28 – How to Prepare A Picture For Laser Engraving – Part 2 (50:35)

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Welcome to another Lightblade learning lab, I’ve got the sun shining on my face

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through my workshop window it might make me look like a film star yeah I’m a bit

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delusional I have to admit

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anyway today we’re going to carry on with something we started off last time

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which is dots now today we’re not going to really be talking too much about the

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dots themselves we did an in-depth analysis of how dots can be formed why

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they should be formed you know exactly all the things we’re going to be looking

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for in this session we had to do the preparatory work because there was a lot

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to get through now this might look like white wine trust me it’s not

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it’s just lime cordial

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it’s been a very hot day and I’m looking forward to the cool of

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the evening and settling down showing you guys something interesting today

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we’re going to get into pictures and photographs and all our hard work from

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the last time is going hopefully show some good results now there might be

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some surprising results but I hope they’re going to be interesting for you

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now before we start we’ve got a couple of very important housekeeping tasks if

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you really must perform at some stage before you start using this machine for

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producing photographs or even for logos so we need quickly to just to jump into

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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RDWorks and I’ll show you a little test program that you should design

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yourself and you can use on this machine alright we’re going to select a square

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and then hold down the control key I’m going to just draw a square doesn’t

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matter what at the moment we’re then going to put a handle around it and

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we’re going to come up here to the dimensions and we’ll close the padlock

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and we’ll set one of these dimensions at the top here and there we go we’ve drawn

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a 10 millimeter square and that’s all our tests program is going to be we’re

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now going to come off across to the parameters I’m going to turn this into

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an scan program we’re going to scan it at various speeds so we’ll just set this

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to 400 millimeters a second which is one of the fastest speeds that we like to be

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using on our tests power we’ll leave it at 13% at the moment

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no ticks X swing which is important the interval at the moment I’m going to make

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it half a millimeter point five now that’s a huge interval but you’ll see

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why in a minute okay now I’ve got a small piece of acrylic in there at the

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moment I always like to use acrylic for test purposes and what I’m going to do

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is just set the focus up to the correct focus for this particular lens at seven

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and a half millimeters before I touch anything in the program we’re going to

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just run a test

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the first line at the bottom there was done moving from left to right

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and that is quite important to remember that if you remember these strange

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pictures that I showed you before the actual beam itself carries on dying

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white way much longer than the laser beam switching off now that’s important

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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to note when we look at this pattern here because this pattern starts off

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here and it runs to this side here and you can see there is the end of the line

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where it turns off hangs over the beginning of the next line so what we’re

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going to have to do is we’re going to have to put in what they call an offset

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correction and RDWorks allows us to do that and let me show you where it

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happens, now we need to come up here to config

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and in conflig we’ve got system setting and if we drag up system setting just

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here we need to tick beside this scanning reverse interval and now we can

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come into this list here and I have not got anything set up for 400 millimeters

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a second which is the speed we’re running and it is important that you

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always set up one of these parameters for the speed that you’re going to run

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at now in this particular instance we’re going to run at 400 millimeters a second

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now there’s something here called reverse interval which is an offset that

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we can apply at the moment we didn’t have anything set up so the machine is

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doing its own thing what I’m going to do is now that I’ve set 400 millimeters a

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second up I’m going to leave it at zero and do another test and see what result

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we get the other thing that’s underneath here is called offset replay now you don’t

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need to touch that at all if you play with that all it would do is move the

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position of this square pattern around so we don’t want that to happen so we

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leave it alone and there we are we can immediately see

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the difference I’ve now set the offset to zero and the machine knows now that

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there’s an offset of zero I’ve got a point oh 3 shift in there which

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is one thousandth of an inch I don’t think it’s made any difference it’s not

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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made it better and it’s not really made it worse, if we use X unilateral it will

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take twice as long but we’ll only get scan lines going in one direction so we

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won’t experience this problem now bear in mind we’re looking for the perfect

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dots to get the perfect dots we must have the focus set onto the surface as

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perfectly as possible what we’re going to do is we’re going to check the focus

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I think the focus on here should be about seven and a half so what I’m going

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to do I’m going to set it to eight and a half

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and then I’ll set it to seven-and-a-half

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and then I’ll run down at six and a half now thing if you study those lines

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carefully you can clearly see that the one in the middle is the thinnest line

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which looks as though it’s probably pretty close to the theoretical point

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one because the gap between those lines the pitch between those lines is 0.5 so

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just a quick estimate visually says yeah we’re doing pretty damn good the problem

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is we’re not going to get dots that size we’re going to get sausages that width

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and that’s going to be a bit of a problem when we run at 400

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millimetres a second but that’s all going to come later when we start doing

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some some actual photographs and some dots I’ve got to go and set some scan

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offsets for various other speeds you know how to do it now you don’t need to

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see me doing it now what I’ve got here is a piece of card which is one

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millimetre thick and if we look at it you’ll find that it’s not entirely flat

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it’s got a little bit of a bow in the middle all I need is a couple of small

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neodymium magnets in the middle here and that will hold that sheet completely

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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flat because we changed the thickness of the material set this back up to seven

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and a half millimeters which is the ideal focus that we’re after so I’ve got

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the air assist turned off in the programme because otherwise any fumes

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that come up will get blown down and paint the whole thing a brown hue

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okay now despite the fact that I normally use Photoshop I’m going to be using

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RDWorks in its entirety some of the tools are very clunky in here but I think it

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will be better if people don’t have to use Photoshop I’ve got a 300 PPI picture

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here I’m going to use the bitmap handle you can see up here it

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says 300 pixels per inch well one of the things that I can do is I can change the

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resolution of the output here so we’ll change that to 150 and we’ll let RDWorks

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do the change for us so I can apply that to the view

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doesn’t look as though it’s changed much

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now dithering is the thing that will turn it into black and white dots so

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we’re going to be using dot graphic

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and we’ll now apply that to view

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now it makes a big difference

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and that’s what we need to start with apply to source and okay and now we should

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find that we’ve got when we click on there

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dottie graphics we’re now go and set the parameters that green is just a border

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an a4 border which is not going to print it’s just so that I can locate in the

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bottom corner let’s just show you I’ve got my zero set down in this bottom

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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corner here that’s where we’re going to start and we’re going to start across

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the bottom of the picture because I want the scanning to move up the picture so

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that any fumes get drawn across the paper and any picture that’s produced

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remains a nice clean smoke free picture behind it we’re going to set the speed

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to 50 and we’re going to set the power down at 11 which is about the absolute

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lowest that this machine will run at you take all the ticks away from here we’re

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going to set the resolution to a hundred and fifty {pitch} point one six nine three

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make the line interval match the pixels okay let’s see what we get now bear in

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mind that that’s a dotty picture at a hundred and fifty pixels per inch I have

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to say that’s come out substantially better than I expected

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that’s almost newspaper quality yeah but you see lots of dots in there but what

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we really ought to do now is go and have a look at this under the microscope to

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see just what sort of quality we’ve got on these dots I mean I can see all sorts

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of little details in here despite the fact that they’re dotty I can see in hairs. Quite remarkable actually

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by looking at that streak of hair that runs across her forehead and well I

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think generally when we look at this picture all we can see are fairly even

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brown dots which is actually very good news because we haven’t got gradations

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of brown they’re more or less all the same color

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there are some black ones which are obviously where some of the pixels have

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been doubled up but in general the single dots are all about the same color

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now they’re slightly sausage-shaped but not terribly so maybe one and a half or

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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two to one ratio we’ve got just a little bit of gap between those lines which I

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suppose is good in a way because it does mean to say that well we put the pitch

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at point one six nine and I suppose the lines the burns are about point one just

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over point one maybe so it does make sense that we’ve going to get one or two

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gaps between those lines while doubling the resolution has done absolutely

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nothing for us at all except take all the color out of the dots as you can see

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right this is 50 millimeters a second so we have still got dots but the dots have

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lost all their color and that’s because we have basically doubled the resolution

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doubling the resolution for 150 to 300 has basically half the amount of burn

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time for each dot I know it’s a rather strange description but it looks as

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though we’re almost getting greyscale dots now these are our first two

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pictures we’ve sat them side by side so that you can compare them closely now

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there’s always a temptation when you’re doing this sort of work to rush off and

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say ah yeah but we’ve got this we can we can we can make that picture a lot

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better by increasing the resolution we can go faster we can get it done

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quicker you know there are so many things that you could play with so many

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factors but what I want to do is just stop you in your tracks for a minute and

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say look let’s have a think about this don’t rush into it we know a lot of

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information now let’s put that information together and see if we can

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start sorting out how we can get better or not pictures this picture here was

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done at a hundred and fifty dpi in both x and y although the picture is 150 dpi

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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in both directions it doesn’t mean to say that you have to

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do it 150 dpi in both directions we can’t change the number of pixels in

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this direction and we can’t change the number of pixels in that direction but

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we can in this direction if we want to change the interval and we could

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effectively miss out every other pixel line so we’ve only got half the

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information while I was doing this I imagined possibly that I could get

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better results by increasing the resolution from 150 pixels per inch

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to 300 pixels per inch so in other words if I increase the resolution

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of the picture I’d better get a better quality picture well I think you can see

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for yourself that isn’t the case but why not because we’ve kept the speed the

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same 50 millimeters a second the only difference is we have in fact changed

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the Y pixels per inch so we’ve we’ve scanned half the information so let’s

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just stop for a second and have a quick think about what we’ve done well we know

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that a hundred and fifty pixels per inch which is what this was done at it’s

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likely to look like this because at 50 millimeters a second we’ll likely get a

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dot which is around about point one and slightly sausage-shaped

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now the ideal dot would be point one but at 150 pixels per inch

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each pixel is point 169 and their dots are only likely to be

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point one wide therefore we’re going to get some white extra white between the

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dots so in this picture as we saw we had we did have a small amount of separation

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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between the lines because we’ve looked at this piece here across this piece of

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hair across here and we did see that we’ve got a small amount of white

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between the pixels it probably wasn’t as much as I’ve shown here but this is the

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principle that we’re basically operating on when we’re working with this picture

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now when I decided to do this picture at 300 pixels per inch but I made a silly

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decision to only go down in Y at a hundred and fifty pixels per inch let’s

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analyze what I’ve done so in this particular case we’ve got a pixel size

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of 0.0847 which is nearly 0.1 which is approximately the size that we thought

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our dots were going to be so if we look at how they sit in this grid they sit in

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there we’ve got the ability at fifty millimeters a second to burn probably

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every single dot maybe not fully black because we’ve got half the amount of

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time remember and half the amount of time means we’re less likely to burn the

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whole strength of the dot so that may will be black and that will make that

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may well be only half black a gray or in this particular instance a half brown

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and so consequently even though we’re running at the same speed because we’ve

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got half the amount of time for each one of these pixels we’re going to

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automatically get a lighter picture so there’s a good logical reason why this

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picture is much much lighter than that one even though technically it’s at a

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finer resolution although I’ve drawn these as dots as I’ve demonstrated on

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here they could be single dots with a space between them or they could be

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joined up dots I’ll just leave that to your imagination. I know

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they’re not the same size but that’s because I’ve drawn the same number of

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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pixels this is a 10 by 10 pixel block this is a 10 by 10 pixel block and this

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is a 10 by 10 pixel block but it’s at different resolutions and you can

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automatically see how the size has changed quite dramatically but of course

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the one thing that doesn’t change dramatically is this thing here the dot

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size is influenced by the power but we’re keeping the power very low at the

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moment so I’m keeping the dot sizes all the same so that you can see this

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massive comparison as you supposedly think you’re going to get a picture a

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better picture by increasing the resolution now all you’re going to do is

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put the same dot if you choose you could in this particular instance look you

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could at 300 pixels per inch as we tried to you could just use half as many

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pixels or if you go to 600 pixels per inch and try and do every single line

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you’re going to get dots sitting on top of dots sitting on top of dots sitting

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on top of dots and you’re gonna get a very dark burn now I know this is a fact

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because I have actually experimented with them but what I’m saying is you

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don’t need to experiment with them if you just stop and think about it look

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we’re going to compare these two pictures now this is 150 pixels per inch

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and this is 150 dots per inch this one is 150 pixels per inch with 150 dots per

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inch in both x and y now this picture doesn’t have anything like that picture

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why not well two reasons why not first of all I’ve increased the power from 11%

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up to 15% so in terms of power this 11% is probably something like about 3 watts

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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and this 15% has jumped all the way up to probably something like about 14

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watts so there’s a huge difference in the

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power for a very small percentage gain you need good control of low power you

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do not get good control of low power if you’ve got an eighty or a hundred or a

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hundred and fifty watt tube in. Your best choice for engraving is going to be

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somewhere in the region of a 40 or 50 watt tube it’s not your best choice for

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cutting but it is your best choice for engraving now I’ve got a 60 watt tube in

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this machine and I can just about get good results but I have to be very

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careful at the bottom end here just pushing the power up from 3 watts to 14

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watts has caused this pretty gross over burning but in addition to that to try

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and compensate for the over burning look what I’ve done I’ve increased the speed

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to 150 millimetres a second from 50 millimetres a second so there’s two or

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three variable changes and it makes a gross difference in the quality of the

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picture that you get just to sort of reinforce this situation that I’m

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talking about here at 600 dots per inch here is a 600 dots per inch image and to

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try and stop it over burning which as you can see it’s got lots of gingereness and

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burning and smoke stuff and I can I can feel her eyes are very nearly burnt out

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when I touch her hair it’s got a 3d feel to it because of the way in which it’s

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burned into the picture here and in fact let me just stop a second yeah that’s

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exactly as I remember her… to try and compensate for the extra power that I

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put into it because at 600 dots per inch I thought well I need to go a little bit

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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more powerful I also went very very fast of 400 millimetres a second yeah it

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still works but the problem is when we start looking at the dots in here and we

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will go back and have a look at some of the dots in these in these images you

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will see that we do not have dots they’ve disappeared what we’ve got are these

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what I call greyscale splurges different levels of colour caused by the fact that

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we have got insufficient time at 400 millimeters a second and insufficient

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space because we’ve got 600 pixels per inch those two factors are working

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together to make the time scale infinitesimally small for any single

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pixel so to try and get the pixels to burn you put more power in but that

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means that when you do get blocks of pixels that are joined together this

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power takes over and you get terrible burning so trying to find a compromise

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you say right okay 600 pixels per inch we run 600 pixels per inch resolution

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down the page as well and we’ll run slower to try and get a bit more color

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into it but we’ll put less power into it at 12% it still doesn’t work at the end

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of the day the most balanced picture that we can come up with is one made up

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of dots these are not dots as you will see when we look at them under the

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microscope the crispest picture is that which is done slowest 50 millimeters a

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second and a very coarse resolution but the point that I’m trying to make here

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is with photographs running fast running powerful and running with high

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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resolutions is not going to get you a good quality picture you’re going to get

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your best results probably down at low resolutions and low speeds it’s probably

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better to experiment with maybe 60 or 70 millimeters a second trying to keep the

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dot as round as possible but increase the resolution maybe a

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little bit up to 200 now the one thing that you must not forget is that your

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lens has got a theoretical spot size let’s just look the best spot size that

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we can think of which is a one and a half inch lens with

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a spot size of point zero seven five millimeters well put it another way

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point zero zero three inches now that means that basically the best that we’re

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going to get if we put these dots together like this is three hundred and

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thirty three pixels per inch anything above 300 pixels per inch resolution

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picture and really I think you’re wasting your time now do not lose sight

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of this fact because this is fundamental and the other thing that you must

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remember is this is a theoretical spot size and when you come to put it on your

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material whatever that material is if you do a test burn you may well find

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that your spot size is not as you think that size but it’s actually that size

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and you could be down quite easily at a hundred and fifty P P I for your picture

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putting more than 150 PPI into the picture it’s not going to get you

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anywhere now if you’re after an art poster this one looks quite a nice soft

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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dreamy effect hazy soft focus but if you want a good creation then you’re looking

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at something like this where the dots are actually crisp and clear and it’s

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your eye that gets fooled this is that curl across her forehead that I look at

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as a reference every time and we can see clearly some lovely brown lines that run

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across there and we’ve got separation between the lines so that means we’ve

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got our scan lines which are actually quite well defined but the gaps between

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them are because this is only done at a hundred and fifty dots per inch in the Y

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direction and so these are exactly the same line separations that we saw in our

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very first crisp clear

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dot image the difference is that this is not a clean crisp dot image this is a pseudo

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grayscale as I keep calling it because look with all these shades of brown in

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the background where different amounts of time different amounts of power are

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causing different colored dots so yeah this is not a grayscale picture because

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we are using the same power Max and min and grayscale pictures come from using

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different power Max and min so this has been created by a completely different

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mechanism but even though it’s not part of this session I have a little bit of

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curiosity that needs to be satisfied so I’ve imported this 600 PPI picture again

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and we will just set up a different set of parameters speed same as it was

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before 400 millimeters a second power well this time the minimum power that we

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ever found that we could use was 11% and the maximum power that we used was 40%

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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now we need to come down to here and this time we’re going to output direct

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and basically what that’s going to do it’s going to give us grayscale

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engraving now I’m going to set the interval exactly the same as it was for

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the last picture which is 150 dots per inch in the Y direction which is point

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one six nine three well we can clearly see the beam is on virtually

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continuously and stable the whole time except when it turns off right at the

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end of the stroke and then back on today yeah we’ve only got about a 10 percent

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variation in power across there because in the end I had to set it to between 11

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and 20 percent because otherwise I was just burning through the picture so I

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obviously haven’t got the correct parameters here but these are parameters

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similar to the last picture that we created with dotting and this is really

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all the comparison is about it’s quite entrancing isn’t to watch I’ve been

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dancing around

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ok now the one thing I keep meaning to say when we’re looking at this

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picture that mauve is not the laser beam that mauve is just ionised nitrogen

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it’s the powerhouse that drives the carbon dioxide to go into lasing mode so

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just because you see that beam there does not mean to say you’re necessarily

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going to get power out of your laser because if there’s no carbon dioxide

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left in your tube you’ll get no power out but you will be able to see that

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lovely mauve beam in fact that beam might go slightly paler and whiter as it gets

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towards the end of its life because there’s more nitrous oxide from the from

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the free oxygen that’s been released from the carbon dioxide when it’s broken

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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down into carbon monoxide and oxygen so just bear that in mind the mauve is a very

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good sign that your power supply is working but it’s not an absolute certain

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sign that you’re getting power out at the end of the tube. What you’ve just been

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watching is me trying to produce something called a grayscale photograph

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when this picture started off life originally it was full of color the

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first thing that RDWorks did to it was remove the colour and when the colour

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is removed it left a black-and-white picture which is basically a mixture of

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shades of grey and that was what we have tried to simulate here with this dot

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picture we’ve created the same sort of thing we’ve fooled the eye into thinking they are

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Shades of colour on that picture but there

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are not we’ve only got black dots and nothing it’s just the different

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densities of those dots are fooling your eye into thinking this is a photograph

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now as we’ve already explained the way in which the laser produces this picture

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is very simple it takes the power parameter 11% and it sets it at a fixed

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value of 11% the dot every time we need a dot the power switches on and we

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produce a dot and then it switches off then it travels along to the next dot or

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in this instance group of dots and then it switches off dot dot group of dots

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there is a very powerful function built into RDWorks it has the ability to

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look at a grayscale picture and sort out every single pixel into a gray value now

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the value of gray runs from white at 255 down to black at zero every one of those

31:52

shades of gray is given a power value and then this is where the clever bit

31:58

takes place when you run your program the first thing that happens is the beam

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switches on and it stays on for the whole of your program but every scan

32:13

line that goes across looks like this it starts off zero and then it looks at the

32:20

very first pixel and says oh yes that’s a mid gray that’s halfway up the scale

32:25

and so it produces a pixel value like that and then it looks at the next pixel

32:31

and says oh that’s nearly white white is not much power at all so we’ll turn the

32:35

power off then the next pixel is a slightly heavier shade of gray and then

32:39

a lesser shade of gray and as we go across every pixel

32:49

has a varying power obviously if you start running the machine too fast

32:54

ie 600 pixels per inch or at very high speed the machine is just not capable of

33:02

keeping up with your requirements even though the requirements are there the

33:08

power supply and the laser just cannot do it this is how we basically would

33:13

attempt to produce my grayscale photograph now obviously I can only hope

33:18

to perform something like this on a piece of organic material because with a

33:22

piece of organic material I can get different shades of brown when it comes

33:27

to a non organic material such as acrylic in this instance or glass or

33:32

stone or slate or granite or something like that then the only choice that

33:38

you’ve got is a colored dot of one shade or nothing

33:43

so there is no gradation that you can use with solid materials now how

33:50

successful were well there we are the answer is not very it’s a horrible fuzzy

33:59

picture yes it’s grayscale but no there is no definition in it at all so we were

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using the same resolution base picture 600 dots per inch we were using the same

34:12

scanning rate of a hundred and fifty dots per inch down the page we were

34:17

taking about a quarter of the information but that isn’t the reason

34:20

why it’s fuzzy because when we did it using the dot method exactly the same

34:26

picture looks like this so there is a huge difference between using dots and

34:33

using gray scale basically grayscale is not for producing grayscale pictures

34:39

it’s another completely different function that you can use grayscale for

34:44

it’s for 3d carving and we will get on to that subject which is a fascinating

34:50

subject in a future session the only way that you’re going to get a picture of

34:55

any sort onto a material is with the dot process now you don’t always

35:01

see the dots this is a smeared dot picture it isn’t a proper dot picture

35:07

this is a proper dot picture and you can see that there’s an element of crispness

35:12

about this that there is not there as soon as you start running at different

35:16

speeds and different different resolutions you could smear the dots

35:22

overlap the dots overlap the powers and you get all sorts of interesting

35:28

pictures some of them very soft focus something like this

35:33

no dithering at all all it is it’s basically a black-and-white picture now

35:39

here we have a completely different material this is anodized aluminium and

35:42

you see that we’ve managed to get a photograph down onto the surface it’s

35:47

only again a binary surface white and the background colour in this instance

35:53

we’ve got a silver background so you would expect that probably a silver

35:56

background wouldn’t show through at all but as you can see we get a sufficiently

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36:00

good contrast to see quite a reasonable photograph I will point out to you two

36:04

things first of all 80 millimetres a second very slow speed and 11% power

36:11

very low power now look what happens when I changed just 10% look at the

36:17

quality difference in the in the image again I’m reinforcing that control of

36:21

low power is an essential thing when you come to engraving well we’ve banged on

36:27

enough about dots and photographs and I think you’ve now got enough information

36:32

in your toolbox to go away and play for yourself so for the final part of this

36:38

session what I’m going to do is show you a real project that I had to carry out

36:42

for a friend of mine so it involves Photoshop I’m afraid or some sort of

36:49

photographic processing software because quite often you cannot get the correct

36:55

image that you’re looking for down onto the medium that you want to apply it to

37:00

now this particular project is basically going out of my comfort zone I’m gonna

37:05

have to go into Photoshop which okay I know my way around Photoshop but but I

37:10

am NOT a graphic artist in fact I’m not any sort of artist

37:14

except the up against the wall type so you’ll have to forgive me for some of

37:19

the liberties that I might take I’m an engineer not an artist and I make no

37:24

excuses for that at all so I hope that what we’re now going to see is a

37:27

practical demonstration of all the elements coming together that we’ve been

37:32

learning about I’ve got a real job to do for someone a friend of mine who has

37:37

asked me to immortalize her dog on some coasters as you can see this is not

37:42

exactly the best picture in the world to work with it’s not a studio quality

37:46

picture so somehow I’ve got to get the essential qualities of this dog’s face

37:52

onto a piece of wood now I’m not going to take you through every single step in

37:57

detail but I am going to show the outline of what I’m going to do to

Transcript for How to Prepare A Picture For Laser Engraving (Cont…)

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manipulate this picture so the first thing I’ve got to do is to physically

38:05

crop the head fairly tightly so that I don’t get too much of that bright red

38:11

coat in the background now let’s bring the picture up to a decent size so we

38:16

can see what we’re working with o M G is your immediate reaction look at the

38:21

state of his tongue saliva mud so we’ll choose that area there and there we’ll

38:27

start working away to try and put some pink once this goes into grayscale

38:34

it’ll be a shade of gray well that’s not a perfect tongue but at least it’s

38:39

better than it was so we then used the clone stamp to copy

38:45

the colors off of his muzzle here and try and get rid of those mud spots we

38:54

can do this with a lasso tool we can work our way around his head

39:01

approximately

39:10

so now we’ve got another layer which is

39:16

that layer there and you can see we’ve probably removed a large part of the

39:24

background we also removed some of his tongue but this is not what I finished

39:29

up with now the biggest problem that we’ve got here is if we take a look at

39:34

image adjustments we can check brightness and contrast and we what

39:40

we’re trying to do is to bring his eye up this eye here is not very prominent

39:50

even when I push the contrast up which is what I should need to do

39:59

that eye is not very distinct I’m going to capture this eye here

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rather carefully

40:19

edit copy edit

40:25

paste and you say well you haven’t done anything

40:30

well yes I have because if I select this layer and I now use the pointer look I

40:39

can pick up his eye

40:44

and I can now put that over there

40:49

so now I’ve got two fairly bright eyes to work with the other thing that I’ve

40:55

got to do is because I know that when these eyes are on wood they will not

41:04

show up against this black dark background and so consequently what I’m

41:12

going to do I’m going to choose some rather hideous color like that and I’m

41:19

going to turn him into a werewolf now you definitely wouldn’t want to meet

41:23

that dog on a dark on a dark night would you and so you can see how I had to

41:32

basically manipulate that oh one other thing I didn’t mention which I had to do

41:38

I had to take a clone stamp and I had to clone these little frilly bits of the

41:45

tops of his ears here and I had to put them on the crown of his head because

41:50

there was no definition between this white section here and the background so

41:56

although this hair isn’t real it just gives the impression it delineates the

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outside of his head so you can see if you look at that in detail it’s not

42:05

necessarily a very good quality picture okay now when we import that picture

42:11

into RDWorks it looks pretty scary doesn’t it so the first thing we’re

42:16

going to do with that picture is make it ninety five millimeters and then I’m

42:22

going to create a square 100 and then we’re gonna put that square around the

42:32

outside of the image and we’ll make that into blue

42:35

so the bitmap is black and we’re going to have a go at cutting that in a minute

42:45

at about a hundred and I think we’ll probably set the power to just a little

42:54

bit over the minimum I think that 12% is pretty good blowing no we’ll check the

43:01

cut speed the cut speed is about five millimeters a second because this is

43:07

going to be done out of probably five millimeter marine ply probably 67

43:17

percent 67 percent which is about as high as my tube will go okay so now

43:23

let’s go back to the picture itself

43:28

bitmap handle and you can see we’ve got a resolution here of over a thousand

43:38

think we’ll set that to 200 we’ll push the boundaries of what we’ve just

43:43

discovered and then we will do dither and we’ll set it as dot graphics we

43:52

could play with the contrast and the but at the moment I think it probably looks

43:58

reasonable so we say apply to view and immediately we lose all the detail

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so now we can play with these colors here contrast and brightness apply to

44:13

view

44:17

and there we go we can get some of the detail back here’s you see now that

44:21

looks like a reasonably balanced view so we can say apply to source now and then

44:27

when we look at this there we go

44:34

and this time you can see the smoke being pulled away nicely towards the

44:38

back of the machine where it’s extracted down the slots

44:47

well I’ve now put the cover down so that we get a good jet of air flushing across

44:51

the surface there and as you can see you can probably see hardly any smoke at all

44:56

it’s all being dragged backwards really really quickly

45:11

now what you’re seeing at the moment is a cut taking place where the air assists

45:16

has actually turned on automatically on its own

45:22

now if we take a look at the quality of that cut you can see that there is

45:25

absolutely no smoke burning on there at all except

45:33

the only hint of browning we’ve got is at the very very start point there and

45:38

the very very finish point but everywhere else is absolutely clean

45:45

and the reason why we’ve got a lovely smoke-free finish here is because the

45:50

smoke is passing all the way through this job

45:52

there’s nothing hitting the top surface it’s all going down underneath then is

45:57

either being drawn away by the airflow underneath or has been condensed on this

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surface here as you can see leaving a Hobby horrible sticky goo behind

46:07

now that’s another reason why I’m using a solid steel plate because when this

46:11

job is over all I’m going to do is to wipe that plate clean if I had been

46:15

using a honeycomb table I can’t clean the honeycomb table as you can see all

46:22

this muck on here look it’s all horrible Browns sticky muck that’s the stuff that

46:25

would have gone on to the top of your cut and onto the top of your job had you

46:31

have had the air assist on while you were engraving and that’s the stuff that

46:34

actually paints the surface of your wood Brown you don’t want it you want to get

46:40

rid of it before you blow it back down onto the job so basically for air assist you

46:45

only need it for cutting and you want to blow all your muck out of the bottom of

46:49

the job but for good engraving you want to let it drift up into the air and get

46:55

it sucked away and not blown back onto the surface of the job

46:59

See all this brown muck here? Well sometimes you can get away with something as simple and benign as a

47:04

white vinegar so let’s give that a try it really depends on the debris itself

47:16

now because that’s a natural wood and that’s probably just a normal resin it

47:21

came off fairly easily with white vinegar but here we’ve got

47:28

some acetone now obviously it’s not the sort of thing that you would let

47:32

kids play with and you would normally have rubber gloves on or plastic gloves

47:37

so that you don’t take the oil out of your skin

47:41

but I’m afraid at my age I’ve got a very tough skin I’ve been involved in

47:47

engineering for many years

47:54

for just a few seconds work it’s not a major problem but if I was handling this

47:59

stuff all day my skin would literally dry and crack so it’s not the sort of

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thing you normally use without gloves now here are our coasters and you may

48:08

possibly spot that there are two at the back look slightly softer they’re not

48:15

quite as crisp as these when you look at them with the light across them and

48:19

that’s because these are coasters and they are going to be subjected to

48:24

spillage whether it be beer wine whiskey something is going to be spilt on these

48:30

you can be assured of it if it’s me well it’s got to be black cock here I’ve got

48:35

some just natural beeswax this is called bright way it’s mainly beeswax with a

48:41

sort a little bit of sort of something like white spirits in it to make it

48:44

slightly soft it’s not hard beeswax as you can see in here it’s a sort of a a

48:50

slightly soft creamy mixture but it is a natural material and it sinks in to the

48:58

wood and so what I do with these I protect the wood

49:04

when you first put it on you think oh my goodness what’s happening here we’re

49:07

gonna fill in all the engraving

49:12

but because it is a wax and oils what tends to happen is over a few minutes

49:17

maybe 20 minutes half an hour you’ll find the the wax actually sinks into the

49:24

wood and here we are look

49:28

when you first do it it looks pretty horrendous but just be patient and all

49:34

will come good in the end paint the edges which sells any coloration that

49:40

may be wanting to come off it seals it in and then we do the backs as well, so just paint

49:47

it on with a brush don’t put it on with cloth because cloth will leave lint and

49:51

various other pieces of white in your engraving yeah it feels so real now I do

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hope that that lasts practical demonstration has brought the whole

50:05

thing together now it was no cheating with that at all

50:08

there was no practice I went straight in with a resolution I went straight in

50:13

with a speed I went straight in with a power and we got excellent results and

50:18

that’s what I hope this session has given you confidence to dive straight in

50:24

with a set of good maybe not perfect but good parameters so until the next time

50:32

Cheerio