Welcome to another Lightblade learning Lab.
Today, we're going to carry on a bit with Parameters, but we're actually not going to
do any parameters today.
We're going to look at some problems that we shall have as we tackle some more parameters.
Particularly associated with engraving.
Now we have already touched on some of these little problems in the last session on cutting
parameters.
But I didn't enlarge on them too much at that point in time because there is a great deal
that I don't know about engraving.
And so what we are going to do today is some exploratory work, that is new to me and probably
new for most people because I've not found anybody else doing this sort of work.
It's a bit; when I say controversial... it can't be controversial because we shall either
decide that it does, or that it doesn't work.
The controversial element of it will be the fact is that we're probably going to do quite
a lot of work with no air assist.
(draws in breath) Ooh well we touched on this last time, and
err we got some quite staggering results.
Hopefully we shall find similar sorts of things today.
I indicated to you right at the beginning of this series that I'm not a tutor, I'm not
a teacher, I'm an engineer who enjoys discovering things and as I discover things, you will
learn.
Um, and hopefully these sorts of things will help you understand more about the machine
and the way in which you can look at things in a slightly obtuse way, to try and get solutions
to problems, because I suspect that most of you guys will be using this machine for real
jobs and real work - earning money.
And you will want to be most efficient that you can be at the job job that you're going
to do, and some of this knowledge and background information will help you make decisions to
improve your manufacturing process.
Before we dive in, a couple of things, first of all - ooh that's nice and warm now, that's
my cinnamon roll mmm that's absolutely delicious.
It's quite cold out here today, now I want to just draw your attention to this little
thing that I'm holding here.
I'm not likely to lose it as you can see.
It's a keep things warm or a keep things cold cup.
And it's got my normal black coffee in it, but the interesting thing about it is, this
is stainless steel, and it's been powder coated and the powder coating has been removed by
a machine just like this.
So you're dealing with something here, with this machine, which is capable of all sorts
of good things.
Now something else I would like you to look at, this is what I call my wall of wind.And
I hope, that we will be using this with some success today.
It may be a total failure, I've only just recently made it, so I've not even had a chance
to test it.
It works, I've got it on a variable voltage transformer so I can change the amount of
blow in it by 50 %. Ok now, to start this session off what I've got, is I've got the
steel plate on here, um for a good reason as you'll see in a second.
I've got the 2" lens in here, so I'll just set that to 5mm gap and I''m going to run
a very simple program.
The first part of this exercise is some engraving, some scanning.
Followed by some cutting.
Now this is a very cheap hardboard, very soft, this is not MDF, this is nothing like that
laser board that we used in the last session.
So, what have we got here?
Well, yes it's cut.
But two things I want you to note: first of all, this is a right mess.....
I mean it's full of dust, we can take some of the dust off, but we've still got all this
brown haze around the outside.
Now what is that brown haze?
Where did it come from?
Well the answer is pretty simple actually, see this much here?
Well this muck here is sticky,
It's basically condensed residue of the smoke that was generated when this was burned.
If you take a look at the cut around the edge, the cut is pretty clean.
That's because all the smoke and residue, went downwards and condensed here.
But when we were doing engraving on the surface here, where did the smoke go?
- UP
and then immediately down again because the air assist was forcing it back onto the surface.
So, hence the reason we've got all this brown muck here sitting around the outside of what
should be a nice clean engraving.
How are we going to deal with this problem?
Well, to be honest, I can't answer that question at the moment because I'm certainly no engraving
expert, and that's the whole point of today's session.
We're gonna see how we can change from this, I was going to be a bit crude with my language,
but I'm going to say with this "not very good" attempt.
To something that hopefully gets better.
Now we'll carry on at the moment, using this fairly cheap um fibre board, this hardboard,
because we've got some references.
Before we put this away, which I'm going to get rid of this now, lets just remove this
horrible debris off of here with some white vinegar.
Oh dear, white vinegar usually does the trick.
But if it fails, I'm afraid we're going to have to go for something a little more aggressive.
This is acetone.
Again, just a tip more than anything else, A steel plate, and it doesn't have to be a
plate like I've got here, it could just be a flat steel plate.
It can be very useful to you, because first of all, as you can see it's very easy to clean.
I mention about the steel plate being easy to clean, because as you can see, after a
little while all this brown crud, we've collected on that plate, is going onto this surface
here, and this is a lot more difficult to keep clean.
And what happens is this stuff here, will burn when you run the laser beam across it,
and it will produce fumes.
Which will come back onto the back of your job.
So this is actually, in some ways it's great, and in some ways it's nothing but a pain.
It has it's uses and one of the great uses for it is that it has got a lot of air flow
through it.
Now if we leave the machine here, we've just got a great big cupboard cavity and that's
where this fits in to.
You can see the pattern of the grill underneath there and look you can see my hands shadow.
Now in here we've got a big extract tube that's sucking the air out from underneath this area
here, so this is like a big Plenum chamber underneath here and it sucks all the air down
into it and extracts it into this amazing Purex unit.
NOw I've always been used to throwing my waste products down a duct and to the outside world.
But of course I'm also throwing heat away, if there was any heat in this cold workshop.
Um, whereas this is a recirculating system, not only is it a recirculating system it gives
me environmental protection because not only is it filtering out smoke, it's filtering
out through an active charcoal filter all the poisonous fumes that are in the atmosphere.
So I can do some plastic cutting on this machine that I wouldn't normally recommend you do,
but with a certain amount of caution and care, and I would probably ask you to go back to
thinklaser or to Purex and ask their advice about the product that you are going to cut.
You can have products that are dangerous to your health, but not dangerous to the machine.
And there are other hazardous products that are hazardous to you and to the bare metal
work and electronics in this machine.
So, you need to be careful we talked about hazardous materials in a previous session.
Now I'm just going to mention it again, because it's a very important subject that you mustn't
overlook.
Back to this honeycomb table, same material, same program, let's take a look at what happens
this time.
Now because I've changed the table we shall need to reset the focus and I can do that
either with the Z/U button or in this particular instance I'm just going to let it drop onto
my step gauge.
Like that, that's a nice simple way of doing it.
Now if you remember what we learned last time, this edge looks pretty black and also look.....
It's got a lot of soot on it, now that would indicate to me that we could go faster.
Now I'm standing them up side by side so that you can take a look at them and you'll see
that the one that was done on the flat table is in fact cleaner than the one that's done
on the honeycomb Table.
Strange that isn't it?
And the back looks nice and clean again, although I could make this run faster as we said, I'm
not going to, we'll keep all the parameters the same.
The only thing that we are going to do is change the way in which we feed air to and
from this product.
So this is all about how air can affect the quality of your product, and air flow can
affect the quality of your product.
OK so now we've got the job sitting on stand-offs, so that there is an air gap underneath the
product as well.
Now I've got the lid open at the moment, which is something that you won't have, you'll be
running this with the lid down.
How does this one compare?
Well I would say that probably, on balance, it's not quite as mucky, there isn't quite
as much haze there if you notice, but I can take it off just as I did on the first one,
and to be honest, there isn't a great deal of difference between these two.
This one is a lot whiter, these are both darker.
Now the next variable that we are going to introduce is this..... we're going to turn
the air assist off completely, now we're in for some fun.
Oh dear.... that's lovely isn't it.
Now what is that flame coming out of the back there do you reckon?
What do you think to that one?
Let's put in down against our first one, which is the best we've had so far.
Hopefully I'm making a point here, the importance of air assist or no air assist.
The debris that's coming up with this one is not being blown back down onto the job,
it's being allowed to come up and blown away by the air that's moving past here.
Even though it's not necessarily the best air flow that we can possibly get, it's a
gentle airflow.
The interesting question is, look at the edge, you might be able to see how this has got
a shiny edge around here where the debris has settled onto the surface and it's produced
this... .although it's not, it is a little bit brown around here, it's not terrible,
but when you turn it into the light, you can see the silvery edge that's around here, the
shiny edge where the resin has settled back down again.
Now when you look at this one, there's nothing.
Why is there nothing?
Well the answer is..... we burnt it, you saw it burning.
If it's burnt it doesn't settle back onto the job, so in some ways burning it is even
better than trying to blow it away gently.
This is a burning process, it is converting a piece of wood into gas and gas is a lot
more volumetric than the wood and so consequently it's expanding up and producing all this debris
which is in the air.
And that's the fundamental problem that we've got with engraving of any organic material.
We're going to produce this smoke, and that's what we've got to try deal with.
Now there are several ways that we can deal with it, one of them is to put masking over
the top of that, which would be fine for something like this and let me just demonstrate, and
I'm not going to do the cut, I'm just going to do the engraving to demonstrate the point.
Now I'm going to turn the air assist back on because you know what happens when we put
air assist on, we get all this muck on the surface.
So lets go back to muck on the surface mode.
I'm going to cut that in half like that, and peel off this piece here.
So we've got a nice clean product.
Well, I say clean, but you'll notice that this is dark and this is light, because even
though we've got a nice clean edge around here, we still finished up painting the text
with all our rubbish.
So we didn't get clean text, we got resin coated text.
Which in some instances might look quite good.
Ok so we've basically discovered that we do not want the debris to be blown down and the
best thing that we can do is to have the air assist off.
But if we have the air assist off and we've got a composite job, cutting and engraving,
I mean this is easy to do for engraving because all we have to do is turn the air assist off.
Ok so now I'm going to carry out a test and we'll stop it after the engraving.
You will notice how the smoke has been thrown in the air and is getting carried away.
That is exactly what we want, we don't want it to go back down onto the job.
Now I am going to turn this around, so that we can see the difference, if there is a difference
between working at the front of the machine and working at the back of the machine.
To be honest, it doesn't really look very much different.
Which is good news, because all we need is a waft of air across it.
Now just look how beautifully clean that is.
And that's no air assist, if you remember last time, when I say no air assist, you can
hopefully see that there is a small amount of air leakage across the valve, which is
actually just keeping the lens protected.
But it's not enough flow to interfere with what's going on with the air flow down here.
Now we're back with our piece of trial material, and what we are going to do now is to see
if we can get a compromise whereby we get a nice clean engraving but also a fairly good
cut.
Now we've already had that situation once, which was basically this one here which was
no air assist, it was on this honeycomb and it was on stand-off.
So, we've already got this test in the bag.
So we don't need to do that again, we need something different.
Now i'm going to lift this probe, right up out of the way, so that it's not in the line
of fire, if we get fire, because we've already got some sticky residue on here from the comet
trail.
Now this is where I want to play with my experimental "Wall of Wind" I want to see if I can introduce
quite a high speed cross flow that will keep the flame extinguished and blow the debris
away, I've put the voltage on this up to full volts "24 volts" and if we take a look, as
you'll see, we've got a fair old wind blowing across there, so if you're going to blow anything
away, this is how we're going to do it.
So what we're attempting to do here, those flames are caused by residues that are lifted
out of this material and they are flammable residues that are being, they are being ignited
by the laser beam itself, because we've got a very high power laser beam on there at the
moment.
And what the attempt will be to do here is to dilute those fumes to such an extent that
they do not ignite.
And nothing there, and well I think we're getting a much smaller flame trail.
And in fact it's a very clean ... we can go faster, but that's a secondary issue.
Ok well that was fairly successful, um the flame trail was very much reduced, but what
I'm doing at the moment is forcing the air across the surface.
Now maybe I can achieve the same result by blocking off the honeycomb table, because
at the moment the honeycomb table is compromising our flow.
We've got the cover going down, which is the way that you would have to operate this machine,
and so now if you remember, I've got a 1/2" air gap underneath the front of this machine
here.
I've put some fairly thick rubber feet under the end here, so I've got a nice air gap under
here, which is blowing in and allowing a large amount of air, relatively speaking to flow
in and blow across the job.
At the back of the machine, you can see these holes, this is where the only air is going
down into the table beneath.
There is a small amount of leakage around the edge of the table here , but most of the
air is being drawn in and across the machine and going down through those holes at the
back there.
So what we've done, we've introduced basically a cross flow of air, both beneath and above
the work.
Lets see what the results are like compared to my "Wall of Wind"?
Basically a very large comet tail.
Now the end result compares well with our "Wall of Wind".
Here are our 3 no air assist samples, we've got the one with the big comet tail, and maybe
it is sort of um, Just very slightly hazy in this area.
This one is perfectly clean, this had big comet tails on it as well.
This was the wall of wind, and that looks quite nice, but no significant difference
between that and this.
Except the flame, now as I said to you, you Shouldn't really be worried about the flame,
providing you are with the machine and there is nothing around here which is going to suffer
from being heated, then that trail of flame is actually doing the best thing it possibly
can do, which is burn up all the debris.
So it never settles back on your job, now I did say that this was going to be slightly
controversial and I'm sure Thinklaser wouldn't want you to run your machine with a comet
tail.
So we're going to have to find another way of doing it.
Well I did say what we're going to do next, you will not be allowed to do half of the
things I'm able to do, so I've just had a bit of a think and a bit of a brain wave,
and I'm wondering whether an adaption that I've made to the head will actually work.
So I've turned the air assist back on, but as you can see the air assist is not exactly
going where it went originally.
Let's press the button and see what happens....
Well so far, so good.
Well we still have a flame, but of course now it's not doing any damage.
Ok so that was a bit of a failure wasn't it, um, the results were quite good, but then
again as we've seen before anything with a fiery tail produces quite good results.
Um not necessarily good for the machine as I said.
It will certainly be frowned upon by everybody, including Thinklaser.
You see, what was the thinking behind what I was trying to do.
Well it was a small shroud that i put around the nozzle and on one side of the shroud I
drilled a big hole like that, and on the other side of the shroud I put in a tube, like this,
for my air assist and the idea was that the air assist was going to go out here and as
it went out here with a sort of a Venturi effect it was going to draw air out from the
inside and hopefully produce a swirling effect as it did so.
In other words, I was producing a sort of a Whirlwind inside that enclosure, the attempt
was to try and draw air up and in, and produce a negative pressure inside there to pull the
fumes up and throw them out the side.
Rather than try and eject them up through like a vacuum tube or a vacuum cleaner that
would need an external source I had hoped to use the positive pressure of this air assist
to produce a sort of vacuum.
Well, thinking about it, it's got to be a hell of a vacuum, a hell of a suck to take
away the fumes and prevent burning.
Maybe upon reflection, not my brightest idea today.
Now apart from a little bit of collateral damage here, which a little bit of acetone
will very quickly cure, um no parts of this machine were harmed in the making of this
video.
Now as they say on kids programs, "Please don't do this at home" and in a strange sort
of way, I've got to say the same sort of thing.
I've mentioned it before, I can do things with this machine that you will not be allowed
to do because you won't be able to get into this machine to use it in the way that I am.
And I wouldn't want you to do some of the things that I am doing today.
I'm doing them so that you don't have to, if you've got an inquisitive mind then hopefully
I'm there before you and I will take away the need for you to do some of the things
I've done today.
But the fundamental lesson is, that we need full air assist when we're doing cutting,
otherwise we shall get comet trails and fire extinguishers at the ready.
We need zero air assist for clean engraving, now that is totally contrary to most advice
that you will get and you certainly won't find anything about this information when
it comes to parameters.
So I've dealt with this as a separate issue outside the parameters because I don't really
want to go back and explain why I'm using zero air assist when we talk about engraving
parameters.
It's a big enough subject all on it's own as you've seen.
Now I must hastily add quickly this applies to organic materials, acrylic is a special
subject all on it's own and it deserves a full session talking about cutting and maybe
a full session talking about engraving acrylic because it is a very very interesting material.
Thank you very much for your time and attention today and I hope you've enjoyed some of the
fireworks.
Fire extinguishers away now, and relax.
See you next time.
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