05 – We Have Lift Off

The Tangerine Tiger Series with Russ Sadler

In this Series, Russ has purchased a new 500 x 300mm, 50W laser machine from eBay with a view to modifying and upgrading it. In fact, he rips out the glass laser tube and high voltage power supply and replaces them with an RF laser source and PSU from Cloudray. Find out how this laser tube upgrade from a Glass Tube to an expensive RF laser source works out. Prepare to get your hands dirty!

If you are considering purchasing a CO2 laser machine with an RF laser source from one of the big boy suppliers, I would suggest you check out this series before making a decision!

Laser Tube Upgrade
Laser Tube Upgrade – On A Chinese Laser Machine

Contents

This is a milestone video where we finally have a fully functioning machine available for testing. As usual there are many hurdles and mistakes to overcome.

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We Have Lift Off (Laser Tube Upgrade) Transcript

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0:00um welcome to another session with my little tangerine tiger um today i think we’re going to have to

0:05have a little bit of a tidy up day hopefully by the end of this session

0:11we’ll actually be able to fire up the actual laser tube itself i just need to make sure everything’s tidy before i

0:17do the final bits because i don’t want to be tempted into using the machine and having it half

0:23finished that’s why i’ve been a little bit meticulous about tidying things up as i

0:28go so one of the first things we’re going to have to do is go in and modify the vendor settings because if you remember

0:34the last time when we swapped the belt over to the flexible rack and pinion system then everything

0:42was reversed in the x direction a similar situation will occur whenever you get a failure of one of

0:48these micro switches when you turn the machine on it’ll go bonkers and do silly things

0:54so one of the first things i’m going to do is to put the head to the middle of the machine or even to

1:00the front of the machine in the case of the y-axis more or less because it’s going to move slowly in these

1:06directions this one’s going to go in the wrong direction and away from that but this one’s going to be correct and

1:12move towards that if it’s out of control the simple solution is

1:18once it starts to move just press the escape button and it will stop finger on the escape

1:24button and there we go so the machine is now stopped safely

1:32it says all sorts of strange numbers on the keyboard but that’s not important we’ve still got power to the machine and it’s under my control

1:38so we’re already hooked into rdworks and we’ll go to vendor settings rd888

1:48so the first thing we’ll do is press read and that will also test that we’re connecting up to the machine properly

1:53and there we go we are it tells me we’ve got 500 in x

2:00and y 300 which is correct okay so the x axis

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

2:07at the moment direction polarity is negative

2:13so we need to make that positive and that will change its direction

2:18we’ve got to change this keying because our direction keying is the wrong way round

2:24so invert direction we’ll remove that tick and we’ll write

2:31the information back to the machine now press the reset button and see what happens

2:40so wires homed x is honed [Music]

2:47we’re back in control just check the keys left wrong way around

2:54right so we need to go back into the vendor settings and just put that tick back okay so

3:01we’ve reverted the key and let’s check check and now everything’s going the right way

3:07left right backwards forwards but we could just see

3:13where our limits are now so if i press the down arrow key we’ll find out how close y is to the

3:20front of the machine and look we can have at least another 10 millimeters here

3:25and we’re clear of everything let’s go over to the extremity over here and see what happens

3:32and on this side look i can get my fingers in there so i’m not going to hit anything there

3:37so i could add another 10 millimeters to the width and another 10 millimeters so i can make this table now 310 by

3:45t so back into the vendor settings and x we can make the breadth across here

3:54five ten five one zero and then we can make y three one zero

4:05and write that back to the machine so we should be able to drive this another ten millimeters in this direction now

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

4:14and there we go we’ve still got five millimeters clear there we’re not hitting anything and then we should be able to go that

4:20way another 10 millimeters as well and

4:27sure enough we’re completely clear here as well as you can see i’ve managed to find some

4:33five volt leds self-adhesive it’s amazing what you can find when you

4:39dig around in cupboards and there just happens to be enough to run

4:44backwards and forwards so i can have two strips underneath there so we can now see how beneficial this

4:50side entry is so yeah i’ve had to make a small modification here as you can see i’ve had to put a cut out in

4:56this motor plate to allow the cables to track down underneath into the cable tray otherwise

5:02they would have stood out the side here and they kept on getting caught on various things so yeah everything’s worked out quite

5:07neatly in the end what i’m going to do here is i’m not going to rely on the thread

5:13in this plastic here to lock this nut in what i’m going to do is i’m going to use some m5 half nuts now

5:19these are very thin nuts so we’ve put our lock nuts on there

5:24and then this five millimeter thick material i’ve counter-bored it about hmm

5:31three-quarters of the way through so that it fits over the nuts and then we’ve got

5:39some wing nuts on here so that it’s easy to take them off now notice as i was pulling under there that the

5:45solenoid valve for the air assist was warm and of course then i checked here and

5:51found that it was manual on so i’ve turned it back to auto and that

5:57means now the solenoid is off which it will be most of the time it’ll only be overridden

6:03when you need it i also remembered we’ve got a little bit little bit of tidying up to do in here but we’ve got this this big gap in here

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

6:10where i tried to fit this back plate and i didn’t need it so

6:16we’re gonna have to cover it over because we need something to do this y-axis switch properly it wasn’t done

6:23properly before as soon as you undid the connection this fellow into the back

6:28well it won’t any longer because i’ve made a proper connection here and then i remember to put the nut in

6:34the washer on the back here nothing’s going to hit the clash no

6:42there’s nothing wrong with the camera look you can see the control panel over here on the right

6:48but i just want to show you this you can see the table without getting

6:53blinded

6:59okay apart from playing with the lights what else have i been doing you don’t need to see me doing this i’ve

7:04just made a lovely name plate to go on the side here i’ve repacked and tidied up all the cables in there

7:11okay well we’ve wired the tube up now would you believe and everything is tidy and

7:19ready to go but before we do that we’ve got to set the vendor settings now we’ve got to go

7:25into laser the first thing we’re going to select is one tube oops the first thing we’re

7:31going to do is select is read forgot about that glass tube

7:38no it’s going to be an rf laser with pre-ignition so the pre-ignition

7:45voltage is set within the laser system itself so it’s one tube and the attenuation is

7:52going to be zero so we’ve got minimum power set at one percent which is fine

7:58maximum power 99 the laser frequency now that’s the actual base

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

8:05frequency of the pulse width modulation that’s exactly the same as was set for the glass tube

8:11where the only thing that was changing was the duty cycle it was a constant 5 volt dc

8:18that was when switching on and off proportionately with the pwm signal to give us an output

8:24voltage of anything from zero to five volts if you don’t know quite what the duty cycle means

8:30then go and take a look at duty cycle on wikipedia pre-ignition frequency uh preset to 5000

8:37and i think that’s the value that i was recommended to use and the

8:43pre-ignition pulse half a percent i think again that was what was set

8:50water protect we don’t need water to protect because we haven’t got any water protect so we should be able to write that back

8:57we should be ready to give this thing a little pulse so i think we’ll start off by setting the pulse

9:04max power to 10

9:12enter and then we’ll just go and check

9:19somewhere else which is the laser set

9:25and we’ll see how that is configured at the moment it’s set to continuous

9:33which means as long as i put my finger on the button it will pulse

9:40i’m happy with that because it then means it’s under my control before we do that let’s put a target on

9:45the mirror should we and see how well we’ve got the tube set up in relation to

9:51mirror center now this is supposed to be a very small two millimeter diameter beam and if that is the case then we have on

9:58a 25 millimeter mirror we’ve got a lot of scope for being off center and it really won’t matter

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

10:04well here we are we’ve reached that big moment there’s a certain amount of anticipation

10:10on my part um because i’ve got no idea what to expect i don’t know whether these fans are

10:16going to suck or blow i’m expecting to see a couple of lights here but

10:22let’s turn it on and see what happens later on

10:31green light

10:39so they’re sucking that’s good news because it means all we

10:46need is ventilation holes in here to allow the air to come out

10:56we’ll have a quick press of the pulse button

11:02maybe i’m missing by a mile let’s see where we are shall we

11:14well that’s a long way off center why why why am i so far out i wonder well the good

11:21news is we know it all works the bad news is i’m not the perfect

11:27engineering expert you think i am good news is that we’ve only got two fixing screws on here

11:36to clamp it in place

11:42i should be able to just swing this out like this because there’s a screw at the other end

11:47there which is holding this in

11:52and now i can get access this mirror the good news is

11:58i can run it like this because all i’m trying to do is to align mirror one to the laser tube i

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

12:04should be able to find [Music] almost a perfect center position now

12:10because the mirror is just standing there doing nothing

12:20that’s not bad that’s perfect central alignment

12:30[Music] so what we need to do there’s nothing

12:35more than put something like a five millimeter hole in there i suspect

12:41and that will allow me to lock that mirror in that one position which is all i need but hey i’m a long

12:47way out so i’ve got to move the center of that pattern across there 12 millimeters

12:53to line up with the settings that i’ve got i’ve designed this piece of channel here

12:59to suit a glass tube and this lines up with the center of that channel

13:07okay so here’s the channel

13:20and i’ve made the center of my fixings here the slot

13:28so that i can adjust it backwards and forwards on the center of the tube center line what i’ve done

13:35i’ve very conveniently mounted the four fixing pillars for this laser machine symmetrically

13:44on that same center line but the laser beam is not on that center

13:52line the laser beam is on a different center relative to the

13:59mounting points in trying to be a bit of a cheapskate and use this piece of equipment for

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

14:05two purposes i’ve created a bit of a problem for myself so yeah it’s easily overcome

14:14with just one fixing hole

14:21just in case you’re worried i’ve covered over the output window for the laser when i did that blowing i’ll just remove

14:27the tape again it’s a lot easier to rotate the part

14:32than it is to rotate the screw

14:39you might as well have a front row seat might

14:59that’s good enough it’s a very small beam so it’s not going to worry us if we’re very slightly off

15:05center now comes the second problem because now what we’ve got to do is to move this whole thing

15:12backwards and forwards here’s my mirror

15:17the corner of that mirror is a certain distance

15:23away from the wall of the machine now my number two mirror is exactly the

15:30same style mirror as that and it’s sitting at 45 degrees

15:36out here i’m pretty sure that that corner and that corner will finish up at

15:41virtually the same dimension so i’ve got to go around to the front of the machine now and measure how far

15:47the number two mirror is away from the wall of the machine and set this one to that same dimension you

15:54don’t need that noise on for the moment in practice it’s easier to measure that

15:59corner 91.4 so it’s got to come this way quite a long way

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

16:09it’s about 91. so that’s not far off now the reason why i need to know that

16:16is because i’ve got to punch a hole through here fairly accurately and to do that what i’m going to do is

16:21to stick that on there i’m going to check the gap on my mirror

16:31to make sure they’re all approximately the same

16:37here here and here my mirror almost in a vertical plane at

16:4345 degrees and caused the reflection to bounce onto here in pretty close to

16:49the correct position for me to drill a hole through because i want the smallest hole

16:54possible through there to point to mirror number two once i’ve got this thing set

17:00i don’t need a big hole for adjustment

17:06so we’ll let the laser do the work for us

17:14there it is

17:21[Applause]

17:47yep that’s pretty good so now we go and check how that beam is hitting mirror number

17:52two now i’m going to loosen the slide at the back here

17:58i’m going to drag the laser back by a quarter of an inch

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

18:05turn the laser on and see what effect we’ve had

18:13gone too much now minor adjustment and

18:24a little bit more we don’t have to be perfect but we can be because i’ve got all the

18:30adjustment in the world that i want and that should be just about spot on center

18:40now that i’ve tightened the laser up and clamped it down

18:46spot on center basically made sure that the beam is in approximately the right place at this end

18:51to put a target on there and start aligning it with the x-axis for real so there’s our target burn

19:00pretty central and here comes our alignment burn now

19:06we’re not on the mirror

19:12it’s not too far off it’s probably right on the right hand edge of the target it’s right over here now

19:21we’re pretty close now you can never set this

19:27in one because it is an iteration process well i’ve just shut down the machine for

19:33a few moments because i feel i need to explain what i’ve just said iteration process

19:41many people set their machines up and they follow this routine of target set target set but they don’t

19:47actually realize what they’re doing let me try and take a few moments just explain the technique that you’re

19:54actually using here’s a bearing rail and what we’re trying to do is set the beam at the moment it’s a

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

20:02red beam because it’s reflected off this mirror here at a funny angle we’re trying to set that red beam to

20:10this position here which is the dotted move line which is actually completely parallel in both the vertical

20:17and the horizontal direction with the bearing rail so that’s our target that we’re

20:23eventually trying to achieve the first time we put mirror 2 close to mirror 1 we don’t know

20:30how this beam is reflecting off of mirror 1. and the first time we do this

20:35we’re going to produce a green target burn on mirror 2. so we move mirror 2 a long way away and

20:43hey here’s our green target and our beam is nowhere near the green target so our burn is out here so we

20:50adjust mirror one to bring this beam onto target so now what we’ve got

20:59we’ve got a blue beam and you could easily be forgiven for thinking that you’ve now set your machine correctly

21:04because you’ve actually set the beam onto the target and it perfectly matches it’s not quite

21:12as simple as that because now when we move this mirror back to position one

21:19we shall find that the blue beam when we fire it again for the second target is actually making

21:25a target burn here the first target burn was here but the second target burned is here

21:32so now we move this mirror away and here’s our target that we’re aiming

21:37for and of course look the beam is pointing here at the previous target

21:44so now we have to adjust the beam yet again at mirror 1 so that it points to

21:50the blue target which is our second target and as you can see now that we’ve gone

21:56and set the orange beam to target number two

22:02we’ve got a lot closer to perfection we’re not perfect yet and if we go

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

22:09through one more iteration i.e one more set of corrections we should be pretty

22:16close to perfection so you’re not a failure if you didn’t do it in one

22:22you’re pretty lucky if you manage to get it in two

22:28the chances are you’re going to have to have three attempts or maybe even four attempts to get your distant burn

22:34the same as your target burn this is a what i describe as an iteration process

22:40a process of gradually creeping towards perfection

22:50and we’re going to have to make probably one more adjustment now if we’re not

22:56interested in absolute position for center we can turn the target over

23:05do the same thing again

23:15that’s pretty good because we’d like to be a little bit more perfect than that we can now move the beam back slightly

23:23across that way without affecting the adjustment that we just made to the y-axis we just

23:30set the y-axis up but what we haven’t done is set the set the beam so that it’s on the center of that mirror

23:37so we’d like to move the beam across about three millimeters well it’s on center we’re high remember but

23:43don’t don’t get upset because we’ve got to clamp the beam back down again

23:48and we should be back on center in more or less both planes

23:54and there we go the one thing i will say to you is once you have been playing with this

24:00beam you’ll notice that there’s some condensate formed on the mirror there

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

24:05the fumes come through the paper it will eventually disappear

24:11but i’ve got some toilet tissue here or some lens tissue whichever you fancy

24:18the proper stuff is lens tissue we’ll just clean that mirror there’s nothing more than just a hazy

24:25residue on the mirror at the moment you’ll note i haven’t even got a mirror in number

24:30three it doesn’t matter i can still set up

24:37x without that mirror in place now the galaxy lights in this instance

24:44are annoying when i switched the gantry lights off

24:49all of a sudden you could see this target they were causing the aperture to close down

24:55there’s a good logical reason for me at least to have my lights switchable pulse

25:05it’s way way low when i look at these i can see that i’m right at the top of the adjustment it’s

25:12not important at the moment but we will just drop that down to roughly

25:18the halfway point in the adjustment which is about here

25:25right let’s not worry about where it is in relation to center at the moment what we’re more interested in is where

25:33it is when we get over to the other side there and suspectually quite low so let’s just

25:39test it

25:53we’ve lost quite a lot of power as well and the beam has grown we need to raise

25:59the beam up we need to send it across we now need to lift it up a little bit

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

26:05okay now we’ll compare it to our target

26:16to get that hole there roughly on the same center line as the target because that is

26:23approximately the center that we’re aiming for

26:28so it’s quite a nice sharp beam there and yet when we come across to this end

26:38well we’re well lined up but the theme itself is pretty poor

26:46i’ll show you what i mean it’s no longer

26:52a crisp black bean look it’s taken a long time to burn

27:00mirror too is causing some sort of problem

27:07i’ll just go and get some proper lens tissue depending on the sort you get

27:15they all feel slightly different this particular stuff feels similar to toilet tissue

27:23which is why in an emergency i will use soft toilet tissue never use kitchen

27:29rolls this kitchen roll has got kale in it and kaolin is an abrasive

27:35and it will scratch the surface of your mirror without fixing the mirror on let’s just see if we’ve improved the

27:41pulse at least it’s the same size now not quite as dark and i noticed i had to

27:47press more on the pulse button to get to that texture so i i know from

27:52a field point of view that it’s lost power by the time it gets to this position here i might change

27:57that later but for the moment we’re not going to get too concerned

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

28:03we’ll just go back we’ll put the screws in and we’ll just check that we haven’t messed the alignment of

28:08x just fitted up the mirror holder onto this head and to put the mirror in it’s normally

28:14pretty easy because look you undo these two screws that are diagonally opposite and you should be able to just drop the

28:20mirror in you might need to undo the screws just to shade more

28:30but the mirror should go in without the screws coming out you set these grub screws

28:36here so that we’ve got an even gap along the top and the bottom around

28:42about a mil and a half that will be determined by this screw here

28:48so you’ve got a pivot screw in the corner here which doesn’t do anything but you need to make sure that you start

28:54off with it in about equal equal now just remember the nuts on the top here are loose so put your

29:00finger behind here when you tighten these up right so what we’re more interested in at the moment now

29:06is firing this beam across here and going down onto the table anywhere onto the table

29:13just put our piece of card down shall we we’ll have a go up burning well first of all we’re going to bring the table up as

29:19high as that we can pathetically slow isn’t it and bringing the table up high

29:24is revealed i’ve got a potential clash here i’ve still got an inch to come on the table but i’ve only got about half an inch

29:30here so i’ve got to take some material off the bottom of this sensor switch and also tie this cable back that’s high

29:37enough for what we want at the moment so let’s make a mark on there

29:50and drop the table down that’s quite a long way off where i expect it to be but hey let’s not worry at the moment

29:59oh what’s happening

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

30:04something is jamming

30:10pretty tight that felt but it’s still something is very stiff

30:15here and it’s not driving very well at all that is

30:22four or five millimeters lower there than it is here

30:30shut that off while we try and sort this problem out this is not part of the plan but hey the

30:36way in which you adjust these take to make the table level

30:41is on these pulleys normally somewhere you should find a couple of grub screws

30:48fixing the pulley to this shaft

30:55[Laughter]

31:01you need to undo those grab screws if you can get to them you need to

31:08rotate this to take the table up or down

31:19wow this table is out by a long way about the same level as that one and then that one at the back is totally

31:27wrong as well but that one looks as so the grub screw is loose and that may well be what the problem is

31:33so the back one is about right now it’s reasonably level now so they shouldn’t be jamming

31:39[Music] so now we’ve got to diffuse this little

31:45time bomb that our chinese friends have sent me

31:51i’ve taken the belt off so that i can actually feel each one of

31:57these and that one is pretty free

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

32:03the one at the back there [Applause]

32:08marginally stiff but not as free as i’d like it certainly not as free as this one

32:16this one over here is pretty free as well this one at the back here is extremely

32:26sticky as it goes up it gets sticky as i move it down to out of level

32:35it frees up i’m suspecting that this bearing here

32:44is not lined up properly and it’s clamped out of position take

32:50all those screws loose and see what this feels like now no it’s getting tight again

32:58it’s getting very tight and these these threads are bent because i can feel them

33:03going tight and loose as i rotate them the gauge i’ve got here measures to

33:08within 0.1 of a millimeter so i’m going to set that to exactly 11

33:13here on each corner of the table they’re level as far as the nozzle is

33:21concerned or as far as the head is concerned it doesn’t mean you say the level with the bottom of the machine of course i’ve

33:26now taken the motor off and i can see why this doesn’t rotate it’s got a planetary

33:32gearbox associated with the motor right but what i’ve now done i’ve taken

33:37the original gear off which was pathetically slow remember at raising and lowering the table

33:43and i’ve found this matching gear from another machine and

33:50look at the size difference it’s going to go up and down like a rocket now i’ve just come to fix this motor back on

33:56and several things you can see first of all it’s very unstable

34:01you can see how it’s actually only fixed to a very paper thin floor of the machine

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

34:07and m4 screws through a piece of metallic paper is not exactly a very

34:13good idea is it i mean i’ve already stripped three of the four threads on there

34:18and let me just demonstrate something there we go that’s how strong those

34:25threads are so it’s something else i’ve got to fix so with the torque on this motor and the

34:31flex no wonder it’s not possible to tension it up properly and it keeps going click

34:36click click click i’m very lucky and i’ve got all sorts of kit i’ve got a piece of three millimeter

34:42stainless steel plate there that i will be able to just conveniently fix in there and

34:49bolt that too that will stop it from flexing well this larger

34:55pulley which hopefully was going to make the thing run faster was just asking

35:02too much of the torque available from this motor so i’ve had to put the original small

35:07drive pulley back and it it looks and feels a lot better

35:13now that we’ve got the motor mounted really stiff it can’t jump teeth

35:20with this amount of tension on the system so what we’ve got to do now is to go around the other side of the machine and

35:27again we’ve got to set the table level now while i’ve been messing around with this table and leveling it all up

35:35i keep getting bugged by this loss of power increasing billing beam

35:42size look we’ve got a lovely tight beam there and yet by the time we get to the end of the stroke we’ve got a fuzzy beam

35:49just across this x-axis is it a mirror problem or is it a distance problem from the

35:55tube that’s causing the beam to grow i don’t believe it is

36:00but of course i will never know until i prove it so we’re going to have a look and see

We Have Lift Off – Laser Tube Upgrade Transcript (Cont…)

36:06how this beam grows with distance i can do that on this machine because of the way in which i’ve designed the tube

36:12so let’s go and have a look and i’ll show you what i mean having set this beam up in the x-axis to give

36:17the correct position on mirror number two i don’t really want to lose that so what

36:23i’ve done i’ve marked at this end the position and i’ve also put a mark

36:29that end at the end of my tube mounting so what i can now do i can with impunity

36:37undo my tube because i know that it’s referenced off the back face and i can always put it back

36:43into the correct position on the back face we take the front clamp screw out and i’ve very slightly

36:49loosened the rear one so that means i can now do this with my tube

36:56i can pull it out like this so all i’ve got to do is remove my mirror now

37:09[Applause] and provided i push it back just a little bit more

37:18i can move my beam out beyond the end of the machine because it will fire through the mirror now

37:25and if i line you up properly you are looking down the barrel of a gun what i’m going to do is i’m going to

37:31fire the laser at various distances into a piece of card and we’re going to see how the beam

37:37changes shape with distance so by the time we get to mirror number

37:42three we are 1260 millimeters away from the face of the laser

37:48now i’ve got some large sheets of card here which are used for making boxes we

37:54shouldn’t be able to miss this should we so there we are we’re roughly 1300 millimeters away

38:00from the laser tube now so let’s turn it on

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38:12same 10 power and let’s see what we can do at 300 millimeters there it is there

38:19look let’s just see whether or not it is the dot

38:26so that i can look at it from a distance

38:33let’s see if i can make it bigger

38:41no the dot is actually here look

38:49there’s my dot there

38:56so we are not overly impressed are we it’s losing power with distance

39:05and it’s also the beam is is growing quite substantially with distance

39:10and i’m having to hold the power on for quite a long time now i could push the power up and see

39:18what effect that has we could move this across a bit

39:23and i’ll push the power up to 100

39:35wow that’s a pretty abysmal beam isn’t it that’s not

39:42a mode zero beam

39:48i was sent this test certificate with this laser now look at all this data up

39:55here and i can’t find anything about distance away from the head

40:02when they measured this data that you can see here this very clearly

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40:08shows a lovely what they call tem00

40:14proper gaussian shaped beam and then they do all sorts of statistics on this graph down here about

40:20the gaussian fit but at the end of the day we don’t have

40:25a gaussian beam 1.3 meters away from the laser

40:33as i said a gaussian beam as described as a tem000 mode

40:38what we have here is um well it’s the shape of my bottom almost so

40:44it’s a 10 0 1 beam that we’ve actually got and i can do nothing with that i mean it may

40:52cut okay it may weld okay but it certainly won’t be any good for laser engraving because there is no

40:58sharp point this is not going to work for me so i’m not going to go any further with

41:04this exercise until i’ve spoken to cloud ray as i was editing my video and remember

41:09we looked down the barrel of the gun if the beam was small and compact and passing right through the center

41:15there there would not have been a problem but bear in mind i think this beam is

41:22expanding and therefore there is the possibility that i could be getting reflections off

41:28the side of as it passes through this mirror aperture so what i’m going to do is to remove the

41:35mirror before i finish up with egg on my face

41:41and we’ll try the same thing again not entirely sure where it’s going to land but it’s going to be somewhere about

41:47there oh that’s the current since it’s right in the same spot let’s just move that

41:53across a little bit that’s just a quick single pulse we have still got a 100

42:02beam at 1.3 meters after all which is excellent news we’ll just stick

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42:09one of my paper targets on there so that we’ve got a nice consistent material to work with

42:19i’m not going to touch it i’m going to do it again and see if i can just burn the center

42:31so we’ll just watch for the red glow is it in the center

42:39yes so we have got quite a nice beam after all

42:46yeah look at it it’s huge

42:51so that beam is almost 10 millimeters diameter we certainly don’t need any beam expanders on here

42:57the beam expands on its own thank you so for the time we get to our lenses we

43:03have got a relatively low energy density so that’s good news because

43:08hey anything that we interpose in the path is going to absorb power and we’ve only got 30 watts here

43:16anyway so you know we want to make the most of that so i’m very happy that we’re not

43:21going to have to use a beam expander so this has been a very interesting exercise

43:26down up down up and eventually what you carry on so what

43:33we’ve just found out is that the beam grows as it reaches mirror three by the time it gets there

43:40it’s 10 millimeters diameter now you’ve got a 25 millimeter mirror

43:45which is canted over at 45 degrees that means the effective height of that

43:51mirror that the beam can see is only around about 14 or 15 millimeters so we’ve got to be

43:56pretty accurate with our alignment onto mirror 3. but the good news is because of the way

44:04in which we are lying mirror 3 with the center of the axis of the lens tube

44:10then we’re automatically going to put the beam onto the sweet spot of mirror 3 which is the central point

44:18if i’ve designed it correctly so things are looking pretty good for the

44:23next week or two i’ve got other projects that i’ve got to get involved with i might not be

44:29completing this work for a little while yet so you’ll have to be a little bit patient but now you’ve seen that we’ve got a working

44:35machine we’re flying and on that happy note i’ll say cheerio for now

44:40thank you for your time and patience and I’ll see you in the next session

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