32 – The Russ Formula for a Successful Laser Engraved Photo (43:44)

The Lightblade Learning Lab with Russ Sadler

The Lightblade Learning Lab is a series of videos that Russ did for Thinklaser Limited based on using the Lightblade 4060 Laser Cutting and Engraving Machine. Thinklasers Lightblade 4060 has a 400 x 600mm bed size and was supplied with a 60W EFR laser tube. In this session, Russ teaches us his personal formula to achieve a great laser engraved photo.

Laser Engraved Photo - Warcraft Image
Laser Engraved Photo – Warcraft Image

Contents

  • (Russ has created a PDF document which summarises all the steps in the video. It is available here.)
  • Choosing the lens.
  • Cleaning the nozzle with a 2.5mm drill.
  • Description of the lens.
  • The density of dots creating an impression of greyscale.
  • Organic materials burning to create a brown mark.
  • Mineral materials or plastics creating white dots so it ‘prints’ in negative.
  • Example of engraving white card.
  • Use of the step gauge to set the height of the lens.
  • Running a test program and use of a linen gauge (aka linen tester).
  • The test pattern which allows one to see the diameter of the dots.
  • Setting the programs parameters in RDWorks.
  • Looking at the engraved test pattern under the microscope to decide the best lens height to get the focus right.
  • Resolution of photographs and pixels per inch.
  • Importing the photo into RDWorks.
  • Using the padlock to keep the proportions of the photograph the same while changing the size.
  • Changing the output resolution.
  • Dithering the picture.
  • Changing the brightness and contrast. Using ‘Invert’ if using non-organic materials like acrylic.
  • Setting the laser parameters.
  • Working out the correct speed to use.
  • Testing the engraving with a 2” lens.
  • Reviewing the result.
  • Modification to allow fitting a 1.5” lens.
  • Inserting the 1.5” lens.
  • Mild steel sheet bed – change in airflow better for engraving.
  • Direction of engraving for better results.
  • Cleaning the steel sheet.
  • Running the test program again.
  • Examining the results and redrawing the picture as a result.
  • Calculating the optimum speed.
  • Setting the power.
  • Reviewing the difference of the shorter focal length lens.
  • Summary of results.
  • Design files associated with this video are:
  • Focus Gauges (DXF) – http://bit.ly/2ydiiaF
  • Grip ring with lever (DXF) – http://bit.ly/2xP5s1m
  • Test Pattern (BMP) – http://bit.ly/2xDCO3m

My thanks go out to Tom at Thinklaser for giving permission to embed these videos on this site. If you are looking for a new laser machine from a quality supplier, then I would suggest you check out their website: www.thinklaser.com.

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Video Resource Files

PDF document – the Russ Formula for Successful Photo Engraving

Focus Gauges (DXF)
Grip ring with lever (DXF)
Test Pattern (BMP)

There are no more resource files associated with this video.

External Resource Links

www.thinklaser.com

www.rdworkslab.com

What can a laser cutter cut?

There are no more external resource links associated with this video.

Transcript for The Russ Formula for a Successful Laser Engraved Photo

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0:10welcome to another Lightblade Learning Lab in a fairly recent session I attempted to

0:22give you all the knowledge I had about photo engraving now I’ve since

0:28been able to learn a little bit more and rationalize all that I’ve learned into a

0:35fairly simple set of instructions now there are some calculations in there but

0:40nothing difficult and what I’m going to do today is to summarize in just this

0:48one simple session how to go about producing excellent quality photo engravings

0:55these are basic rules and they will guarantee to get you good quality product

1:01but you might decide to veer away from those rules and experiment for yourself

1:07that’s your choice I’m only giving you the foundation upon which you can build now

1:13to go along with this session we have a two-page document here which summarizes

1:18all the steps that I’m going to demonstrate to you today so in

1:23conjunction with some of the fiddly details that I’m going to show you on the video you can go through the basic steps here with this document that will

1:31be published on the Thinklaser website now today’s session

1:37we’ll start right at the beginning and we’re going to do every step of the process but in future you won’t need to carry out every single step of this

1:47process only some of the steps because once you’ve gathered the information today it will be valid for the future step number one is to choose the lens

1:58that you’re going to use now the one thing that you will find about doing

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

2:03engraving work is that the nozzle will tend to get sticky around the outside because of the

2:14way in which the fumes will come upwards and stick to the outside of the nozzle

2:20so from time to time you’ll need to inspect the nozzle and maybe clean it

2:25with some acetone now before you do that you might want to check that you’ve got a nice clean hole in the end of your nozzle and you can do that with a two

2:34and a half millimetre drill literally just make sure the nozzle is clear and

2:40then we’ll just clean the outside of the nozzle there now the inside does tend to

2:46get a bit fogged and messed up but it’s not essential to get in there to clean it although from time to time I do just to take the debris off the inside of the

2:56nozzle as well your Thinklaser machine will be supplied with three lenses it has a 2

3:04inch lens which to be honest is normally a very good quality meniscus lens now if

3:12when you look in there you’ll see that it’s a greenish color and if you hold it up to the light you will not be able to see through the lens and that’s because

3:22it’s made of a material called gallium arsenide now most lenses that you can

3:27get the cheaper lenses are made from something called zinc selenide which work perfectly well this is a good quality lens and the meniscus lens helps

3:37to focus the light down to a slightly sharper point so

3:43whatever lanes you’re using and I would normally recommend for engraving work

3:50the use of one a half-inch lens but sadly this system does not allow you to

3:57use a one and a half inch lens a two inch lens will be perfectly okay you’re

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

4:02pretty able to produce perfectly good results with a two inch lens but you

4:08would get slightly better results with a one and a half inch lens and if we get time I have got an adaption for this system which will allow me to put one

4:17and a half inch lens in here and we’ll see what the difference in the quality of the pictures are and I think you’ll see that there isn’t a huge difference

4:24so step number one Choose your lens and make sure it’s in good working order clean

4:30and the next thing is to make sure it’s correctly focused now I’ve shown you

4:36this photo engraving of one of my old girlfriends on previous occasion it is

4:43almost the perfect formula but not quite now as

4:49I’ve mentioned before this binary picture is composed of just dots there

4:58is a white background and dark dots now it looks as though we’ve got lots of

5:06different shades of dots in that picture not true they are literally one color dot but it’s the mixing of the white background

5:16with the different densities of those dark dots that creates this impression

5:22of a grayscale now that’s a very very important thing to remember the white

5:29background is very important if you make the dots too big or you overlap the dots

5:36because you try and make the picture too higher-resolution your eye will not be

5:43able to sort out a white background it will just have a series of dark dots and

5:49so the grayscale effect that you’re looking for disappears today is all about the rules for getting the features of this picture

5:59correct the dots the size of the dots the power of the dots and the resolution

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

6:06of the picture that you start with now with a card which is what this is or

6:12leather a natural leather maybe a piece of MDF and all those sorts of

6:18materials wood they’re all what I call organic materials they will burn and

6:26they will burn with a brown mark which is great because Brown is quite a dark

6:33mark so we can have a dark dot on a white background which is exactly what

6:39we want to get the good quality picture now when it comes to what I call mineral materials slate stone granite or

6:48plastics like maybe clear acrylic the situation is different we do not get

6:55black dots we get a black background or a clear background with in the case of

7:01acrylic but we get white dots now that means to say that the picture has to be

7:08converted into a negative before you print it so something else that we’re

7:14going to talk about along the way for the purpose of this exercise I’m going

7:19to be using a white card it’s about one millimetre thick and to be honest I

7:25think it’s the sort of card fairly soft card that you probably would make beer mats of it’s not high quality but it’s nice and soft so it’s actually very good for

7:38doing pictures on and it’s not expensive to buy

7:45now it is important that you use a piece of the material that you’re going to work on to do these settings because what we’re going to do now is find not

7:54only the focus but we’re also going to find the size of the dot and to do that

8:00we need to be working on the correct material because different materials will produce different size dots

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

8:09okay now my focus gauges are basically this one is millimetres and this is 0.5

8:16of millimetre so for instance this one runs from I think one to 20 and this one

8:22runs from 1.5 to twenty point five because I’ve added an extra half a

8:27millimeter onto the bottom so they’re very simple gauges to make

8:33and what we’re going to do is we’re going to lift this up

8:39and we’re gonna drop it down initially onto the 8-millimeter step

8:52we’re going to run my test program and that’s it that’s all the program is so

9:01this is seven point five just drop it down on to seven point five now I’m

9:10going to do a manual inspection on these using this device here now this is

9:15something called a linen gauge and it’s a very handy device that you will

9:21probably need to measure these and to look at these with now this is easily

9:27available on you get it off eBay for about five pounds for a plastic version ten times magnification which is absolutely super for doing this job so I put all

9:36the details in my separate write-up. No for 6.0

9:43not really for 6.5, 7.0 looks a lovely clean set of holes with dots, 7.5 not bad but

9:56in general I would think I’ve got a crisper set of holes at 7.0 & 8.0 that’s not

10:03particularly brilliant either but we’ll see those under the microscope and you’ll see what I mean now this little pattern is very carefully designed to

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

10:11tell you all sorts of things the first thing it will do it will enable you to estimate the size of the dot and I would say that we are looking at dots

10:22that are probably 0.2 diameter and I’ll explain more about that when we see

10:31them under the microscope now before I try and describe what we’re seeing under

10:36the microscope let’s just take a look at the pattern that I laid down as the basis of the test what we’ve got here is a set of pixels these are very carefully

10:48sized each one of these pixels or spaces on the bottom line is 0.1 of a

10:56millimeter let’s take the bottom line for example if I see a dot then a space

11:03then a dot and the space is the same size as the dot then I can estimate

11:09that I’ve got 0.1 millimetre dots now if the dots touch on that

11:18bottom row then it can only be because the dots are 0.2 diameter now we can

11:25apply the same principle to the next two rows of dots so if I get point two dots

11:32there will be a dot a space a dot a space a dot a space and the space

11:38between the dots should be the same size as the dots themselves so that will tell

11:43me that I’ve got 0.2 dots and then obviously if the dots are touching then

11:50it means those dots are point four diameter and of course between the point

11:55two and the point 4 we can estimate a 0.3 dot. so i don’t expect anybody

12:02to be using point 4 dots but if you’ve got your focus badly set you may well

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

12:09find that you’ve got 0.4 dots now the purpose of the top line with those

12:15dashes on it there’s nothing to do with sizing the dots that’s all to do with assessing what power we’re going to use to do the picture and that will become

12:25obvious as we do the next test later on now this bitmap pattern will be

12:31available on the Thinklaser website but you’ll have to put your own parameters to it and what I suggest you do is to run this at fairly low values

12:43first of all I would set the speed at about 50 millimetres a second we’ve

12:49talked quite a bit about high frequency impact engraving and how there is this strange pre ionization zone on your tube before it really kicks in and starts

12:59developing power most engraving really needs to be done at low power and this

13:06particular zone up to on most tubes it could be 12 could be 14% you will need

13:13to test your own tube to find out where the limit for that zone is and I would

13:19stay inside that zone if you possibly can because you will get much better

13:25results on both my machines I can safely say 11 or 12 percent stays inside that

13:32zone so I’m going to set this to say 12 percent we need to make sure that we’ve

13:37got none of this stuff here ticked we’re just going to use standard x-swing but bear in mind what I told you was that the size of these dots is 0.1

13:48millimeters therefore that’s what we’re going to be using for a pitch 0.1 so let’s go and have a look at the results that we got right we’re

13:57gonna check out the test pattern for our 2 inch focal length lens now the first thing we did was to set the gap underneath the nozzle to 6 millimetres

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

14:07and here’s what we got now our first two lines at the bottom here ah hmm

14:15well they’re not really two lines are they they’re a bit of a blur you certainly can’t see any dots so let’s move to six point five and all of a

14:27sudden we can see some dots that’s half a millimetre difference in the focus

14:33makes a significant difference so let’s step up to seven millimetres and here we

14:41are we can see definite dots now please excuse me I’ve got no idea what these

14:48funny s-shaped things are here they’re supposed to be single pixels like the line above but they’re not and my suspicion is that I’ve got two pixels

14:58overlaid on top of each other and I’ve got a scan left and a scan right which is shown up there so I’m gonna have to go and check my pixel pattern out before

15:06I release it to you guys it doesn’t make any difference because what we’re trying

15:13to establish is the quality of the dots on those bottom two lines and if I show

15:18you the seven millimetre at the bottom here and the 7.5 at the top they’re

15:26fairly similar but if you look closely at the 7.5 ones and compare them to the

15:337 millimetre ones you’ll find that the 7.5 are slightly bigger dots you know

15:38it’s only a very slight subtle difference but that’s what you’re looking for there’s only half a millimetre difference in these focal

15:46distances and that is obviously quite critical even on a 2-inch lens which is

15:52what we’ve got in here where the focal depth is supposed to be more tolerant this demonstrates just how critical you need to be with your settings so we’re

16:03going to settle with the 7 millimetre and we’ll concentrate on that now because what we’ve got to do is to establish the size of the dot what from

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

16:11that pattern yeah well it’s not too bad because remember I described to you that

16:16here we’ve got these little black dots and they’re definitely all touching

16:22there’s no gap gap gap so if you had a dot gap gap then you could say well I’ve

16:28got point 1 dots that was the pitch of those along the bottom line there and we can confirm that we’ve actually got point 2 dots because remember what I

16:37said about the second pattern up if we get a dot a space a dot a space and

16:42those dots and spaces look approximately the same then we’ve got point two dots

16:47well we’ve got two important pieces of information off that test this is

16:53critical knowing what the dot size is and the second thing is to make sure you

16:58get the focus set dead right because if you don’t get the focus dead right then you’ll finish up with the dot that’s even bigger than that so what we tried

17:08to do when we look down this pattern here is to find the smallest crispest dots and that tells us where the correct focus point is now before we move off of

17:17our focal distance here I will just mention again something that I nearly forgot and that is the fact that in addition to a two inch lens this machine

17:28is also supplied with a two and a half and a 4 inch lens now I would honestly suggest you do not try and use either of those lenses for this sort of work

17:37now the only time you’d want to probably use something like that is if you’re a little bit on the I won’t say desperate side but there’s no other solution is if

17:48you’ve got an object like this that you’re trying to engrave a picture onto and it’s got a curved surface you’ll need to make sure that as you scan

17:57backwards and forwards along that curved surface you don’t get too much change in the quality of the picture and a 4-inch lens has got a much longer a depth of

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

18:07focus on it so yeah it may have a use it will also be a much coarser picture now

18:15I’m using the word coarse there but what I really mean there’s less pixels per

18:22inch because the dot size will be bigger every picture has got an inherent resolution in it if it’s a bitmap or a

18:30photograph and if you check out what that is it will always tell you that it

18:36is pixels per inch PPI now this machine and we’ve already started doing it works

18:43in millimetres if we look over here we’ve already decided that the dot size is 0.2 of a millimetre so somewhere along the way we’ve got to

18:54define what resolution we can use that point 2.dot for, so there are twenty five point

19:06four millimetres in one inch okay now these are pixels per inch so there is

19:16twenty five point four millimetres now if we divide that twenty five point four by 0.2

19:24which is the size of our pixel dot we’ve got to make sure that our pixel is the

19:31same size as our dot and that will give us an answer of 127

19:39pixels per inch so that’s the resolution of the picture

19:45that we can work with anything more than that resolution and our dots will start

19:51to overlap and if we overlap the dots you remember we’re going to finish up with double burns here we’ve got a picture at 127 dots per inch and if we

20:04draw a pattern and we’ve got the correct ratio of black to white in that set of pixels so here we’ve got some dots at 300 pixels per

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

20:15inch and of course what happens if I’ve got my point two dots and what will

20:21happen is the point two dots will do that and all the gaps that you’d planned

20:27to have will disappear and all these will overlap and double burn so you know

20:36this is going to be a complete mess so I urge you do not mess with this number

20:43that’s what the equation says you should use use it so let’s go and have a look

20:50now putting our picture into RDWorks and setting this magic number okay so

20:59there’s my picture imported into RDWorks and you’ll recognize this picture is something that we have used before I’m going to put the bitmap handle around

21:08it and just take a look at what its properties are so at the moment it clearly tells me at the top here at 600 pixels per inch which is fine now while

21:18I’m in here I’m going to put these to zero just put some new handles around that and up here we can see that we’ve got a picture size of a hundred and one

21:26millimeters now I’ve already put the padlock on so that the proportions

21:31remain the same because I want the horizontal dimension to go up to a4 size which is 297 and there we go now if I put the bitmap handle on again you will

21:46see something else has happened it was 600 pixels per inch remember well we’ve

21:53now changed the size of the picture and an RDWorks has actually rescaled it for

22:00us to a different resolution now remember just a few moments ago we

22:06established at the best resolution that we could ever work with was 127 pixels

22:13per inch well first of all just make sure that these two are set to 0

22:18forget the invert we’re not going to be using a mineral material we’re going to be using an organic material we’re going to set the output resolution to what we found

22:28we had to set it to 127 pixels per inch okay so we can say apply to

22:39view but now what we’re going to do we are going to dither the picture and we’re going to dither the picture with dot graphics and now we shall say apply to view and

22:50there we go we can see we’ve got all sorts of dots in there and now we’ve got

22:59this in dot form we can see how the picture is going to change now this is

23:04where you need some skill some experience some luck because you’ve got

23:12to basically distort this picture slightly to get a good quality result

23:18onto your page it won’t come out quite like this so what we’re going to do is

23:24we’re gonna take the brightness up to start with because almost certainly we

23:30shall need a brighter picture but go up in five percent steps or there about 4.2 and apply to view not much difference let’s have ten percent well

23:43you can see that we’re bringing in some of the hairs in the background here we’re getting a bit more of the background coming forward but it’s a

23:51little bit washed out so we need to crisp it up with contrast so again we’ll

23:56go up in five percent steps apply to view five percent step again

24:03ten percent

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

24:08and maybe one more 15% now this piece of software is very very limited in its

24:15ability to play with the picture and sometimes you need to work on this picture in a piece of external software before you bring it in

24:24but I’m not going to do that today we’re going to stay here we’ll try and make the best of a bad job here so let’s take the the brightness up again I don’t

24:35think we can get a great deal better than that we’ve got quite a crisp eye there as you can see this eye is not bad either so we can apply that to the view

24:43which we’ve already done and then we’ll apply it to the source we need to click

24:50on here and there we go so you see that picture now tends to pop out at you it’s

24:57got more brightness in it and we can see more of these hairs in the background if

25:04you were going to put this picture onto acrylic or some mineral material what

25:11you would do you would go back into the bitmap handle once you’re happy with the

25:18picture and you can see it on your screen looking good you can go back in there and you could you cannot any longer play with the contrast and the

25:27brightness they’re fixed you could possibly reset the resolution if you

25:32wanted to but we’re not going to but you do get the opportunity to go back and invert apply to view and there we go now there is absolutely no way that you’d be

25:45able to work on this picture in a negative form unless you’ve got some sort of perverted brain so you don’t actually convert to an inverted form

25:55until the very last minute so now and we’ve got to set the parameters well we

26:02know that it’s going to be a scan and we’re not going to be blowing we’ll try 11% and see what happens now we want nothing ticked down here at all we’re

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

26:14going to leave it with X swing which means it’s going to scan in both directions and this time the interval we know what the interval is

26:22because we determined that when we said the dot size was naught point two of a

26:28millimeter so that’s what we set the resolution into the picture to one to seven which is equivalent to point two so we know

26:37what the interval is the only thing that we don’t know at the moment is what speed we’re going to run at and this is quite a critical factor this is one of

26:49the secrets that I have discovered I know from work that I’ve recently done that it takes three milliseconds or somewhere in that sort of region for a

26:59single pixel to reach its full power now if you want to push the power up to 20

27:0630 40 50 percent it may well take longer but I know that when we’re using dots

27:12we’re working right down at very low powers and at low power 3 milliseconds

27:17is an adequate amount of time to allow a single pixel to form properly the next

27:24thing is we’ve already determined that our dot size is 0.2 of a millimetre so there’s 1 millimetre and therefore we have 5 pixels in every

27:36millimeter now that’s quite important because we’re now going to take 3

27:42milliseconds for a pixel to form times 5 pixels per millimetre and the net result

27:51is it’s going to take 15 milliseconds for a millimetres worth of pixels the

27:58speed of the machine is set as millimetres per second and so therefore

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

28:03if we take one second and one second is equivalent to a thousand milliseconds

28:09and we take that thousand milliseconds and we find out how many 15 millisecond

28:17intervals or how many millimetres there are what it amounts to is 67 and so we

28:26set the speed to 67 millimetres per second so we now go in and do that and

28:32we set the speed to 67 that’s not something we can change okay so there’s all the parameters set we should now save this and go back to

28:43the machine I’ve got my head set down at the bottom right hand corner if you remember and so we’ll just set the origin there and do a frame check

29:00now this is going to take a long time to do so we should come back and see it

29:10and there we go I think you can probably see the effectiveness of the cross flow there you can see the smoke being drawn away

29:23if you look very closely you can see dots but when we pull away

29:36I think he’ll agree that’s a pretty good photo rendition

29:45now that’s what you can expect by being careful but doing it slowly

29:57I also think you’ll see there’s a significant improvement between what we were trying to do about six weeks ago

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

30:09and that there is no comparison I was scrabbling around in the dark when I was doing that

30:21that took about 40 minutes to produce that picture and I’m sure you’ll agree it’s been worth it we can see all sorts of detail

30:31on the hairs out here you can see all these little teeny-weeny hairs on his

30:37beard down here we can even see these rings you know there is a huge amount of detail in there that was not evident on

30:47the original when we first looked at it look we can see the sword in the

30:52background that’s been pulled out so now I’m just going to remove the 2-inch lens

30:59and replace it with a one and a half inch lens there’s our 2″ lens and this was a 4″ lens where I’ve taken the lens

31:11the 4″ lens out of the back of the tube and in the front of the tube here I’ve put an O ring and I’ve modified the inside of the nozzle itself now that

31:24allows me to pop a smaller this is normally a 20 millimetre lens system

31:31here I’ve got an 18 millimetre diameter one and a half inch focal length lens now we always put it flat side down and on top of that I’ll put a small

31:40compression tube and by the time I screw that in there against the O-ring

31:49it’s completely solid just very lightly clamped okay so now we’ve got a 1.5

31:56inch length in here but I stress again this is not something that’s standard

32:01and available from Thinklaser this is something that I’ve designed and made

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

32:06myself we’re going to use the same paper but we’ve got to go through exactly the same exercise because we’ve changed the focal lengths and we don’t know what

32:14size the dot is that we’re going to produce and we don’t know exactly what the focal length is so we need to prove it while we’re here at the moment what I

32:23want to do is just point out to you the fact that I have got a mild steel plate

32:28sitting on top of the bars and this mild sheet steel sheet is approximately level

32:34with the frame of the page there’s a good reason why I like using this steel

32:41plate first of all as you can see I can put magnets on it secondly it does not allow the air to pass down through it it blocks off the

32:52air that would normally pass through either the bars or the honeycomb table

32:57that you have on the top here and in this particular instance what will happen is the air passes across the top of the table like this to those holes at

33:06the back there now that produce a cross flow which is absolutely essential in my opinion when you are engraving because you don’t want

33:16the air to go that I mean let’s face it if this is the size of the picture and that’s the size of the open area around it there’s more open area than there is

33:25picture so what will happen is you’ll get most of your air just disappearing straight down there and it have no cleaning or purging effects on the top

33:34surface of this this graphic that we’re going to work with so I always make sure

33:40that I get a cross flow a very high speed cross flow to pull the fumes backwards and the other thing that I do and I

33:48mentioned it before is that we set the set the graphic start point down here so

33:54that when we engrave we shall be engraving backwards and forwards like this in gradually moving towards the back of the machine and that means that

34:00all the smoke that’s generated during the engraving process is being pulled backwards now it tends to come up in the air before it goes backwards so very

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

34:08little of it as ever going to reach this clean paper here but just in case it

34:13does by going backwards it means that we’re going to not get any of that debris painting our picture we’re going to leave the picture that we’re

34:23producing in a nice clean smoke-free environment now this steel plate is not something that is standard on the Thinklaser machine you’re gonna have to make

34:31this for yourself don’t get any plated material just plain raw mild steel if it

34:37goes a little bit rusty or a little bit messy picking up fumes and condensation

34:42particularly if you’re doing MDF you can get horrible Brown mucky stuff on the

34:48surface there so acetone will clean it off and if it goes rusty then all you

34:53need is an industrial cleaning pad and this abrasive pad will keep your table

34:59nice and clean so we think this is seven and a half mil

35:05so what I’m going to do I’m going to start eight and a half and we’ll work our way for a millimetre above and a millimetre below the ideal setting point

35:23now I will inspect these mmm and then we can look at them under the microscope

35:31there’s better separation between 7:00 than there is between the 7.5

35:37so in fact I’m going to award that one

35:44the prize seven millimetre and now we’re going to estimate the dot size now this is going to be interesting

35:54that’s my estimate for that one 0.15 so they’re slightly

35:59smaller which means we’ve got to go back and we’ve got to revise the picture

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

36:08because we’ve got to reset the pixels per inch we could run the same picture

36:14but I don’t want to do that because the rules are the rules so I’ve redrawn the picture so that it’s got an interval 0.15 and a resolution of

36:26170 pixels per inch now what we got to do is calculate the speed which I can

36:34modify here on the machine the key thing is three milliseconds is the time that

36:41we’re working with for a single dot this time we’ve got one millimetre and in one

36:48millimeter we’re going to divide that by 0.15 and that equals 6.7 pixels per

36:59millimeter we’ve got this magic number of three milliseconds that applies

37:06regardless of the number of pixels per inch that’s just a fixed constant

37:12consequently we’re gonna have to multiply the three milliseconds

37:19by the number of pixels per millimetre so that tells us it’s going to take 20

37:24milliseconds to do a millimetres worth of pixels remember our speed as

37:30millimeters per second so in one second we have a thousand milliseconds and

37:38we’re going to divide that thousand milliseconds by 20 that’s going to

37:43generate a speed of 50 millimetres a second higher resolution lower speed so

37:52we’ve now got to set the speed to 50 millimetres a second because we’ve

37:57reduced the speed the chances are that we shall probably have to reduce the power as well at the moment the power is set to 12% so now we’ve got to go back

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

38:08to our test pattern again

38:14now I’m sure it’s pretty obvious to you that 10% is so much lighter than the 11%

38:22there’s a huge difference there between those two but there isn’t a huge difference between 11 12 and 13 in terms of color but there probably is in terms

38:31of depth of pixel so what we’ve got to do now is very carefully look to see whether or not we’re going to use 11 or 12 now that’s one of the reasons why

38:41when we look at this pattern you’ll see there’s a load of bars across the top they are multiple pixels and they will help us to decide whether or not we

38:51should choose 11 or 12 is 12 burning too deep relative to a single pixel or is 11

39:00a more balanced view between one pixel and a group of pixels and that’s an

39:05assessment that we’ve got to try and make

39:10but I think I’m gonna settle on 12% because 13% the dots are getting just a little bit bigger the color difference

39:21is not huge so I think we’ll settle on 12%

39:29so 12% and 50 millimeters a second those are the settings

39:51we were very pleased with the quality of picture produced by the two-inch lens

39:56let me show you what happens with a one and a half inches

40:02it’s quite staggering I have to say I did not think it would be as big a

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

40:08difference as that now part of the advantage of this is the fact it’s got a

40:13deeper color to it and when you think about it the reason for the deeper color is because although I’ve reduced the power very slightly

40:25the energy density in the lens is twice as much as it is in this lens so I’ve

40:31got a much sharper hit but look at the clarity of some of this stuff down here

40:39this is the same picture by the way I haven’t messed with the tonal range of

40:44the picture it’s exactly the same picture as this one the only difference is the fact that it’s done with the 2-inch lens and probably the the color

40:54difference between the two is because we’ve got a higher power density in each

40:59one of these dots okay so I was slightly wrong again there

41:05is a big difference between a one and a half inch and a 2 inch lens but the whole purpose of today’s project was to demonstrate that there is a

41:15formula that you can follow to get a good quality photo engraving I’m

41:23extremely pleased at the results we got today the 2-inch lens was exactly what I expected it to be it was a good quality rendition of the original but when we

41:33compare it to the one and a half inch lens where we get a really good deep

41:38contrasting picture because we’re able to get a much deeper burn it does show

41:44you the value of having the right material in the background and the right concentration of energy I think we’ve got much higher energy densities here

41:53that’s able to produce this burn without actually etching away the material if

41:58you start overlapping your dots you get a 3d feel to your picture and there are

Transcript for The Russ Formula for a Successful Laser Engraved Photo (Cont…)

42:05no 3d feels to either of these pictures so I know that my dot quality is good

42:10these are exactly the same picture these are exactly the same cards these are done as it happens and exactly the same power this one was done at 12% this one

42:21was done at 12% I think this one was done at 67 millimeters a second and this

42:26one was done at 50 millimeters a second this is lower energy density and faster

42:31which maybe accounts for why it’s slightly more washed out now I’m not trying to put Thinklaser into a tight corner or anything like that but I think

42:40that you can see from these results that the difference between the 2″ lens

42:45and the 1.5″ inch lens which is not available as standard is quite staggeringly different now without anything to compare it with this is

42:54still quite a nice photograph but this one here is something a bit special this

43:01is almost a perfect sepia photograph so we’ve succeeded in our aim there is a

43:09formula which will guarantee that you get almost the perfect photo engraving I

43:15think that in a future session we ought to take this a little bit further and go into mineral materials such as glass slate and maybe into plastics like

43:25acrylic which are things that people tend to use a lot of so whether we use the

43:31same picture which might be a good comparison to see just how we get on with this picture within different materials we’ll have to see but thank

43:41you very much for your time today and I’ll see you in the next session

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