically, I’ve used the laser engraving process to heat the material up beyond its plastic limit
Transcript for How to Laser Engrave – An Overview (Cont…)
54
00:05:58,500 –> 00:06:05,460
so that it would sag and allow me to fold it and put a 90 degree bend in it.
55
00:06:05,460 –> 00:06:10,710
If you go to YouTube and you just put laser origami into the heading, you’ll find that
56
00:06:10,710 –> 00:06:17,520
there’s quite a lot of things that people do with this, which will probably whet your appetite for trying it yourself.
57
00:06:17,520 –> 00:06:20,960
There’s something that I’ve added onto the bottom here called lacework.
58
00:06:20,960 –> 00:06:26,370
Now here I’ve got some very thin card and this looks like a very delicate laser photo engraving.
59
00:06:26,370 –> 00:06:34,400
Let me just put it up to the light. I think, as you can see, this is not quite what it appeared originally.
60
00:06:34,400 –> 00:06:40,850
This is actually full of very, very, very fine holes that’s actually allowing the light to come through.
61
00:06:40,850 –> 00:06:46,390
That’s what I call lacework. They’re just subjects.
62
00:06:46,390 –> 00:06:51,940
Now, the other thing that we haven’t talked about is what materials can we engrave?
63
00:06:51,940 –> 00:07:01,840
So you’ve only got to go back to the first science sessions. When we talked about materials and we said all materials are made up of atoms,
64
00:07:01,840 –> 00:07:13,150
but the way in which atoms combine together to make little groups called molecules, the combination of atoms to produce molecules is gazillions.
65
00:07:13,150 –> 00:07:21,070
All the gazillions of different combinations produce these different materials, and every different material has got its own properties.
66
00:07:21,070 –> 00:07:28,690
As we talked about, there are two or three special groups of materials, metals which we use for mirrors.
67
00:07:28,690 –> 00:07:34,330
These rather special transparent materials which we use for lenses and then everything else.
68
00:07:34,330 –> 00:07:42,520
Well, what we’re talking about here is everything else, because everything else will absorb or react with the ten point six micron light.
69
00:07:42,520 –> 00:07:49,840
And remember, what’s happening is we’re really stimulating the surface molecules to make them vibrate.
70
00:07:49,840 –> 00:07:53,320
And the faster they vibrate, the hotter they get.
71
00:07:53,320 –> 00:08:03,460
And they get to a certain temperature or a certain energy level where the bonds between the molecules can no longer be sustained.
Transcript for How to Laser Engrave – An Overview (Cont…)
72
00:08:03,460 –> 00:08:09,970
They break and the molecules fly off and we change from one material to another material.
73
00:08:09,970 –> 00:08:15,160
You must keep remembering that basic philosophy of how materials react.
74
00:08:15,160 –> 00:08:20,560
You cannot attack the inside of a piece of wood or any other material.
75
00:08:20,560 –> 00:08:26,410
You can only attack the surface with light. So whatever’s happening is always happening
76
00:08:26,410 –> 00:08:38,850
on the surface. It might be getting deeper and deeper and deeper, but it’s still the surface that’s being attacked, not the material inside.
77
00:08:38,850 –> 00:08:44,670
So, we will start talking about these different materials when we start doing the laser engraving process,
78
00:08:44,670 –> 00:08:51,420
but we’ve got these organic materials now, organic materials have got, they’ve got a rather special property.
79
00:08:51,420 –> 00:08:59,220
They will burn. They will chemically transform from something into nothing.
80
00:08:59,220 –> 00:09:07,500
Gas, they will vaporize. There are lots and lots of different woods which are made up of different molecular structures.
81
00:09:07,500 –> 00:09:16,700
So every wood is basically a different material. And it gets even worse than that because,
82
00:09:16,700 –> 00:09:21,500
look! This is all the same settings.
83
00:09:21,500 –> 00:09:31,680
Look at all these different structures of wood in this bamboo, and as you go across here, you can see that as we move from this basic structure.
84
00:09:31,680 –> 00:09:36,530
To a different piece of wood here, look at the different texture.
85
00:09:36,530 –> 00:09:43,130
This wood is reacting differently to exactly the same light that this wood was doing,
86
00:09:43,130 –> 00:09:49,580
because there’s something different about the molecular structure of this part of the wood than there is to this section here.
87
00:09:49,580 –> 00:09:55,970
You can see this is made up of strips that have been bonded together. Within parts of a millimetre,
88
00:09:55,970 –> 00:10:02,870
this wood is changing its material structure. This is really the point I’m trying to make.
Transcript for How to Laser Engrave – An Overview (Cont…)
89
00:10:02,870 –> 00:10:08,480
There is no such thing as wood. Wood is a continuously variable material.
90
00:10:08,480 –> 00:10:14,490
It’s just a family group. OK, stuff that burns.
91
00:10:14,490 –> 00:10:19,980
Now, card is basically just wood pulp that’s been bonded together,
92
00:10:19,980 –> 00:10:34,410
and one of the things about wood, card, leather, MDF is they have something that I would like to call a range of colour available to them.
93
00:10:34,410 –> 00:10:40,950
You can either very, very lightly scorch a piece of wood or you can make it black.
94
00:10:40,950 –> 00:10:48,360
So between black charring and light scorching, you’ve got a colour range of brown.
95
00:10:48,360 –> 00:10:54,600
And that’s what you can see in this picture here. But that range of colours looks like the old sepia photographs,
96
00:10:54,600 –> 00:10:59,340
and it’s very pleasing to the eye, even though there isn’t a white dynamic range in there.
97
00:10:59,340 –> 00:11:04,860
So that’s one of the properties of these materials, these organic materials.
98
00:11:04,860 –> 00:11:16,860
They have got a colour range that you can work with. Now, this next range of materials,
99
00:11:16,860 –> 00:11:30,150
I call them mineral materials because they are stone type materials, slate, granite, marble, glass, ceramic tile.
100
00:11:30,150 –> 00:11:37,060
I showed you an example there.
101
00:11:37,060 –> 00:11:48,250
Now, this next section here, mineral’s: slate, granite, marble, glass, ceramic tiles, they are what I call binary materials.
102
00:11:48,250 –> 00:11:53,020
There is no colour range on these materials.
103
00:11:53,020 –> 00:11:59,170
When you hit them with the laser beam, you produce a colour, whatever
Transcript for How to Laser Engrave – An Overview (Cont…)
104
00:11:59,170 –> 00:12:03,820
that colour is, and in this instance it’s a sort of a light grey. Okay.
105
00:12:03,820 –> 00:12:13,330
Now we appear to have a tonal colour range here, ranging from black to fairly light grey.
106
00:12:13,330 –> 00:12:17,140
So we’ve had to do some trickery to put a photograph on here.
107
00:12:17,140 –> 00:12:22,990
Now, Glass is another interesting material which we’ll talk about later on, along with granite and marble.
108
00:12:22,990 –> 00:12:30,280
Now we’ve got some more materials, plastics. There are a limited number of plastics that you should be working with on this machine.
109
00:12:30,280 –> 00:12:38,080
Some of them produce really nasty and dangerous fumes. So before you do any plastic work, do some research
110
00:12:38,080 –> 00:12:46,210
work on Google and find out what happens when you burn the material, what sort of toxic fumes you produce.
111
00:12:46,210 –> 00:12:50,440
The same problem exists with plastics as it does with mineral materials.
112
00:12:50,440 –> 00:12:52,060
You only have two colours
113
00:12:52,060 –> 00:13:03,910
normally. This is basically changing black acrylic into white acrylic so that we can produce a white image on a black background.
114
00:13:03,910 –> 00:13:10,490
Now, here we’ve got clear acrylic. Yeah, so what’s so fascinating about that?
115
00:13:10,490 –> 00:13:20,790
Well, of course it’s rubbish because you can’t see it unless you do something like this and you put a black background behind it.
116
00:13:20,790 –> 00:13:28,650
OK, so again, this is a binary material, it can only produce white marks on clear acrylic.
117
00:13:28,650 –> 00:13:33,630
Now, I haven’t got any Corian at the moment to show you, which is used for worktops
118
00:13:33,630 –> 00:13:42,230
normally. You can sort of do laser 3D engraving, with it even. It’s basically acrylic, which you can laser engrave, as you can see, but it’s filled with a powder.
119
00:13:42,230 –> 00:13:47,610
And so what you do, you’re basically melting or evaporating the acrylic away, leaving the powder behind.
120
00:13:47,610 –> 00:13:56,220
It’s a very messy process. Then we’ve got things like synthetic rubber, which is really a plastic, even though it’s a rubbery material.
121
00:13:56,220 –> 00:14:02,800
And here’s an example of that. And I’ve been successful in making rubber stamps with this material.
Transcript for How to Laser Engrave – An Overview (Cont…)
122
00:14:02,800 –> 00:14:09,930
OK, and this is laser relief engraving. So here’s an example of this polyester powder coating that I was talking about.
123
00:14:09,930 –> 00:14:15,900
These stainless steel flasks have been painted with an epoxy powder coat resin.
124
00:14:15,900 –> 00:14:22,800
And then what you do, you burn the resin off to leave the stainless steel finish underneath.
125
00:14:22,800 –> 00:14:31,300
And then we come to the last group, which is laser engraving metal. Now, remember, metal is very, very reflective,
126
00:14:31,300 –> 00:14:39,760
you cannot laser engrave it. In the pursuit of science and proving to you guys that you cannot laser engrave metal, I’ve done it.
127
00:14:39,760 –> 00:14:53,640
I’ve messed up lenses. What you can do, there are ways of changing aluminium, plain aluminium into a different material.
128
00:14:53,640 –> 00:15:00,730
This is a black surface, but underneath, if you look, we’ve got white.
129
00:15:00,730 –> 00:15:07,230
Now this white material here is basically aluminium oxide and aluminium oxide.
130
00:15:07,230 –> 00:15:11,400
It’s the sort of stuff that you use for grinding wheels, sandpaper.
131
00:15:11,400 –> 00:15:14,250
It’s a very hard material.
132
00:15:14,250 –> 00:15:24,000
And you can take aluminium, put it through this process called anodising, and it converts a very thin maybe two to five micron,
133
00:15:24,000 –> 00:15:30,780
maybe 10 microns thick layer on top of the material into aluminum oxide.
134
00:15:30,780 –> 00:15:36,180
Now, question: is aluminium oxide. Metal?
135
00:15:36,180 –> 00:15:45,650
No. It’s a, it’s a metallic compound, but it is not metal, and because it’s not metal,
136
00:15:45,650 –> 00:15:51,380
it comes into this everything else group of materials that will absorb energy.
137
00:15:51,380 –> 00:16:00,810
You can fire the laser at this material without it reflecting. Now.
Transcript for How to Laser Engrave – An Overview (Cont…)
138
00:16:00,810 –> 00:16:16,710
When they, when they finished the process off, before they finally seal the process, they allow dye to infiltrate the surface of the aluminium oxide.
139
00:16:16,710 –> 00:16:25,110
So this black on here is just a water based dye that’s been soaked into the surface of
140
00:16:25,110 –> 00:16:30,750
this metallic material. The structure of this aluminium oxide is a bit like grains of salt.
141
00:16:30,750 –> 00:16:37,740
They’ve got little teeny weeny pores or gaps between the grains, and that’s where the dye infiltrates.
142
00:16:37,740 –> 00:16:43,140
And that’s what you can see here, a dyed surface of white aluminum oxide.
143
00:16:43,140 –> 00:16:51,540
If you’re very careful about this process, you can heat the dye up, make it evaporate and left the aluminium oxide behind.
144
00:16:51,540 –> 00:16:55,890
So we’re not actually working with raw metal.
145
00:16:55,890 –> 00:17:04,020
We’re working with an oxide of the metal. And that allows us to do things like that.
146
00:17:04,020 –> 00:17:09,340
We can put photographs on here, we can put text on it, we can laser engrave on it.
147
00:17:09,340 –> 00:17:15,630
And then finally, we’ve got stainless steel. Now, again, stainless steel is very, very reflective.
148
00:17:15,630 –> 00:17:19,830
It’s probably in the 96, 97 percent reflective range.
149
00:17:19,830 –> 00:17:24,780
The only thing we can do is stainless steel is to chemically mark it.
150
00:17:24,780 –> 00:17:30,540
Here’s just an experimental test piece. It’s the only thing I can dig up at the moment.
151
00:17:30,540 –> 00:17:39,180
And you can see here, this is very shiny stainless steel. But I painted something on here and then I did some etching.
152
00:17:39,180 –> 00:17:44,820
When I take this grey stuff off, what’s left behind is a black mark.
153
00:17:44,820 –> 00:17:54,600
And that black mark is very, very durable. So some of the chemistry of this material has etched itself and bonded into the surface of
154
00:17:54,600 –> 00:17:59,670
the stainless steel because it’s reacted with some of the chemicals in the stainless steel.
Transcript for How to Laser Engrave – An Overview (Cont…)
155
00:17:59,670 –> 00:18:03,060
So that’s the only way you can mark stainless steel.
156
00:18:03,060 –> 00:18:09,930
You cannot laser engrave it. That’s a quick preview of what you’ve got coming up over the next many sessions.
157
00:18:09,930 –> 00:18:17,700
So each one of these materials and processes requires its own special knowledge.
158
00:18:17,700 –> 00:18:25,020
As I said, this is a very, very wide subject. Not only do you need to understand the laser beam technology,
159
00:18:25,020 –> 00:18:32,790
you need to understand something about material technology as well, because you’re trying to disrupt molecular structures
160
00:18:32,790 –> 00:18:40,320
remember, from the surface down. Never forget that fact, surface damage
161
00:18:40,320 –> 00:18:45,630
only. Now we’re going to start doing a section with a little demonstration.
162
00:18:45,630 –> 00:18:50,370
And I’ve got I’ve got the machine cover down for a good reason.
163
00:18:50,370 –> 00:19:12,530
I’d like you to observe some things that are going on. First of all, can you see the way in which the flame is blowing backwards?
164
00:19:12,530 –> 00:19:32,520
Secondly, I think you might be able to see that very, very bright light. Now at the moment.
165
00:19:32,520 –> 00:19:37,990
We put this piece of tape down here so you could see something else.
166
00:19:37,990 –> 00:19:48,150
The tape is, first of all, probably marking slightly wider than the beam.
167
00:19:48,150 –> 00:19:54,030
Certainly up here, look you can see that the tape, has burnt away a lot wider than the beam.
168
00:19:54,030 –> 00:20:00,320
We’ve got different damage. For different materials.
Transcript for How to Laser Engrave – An Overview (Cont…)
169
00:20:00,320 –> 00:20:09,590
This one is masking tape, which is so thin that it has no effect on the focus, but look what it’s done to the beam here.
170
00:20:09,590 –> 00:20:19,750
When I’ve got lots and lots of power very, very slowly. It was able to just burn through and basically hardly have an effect on the cut width.
171
00:20:19,750 –> 00:20:26,230
Here, it’s starting to have an effect on the cut width. Here it’s having a significant effect on the cut width.
172
00:20:26,230 –> 00:20:33,730
Here it’s virtually wiped out and absorbed all the power before its started to cut the wood.
173
00:20:33,730 –> 00:20:40,870
So that all the energy now, has gone into cutting the tape and nothing has gone into the wood.
174
00:20:40,870 –> 00:20:46,780
This is an interesting fact, do you remember this from a few moments ago?
175
00:20:46,780 –> 00:20:56,410
If we get the balance of power and speed right, we should be able to just remove the paint and do virtually no damage to the
176
00:20:56,410 –> 00:21:03,420
material underneath. There’s a huge amount of information in this very simple test.
177
00:21:03,420 –> 00:21:14,470
Which I want you to try and remember. Question one: Why are these lines A, changing width and B, changing colour?
178
00:21:14,470 –> 00:21:20,610
The next question is, why if we got a different level of damage here and here?
179
00:21:20,610 –> 00:21:30,780
Than we have here and here, but on this one, look, we got quite a large mark at the end and a little teeny weeny burn mark there.
180
00:21:30,780 –> 00:21:34,980
And then we’ve got a little blog here, which is bigger than the beam.
181
00:21:34,980 –> 00:21:43,580
I’m going to put my hand in that flame. How brave is that?
182
00:21:43,580 –> 00:21:49,380
Look, it even damaged me, you see, it’s even put a mark across, a black mark across my fingers.
183
00:21:49,380 –> 00:21:55,870
I could feel the heat from that flame as I move my hand across there.
184
00:21:55,870 –> 00:22:01,580
And it marked my hand. What happens if I do this?
Transcript for How to Laser Engrave – An Overview (Cont…)
185
00:22:01,580 –> 00:22:11,760
Apart from the fact that I’ve blown it out. I can hardly feel the flame.
186
00:22:11,760 –> 00:22:19,790
Why is that? I think you could answer the question the other way round.
187
00:22:19,790 –> 00:22:28,850
Would I do this? Come on, stop. Would I actually pass my hand through that plane at that speed? Ha Ha Ha
188
00:22:28,850 –> 00:22:40,070
I think you know the answer to that question and why, but try and analyse why I’m not able to run my hand through that flame slowly.
189
00:22:40,070 –> 00:22:44,940
I have got a damage threshold on my skin.
190
00:22:44,940 –> 00:22:54,670
If I move my hand through that flame very, very slowly, I shall A: exceed my pain threshold and B: I shall exceed the damage threshold
191
00:22:54,670 –> 00:22:59,850
of my skin and the molecules will start flying apart and do stupid things.
192
00:22:59,850 –> 00:23:06,520
Anybody familiar with photography will know what exposure means and that’s what I’m doing here.
193
00:23:06,520 –> 00:23:14,940
I’m exposing my hand to a certain amount of power in a certain amount of time.
194
00:23:14,940 –> 00:23:22,740
Now, if I reduce the time by going faster, I’m reducing the exposure time and reducing the exposure
195
00:23:22,740 –> 00:23:29,340
time, keeps my skin above the damage threshold for the flame.
196
00:23:29,340 –> 00:23:34,650
Now, I can pass that card through that quite quickly and it doesn’t mark the card.
197
00:23:34,650 –> 00:23:42,780
And now I go really slowly. And I’m in trouble.
198
00:23:42,780 –> 00:23:47,370
That’s a good demonstration of damage threshold.
199
00:23:47,370 –> 00:23:49,290
And exposure time,
200
00:23:49,290 –> 00:23:59,790
the material has a certain damage threshold and I’m exposing that material to a certain amount of power for a certain period of time,
Transcript for How to Laser Engrave – An Overview (Cont…)
201
00:23:59,790 –> 00:24:07,140
a certain exposure period. OK, so power and time equals exposure.
202
00:24:07,140 –> 00:24:17,130
So that begins to explain why we’re doing less and less damage as the speed increases.
203
00:24:17,130 –> 00:24:23,580
We’ve got the same power. And yet we’ve got and we’ve got the same damage thresholds on these two materials.
204
00:24:23,580 –> 00:24:33,430
But we’re exposing the material to a lower power per unit of time.
205
00:24:33,430 –> 00:24:45,350
And so consequently, the damage is less. That explains why the lines are getting lighter.
206
00:24:45,350 –> 00:24:50,290
There was less damage, so therefore we’re going to get less browning.
207
00:24:50,290 –> 00:24:56,870
Why are these lines thick and these lines thin? That’s for something completely different.
208
00:24:56,870 –> 00:25:01,060
That’s unique to the laser beam.
209
00:25:01,060 –> 00:25:09,250
We’ve talked about it before, but we’ll discuss it again because it’s an incredibly important feature of this machine.
210
00:25:09,250 –> 00:25:12,310
Now, you remember my little light here, how it’s very,
211
00:25:12,310 –> 00:25:19,500
very intense in the centre and it gets less and less intense as I move away from the centre of the light.
212
00:25:19,500 –> 00:25:23,980
And I said that was an exact simulation of the laser beam.
213
00:25:23,980 –> 00:25:29,590
Now, I’m going to start using a word that’s really very important.
214
00:25:29,590 –> 00:25:36,090
Intensity now some people technically will use the word energy density.
215
00:25:36,090 –> 00:25:42,780
I don’t think the word energy density conveys the right impression, whereas light intensity,
216
00:25:42,780 –> 00:25:49,320
you immediately know what it means, it’s brighter than anywhere else if it’s more intense.
217
00:25:49,320 –> 00:25:56,430
Well, the light at the centre of this beam is more intense than it is at the edge of the beam.
218
00:25:56,430 –> 00:26:01,560
This is just a graph of the light intensity within our laser beam.
Transcript for How to Laser Engrave – An Overview (Cont…)
219
00:26:01,560 –> 00:26:08,520
And as I said to you before, this is something called a Gaussian distribution.
220
00:26:08,520 –> 00:26:17,400
That’s the ideal shape of the intensity within a laser beam, not all laser beams conform to that pattern.
221
00:26:17,400 –> 00:26:21,420
If yours doesn’t, then it might be close to junk.
222
00:26:21,420 –> 00:26:27,750
I know that the beam on this machine is pretty close to that intensity distribution.
223
00:26:27,750 –> 00:26:30,570
Another very important factor, which I’ve mentioned before,
224
00:26:30,570 –> 00:26:38,620
but I’m going to keep stressing this because it’s, it’s just the most important thing that you can remember about this laser beam.
225
00:26:38,620 –> 00:26:44,200
The more intense the light, the faster it will do damage to the material.
226
00:26:44,200 –> 00:26:55,780
So the height of that graph represents the intensity and the more light intensity we have, the faster we can damage our material.
227
00:26:55,780 –> 00:27:00,640
How much damage are we going to be doing to the material just here?
228
00:27:00,640 –> 00:27:03,430
You’re absolutely right. Zero.
229
00:27:03,430 –> 00:27:15,400
And as we start climbing up this curve, we’re able to do a little bit more damage to the material provided we give it enough time to do the damage.
230
00:27:15,400 –> 00:27:20,110
If we want to do the same amount of damage from the power down here,
231
00:27:20,110 –> 00:27:28,480
we’ve got to allow that light to be exposed longer so that it can do the same amount of damage as that light up there.
232
00:27:28,480 –> 00:27:34,240
Can you see how down the centre here we’ve done a huge amount of damage and yet as we get to the edge here,
233
00:27:34,240 –> 00:27:41,980
look, it drops off fairly quickly to less and less damage to just a faint brown mark just here.
234
00:27:41,980 –> 00:27:47,260
We’ve allowed enough time for that,
235
00:27:47,260 –> 00:27:50,200
width of line there to do damage.
236
00:27:50,200 –> 00:27:59,890
There’s enough power here and there’s enough power here right at the edge of the beam width to do some browning just here, scorching.
Transcript for How to Laser Engrave – An Overview (Cont…)
237
00:27:59,890 –> 00:28:10,020
But in the centre here, this look, this section here. Which you can clearly see.
238
00:28:10,020 –> 00:28:20,990
On here. That farrow right down the centre, there’s so much power there that it’s able to do a huge amount of damage.
239
00:28:20,990 –> 00:28:31,750
Just there, but once we get outside that damage zone, the damage gradually creeps off like this.
240
00:28:31,750 –> 00:28:35,890
So we’ve just got lots of browning here, but we’ve got lots of damage in the centre.
241
00:28:35,890 –> 00:28:45,430
Now you can’t see in there, but that damage has gone in and done something like that. Now as we get towards this faster speed,
242
00:28:45,430 –> 00:28:54,020
only the highest amount of intensity, this bit just here.
243
00:28:54,020 –> 00:29:01,910
Will be able to deliver enough damage to the material in the time that’s available to it.
244
00:29:01,910 –> 00:29:05,600
So what we shall finish up with is a line width that
245
00:29:05,600 –> 00:29:12,860
is that wide. But look at the change of intensity across the top of that shape.
246
00:29:12,860 –> 00:29:15,350
It’s virtually a flat line.
247
00:29:15,350 –> 00:29:27,680
So we’re going to have no change of intensity. All we’re going to do is get like a paintbrush effect, just a very slight browning across that zone.
248
00:29:27,680 –> 00:29:36,460
And that’s why it is a thin line and not a
249
00:29:36,460 –> 00:29:44,950
thick line. I hope that this explanation gives you some sort of feeling for this concept of exposure time.
250
00:29:44,950 –> 00:29:54,640
This also explains why we’ve got these blobs at the end here, because the velocity of this beam starts off at zero,
251
00:29:54,640 –> 00:30:00,100
accelerate up to 240 millimetres a second, and then drops back to zero.
Transcript for How to Laser Engrave – An Overview (Cont…)
252
00:30:00,100 –> 00:30:06,760
And as it drops back to zero. So what we’re doing, we’re getting closer and closer to this situation
253
00:30:06,760 –> 00:30:14,990
again. We’re increasing the exposure time right at the end of the lines.
254
00:30:14,990 –> 00:30:27,240
Now, I’ve done this without any lens in the system because it shows this very clearly when we’re looking at a naked beam.
255
00:30:27,240 –> 00:30:33,810
This situation does not change when we put a lens in. Now, as I’ve explained to you before.
256
00:30:33,810 –> 00:30:40,800
There are two types of lens. We’ve got these which are flat on one side and curved on the other.
257
00:30:40,800 –> 00:30:43,080
They’re called Plano Convex.
258
00:30:43,080 –> 00:30:55,980
Now, this is one way that you can use a Plano convex lens, which everybody steers away from because it’s got, and this is grossly exaggerated.
259
00:30:55,980 –> 00:31:00,240
This has got something called spherical aberration.
260
00:31:00,240 –> 00:31:09,540
The actual shape of this lens as part of a sphere causes this problem here to happen to the light rays.
261
00:31:09,540 –> 00:31:21,300
We do not focus down to a sharp point. The rays that come in from the outside focus here and the rays that come down the centre focus down here.
262
00:31:21,300 –> 00:31:30,150
So we’ve got a huge range of focus. Now, if we turn the lens over, things start to change.
263
00:31:30,150 –> 00:31:37,020
The light comes in here. It’s refracted twice, once into the lens and once out of the lens.
264
00:31:37,020 –> 00:31:44,030
And we get a much smaller range of spherical aberration.
265
00:31:44,030 –> 00:31:53,960
There is still spherical aberration, because this is part of a sphere and it never comes down perfectly to a focal point.
266
00:31:53,960 –> 00:31:59,390
And that’s why you will be told this is the correct way to install a lens.
Transcript for How to Laser Engrave – An Overview (Cont…)
267
00:31:59,390 –> 00:32:04,640
And in general terms, it works for most things most of the time.
268
00:32:04,640 –> 00:32:10,450
And one of the ways that you can get rid of, nearly get rid of
269
00:32:10,450 –> 00:32:20,080
the spherical aberration. Is to put another spherical concave surface, it still doesn’t focus it to perfection,
270
00:32:20,080 –> 00:32:24,760
it only does an improvement on this situation that you can see here.
271
00:32:24,760 –> 00:32:32,800
We’re going to go for one final demonstration in this session. We’ve been using a beam full power, so we’ve been using it in sharp mode.
272
00:32:32,800 –> 00:32:38,500
It’s been doing a huge amount of damage at the centre and not much right at the edge of the beam.
273
00:32:38,500 –> 00:32:46,730
As we reduce the power in the beam, we’re changing the relativity of intensity between the edge
274
00:32:46,730 –> 00:32:55,610
and the centre. We can reduce a sharp beam to a blunt beam under control by reducing the power.
275
00:32:55,610 –> 00:33:40,340
So I’m going to run this same test, but this time we’re going to do it 20 percent power.
276
00:33:40,340 –> 00:33:46,970
He’s the imagined shape of our laser beam intensity diagram at 90 percent power.
277
00:33:46,970 –> 00:33:56,600
We’ve got a huge amount of intensity right at the centre of the beam, and we’ve still got nothing at the edge. When we reduce the power to 20 percent.
278
00:33:56,600 –> 00:33:59,350
We’ve still got nothing at the edge.
Transcript for How to Laser Engrave – An Overview (Cont…)
279
00:33:59,350 –> 00:34:09,430
But what we’ve got, is a much, much lower intensity right at the centre. So we haven’t just changed the power of the beam from 90 to 20.
280
00:34:09,430 –> 00:34:15,130
We completely changed the damage ratio of the beam itself.
281
00:34:15,130 –> 00:34:24,370
Its ability to damage has been changed because the intensity shape is completely different at 20 percent than what it is at 90 percent.
282
00:34:24,370 –> 00:34:30,130
And I hope you can see that from this diagram, when you change from 100 percent power to 50 percent power,
283
00:34:30,130 –> 00:34:33,850
you’re not really changing to 50 percent power.
284
00:34:33,850 –> 00:34:43,800
You’re changing all sorts of intensity things within the beam which are having an effect, a non-linear effect on the output.
285
00:34:43,800 –> 00:34:51,110
If you wish to have a linear change to the power of your beam.
286
00:34:51,110 –> 00:35:01,370
You don’t change the power, what you do, you change the exposure time, so if you change the speed from 120 to 240,
287
00:35:01,370 –> 00:35:08,030
you’ve actually doubled that, doubled the speed at which the beam is traveling and you halved the exposure time.
288
00:35:08,030 –> 00:35:13,100
You’ve halved, linearly halved the amount of damage you’re doing to the material.
289
00:35:13,100 –> 00:35:21,320
So I think you can clearly see here, the shape of the beam at this five millimetres a second.
290
00:35:21,320 –> 00:35:27,770
We’ve still got most of the beam width available to us here. But as we get a little bit faster, a little bit faster,
291
00:35:27,770 –> 00:35:35,870
we very quickly run out of beam width. By the time we get to our intensity just here, at 40 millimetres a second.
292
00:35:35,870 –> 00:35:37,910
We’ve run out of intensity.
293
00:35:37,910 –> 00:35:46,640
Now with this one, we may well have gone as far as 300 millimetres a second before we matched the intensity level of this one.
294
00:35:46,640 –> 00:35:51,320
And this one reached its intensity peak at 40 millimetres a second.
295
00:35:51,320 –> 00:35:58,820
So I hope this is sufficient proof to show you that this diagram is very valid.
Transcript for How to Laser Engrave – An Overview (Cont…)
296
00:35:58,820 –> 00:36:03,740
And you should imagine this diagram when you think about changing the power of
297
00:36:03,740 –> 00:36:09,500
your beam and also consider whether or not you’d do better to change the speed,
298
00:36:09,500 –> 00:36:18,800
then the power. I’ll leave you with all those complicated thoughts and the fact that we haven’t even put a lens in yet.
299
00:36:18,800 –> 00:36:23,070
Are you sure you want to keep your machine? Is this the time to send it back?
300
00:36:23,070 –> 00:36:30,741
I’ll catch up with you in the next session.
Transcript for How to Laser Engrave – An Overview
Disclaimer
Last updated August 26, 2021
WEBSITE DISCLAIMER
The information provided by n-Deavor Limited, trading as Laseruser.com (“we,” “us” , or “our”) on (the “Site”) is for general informational purposes only. All information on the Site is provided in good faith, however we make no representation or warranty of any kind, express or implied, regarding the accuracy, adequacy, validity, reliability, availability or completeness of any information on the Site.
UNDER NO CIRCUMSTANCE SHALL WE HAVE ANY LIABILITY TO YOU FOR ANY LOSS OR DAMAGE OF ANY KIND INCURRED AS A RESULT OF THE USE OF THE SITE OR RELIANCE ON ANY INFORMATION PROVIDED ON
THE SITE. YOUR USE OF THE SITE AND YOUR RELIANCE ON ANY INFORMATION ON THE SITE IS SOLELY AT YOUR OWN RISK.
EXTERNAL LINKS DISCLAIMER
The Site may contain (or you may be sent through the Site) links to other websites or content belonging to or originating from third parties or links to websites and features in banners or other advertising. Such external links are not investigated, monitored, or checked for accuracy, adequacy, validity, reliability, availability or completeness by us.
WE DO NOT WARRANT, ENDORSE, GUARANTEE, OR ASSUME RESPONSIBILITY FOR THE ACCURACY OR RELIABILITY OF ANY INFORMATION OFFERED BY THIRD-PARTY WEBSITES LINKED THROUGH THE SITE OR ANY WEBSITE OR FEATURE LINKED IN ANY BANNER OR OTHER ADVERTISING.
WE WILL NOT BE A PARTY TO OR IN ANY WAY BE RESPONSIBLE FOR MONITORING ANY TRANSACTION BETWEEN YOU AND THIRD-PARTY PROVIDERS OF PRODUCTS OR SERVICES.
AFFILIATES DISCLAIMER
The Site may contain links to affiliate websites, and we receive an affiliate commission for any purchases made by you on the affiliate website using such links. Our affiliates include the following:
- makeCNC who provide Downloadable Patterns, Software, Hardware and other content for Laser Cutters, CNC Routers, Plasma, WaterJets, CNC Milling Machines, and other Robotic Tools. They also provide Pattern Files in PDF format for Scroll Saw Users. They are known for their Friendly and Efficient Customer Service and have a comprehensive back catalogue as well as continually providing New Patterns and Content.
- Cloudray Laser: a world-leading laser parts and solutions provider, has established a whole series of laser product lines, range from CO2 engraving & cutting machine parts, fiber cutting machine parts and laser marking machine parts.