15 – Is Ordinary Laser Engraving Another Disappointment?

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 Russ gets on when he tries engraving with a RF Laser.

Engraving with a RF Laser - Example Engravings
Engraving with a RF Laser – Example Engravings

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!

Contents

Ordinary engraving is one of the areas where the almost instant switching capability of this technology should excel. In this session we explore the superficial properties of this high-speed engraving capability. However, with only 20 watts of burning power, just how fast will that allow us to go. We know this machine is currently capable of at least 1400mm/s but does that mean faster cycle times? Caution…… there may be two limiting factors that will prevent this speed being usable. First is POWER, just how thinly can I spread 20 watts and get acceptable results? Second is ACCELERATION, the faster the linear speed, the longer it takes to accelerate and decelerate. We have already seen how this second factor can have a HUGE effect on cycle time. Hence, the headline speed capability of a machine maybe impressive but without sufficient watts and motor power that number may be meaningless.

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Transcript for Is Ordinary Laser Engraving With a RF Laser Another Disappointment?

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0:00[Music]

0:03it’s almost like a little sewing machine

0:05isn’t it

0:08welcome to another session with my

0:10tangerine tiger now what you’ve seen

0:12there

0:12is a quick test that i’m carrying out to

0:15see if i could find out what was going

0:17on

0:18because i noticed one or two strange

0:20patterns

0:21when i was doing my photo engraving last

0:24time

0:25now whether i was doing pictures this

0:27way if we take a look here you’ll see

0:29that there’s some

0:30sort of patination that runs across the

0:33picture

0:35this picture was done this way and we’ve

0:38got

0:39patinations that run across that way

0:42this picture was done this way and we’ve

0:45got those same

0:46narrow lines there and the lines get

0:48they almost disappear at the top there

0:51and here they’re pretty obvious down the

0:53bottom here

0:54they’re not exactly all the same pitch

0:57and then they tend

0:58to disappear to nothing as we get

0:59towards the top and look we’ve got the

1:01same things again happening here

1:03so this is not any sort of aliasing

1:07pattern

1:08within the actual software itself

1:11this is a machine problem of some sort

1:14the only machine problem that it can be

1:16is to do with the drive belts on the

1:18y-axis

1:20but hey these are not curtains in the

1:23same way

1:24that we saw curtains on the x-axis

1:26they’re more than three millimeter pitch

1:28and secondly they’re not uniform as we

1:31get further

1:32into the stroke the gap gets wider and

1:36wider

1:36we’ve got a little bit of a problem

1:38there which i think i understand what

1:40the

1:40problem might be and the very simple

1:42test

1:43that i carried out was to see if i could

1:47identify the same pattern as i worked up

1:49that strip

1:52to be honest the answer is no there

1:55seems to be very little problem there

1:57but

1:58i’m pretty sure i do understand what the

2:00problem is to do with those belts

Transcript for Is Ordinary Laser Engraving With a RF Laser Another Disappointment? (Cont…)

2:02and we will have a go at trying to fix

2:04the problem or identify the problem in a

2:06later session

2:08it’s not important at this moment in

2:09time for some of the stuff that we’re

2:11going to do

2:12but it is an interesting problem which i

2:14will come back and investigate

2:15because today i want to step onto some

2:18rather

2:19hallowed ground the whole point about

2:22these rf machines

2:24is that they’re supposedly good at doing

2:28just ordinary engraving whether it be

2:30bitmap text and logos

2:32or whether it be filled vector graphics

2:34it doesn’t matter

2:36this machine is supposed to be super

2:38fast at doing that when i look at the

2:40demonstration videos

2:42yes you can see that the machine is

2:44going very fast

2:45just like you saw my little sewing

2:47machine going very fast here at the

2:49beginning

2:50so today we’re going to as i said step

2:52onto that hallowed ground

2:54and take a look at what might be going

2:56on

2:57with just ordinary engraving the

3:00simplest thing that we could possibly do

3:01the great thing about this machine is we

3:03know

3:04that it will do superb quality engraving

3:07because it switches on

3:09and off so quickly so speak technically

3:12speed is not an issue here we’re not

3:14limited by the power supply

3:16the response time of the power supply

3:18what we are limited by

3:20is physical power as i’ve explained to

3:24you several times before

3:26candle flame put your hand over the

3:27candle flame

3:29move it fast enough and you won’t feel

3:30any heat at all but move it slow enough

3:33and you damage your hand now that’s

3:35exactly what happens to this paper

3:37the faster you move it the less energy

3:40you’re putting down

3:41per distance and the lighter the cut

3:44will become

3:45and the thinner the line will become if

3:47we’re running fast

3:48if you have limited power available to

3:50you there are really

3:52only two parameters that you’ve got to

3:56affect damage to the material that

3:58you’re cutting now

3:59every material will have a different

Transcript for Is Ordinary Laser Engraving With a RF Laser Another Disappointment? (Cont…)

4:01damage threshold

4:03but that damage threshold can only be

4:06exceeded

4:07if you have got enough power to damage

4:09the material

4:10and the only way that you can control

4:12that damage is either by moving

4:14slowly or by doing a small amount of

4:17damage

4:18multiple times you’ve only got those two

4:20choices

4:21the fact that this system is controlled

4:23by the pwm seat i’ve either got 20 watts

4:26when it’s switched on or know what’s

4:29when it’s switched off

4:31i’m doing engraving i don’t want any

4:34dead periods

4:36i need 20 watts all of the time

4:39so i’ve got to set this onto basically

4:42100

4:43power which basically means i’m not

4:46going to have

4:47any of these i’m going to have a

4:49straight line of 20 watts continuously

4:53so there is no point in having a pwm

4:56controlled machine when you’re doing

4:58engraving the machine will switch off at

5:00any black white interface

Transcript for Is Ordinary Laser Engraving With a RF Laser Another Disappointment? (Cont…)

5:02instantly and quickly regardless of the

5:04pwm signal that immediately asks the

5:06question

5:07what’s so fantastic about rf technology

5:10as i mentioned to you when we’re

5:11comparing the the rf

5:13and the glass tube system rf

5:16radio frequency is only a different

5:18means by which we’re producing

5:20the laser beam itself this control

5:23system here

5:24the pwm control system seems to be

5:27unique

5:27but it doesn’t seem to be a positive

5:29advantage yes

5:31you’ve got power control but it’s not

5:33really power control

5:34because every time you turn the machine

5:37on you’re putting

5:38out the same level of power it’s just

5:41that

5:41on average which we’re not worried about

5:43because we don’t do

5:45average damage we might use average heat

5:48if we were doing welding or something

5:50like that but when we come to damaging

5:52material

5:53every time the pulse is on at 20 watts

5:55it’s doing 20 watts worth of damage

5:57just because it’s on for 50 percent of

5:59the time doesn’t mean to say it’s doing

Transcript for Is Ordinary Laser Engraving With a RF Laser Another Disappointment? (Cont…)

6:0110 watts worth of damage

6:03that’s the puzzling thing that i can’t

6:05understand about this technology

6:07it’s basically constant current

6:09technology

6:10diluted by pwm am i being naive about

6:14this

6:15for our first test we’re going to carry

6:18out one of the

6:19party pieces that you’ll see the rf

6:22laser

6:23performing at any exhibition that you go

6:25to

6:26the aztec calendar huge amount of detail

6:29on there so i’m going to run this at a

6:31thousand

6:32millimeters a second 100

6:35power it really doesn’t matter what the

6:38frequency is because it’s not going to

6:39come into play

6:41and we’re going to use my standard pitch

6:44of 0.1

6:45which is roughly going to be the

6:47thickness of the lines that i can

6:49produce

6:49remember the candle i’m not expecting a

6:52great deal of

6:53damage to take place

6:56at that sort of speed and that amount of

6:58power but let’s give it a go and see

7:01what we get now

7:01what i’ve got here is a piece of beech

7:04faced

7:04plywood

7:08well i’m pretty impressed to start with

7:11that’s

7:12more color than i thought i was ever

7:13going to get

7:20and that’s a thousand millimeters a

7:22second

7:25okay so i am impressed by that

7:30we’ve found a party trick that it can

7:32perform well at

7:37but it is playing to the strengths of

7:38this machine which is an extremely fast

7:41switching capability

7:44the color is something i wasn’t

7:47expecting

7:49and that took two minutes 34

7:52so that’s pretty good going um i have to

7:55say

7:57for the first time i am impressed with

7:59something this machine can do

Transcript for Is Ordinary Laser Engraving With a RF Laser Another Disappointment? (Cont…)

8:01this is a picture i borrowed off of

8:03wikipedia

8:05consider that against the size of my

8:07hand you can see that it’s

8:09some of this detail in here is very very

8:11fine we look at the incredible detail on

8:13there

8:14considering the size the relative size

8:16of my finger

8:19i’ll have to give this 10 out of 10 for

8:21the moment

8:22i’m very impressed with that bearing in

8:25mind it was a roundabout if i remember

8:27two minutes thirty something or other um

8:30we’re now going to run the same thing

8:31but we’re going to try and do it at 1400

8:34millimeters a second and see how the

8:35color

8:36changes just ordinary text and graphics

8:38is going to be easy

8:40after looking at this amount of detail

8:50it’s 33 which is about the same so

8:53really speed

8:54didn’t make a great deal of difference

8:55because in running faster

8:57we’ve got a longer over track impressive

9:001400

9:01yes but a thousand gives me a deeper

9:06color as you would expect

9:09so with no difference in time

9:12that’s got to be the choice running

9:14slower actually produces a better result

9:17for no extra cycle okay let’s try on a

9:20piece of poplar plywood now

9:22we’re going to run this at 1200

9:23millimeters a second

9:27now the burn characteristics of this

9:29material are completely different than

9:30that of

9:31plywood that’s actually that’s actually

9:34the grain that’s running through the

9:36material which is affecting the color

9:37here it was 1200 millimeter second so

9:40even though we’ve run that slower we’ve

9:43still got

9:44roughly the same time 232 okay let’s try

9:47a piece of mdf

9:48and run this at a thousand

10:02so yes it’s doing a remarkable job on

Transcript for Is Ordinary Laser Engraving With a RF Laser Another Disappointment? (Cont…)

10:04mdf

10:06i have to say i’m impressed at how far

10:0820 watts is going

10:10see that was two minutes 34 we’re

10:12running slower

10:13but it’s not taking any longer but we’re

10:16getting a nice

10:17dark cut that’s remarkable detail isn’t

10:20it

10:22so again i’ll ask this very

10:25silly naive question why have we got

10:27fancy pwm

10:29control on this machine what’s it for at

10:31the moment

10:32i don’t know because

10:36we’re running this without any pwm at

10:39all we’re running it at 100

10:41like a cw like a like a constant power

10:44machine the only

10:47thing that we’ve got is this remarkably

10:50fast

10:50switching speed which is producing

10:53amazing results i mean i’ve got this

10:55machine up to 1400 millimeters a second

10:58scanning and look it’s doing a fantastic

11:02job i’ve got a slight coaster here

11:05i’m not changing any of the settings at

11:07all

11:08thousand millimeters a second directly

11:26even on sleep it’s done a pretty

11:28remarkable job hasn’t it

11:33all right let’s see what it can do with

11:34a piece of cast acrylic should we

11:36seem to be doing a very good job

11:38straight out the box

11:40with it’s not covered in dust or

11:44anything like that look

11:49you just put it against a black

11:51background and you can see how good

11:53it really is

11:58not only is it a nice white colour that

Transcript for Is Ordinary Laser Engraving With a RF Laser Another Disappointment? (Cont…)

12:01hasn’t produced all sorts of fumes

12:03everywhere

12:05it’s absolutely stunning detail

12:09all down to the response time of the

12:10switching of the beam

12:12so we found the major strength of this

12:16machine at last

12:18but just bear in mind

12:22we’ve tried all these materials we’ve

12:24not changed it into the settings

12:26we’ve not used the pwm

12:29we’ve just thrown stuff at the machine

12:34i’m pretty impressed with this aspect of

12:37its capabilities

12:38trying a different sort of engraving

12:41what you saw me doing before was what i

12:42call

12:43drawing or normal engraved there are two

12:44other sorts of engraving one of them is

12:46an architectural technique

12:48called relive which basically is almost

12:51like 3d

12:52engraving where you all the white

12:55for instance in that picture or all the

12:57background in that picture

12:59will be etched away and it will leave

13:03the black lines on the surface so the

13:05black lines will be white

13:07and the background will be relieved away

13:10and that’s one technique this technique

13:13that i’m experimenting with here is a

13:15slightly different technique it’s a

13:16printing technique

13:18and it’s called intaglio now

13:21basically intaglio is where you make a

13:23wooden pattern

13:24like this or a pattern like this and you

13:27size the lines into the pattern

13:30deep enough so that they will hold ink

13:34and the idea is you put your paper over

13:36the top then and put a roller on top and

13:38lift the ink out of the grooves

13:40so you’re basically incising deep

13:42grooves

13:43into your material i’m achieving that in

13:46this instance

13:47by slowing the job down

13:50that’s the only way i can get more power

13:52into this job either

13:54slow it down or add more lines

13:58so that i over burn now i’d much rather

14:00slow it down and go over the job once

Transcript for Is Ordinary Laser Engraving With a RF Laser Another Disappointment? (Cont…)

14:03than do multiple burns but we will

14:06compare the two

14:08so i’ve reduced this to 500 millimeters

14:10in second

14:11instead of a thousand millimeters a

14:13second and it’s looking

14:14pretty good and clean yeah there is some

14:17depth to that but not very much

14:19let me try the same thing again but this

14:21time i’ll run it at

14:23250. so it’s going to take four times as

14:25long this is now

14:26going to produce a lot deeper burn i’m

14:29going to produce more smoke

14:30and i hope i’m not going to brown the

14:34surface too much

14:35i am using my compound lens here so it’s

14:37producing a very very fine

14:39burn line

14:48really a dark very crisp image

14:52i’m again quite staggered and amazed

14:56at what we’re actually capable of doing

14:58here

15:00now when i was doing this at a thousand

15:02millimeters a second you will remember

15:03that

15:04i think it took uh two minutes

15:0730 roughly

15:11but if you take a look now you’ll see

15:12that the amount of over travel is

15:15almost nil

15:19so whereas you would expect because i’m

15:22running at a quarter the speed

15:23it might take four times as long

15:27i suspect it won’t take

15:30what 2 30 will be 10 minutes

15:355 minutes 47 we’ve dropped the speed

15:39to a quarter and we’ve only

15:42about two and a quarter times increase

15:44the cycle time and yes we’ve definitely

15:46got some

15:47depth to that now so we’ll see whether

15:50we can

15:51run even slower now and get a deeper cut

15:55we’ll drop it down to 125 millimeters a

15:58second

15:59i haven’t got my extraction set up on

Transcript for Is Ordinary Laser Engraving With a RF Laser Another Disappointment? (Cont…)

16:01here at the moment because i didn’t

16:02think i’d need it but

16:07yeah it does need some extraction now

16:10this is

16:11one eighth of the speed that we started

16:13off with at a thousand

16:14millimeters a second and a thousand

16:17millimeters a second

16:19we were doing two minutes thirty two

16:21minutes 34 i think

16:24so therefore at an eighth of the speed

16:26you would say well it’s going to take

16:28eight times longer

16:29instead of two minutes 30 it’s going to

16:31be

16:32nearly 20 minutes but the more i watch

16:34this thing work like this the more i’m

16:36becoming impressed by it

16:37okay it didn’t do what i originally

16:38planned to do which was my

16:40photo engraving which was the dream that

16:42i had fast photo engraving but

16:44hey this is doing an absolutely

16:46marvelous job

16:47of some other things there’s a lot of

16:49depth in those grooves now

16:51double that time would be what 10 11

16:55nearly 12 minutes and this one took

16:5910 minutes 50

17:03i’m extremely impressed by that do the

17:05same thing again but this time

17:07i’m going to run it instead of single

17:11lines i’m going to run at a thousand

17:14millimeters a second

17:16and quarter the line spacing in other

17:18words i’m going to put down a .025

17:21line spacing

17:24now i think you can immediately see that

17:27by

17:28burning over the same spot four times

17:34we’re not producing such a clean image

17:36we’re getting that browning effect

17:42let’s see what happens if we change it

17:43to three times

17:55let’s try again with point zero five

17:58see now we’ve got we’ve got a crisp

18:00clean image now

Transcript for Is Ordinary Laser Engraving With a RF Laser Another Disappointment? (Cont…)

18:05whereas the other two look over burnt

18:15so i’ll let this one go to halfway and

18:16work out roughly what the time is

18:21and that took two minutes 42

18:23approximately the same

18:24cycle time this one was done at a

18:27thousand

18:28this one was done at a thousand

18:30millimeters a second

18:31with a 0.05 line spacing

18:35this one was done at 250

18:38millimeters a second with a 0.1

18:42line spacing

18:45the quality of the color is much better

18:49and the cycle time is virtually no

18:51different even though

18:52this one is running four times faster

18:56than that one you can very clearly see

18:58the um

19:00the brown hue that we have around here

19:03because we’re just basically engraving

19:06too deep

19:06this was four point zero two five lines

19:10and this was 3.033 lines

19:14and this was a 0.05 line both of these

19:17lovely clean images were done with a

19:190.1 line

19:22just one pass try something a bit more

19:25manageable

19:26a little less ambitious

19:27[Music]

19:34now we’re going to do exactly the

19:36opposite

19:41but i mean that is pretty good isn’t it

19:46there is no relief

19:55and there we go we’ve got some relief

19:57engraving now

19:59well it’s getting a windy night out

Transcript for Is Ordinary Laser Engraving With a RF Laser Another Disappointment? (Cont…)

20:01there now

20:03this time i went in and had a cup of

20:04coffee

20:07i’m going away with a bit of a smile on

20:08my face at the moment because

20:10at least it’s doing what we all expect

20:12it to do

20:14it’s an engraving machine and it’s a

20:16fast

20:17engraving machine the fact that it’s

20:19rather disappointing at photo engraving

20:22well we found ways around that to make

20:25it half decent at photo engraving

20:29the next test will be its achilles heel

20:32cutting let’s see what it can do for

20:34cutting shall we next time

20:37thank you very much for your time and

20:38patience and I’ll catch up with you then

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