00:14
Now welcome to another Lightblade learning lab today we’re going to do
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something a little bit different now just recently I detected some rather
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strange performance characteristics in my 60 watt tube
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I call them strange they’re strange to me for most in inverted commas normal
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people and people that use the machine for daily production there would not be
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an issue at all but because I’m using it for test work and for experimentation as
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well as the little bit of work, I was finding some inconsistency which meant
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that I couldn’t demonstrate some of the things that I wanted to demonstrate to
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you easily and so consequently I had a few words with Thinklaser and they sent
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an engineer down who looked at the problem and decided yeah it was worthy
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of changing the tube so under warranty without any questions at all I have a
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new tube now the new tube is not in there it’s in a box over there I’ve got
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to fit it that was my choice because I felt that if I fitted that tube it would
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give me an opportunity to show you how easy it is to actually fit your own tube
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what I’m just about to say might sound like a bitch but it’s not Thinklaser
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have supplied in this machine the 60 watt machine one of the cheapest EFR
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tubes you can get now as I said that might sound like a bitch but in fact in
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a strange sort of way it’s a bit of praise because first of all they’ve
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chosen a very good quality tube EFR and EFR manufacture three ranges of tubes
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they manufacture the CL range which is I suppose it could be called the basic range
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which is something that’s been around for many years and it’s design has
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gently evolved and it’s still called the CL range now that’s got a supposed
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life of 3,000 hours they specify in here and I’ll read the words working life
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3,000 now 3,000 hours is only four months, four months? No, it turns out from
Transcript for How to Change a Laser Tube (Cont…)
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the information that I get back from Thinklaser that they’ve been told from
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their contacts in China that this working life actually means shelf life
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like most things that come out of China cynically he said we don’t necessarily
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believe these numbers usually if it says 3000 hours
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it means 2 hours 50 minutes in this particular instance I think 3000 hours
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is a gross underestimate first of all I’ve already had this tubing here for
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more than six months so first of all that numbers bombed out the water I’ve
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got a machine over there which has got a tube life of supposedly 4,000 hours
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when I bought it I’ve had it now in there for about 14 months which is over
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10,000 hours so it’s already gone two and a half times its projected shelf
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life so we can’t really attach a great deal of credence to these working hours
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life because that working hours implies beam on and yet the information that
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they get implies its shelf life who knows all I can say is that lots of
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people have got evidence that tells us that these numbers are way way low if
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it’s shelf life now as well as the CL range the next range that was developed
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by EFR was an F series and the F Series has supposedly got a working life up to
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6,000 hours now although they give the working life of 6,000 hours just like
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RECI or RECI you say tomatoes I say tomatoes um both of these very large
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reputable companies use rather weasle words when it comes to warranty
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on the tubes I mean this 6,000 hours which is eight months has got a warranty
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of 300 days but that’s about right but the first hundred fifty days from exit
Transcript for How to Change a Laser Tube (Cont…)
05:00
works date on the label they do a free of charge replacement if there’s a problem
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but there’s all sorts of riders attached to that and then from the hundred and fifty-first day to
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the 300th day there’s another set of conditions so basically the warranty
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promises that you get with these tubes are to say the least vague the fact that
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Thinklaser came in and just immediately said we’re going to replace
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that under warranty probably didn’t mean that they were going to replace under
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the tube warranty but under their warranty which is great news now there
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is another series which is called the ZS series which is going to have 10,000
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hour working life now there are also additional benefits to this tube as well
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as it’s working life supposedly but in essence what it amounts to is and I’ve
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got some prices and different prices down here if you buy them directly from
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China for example with this ZS tube cost two hundred and seventy-five
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dollars that’s the best price I could find but then again it was three hundred
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ninety dollars shipped and then in addition to that you’d have to pay tax of some
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sort when it arrived in your country so you know at the end of the day that’s
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five six vertually six hundred dollars plus tax for a top-of-the-range
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ten thousand hour tube the middle of the range tube the best I could find was
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including shipping at one hundred and seventy-five dollars plus three hundred
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and thirty one which again is about four and eighty five hundred dollars so it’s
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five hundred six hundred dollars for ten thousand our five five hundred dollars
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for a six thousand dollar
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and here we’ve got something like about $300 total including shipping for a
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three three thousand our to you now at the end of the day three thousand hours
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as we said it’s rubbish it’s substantially more than that and to be honest I
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believe that Thinklaser have actually made the most economic choice by putting
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this bottom of the range tube in, look whether it’s a mini a Ford or a Ferrari
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sixty miles an hour as sixty miles an hour there is no difference in
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performance only how quickly you get there and the luxury with which
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you do it the one thing that really can’t change with a machine like this is
Transcript for How to Change a Laser Tube (Cont…)
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sixty watts so I’ve been supplied with a bottom of the range tube which I believe
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is the most economical and the best tube for this machine and I suspect that this
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tube is going to last me anything from eighteen months to two years which
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nobody’s going to complain about that bearing in mind Thinklaser don’t have
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years and years of experience with these tubes it’s very much here so they are
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taking this bit at face value and what they’re saying is at the end of their
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one-year warranty they will supply you with a brand new tube now that’s a
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fantastic offer but it does mean to say that either you’ve got to pay them to fit
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it or you fit it yourself and that’s what I’m going to show you today how you
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fit it yourself because it is a very very simple task
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now I’ve already taken the protective cover off here as you can see and now
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I’ve opened the lid and you can clearly see what it says on the end of this tube
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danger, there’s 25,000 volts or more at that end there now if you’ve recently been
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running your machine or had it powered on I ernestly advise you to turn the
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Machine off and leave it walk away for an hour because there’s possibly still
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some dangerous voltages stored in capacitors and various other things in
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the power supply now I don’t know and I can’t be absolutely sure because I’m not
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an electronics expert or an electrician but it’s a general safety precaution to
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let any high voltage leak away now do not disconnect your machine from the
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power supply while you’re doing that because it probably needs the little way
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to earth somewhere if you disconnect it from Earth
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it might not leak away so only when you get to the point where you’re going to
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mess around with this should we disconnect the machine now down at the
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bottom there it’s clearly marked with a 220 volt input disconnect that plug and
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now you know the machine is completely safe so before you start you need to
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disconnect the tube from the machine now I’ve done that by brutally snipping the
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cables because the connector that was in there I couldn’t really replace so I’ve
09:54
got several options one of them is very easy and straightforward the second one
Transcript for How to Change a Laser Tube (Cont…)
10:00
is a practical solution for most people because they won’t have these things to
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hand now these things happen to be crimp connectors and they will allow me to
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join two pieces of wire together inside that insulated sleeve which is
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fantastic but you might not have the ability to do that so what we’re going
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to do is show you a possibly an alternative way and the alternative way
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is to use one of those now I’m going to destroy this because I’m going to cut
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cut one piece off and then very carefully without cutting my fingers off
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I’m going to slice the back off like that okay now with a screwdriver
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I should be able to push that metal connector out now that’s got two screws
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on it which will enable me to join the wires together because most people have
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got these little connector blocks somewhere in their workshop so that’s
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stage one preparation there is another important stage that you need and
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that’s to get some sellotape or some masking tape now stage two is to unwrap
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the tube so take the clamp screw out it may or may not come out but don’t lose
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the screw and this flexi clamp lifts up a long way the tube is completely free
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except that the water pipes are still connected but there’s a good reason for
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that and that is the fact that we’ve got water in this tube here now before we
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start the next stage we need again to prepare we’ve got a little bucket here
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nice clean plastic bucket and we need to stand that underneath this return pipe
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here there’s a possibility that we’re going to get a bit of leakage out of
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here when we take this pipe off or at least when we start emptying this tube
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well I’m now going to follow this pipe here and this is the water outlet pipe
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and it comes all the way down here there’s a label on here that says water
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outlet so follow this water outlet pipe back to the chiller and now we’re going
Transcript for How to Change a Laser Tube (Cont…)
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to remove this pipe from the chiller but before the pipe comes off make sure you
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clamp the pipe tight, there we go we don’t have any loss at the moment but
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keep that bucket under there because it is likely that when I hold keep it
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clamped now I’m up in the air I can undo it let go of the clamping and this is
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where I need the sticky tape because I’m going to have to put this pipe up here
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and that makes sure that the water can’t run uphill ok now I’m going to take it
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off for a moment because the next trick is to actually blowi into it and what we’re
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going to do we’re going to blow the water back along here and down
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into the reservoir and that’s when we might get an overflow
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there we go you can probably hear the water flowing now because that’s a
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sealed bottle down there I suspect that what’s happening as I’m
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blowing I’m actually blowing some more water up here but at the moment the tube
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is virtually empty so I’ve got rid of the water out of the tube and now I can
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stick my tube up here so that it doesn’t leak anywhere then we should be able to
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now remove there is just a little bit of water in there but it’s not going to
14:25
cause us a problem I’ll now take that one up as well I’m going to connect this
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end back down onto the chiller now because it is empty and I’m now going to
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remove this one from here just in case I’m going to take that one up there as
14:49
well as you can see here we have one more cable that’s connected and that’s
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this cathode cable from the cathode end of this tube so let me disconnect that
Transcript for How to Change a Laser Tube (Cont…)
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just a tie wrap there and probably a crimp connector underneath there as well
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now this end doesn’t have any high voltage on it at all this is this is
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completely low voltage this end and we’ve got a bullet connector on there
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which is probably okay but if you don’t have a bullet connector in other words
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once you’ve broken that you might not be able to replace that, again what you can
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do we can use one of these connectors a screw connector and that’s what I’ll do
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inside that piece of insulated sleeve so now that I’ve disconnected that black
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wire the tube is completely free and we should be able to lift it out
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okay now I’m just going to put a piece of white paper behind this tube because
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I want to show you something now starting with the most expensive tube
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one of the things that they claim on here is long lifespan catalyst coated
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discharge tube okay now that’s normally something you only find in the long life
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tubes so let’s go back to the 6000 hour and here it says long life the catalyst
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coating on discharge tube that’s the key thing a catalyst coating so when we get
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to the cheap tube the 80 watt tube catalyst doesn’t say yes doesn’t say no
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with the 1200 CL tube which is the one that we’ve got here it clearly says
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catalyst yes and I can see that can you see that pink tube in the middle there
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the fact that it’s pink tells me that it’s been flash coated on the inside
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with gold and that gold flashing is an indicative feature of a long life tube
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it helps to recombine any free oxygen with the carbon monoxide to keep the co2
Transcript for How to Change a Laser Tube (Cont…)
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up to a reasonable level it delays the death of this tube and so this is a
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hallmark of a very very good tube now you won’t find that catalytic tube in
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most economy tubes should we call them okay now sadly the first thing I see is
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I’ve got to be a bit brutal with this tube because it’s got a very very nice
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connector on it which is a proper high voltage connector but I don’t have the
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mating female connector that goes on the other side of it so I’m gonna have to
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cut that off there and make the connection as per we
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discussed so obviously this Red end the red cable
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a high voltage cable goes to this end because that’s the way that we took it
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out this cable here is to come down oh
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they’ve already supplied me with a little connector there which is great
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they’ve already supplied me with a bullet connector well that’s good news so I
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haven’t got a fiddle with that end so there’s absolutely no reason why this
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needs to be fully protected this end
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there is no, there’s no voltage here at all and current well current is very
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minimal it’s only somewhere in the region of around 25, 22 to 25
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milliamps so we can lose that back inside there and that’s that end made off
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we’ve got a fair amount of tube here and that’s good because what I want to do is
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to nick something like about 2 or 3 inches of that tube and we’ll plug that
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back on there and we turn it so that it sits at 12 o’clock and we push it back
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as far as it can go because I need a reasonable gap here to do my tests so
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somewhere in the region of about 40 millimeters I’m gonna leave here I will
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try and just take the end off of it with a cable cutter
Transcript for How to Change a Laser Tube (Cont…)
20:07
and as you can see there’s a plastic coating inside it’s double thickness now
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I don’t think I should be able to get that layer off because it’s bonded on to the
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cable inside is it not taking a huge amount of current it’s just taking a
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huge voltage so that’s one end now as I said, sad to say I’ve got to be brutal
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with this end so I’ve got a nice tight screw clamp connection on there so just
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to be doubly doubly sure before I put over a high voltage connection now that’s
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cleaned it out nicely we’re going to pop that on there like that before I connect
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this side up there we are a nice positive connection it’s only got to
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carry a few milliamps as I said the problem is trying to keep the very very
21:23
high-voltage electricity away from the air because if there is any dampness in the
21:27
air effectively what we’ve got is the potential for lightning between here and
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the chassis somewhere ground and so what we have to do is make sure that we
21:36
completely isolate it that’s why I’m using this thick silicon tube it makes a
21:41
fantastic insulator and we can slide that inside the tube like that and what I’ve
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got here and you can buy this from places like Maplin now this is a white
21:58
silicon sealant and adhesive it’s not bath sealant whatever you do don’t use
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bath silicon because bath silicon has got chemicals in it which you can smell
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and it will corrode the joint in there so you need to go and get non-corrosive
22:16
silicon right there we go we put some in that end like that now as you
22:22
can see that is very nicely sealed off around this cable and the inside of the
Transcript for How to Change a Laser Tube (Cont…)
22:30
tube so there’s no chance of any air getting in there it will probably take
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half an hour to an hour to dry now I’ve put the cable tie on the other end
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because I thought it was going to run right the way through but it hasn’t
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it’s horrible stuff if you get it on your hands and there we go we put a cable tie back on
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this end as well so there we go I’ve just wrapped that round here and it’s
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in its ,this is sitting right in fresh air so there’s no chance of any
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discharge to anywhere and I’ve just tied wrapped it against itself so we can put this
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water pipe on here at the end there’s only one place to put it because there’s
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only one connection free so we will just check that we’ve got clearance on the
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end of our tube when I put the case on so we just put the case on just test the
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case on there and yes it looks as though we’ve got about 3/4 of inch to an inch
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clearance which is fine. We’ve got our cathode connected, we’ve got our anode connected,
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we’ve got our water outlet connected and we’ve got our water inlet
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connected we’re basically done I’ve set this gap here to about 40 millimeters
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which is what I need but if you want to set it closer you can do so now we’ll
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just clamp the tube back up now because these tube clamps have not been moved
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basically I would expect the tube to be fairly well aligned it might need a
24:17
tweak, the beam alignment but that’s all just a tweak and that’s it the tube is
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fitted it’s no more complicated than that 4 wires
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and two water pipes and a little bit of care about how you connect it up it’s
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the method rather than the difficulty one final little job to do so I’ll just
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cut the bottom off of an old water bottle and make myself a temporary
24:50
funnel otherwise this could be a little bit of a messy job job done and that’s
Transcript for How to Change a Laser Tube (Cont…)
25:13
the final little task so we leave it for a few hours now just to let the sealant
25:18
settle around the HV connection and then we can give it a try well we should plug
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the power back in now and we’ll turn the machine on so we’re going to have to
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make sure the tube fills up with water to start with. Here comes the water
25:40
through the tube
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and it’s cleared the bubbles absolutely perfectly so the first thing I’m going
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to do is set max power make sure it’s about 25% which it’s not at the moment it’s
25:56
70% and now I’m going to press the pulse button and we’re just going to check
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what happens there we go look we’ve got a beam very nice okay now in the past
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I’ve used these target holders that we’ve made to sit on the mirrors and the
26:18
targets but if you happen to be unlucky enough to have a machine and you haven’t
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made these then you can’t use that sort of target so what I’ve got here is
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something, a slightly different approach which maybe even Thinklaser can supply
26:39
with the new tube and that’s these little targets here
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so we’ve pull one target off and we’ll go round to mirror one what we’re going
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to do is we’re going to pop this into the mirror orifice and I’m just going
26:56
to hold it in place with a little piece of tape across the top like that now I’m
27:02
going to turn the power down to 15%
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I would say it looks as though that beam has got to go up by about two
27:13
millimetres now how do I get the beam up by two millimetres I want to lift both
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ends of the tube up by the same amount i.e. two millimetres we’ve got these
27:25
screws on here and underneath here we’ve got like a locking collar now that
Transcript for How to Change a Laser Tube (Cont…)
27:35
locking collar can lift up and down
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it’s an adjusting collar twist it down so that it sits on the top of the pillar so
27:46
I happen to have a piece of Perspex here which is two millimetres thick what I’m
27:51
going to do now is once this collar is sitting down on the top of this pillar
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and I’ll make sure that the one at this end is the same I’m going to undo these
28:00
two screws here which will allow me to lift the beam up and I put that spacer
28:08
underneath there and I will lock the screws back up and I’ll do the same at
28:17
this end undo the screws
28:27
lift it up by two millimeters and re clamp it and now it’s gone too high so it
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probably only wants to go up by a millimeter okay well I’ve got a piece of
28:43
one point one millimeter thick material so I can undo the screws again and let
28:53
it drop down onto that piece of material and tighten up the screws
29:04
now that looks to be pretty well spot-on so let’s just run it once more and
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that’s not looking bad at all okay so we’ve driven mirror 2 right to
29:15
the front edge of the machine we’ll put a target into mirror 2
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what we can see that it’s quite a long way out on mirror 2, height is not bad
29:32
this mark is what I call a sighting mark so what I’m going to do is to tip
29:38
mirror one very slightly okay now that’s not far out it does not have to be
29:45
perfect it has to be more or less on center but you know a millimeter
29:50
either way is not probably we replace that target and this time we’ll bring
29:56
the head right to the back of the machine, this burn is what I call a
Transcript for How to Change a Laser Tube (Cont…)
30:02
target burn okay now that’s our marker it’s actually not bad move back to the
30:08
front of the machine and now what we’ve got to do is got to make a mark that
30:14
matches that one we’ve got to adjust the mirror so that the two marks are
30:22
coincident as you can see it very slightly to the right so I need to take
30:27
a little bit off that mirror too much
30:36
and that looks pretty good now not only do they line up with each other they’re
30:41
also more or less on center now it means that the beam is actually lined up with
30:49
this y-axis in both the horizontal and the vertical plane now we’ve got to get
30:56
the beam on to the centre of mirror 3 so we will first of all
31:05
go for our sighting there is another size in here which is a slightly
31:11
different sized target which we shall need to use for this particular
31:14
situation now which will definitely need a small piece of tape on this one
31:20
because there is nothing behind it there’s no mirror behind here to hold it
31:25
so what we’re going to do is we’re just going to drop that into the hole
31:28
okay so I’ve now got the head pushed as far away from mirror 2 as I can get it
31:34
and we’ll do a sighting pulse well
31:44
it’s not terrible but it’s not brilliant but not to worry at the moment because
31:51
what we’re going to do is we’re going to do a target pulse and so here we are
31:58
right up against Mirror 3 (means mirror 2)
32:08
and that’s our target pulse. Sighting pulse,
32:12
target pulse and then alignment is the procedure that you’d go through for each
32:17
one of these axes so that’s our target pulse let’s see where we are
Transcript for How to Change a Laser Tube (Cont…)
32:31
well I would say we’re possibly just about half a millimeter high so we need
32:38
to just drop that very very slightly I now just tweaked that mirror
32:49
I would say that that’s probably just about spot-on and this is where people
32:55
get, can get very confused and why I personally believe that these machines
33:00
are not really designed to make it easy for beam-setting I personally think that
33:07
mirror number two should be a static mirror and then this one should be an
33:14
adjustable mirror because what we want to do now is to move that head to catch
33:20
the beam on that Center we can’t adjust the mirror anymore
33:24
because we’ve already got the mirror set up so that it is the beam is running
33:28
horizontally and vertically true to this X but of course as soon as I twist that
33:34
mirror through 45 degrees look what happens to it it shrinks its height
33:41
changes and it’s no longer 23 millimeters tall it’s probably only
33:46
about 13 or 12 millimeters tall we’ve got to be very accurate with the
33:51
alignment of our beam in this up and down vertical axis how are we going to
33:56
get that beam down well we could go right the way back to the later tube and drop
34:02
it down but hey we just raised it by two millimeters to get it central on the
34:07
other mirrors well the other mirrors are twisted this way so they are a lot less
34:16
sensitive in the height position than mirror number three
34:23
so I’ve got two choices there are some adjusting screws on here which will
34:31
allow me to adjust it this way by a small amount which I could certainly use
34:35
to get this in but I’ve got no adjustment up and down on this head
34:41
other than to put some packing pieces underneath there in other words I could
Transcript for How to Change a Laser Tube (Cont…)
34:51
shou the head up a possibility but a bit of an ugly solution so what I’m going to
35:01
do is go right the way back to the back and drop the beam down by the millimetre
35:06
that I lifted it up fortunately I left the collar set that’s only a matter of
35:14
loosening those screws and dropping it down onto the collar tightening the
35:19
screw up and doing the same at this end and let’s see what effect that’s had on the
35:26
position of that beam hopefully the beam should have dropped down a
35:29
millimeter. And there it is
35:45
and that’s back to spot-on now what it does mean is that the other mirrors are
35:52
very slightly compromised because those mirrors are twisted this way I’ve got to
35:59
be accurate in the horizontal plane less so in the vertical plane so it isn’t a
36:05
big issue this one is absolutely essential now it is very very slightly
36:11
maybe half a millimeter out of position in this direction but again because this
36:18
mirror is tipped this way I can afford to be very slightly out in this horizontal
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direction and so I’m not going to go hunting any further for the problem at
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Mirror three that’s as good as I can get okay now we’re into the final stage of
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setting this beam up which is trying to make sure it comes down here vertically
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to get to the lens now to do that I’m going to remove the air assist and we’re
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going to remove the lens tube itself
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now I’m going to sit that target on there and I’m going to raise the table
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not too much and only guess roughly where the centre is it doesn’t matter
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too much let’s just show you what I mean I know it’s not on center but that
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doesn’t matter because what I’m going to do is to drop the table down by about
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two inches this is the same three-step approach that we used for the mirrors
Transcript for How to Change a Laser Tube (Cont…)
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this is our target pulse well I think you can see that the difference is nil
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which means that that beam is coming true right down the center there because
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it hasn’t deviated in X or in Y that’s about as far as we can go the beam lines
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up with everything as we require it now we haven’t had to do a great deal but
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the one thing I just reinforce to you again is the 3-step principle that I use
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it’s taken half an hour because I’m showing you what I’m doing it would
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probably normally take me no more than about five at the most 10 minutes to
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fiddle around with this three simple steps remember move things as far away
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as you possibly can and get a burn so that it’s approximately in the area
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where you want it that’s what I call the sighting burn then we move this mirror
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close to the other mirror that we’re trying to set up and we then do a target
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burn then we move it back far away and we align the mirror onto the target burn
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those are the three simple steps once you’ve done step one two and three you
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only need to keep repeating steps two and three two and three and you
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shouldn’t have to do that more than about once or twice and you should have
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the beam perfectly aligned with the axis that you’re working on okay let’s put
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this back together now we can now use our what I endearingly called the laser
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thermometer
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this is the final test because we don’t want the beam to clip the edge of the
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orifice otherwise we should be losing power and it does look as though the
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beam is sitting down here at about 6 o’clock so we can really do with trying
Transcript for How to Change a Laser Tube (Cont…)
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to tweak that beam up to a slightly different position now we know that
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they’re all in the same position so we don’t have to go around and check every
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other because we don’t have to check all the positions again so all we need to do
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is just check it in one position
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and there we go dead center so that’s the final check to make sure that the
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beam is not clipping the nozzle it’s got to be in the center of that target give
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or take about point two or point three of a millimeter now unless you have a
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big block of perspex like this you won’t be able to carry out this final test but
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this is something I like to do and I put this right towards the edge
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I’m holding the pulse button on
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okay so that’s the beam going down in relation to a set square I think you’ll
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see that it’s pretty well up right and then if I check it in the other
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direction
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it’s not too bad either well I can remember the feelings that I had the
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very first time I started fiddling with my mirrors was I ever going to get the
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machine back into working order again I hope today’s session has done two things
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for you one it’s given you sufficient confidence that you will be able to dive
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in and change your own tube and if as a result of that you find that you need
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to adjust your mirrors to get the beam back into good alignment then I hope I’ve
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taken the mystery out of that for you now this very simple three-step
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procedure for each axis as I’ve explained it to you is a foolproof
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method it will work every time but you have to think about whether you’re going
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to move the source of the beam or catch the beam today I think I demonstrated it
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would be good and simple to catch the beam but we’ve come up with a compromise
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which works perfectly well on this machine and I’m very happy that this
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machine is completely set up now that we’ve got the machine back into good
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working order in the next session what I need to do is to establish just how good
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that new tube is so we need a record of its performance today
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Brand new. I’ll be going through that process in the next session so until the
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next time thanks for your attention
