10 – Understand and Care for your Lenses (51:11)

00:13

Welcome to another Lightblade Learning

00:16

lab. Today I hope is going to be very

00:19

interesting session, it’s going to be

00:21

packed with lots of tips and features

00:23

and some very important facts about the

00:26

machine itself. Now before you get

00:29

started

00:30

I don’t want you to fall asleep i would like

00:32

you to put this on pause for a few

00:34

moments go and get yourself a cup of

00:35

coffee and while you’re about it

00:38

can you hunt down an old style wooden

00:40

pencil with a lead sticking out the other

00:43

end and make sure it’s nice and sharp

00:46

and then come back and we’ll restart the

00:49

session

00:53

great well hopefully you’re now going to

00:55

be fully aware because we said we’re

00:58

going to start benchmarking the Machine

01:00

now there are many different ways where

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we can start benchmarking the Machine

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benchmarking basically means putting a

01:05

peg in the ground so that we know what

01:07

the performance of the machine is now

01:09

because in six months time three months

01:12

time whenever our machine might degrade

01:15

and it would be good to have the tools

01:17

to know that the machine is no longer in

01:20

tip-top condition and you can either

01:22

have a go at fixing yourself if you feel

01:24

confident or if you’ve got the right

01:26

tools to demonstrate that something has

01:28

changed seriously you can probably

01:29

called Thinklaser in and they will fix

01:31

the problem for you

01:32

ok we could start the laser tube and

01:38

we’ve already discussed the laser tube

01:40

in quite great detail so you know how

01:42

important it is and how it works

01:43

once the laser beam comes out of the

01:45

tube it has to pass around the machine

01:48

via a series of mirrors

01:49

now the mirrors themselves we’ve touched

01:51

on a little bit with reflectance and the

01:53

danger of the beam etc we’re going to

01:56

concentrate on mirrors in a completely

01:57

separate session because they’re a big

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

02:00

subject all on their own and then

02:02

finally we’ve got to get to the lens now

02:06

the lens is the most important part of

02:08

the system because without the lens you

02:11

don’t have a useful machine so today

02:14

what I’m going to do is concentrate on

02:16

trying to give you a conceptual

02:18

understanding of what this lens does and

02:21

understanding of why you’ve got two or

02:23

three or four different lenses with your

02:25

machine there maybe some of you that

02:27

never did any science lessons there

02:29

maybe some of you that did attend

02:31

science lessons but at the point in time

02:32

when the science teacher was trying to

02:35

teach you about optical paths and bits

02:37

of glass and bending light your hormones

02:39

were probably to the fore and you

02:42

weren’t really interested you were more

02:44

interested in the um… the young lady at

02:47

the back

02:48

let’s just start from square one and

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give you 1 or 2 very basics about lenses

02:52

because the way that I want to describe

02:54

them to you hopefully will be memorable

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now I’ve got a picture on the screen

02:59

here of three lenses now they will look

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the same because that’s just my laziness

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the way that I’ve drawn them but they

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have got something called a focal length

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now depending on the shape of the lens

03:13

the laser beam comes in from the top as

03:16

a parallel beam it passes through the

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lens and then its shape changes now

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depending on the focal length of the

03:27

lens and here I’ve shown three different

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focal length lenses we’ve got a

03:31

one-and-a-half inch lens thirty eight

03:34

millimeter at Owens lens which is 51

03:36

millimeters and a two-and-a-half-inch

03:38

lens 64 millimeters that each of those

03:41

lenses has got different properties the

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Key property is the size of the dot at the

03:50

focal length now that determines

03:53

something called the energy density of

03:56

the beam itself now I don’t want to go

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

04:01

into too much detail on energy density

04:04

at the moment but you’ll hear me using

04:05

this word energy density quite a lot and

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it’s very important that you understand

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what energy density is now did you get

04:15

that pencil i asked you to find well if

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you did then what I’d like to do is to

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pick it up

04:23

and with the blunt end of the pencil

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push it into the palm of your hand as

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hard as you can

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you can do it very hard and it doesn’t

04:35

hurt it might make a little mark but it

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doesn’t hurt

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okay now turn the pencil round and

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cautiously pressed into the palm of your

04:47

hand point first now I guess that it

04:50

isn’t going to be very long before you

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say all I can’t do that very hard

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ok if you were to apply the same amount

04:59

of pressure that you did when you’re

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pressing the blunt ending you’d probably

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push the pencil right through your hand

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what we’ve done we’ve concentrated the

05:08

energy that you have applied to that

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pencil into a very very small area ie

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the point and you can do a lot of damage

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with the point but you can’t do much

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damage with the blunt end of the pencil

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now the key word here damage and energy

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density sit side-by-side and that’s what

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I want you to remember energy density

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equals damage so the lower the energy

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density the less damage you’re going to

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do to the material

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ok that’s an important lesson about the

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concept of energy and bear in mind that

05:52

this energy that were firing at this

05:53

lens is invisible

05:55

it’s not light that you can see it’s

05:59

actually heat energy we’re concentrating

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

06:00

this energy this hate energy into a very

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very powerful beam and at the focal

06:07

point it’s able to do a huge amount of

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damage

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ok so the focal points we’ve got three

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different focal points here why do we

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need three different focal points

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well if we take a look carefully at the

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shape of the paths that the beam is

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taking you’ll see that the thirty eight

06:27

millimeter it has got a wasting it

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doesn’t actually between doesn’t

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actually cross over and come to a real

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sharp nothing point it has some spot

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size right at the 38 millimeters

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dimension and it comes in and out very

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quickly and I’ve drawn a dimension in

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there 14.6 62 that’s rubbish

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basically it’s more like in the real

06:54

world it’s more like 1.4 millimeters in

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other words plus or minus about plus or

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minus half a millimeter that’s what they

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called the usable focal depth now that

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basically means that the energy the

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energy density is approximately uniform

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over only points7 of a millimeter above

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and below the focal point so you have to

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be very accurate with your focusing to

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get the best out of your beam now when

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you get to the 51 millimeter 2-inch lens

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you’ll see that that 1.4 millimeters and

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let’s divide the numbers by 10 has

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changed to two millimeters so we’ve got

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plus or minus a millimeter now we’ve got

07:38

a little bit more flexibility in the

07:42

range that we can use the lens and then

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we’ve got the 64 millimeter or the

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two-and-a-half inch lens and you’ll see

07:48

that that’s gone up to two and a half

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millimeters we’ve got an even wider

07:52

range of operating for instance the 51

07:57

millimeter lens has got less energy

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

08:01

density then

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the thirty eight millimeter lens and

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similarly the 64 millimeter lens has got

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less energy density than the other two

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if you want to do the same amount of

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damage with a longer length lens you

08:15

have to have more powerful machine now

08:19

these are concepts that you want to deal

08:21

with in another session completely all

08:23

about energy density and the way in

08:25

which you could use your lenses today I

08:28

want to purely talk about the focal

08:30

length and what I’ve tried to describe

08:33

there is the usable focal length

08:36

changing and why it’s important to make

08:39

sure you get your lens set correctly for

08:42

the focal length on the job that you are

08:45

doing so this is not a subject that we

08:49

can just pass over you need to

08:51

understand about lenses now the machine

08:54

has got an autofocus system on it but so

08:58

I want to tackle the problem from the

08:59

grassroots section upwards and then will

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work back into the autofocus system

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ok so we’ve got to do two things when we

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get to our machine

09:10

we’ve got to establish what focal length

09:14

lens as in the machine to start with and

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secondly we’ve got to establish whether

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or not the machine has got it set

09:21

correctly IE if its a 50 1 millimeter

09:25

lens is the lens set 50 million 51

09:28

millimeters above the workpiece that’s

09:31

important

09:33

how do we do that well I’m afraid there

09:37

is nothing really on the machine that

09:40

allows you to find that out you could

09:42

play around for ages with the spot size

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and see if you can get the thinnest

09:49

possible line we’re going to use this

09:52

session again to make another very

09:54

useful tool that will help us determine

09:56

exactly where the focal length is for

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

10:00

the lens now what we’ve got here on the

10:02

left some paper targets and in the first

10:05

instance we don’t need those as I said I

10:08

always put my designs together in one

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dxf file so that we can import them all

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at once so first of all we delete the

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half that they don’t need and then we’ll

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also delete the material which is five

10:22

millimeter acrylic and and i showed you

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how to cut vector text last time equally

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well what we could do we could put this

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on a separate layer and first of all

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we’ll group it very important this key

10:37

grouping things because now all I’ve got

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to do is touch on one part of that and

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it brings the whole lot up and i’m going

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to put that onto a blue layer and the

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blue layer I’m going to turn this blue

10:53

layer this time instead of a cut layer

10:55

we’re going to turn it into a scan liar

10:58

so this is our first introduction to

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engraving you’ll notice that I’ve got

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the text backwards that’s because i’m

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going to engrave and cut from one side

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of the job but that side of the job is

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actually the back side of the job so I’m

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going to engrave on the back of this

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acrylic so that when you look through it

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from the front you will see a nice piece

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of white text and first vote for

11:27

engraving you will always need to be

11:29

running at high speed now 200 300 400 it

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makes some difference but not a great

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deal of difference the main difference

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it will make is to the depth of the cut

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that you will achieve so I will leave

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this 202 our well I would think we

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probably need to push the pair up to

11:51

maybe river i’m guessing let’s just say

11:55

twenty percent i’m going to put these

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numbers the same

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

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and down here we get other options which

12:04

appear until we talk about it otherwise

12:08

leave / striking his son process and

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leave scan mode as X swing and that’s

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all we need to do so we’re going to cut

12:19

five millimeter acrylic let’s set the

12:23

parameters for cutting speed difficult

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to say on this machine as i said i’m

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guessing because i haven’t got much

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experience with it

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let’s play safe and go down to as little

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as about eight millimeters a second and

12:40

sixty-seven percent power which I’ve

12:42

already used elsewhere which is the

12:44

maximum i can use for this machine so

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all we’ve got to do now is to decide how

12:49

we want to order the cuts now here’s

12:52

where i’m going to show you a few more

12:54

tricks over and above what I’ve already

12:56

shown you what we’ve got to do is

12:57

probably engrave it first then cut the

13:00

holes and then cut the outside shapes

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that’s the order that we’ve got to think

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of but what I’m going to do I’m going to

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grab hold of all of the holes there to

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start with and they were turned into a

13:10

raid group but hang on I’ve also caught

13:14

focus ramp as well that’s turned rate

13:16

and I don’t want focus ramp in that

13:19

group

13:20

so what we do where is up to now I’ve

13:24

shown you how to add things to a group

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by holding the shift key down press the

13:29

shift key down and touch on focus

13:33

and now with subtracted focus from the

13:37

group you can now let go of the shift

13:40

key and we got there more group and what

13:43

we grouped is just the holes so you can

13:47

use your shift key for additive or

13:49

subtractive grouping ok now in the same

13:52

way we can just grab the whole outside

13:55

shapes like that

13:57

hold down the shift key touch on touch

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

14:00

on a ramp touch on a whole group so we

14:05

don’t have to collect the pieces

14:06

individually additively we can also

14:09

collect the pieces by subtracting

14:11

something from the whole now that’s

14:14

quite an important time saving tricks

14:16

sometimes when you get very complex jobs

14:18

or when you select something wrongly and

14:22

you want to subtract just one or two

14:24

items from that grouping I’m going to

14:27

say this is focus one short name but

14:33

I’ve got another focus file to come out

14:34

as well so we save that has focused one

14:36

onto the onto the memory stick

14:40

have a good day then kill and this is

14:45

another trick now we really need the

14:47

other part of the file to do now but we

14:52

could markey this clear the page delete

14:57

it and import it again that’s tedious

15:00

look let’s just do controls it

15:04

123456 we can go back quite a long way

15:13

with controls it and get back to the

15:15

beginning of our import file and now we

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can do the opposite

15:21

we can delete the bit that we don’t need

15:23

which is that bit delete the frame and

15:26

we delete the card specification now

15:28

what we’ve got here is scorched text on

15:34

a piece of card and it outside shape now

15:39

the outside shape again let me just show

15:41

you has got a gap in it at the top and

15:44

at the bottom so these pieces remain

15:47

attached to the card it looks very

15:50

complex to program this it’s not because

15:55

first of all we’re going to do this

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

16:01

and I’ve captured all the text will put

16:05

that into a group and put it onto a blue

16:08

layer now the blue layer is going to be

16:14

a cut layer so we need to make sure that

16:17

it’s cut but we’re not really going to

16:20

cut it what we’re going to do is scorch

16:21

it with cut lines so we’re going to cut

16:25

poorly basically and we’re going to do

16:28

that by talking taking the power down to

16:30

something like about maybe ten percent

16:33

very very low power as well as we can

16:37

get it and the speed well we need the

16:41

speed quite high

16:43

we tried to the hundred because we don’t

16:46

want to burn through we just want to

16:47

scorch the surface and now the outside

16:50

shape

16:51

well we’ve got to cut the outside shape

16:52

that’s only one of them how do we

16:57

collect the outside shapes well go back

16:59

to a trick collect everything

17:03

hold down the shift key and then click

17:06

on the blue layer and it’s gone so now

17:09

we’ve just got the outside shapes in a

17:11

couple of clicks and we can make those

17:13

into a group we click on the black group

17:17

up here

17:18

double-click and we can set the cutting

17:21

parameters now for cutting these shapes

17:24

out speed i’m going to set that to

17:27

something like about 50 millimeters the

17:29

second normally I’d run that about a

17:31

hundred but i’m going to say 50

17:34

millimeters a second and

17:39

we probably only need twenty percent

17:42

power so we’ve got to do the scorching

17:45

before we do the cutting

17:47

but remember we’ve only got two groups

17:50

that we’ve defined on here so we don’t

17:53

need to do very much up and come up here

17:56

to our edit cut property and look

17:59

there’s our two groups get simple we

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

18:03

want that cut first and then we’ll

18:08

do that element there

18:12

so we know save that to you file as well

18:18

ok now you will remember when we were

18:22

here last time that i was commenting on

18:25

the fact that i thought these cuts were

18:28

very wide another was the beam was

18:31

cutting far too wide

18:32

well that’s probably because it is out

18:35

of focus and as I just shown you on the

18:39

picture of the beam if you move away

18:42

from the true central position then the

18:44

beam starts to get bigger and the energy

18:47

density starts dropping off so that

18:48

means your cut is not as good or as

18:50

efficient so what we’re going to do now

18:53

is to make a piece of tooling to check

18:56

that one of the great advantages all

19:00

having an autofocus system although not

19:04

necessarily the pen is that when we get

19:07

it working properly and at the moment

19:08

it’s not working properly because I

19:10

don’t understand how to use it but I

19:12

will find out

19:14

we ideally need to do a graving on the

19:17

surface but when we come to do the cut

19:20

this is five millimeter material the

19:23

ideal place for the focus point we’re

19:25

cutting this material is going to be two

19:28

and a half millimeters into the surface

19:29

to get the most effective cut we’re not

19:33

going to do that today we’re just gonna

19:35

stay with it with the focus on the

19:37

surface more or less i think the focus

19:39

is actually about one millimeter down

19:41

into the material but it’s a compromise

19:43

that I’m using today

19:46

just check that it fits on the material

19:48

which it does and supply on

19:52

extraction on this engraving and it

19:55

takes a long time to do engraving

19:58

because this scanning action that takes

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

20:00

place backwards and forwards

20:03

and that’s why quite often it’s actually

20:05

quicker if you can do outline text

20:09

and if you want something rather special

20:12

now your engraving word and you

20:14

specifically want shape if you just want

20:17

to mark something up for identification

20:19

then outline text to put this way to do

20:22

it

20:26

this doesn’t help

20:30

and now we’re moving from engraving to

20:31

cutting sinceros that white flashes that

20:35

tells me that we’ve got enough power and

20:37

the the cat was going right through the

20:39

material and the extra energy is

20:41

reflecting hot zone section

20:45

now forgot the fits on this job right

20:47

then we might not have to do it it

20:50

should possibly just pressed together

20:51

and we good enough to do the job without

20:54

gluing

20:56

now credit is a very notoriously bad

20:58

material precise you by five millimeter

21:02

acrylic and it might be 4.8 it might be

21:05

5.2 if its cast acrylic it could

21:09

probably plus or minus half a millimeter

21:12

so you can get huge variations in the

21:14

fitness material even on a little piece

21:16

of material like this you get probably

21:18

half a millimeter variation very very

21:21

difficult to get good quality fits when

21:23

you’re trying to turn and grow

21:29

let’s see what we got

21:37

all the parts popped out

21:42

ok now we’ve got a piece of card in and

21:45

remember we’re setting the focus

21:48

manually now so I’ve got to set the

21:50

focus back onto the surface with my

21:52

little gauge

21:54

so we need to reset the bring the table

21:57

up a little bit

Transcript For Cleaning CO2 Laser Lens & Care of Your Lenses (Cont…)

22:02

yup i think it will probably say how

22:04

much security is to just set the focus

22:06

manually than it is to use the pen

22:09

pointer but

22:11

that’s just what I’m used to

22:30

you notice that wherever possible i’m

22:32

using radius corners

22:36

we’ll just strip the protective film of

22:39

our pieces

22:40

now this is the interesting one because

22:45

you can see the way in which the content

22:49

site is settled on the outside of the

22:52

film there it’s even settled on the

22:54

inside of the components when we take

22:58

that off

22:59

we left with the middle of the letters

23:01

in which we’ve got to take off as well

23:02

it leaves a lovely clean surface across

23:06

the back of the machine there we’ve got

23:08

some LED strip lighting it really comes

23:13

alive but that’s another project we’ve

23:16

got two tongues which point downwards

23:19

well these tongues here match with it so

23:22

we’re going to put that one on the tall

23:24

end and this short one on the short end

23:28

and they’re going to find the other side

23:31

of the ramp which is here we’re going to

23:33

drop it on like that and we drop it onto

23:35

the base now doesn’t matter which way

23:37

round on the basic goes because it’s

23:38

symmetrical and there we go is plugged

23:41

into the base and the whole thing is

23:43

actually clipped together very nicely

23:45

now this piece here sits in the middle

23:50

and pointed towards the beginning and

23:54

you can put it on that way but that

23:57

would be wrong

23:58

so what we’re going to do is put the

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

24:00

slots on here towards these knobs that

24:04

are on this end

24:05

so this is the top of the ramp and the

24:08

idea that is that this point here this

24:11

age just hear that is the center of the

24:14

ramp if we take when our paper templates

24:16

that we’ve made we will find that we can

24:19

pop this on here like this and slip it

24:26

into position now at that position there

24:30

you’ll see that it says zero in line

24:32

with the end of this bar that is the

24:35

zero position right in the center

24:37

representing perfect focus and perfect

24:41

focus occurs on this flat plane here so

24:45

we’ve got a large area here that we can

24:48

use to set the focus up now that’s a 4.7

24:51

millimeter space of their i’m going to

24:55

use that just as a nominal spaces to

24:57

start with make sure it’s flat in there

25:07

we’re going to raise the table until we

25:09

get the table to touch on that surface

25:12

they’re just one touches it’s just

25:16

grippy down their looks so they’re that

25:19

these four point seven millimeters above

25:22

that surface there we can take this out

25:25

now because we don’t need this anymore

25:26

temporary and our focus gauge will sit

25:31

on here now if you look carefully you’ll

25:33

see that there are slots underneath

25:35

these tons which actually caused this to

25:38

click down and stay nice and flat and

25:42

you know that that’s the case because

25:43

this will just drop down inside these

25:46

lugs at the end here so we need to drop

25:49

it over the lugs and clip it in and

25:53

these holes here these marks on the end

25:55

tell you which end is which because it

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

26:00

won’t fit

26:06

the other way it completely mr. lines if

26:09

you line up the other way so it only

26:10

goes on one way but there are actually

26:13

two ways that you can put it on you can

26:15

put it on like that and make sure that

26:18

the center’s to flip down or and this is

26:21

a much better way to do it we can put it

26:24

on this way and that is the way that I’d

26:29

recommend that you use it

26:31

numbers down here so it’s rather strange

26:34

one else that because i can’t see what’s

26:36

going on

26:37

wait and be amazed right so we’ve got

26:40

our focus set up with as eight now we

26:44

need to come down here and we’ll check

26:46

power so we set max power it’s set to

26:50

twenty percent i like that twenty

26:52

percent is good

26:53

it doesn’t matter what power you have it

26:55

set to provided it’s quite low

26:58

once you set the power what we’re going

27:01

to do is play with the speed so we’re

27:04

happy with the power at twenty percent

27:06

inter let’s set the speed now we’ve got

27:10

the speed currently set to 200

27:12

millimeters a second

27:15

maybe right maybe wrong let’s set it 250

27:19

and we’ll see what we get

27:21

i’m showing you what I’m doing what I’m

27:22

going to do here i’m going to hold the

27:24

post button on them and drive it

27:26

backwards and forwards I’m going to turn

27:27

the pulse on and i’m going to drive it

27:29

towards me 250 millimeters a second

27:33

so this is looking actually quite good

27:36

because as we look here look you can see

27:39

the line is thick there it gets very

27:43

thin just here and then it’s not getting

27:47

thicker again

27:48

now that’s the thickness of the beam

27:51

changing with death

27:55

now what we’re looking for is the

27:57

thinnest possible point that we can find

27:59

no it’s difficult to find it here let’s

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

28:02

just turn the paper over and see what

28:03

we’ve got

28:04

lift the end there take it off

28:10

and hey that we’ve got a line on the

28:12

other side

28:15

you know that line is actually quite

28:18

long at the moment it runs from about

28:20

three at that end to about two and a

28:25

quarter maybe to the end

28:30

now what we’re trying to do now is we’re

28:32

trying to get that line as small as

28:35

short as we can so that we can find out

28:38

roughly where the most damaging point is

28:41

at the moment it’s damaging this paper

28:43

and i’m using the word damage you’ll

28:45

notice and damaging this paper over

28:48

quite a long li

28:51

but there’s only one point a very short

28:54

area where maximum damage will occur so

28:57

let’s go and see if we can find that

28:59

maximum damage section

29:05

we’ll put that back on again

29:09

and we’re lining this up

29:12

and this time I’m going to change of

29:14

speed up to 200 millimeters the second

29:21

ok now results are becoming clear look

29:24

we’re just about damaging it with just

29:27

coming through you see this line here

29:28

was really crispy clean this one is just

29:31

about making it through and if we look

29:35

for the point where it starts at around

29:37

about plus a half a millimeter and it

29:40

finishes at em just about one and a half

29:44

millimetres so that means a focus point

29:48

is actually

29:53

sitting there at about half a millimetre

29:55

is half a millimetre high or half a

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

29:58

millimeter low well bear in mind that’s

30:02

the top of the ramp with the two dots on

30:04

it it means our focus point is actually

30:07

half a millimeter below center so it

30:11

means what I’ve got to do I’ve got to

30:13

lift the nozzle up by half a millimeter

30:16

to get it spot-on

30:20

ok now we’ve got this little platform

30:22

here which we trying to establish the

30:25

gap between the platform and the end of

30:27

the nozzle and what I’ve got here is a

30:30

little tool that I’ve made previously

30:32

which is basically a 1 millimeter step

30:35

page

30:38

and so i can see that it’s 1234 goes

30:43

under there easily when I got here it

30:48

appears a half millimeter thick steel

30:50

very thin piece of stainless steel ship

30:52

and i would say i can probably just

30:54

about get that four millimeters step 1 2

30:58

3 4 millimeters step under so my guess

31:01

is that the gap is back 4.4 4.5 let’s

31:05

give it one last test and see how we get

31:07

on how we fix the focus problem

31:19

at the moment the line looks as though

31:21

it started about two

31:25

and goes through to about two

31:30

so I would say that we’re just about

31:31

spot-on with the focus into just put

31:34

this very soft piece of plastic up

31:37

inside until we touch the lens now be

31:39

very careful we don’t damage the lens so

31:41

I’m just going to very gently go up

31:43

until it just touches the lens and then

31:47

i’m going to market with my fingernail

31:52

about clamping it just there and that is

31:54

the amount that it’s up inside 33.5 plus

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

32:00

i think we said 5.5 is the clearance

32:05

under here 5.5 48s forty nine

32:12

millimeters which is a strange dimension

32:15

because they don’t make lenses that

32:17

sighs it’s got to be 51 let’s take a

32:21

look at the lens that’s actually inside

32:23

here things that don’t make sense

32:25

worrying me I like to understand how

32:28

things work

32:28

I think we’ll have that lens over there

32:30

and have a look at it you need to be

32:31

very careful handling these lenses and i

32:33

would suggest you either use the latex

32:36

gloves that they provide well I tend to

32:39

use cotton gloves to handle lends itself

32:42

so we should be able to just undo this

32:46

with the special tool that’s provided i

32:51

just got a natural curiosity I like to

32:53

understand exactly how things are and

32:55

what they’re I don’t trust anything I

33:00

think you probably see that in the like

33:01

Kanye this some sort of crap on their

33:04

sorry debris know you are supplied with

33:09

the lens cleaning kit and all the

33:11

instructions but costs like most lakes

33:15

and I’m not reading the instructions

33:21

there are two stages of cleaning lenses

33:23

one is gentle and i just put some

33:31

isopropyl isopropyl alcohol into there

33:35

and I use a cotton bud just like the

33:40

cotton but in that very gently and

33:46

didn’t take much to come off right

33:52

blonde the lens and it’s you can say

33:54

that it’s come off nice and clear on the

33:58

other side of the lens i can see there

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

34:01

is a haze can you see the haze on there

34:04

as well so if we get that off right okay

34:14

well the haze is gone now and then

34:17

within the pack that thing later provide

34:21

there are these things called lens

34:22

cleaning tissues now advise you to

34:25

handle this lens quite carefully because

34:27

the material that it’s made from is a

34:29

material called zinc selenide and it’s

34:32

very toxic you’re not you’re not

34:34

protecting your hands necessarily to

34:37

stop the damaging the lens i think

34:39

you’re protecting hands more to stop you

34:41

absorbing any of the tox it is toxicity

34:43

of that through your skin and the

34:46

chances are that there is not much there

34:49

to be exposed to zinc selenide is a

34:51

material is not very good at

34:54

transmitting the infrared light it

34:58

actually is only about seventy percent

34:59

efficient and the reason it’s only about

35:02

seventy percent efficient is because the

35:04

crystal structure of the material

35:06

reflects thirty percent of the light so

35:09

these lenses are covered in a special

35:12

anti-reflection coating which you

35:14

basically mustn’t damage because if you

35:16

take the anti-reflective coating off you

35:19

reduce the lens to a 70-percent quality

35:21

lens which is useless this particular

35:24

lens got a convex side on the top is

35:26

raised on the top and then it’s very

35:28

slightly dished underneath that gives

35:32

you slightly better

35:34

concentration of the focus point there’s

35:37

less what they call aberration which

35:40

means you get a cleaner focus pointed

35:41

slightly better than the simple plano

35:44

convex lens but it doesn’t matter when

35:48

you put it back in

35:49

you must make sure that the flatter side

35:53

or the con cave side is actually facing

35:56

the work so bear in mind that’s the way

35:59

that the lens tube sits you’ve got to

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

36:02

finish up with the curved side upwards

36:05

so we’re very carefully pop that on to

36:09

back onto its own ring seating like that

36:12

and then I suggest that you don’t try

36:18

and drop this in that way but what you

36:21

do is actually put it in this way put

36:25

the lens in and keep it upside down and

36:28

scroll the tube onto the lens that way

36:39

the lens will stay flat on its eating so

36:43

when it comes to it you’ll feel the

36:44

o-ring just beginning to buy don’t

36:46

over-tighten just just put the smallest

36:49

amount of tension on it to just feel the

36:51

o-ring is compressing now when you look

36:54

through it you should be able to see

36:56

through the lens like that

36:58

previously I couldn’t it with all cloudy

37:00

and that’s the sort of thing that i

37:01

would recommend you do probably take a

37:03

look at that lens once a week and if you

37:07

can’t see through it taken out and clean

37:09

it and keep stressing to you

37:11

the lens is actually the most important

37:13

link to make this machine work without

37:16

the lens you’ve just gotten laser which

37:19

does very little

37:20

it’s the concentration of energy from

37:23

that lens which is the thing that allows

37:25

you to do all the work that we do on

37:27

this machine I mean to replace that is

37:29

probably about 30 or 40 pounds maybe

37:31

even more than that

37:32

so you know you don’t want to get

37:35

through too many of those they have got

37:36

a lifetime and you will eventually have

37:39

to replace it but i suspect to it if you

37:41

treat it well it’ll last you one or two

37:43

years the other aspect of treating that

37:46

lens where

37:47

well is to make sure they always have

37:49

the air assist on don’t let debris and

37:52

smoke come up and filmed this top

37:54

surface this surface of the lens you’ll

37:56

see that we’ve got a hole in there a

37:59

mirror and then a tube that goes right

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

38:02

the way down

38:02

well this is sitting on the end of that

38:04

tube so equally well you can get debris

38:08

dust stuff in this end which will sit on

38:12

top your lens so there are two ways that

38:14

your legs can get dirty and hopefully

38:16

you should find that these two shoulders

38:19

sit against each other they should not

38:21

be a gap haven’t got an air supply on so

38:26

i put the air on

38:27

that’s important

38:32

and we go

38:36

we should be able to see the light on

38:37

here now and it starts at 1.5 it goes

38:41

through there and finishes up at just

38:46

about 1.5 so i think we’re probably

38:49

pretty well spot on with our focus now

38:53

well okay now fitted to

38:57

two-and-a-half-inch lens which they

38:59

supplied on internal measurement which

39:01

says 56 millimeters

39:03

I’ve got fifty six millimeters

39:05

internally and 63.5 is the actual

39:10

direction so that’s about seven and a

39:12

half millimeters and that’s 7.8 so

39:16

that’s a reasonable match for the

39:18

theoretical focal distance so i’m going

39:21

to put it under there and that worked

39:25

absolutely perfectly you can hear i just

39:27

cut off the air supply think back to the

39:31

logic of what i said earlier we’ve got a

39:34

longer lens it’s not God’s it’s got the

39:38

same amount of power going through the

39:40

lens but it’ll have probably half as

39:43

much penetration so i was using this at

39:46

225 millimeters a second to test the

39:51

2-inch lens i suspect i’m going to have

39:53

to drop this down to maybe a hundred and

39:55

fifty eventually but we do we’ll run it

39:58

to 25 to start with just approved the

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

40:00

point of loss of power

40:04

there we go so yes I expected it hasn’t

40:08

made it through so we’re gonna have to

40:10

drop the speed and I’m gonna drop the

40:11

speed to about a hundred and fifty so we

40:15

could run a bit faster because that’s

40:17

running far too long

40:19

I mean that’s running from

40:21

three-and-a-half nearly 4 to about two

40:26

and a half so that means our center

40:30

point is approximately 1 millimeter too

40:34

high

40:35

half a millimeter one millimeter too

40:38

high

40:41

so the way to imagine that is I got to

40:43

raise that focus point up to match that

40:47

one so I’ve got to raise the table up

40:51

those got to decrease the gap to get it

40:54

to come back down the slope so I’ve got

40:57

to come up about a millimeter so instead

41:00

of that gap which is a millimeter gap i

41:04

need to go down to something like a

41:05

seven millimeter gap there we go that’s

41:08

perfect

41:08

so that’s a seven millimeter gap now

41:11

Barry mind this has got a much longer

41:16

but depth of field so it’s always going

41:19

to have a much longer line i’m not going

41:22

to get as much as much contrast around

41:25

the middle but having said that we take

41:28

a look there it runs from about 2 to 1

41:38

so to get that to work

41:42

I’ve got to drop this down half a mil to

41:45

get them onto its ideal position so i

41:47

need to add half a mil to the gap so to

41:52

get a seven and a half mil gap i’ll put

41:55

my half-mile spacer in there and then we

41:58

go back to our seven mil step which is

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

42:00

that one and I’ve just set that now to

42:03

just a snug fit under there

42:06

go down just a shade

42:09

and an 80 millimeters the second

42:12

seven-and-a-half cap

42:16

it means to get to get that point to

42:22

here I’ve got to raise the table up

42:26

which is decreased the gap so instead of

42:29

seven and a half mil it probably is

42:31

going to be seven and a quarter

42:32

millimeters

42:35

I don’t you’re going to worry too much

42:36

about that that’s more or less where we

42:38

expect it so I’m gonna stay with seven

42:41

and a half then thought that’s not 56

42:43

inches that 56 inside 56 millimeters

42:47

inside plus 7.5 millimeters outside

42:51

gives me a total of sixty 3.5 which is

42:54

exactly 2.5 inches so that one is

42:58

absolutely spot-on

43:00

now I’ve got something else that I want

43:02

to try now they told me that I couldn’t

43:06

get a one-half inch lady I’ve modified

43:09

the inside of this nozzle it didn’t have

43:12

a very big shoulder in it inside so what

43:15

I’ve done up machined it out and i’ll

43:17

put a little teeny-weeny press the TV

43:19

when you ring in there and that ring is

43:21

enough to support a an 18 millimeter

43:25

diameter lens this was the 4-inch focal

43:28

length lens hold up which had a lens in

43:31

this back-end here my lens has got to go

43:34

flat side down inside there like that

43:40

and then on top of the lens I’ve got a

43:43

little compression ring spacer and that

43:49

spacer sits against the o-ring to give

43:52

me just the compression that I need when

43:55

I close the whole system down so

43:58

hopefully i should be able to win their

43:59

on and as I wander on at this point here

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

44:02

I should just begin to feel the o-ring

44:06

biting the lens is not rattling so

44:11

hopefully I’ve got a one-and-a-half inch

44:13

lens system now whether or not it’s

44:16

going to work and what the dimensions

44:17

are but I think about got it about right

44:20

it should come out approximately six or

44:25

seven millimeter gap this lens is going

44:27

to be very scalpel like it should give

44:30

me quite a long cut or a deep cut and

44:35

I’m i will have to increase the speed

44:36

quite a lot

44:37

let’s increase the speed to 225 maybe

44:43

you got to 258

44:47

ok

44:51

my calculations in dimensions came out

44:53

reasonably well because at the moment is

44:56

it running to about one millimeter and

45:04

about half a millimeter so I’m going to

45:08

come up about a quarter of a millimeter

45:10

to get it right so that’s still about

45:14

seven millimeters

45:17

I think seven millimeters is close

45:19

enough

45:21

ok so I’m going to do the ultimate test

45:23

of my one-half inch lens now that i’ve

45:25

just created this is something I’ve done

45:27

quite a few times this year on my

45:30

existing machine now what I’ve got here

45:33

is my pin table and a block of metal

45:36

with a couple magnets on it that will

45:39

actually clamp this is sufficiently

45:43

stable and it’s not going to move and

45:45

I’ve got this set the same height as the

45:47

pins so drop the paper onto the pins

45:55

and just drop the magnets on there to

45:58

stop the paper moving

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

46:42

now this is coming out the opposite way

46:43

around 21 normally used to with my

46:46

machine because this is not been written

46:48

for this machine been written for the

46:50

opposite hand

47:04

ok so what we do know is what that lens

47:07

over 2a to insurance and we’ll see what

47:10

happens with the two

47:25

there’s no effective than i thought but

47:27

the detail some of the detail is a

47:30

little bit fuzzy

47:32

some of the very detailed parts together

47:34

overlap and fold

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

48:12

two-and-a-half

48:16

37.5

48:22

now the interesting thing here is on

48:24

right up and about seventeen percent and

48:27

you can hear that hissing noise that the

48:29

cat is making that’s still too high

48:31

frequency impact engraving zone

48:42

well it has made it all the way around

48:45

we need to go and have a close look at

48:46

that to see the differences between the

48:48

lenses but i think that categorically

48:51

proves that we got the three lenses now

48:53

correctly set on focus because you

48:56

wouldn’t be able to do that and that’s

48:58

the focus was correctly set so we’ll

49:01

just take a look at the results under a

49:03

microscope have experienced while

49:05

looking at the quality but we need to do

49:08

some comparison so that you can make

49:10

your own judgment as to which lends you

49:12

would use for doing a job like this at

49:15

the moment you don’t have the choice of

49:16

a one hopping trains because they don’t

49:18

make it I’ve had to make my own but i’m

49:21

sure that in the near future i think

49:23

this will provide free providing with a

49:25

one hopping trains if you need it

49:28

so now we can reflect on the performance

49:31

of these three lenses now for comparison

49:34

what I’ve done I’ve shown you what I

49:37

would normally expect from my ebay

49:39

machine

49:40

the first thing I thought you to look at

49:42

is up at the top right hand corner

49:43

you’ll see that i put an arrow pointing

49:46

towards the line thickness that each of

49:49

the lenses produces is it as a

49:52

comparison

49:53

we’ve got a pencil for one-and-a-half

49:55

inch lens we’ve got a felt tip pen for a

49:58

2-inch focal length lens and we’ve got a

Transcript For Cleaning a Laser Lens & Care of Your Lenses (Cont…)

50:01

markup end for a two-and-a-half-inch

50:03

focal length lens so the lines get

50:06

thicker as the lens gets longer which is

50:09

what we said because the spot size at

50:11

the waist of the lens is bigger for each

50:14

of these when we start doing thicker

50:17

materials woods acrylics then different

50:20

depths of failed and different power

50:23

densities have a big effect and we

50:25

should be tackling those in a completely

50:26

different session

50:28

for graphics work when you’re working on

50:31

a surface or within material such as

50:33

paper you will need the shortest

50:36

possible focus focal length that you can

50:38

get because that gives you the Christmas

50:40

in the best definition

50:42

well thank you very much for your time

50:45

today we’ve covered a great deal on

50:48

lenses and hopefully this will give you

50:50

a better understanding of one of the

50:52

most important features of your machine

50:54

that lens is critical to the performance

50:57

of the Machine and the work that you

51:00

create with it so choose the right lens

51:02

and McCarthy lenses carefully thanks for

51:06

now and I should be seeing you next time

Transcript For Cleaning a Laser Lens & Care of Your Lenses