0:14Well welcome to another Lightblade Learning Lab. Today we’re going to tackle
0:20something completely different, we’re going to go back into the mechanics of
0:23the machine and we’re going to do a little bit of setting. The item that
0:29we’re going to look at is the autofocus sensor switch, otherwise known as a pen.
0:35Now I’m afraid you’re gonna have to put up with another one of my very high tech
0:39drawings. The lenses sit at different points above the work surface, which is
0:46here. The lenses in this particular machine always produce the focal point
0:51at approximately the same position. The idea is that the beam focuses down
0:58from any one of these lenses, this being a two inch, this being a two and a
1:04half inch and this being the four inch.
1:09They all focus down to this one point, which is approximately seven millimetres
1:17below the nozzle itself. I say approximately, because you cannot
1:22guarantee that to within better than probably half a millimetre, even when you
1:27change the lenses. If all the lenses were perfect then once you’ve set the
1:32laser autofocus system up, you would never have to touch it again. It would always set
1:36this seven millimetre dimension here. Built into the RDWorks software in the
1:41vendor settings, for this machine there is something called a five millimetre
1:48offset from Z-zero. What we’ve got here at the side,is a switch and I’ll draw it
1:56like this. The five millimetres that I’m talking about is relative to this work
Transcript for Laser Machine Autofocus Pen (Cont…)
2:03surface. The table will move up, it detects the switch at that position
2:09there and calls it Z zero. Then it goes into its software and it moves the table
2:16down by five millimeters and resets that to zero. So this table position is now
2:26Z equals zero and it’s seven millimeters below the work surface. Now the problem
2:33is because the lenses might not have exactly the same focal point as you
2:38change the lenses, what we’ll have to do is to be able to set this switch to suit
2:44the lens in question. So as you change the lens over we shall have to change
2:49the switch position to give us whatever this dimension is. It could be seven
2:56point five dimension, it could be six point five, we’ll have to
3:01wait and see. Okay well let’s dive in and get started should we. Okay now before we
3:10start looking at how we set this pen relative to the nozzle,
3:17I’m going to be a bit rude and say that I am NOT very much in love with this
3:24piece of engineering here. It’s aluminium, it’s very very fragile, I
3:29have actually got thumb screws in here as opposed to the cap head screws that
3:35were in there originally. Because you’ve only got to put the smallest amount of
3:38pressure on there with an allen key and you’ll strip the thread. I’ve always used
3:43these two thumb screw things,they’re not all that steady look, they you can
3:48still wobble it. You can’t, you can’t put enough pressure on it to clamp this
3:52really securely. So before I show you how to set this up, I’m going to make a
3:59radical change to this design and we’re going to replace this with my own design.
Transcript for Laser Machine Autofocus Pen (Cont…)
4:04Before you even start to think about setting up this system, the one thing you
4:12must know is what the gap is we’re supposed to have between here and here.
4:17Now for most of these lenses it’s around about seven millimetres. It would be a
4:24wonderful dream if all the lenses were set to exactly the same focal point, so
4:31that you only had to have to set this once and then after that you could just
4:35rely on the auto focus to set the correct focal point for whatever lens it
4:39is that you’re using. If we look in here, we shall see that the lens is set quite
4:43a long way back down that tube and that’s because it’s a two and a half
4:48inch focal length lens. Now what’s in here at the moment is a two inch lens
4:53and the lens will be much closer to the front of this tube. There’s also a 4-inch
4:58lens which sits right back here, so the lens will go up and down according to
5:02its focal length but the focal point will always remain approximately
5:07seven millimetres below this nozzle. Now even if you change from one, 2 inch lens to
5:14another 2 inch lens, I would advise you to check the focal distance, because not
5:20all lenses are exactly the same. One might be a Plano convex lens and the
5:25other might be a meniscus lens for example. |Whenever you change the lens in
5:29your system here in the tube and from time to time you’ll need to change that
5:33lens in there, it’s always worth carrying out the focus check. The irony of this
5:40situation is that before we can do any calibration on here, we have to have
5:46something to reference it against and so what I’ve got here are some little step
5:51gauges. This one runs in steps of 1 millimetre between 1 and 20 millimetres
5:59and this one has got an extra half a millimetre added to the bottom of it,so
Transcript for Laser Machine Autofocus Pen (Cont…)
6:05it runs from one and a half millimeters to 20 and a half millimeters. So with
6:10these two gauges we can set any gap between work and nozzle to within half a
6:15millimetre which will be good enough. Now the lens I’ve got in here at the
6:18moment is a 2 inch lens, for each one of my lenses I have already worked out what
6:24the gap is between here and the work piece and they’re not all the same.
6:28For this 2-inch lens it’s 7 millimetres, so the first thing we’re going to do is
6:35to set this gap here to 7 millimetres. Just undo that,
6:40lift the nozzle up as high as we can get it. Raise the table,
6:49when we’re raising the table you can’t really take the surface of this table
6:53any higher than the surface of the frame.
6:59Otherwise it will hit the micro switch. Okay, so we’re now going to cut our piece of
7:05acrylic and make a new bracket that goes on here.
7:17The top surface that we’re going to see is perfectly clean.
7:22Now these little nick’s in here are to make it easier for me to locate when I
7:30drill screw holes, I’ve only got to locate the drill across the work
7:35approximately in the centre, because the drill will automatically focus onto the
7:40V and hold it in the correct position relative to the centre line of the hole.
7:48So first of all I’ve got to set my piece of acrylic up at 45 degrees like that, so
7:56that my holes run vertically downwards. Now I’ve already drilled and tapped
8:01those holes m4, but what I will do is show you how I went about tapping those
Transcript for Laser Machine Autofocus Pen (Cont…)
8:07by doing the last one. the V will automatically line the drill up this way all I’ve got
8:13to do is concentrate on getting it approximately in the centre of the V,
8:19like that.
8:25I’m going to remove the belt from the drill spindle so that the Chuck is
8:28rotating manually, because I’m going to do a bit of an engineering cheat and I’m
8:33going to use this drill as a hand tap, but I’m going to do it so that it holds
8:38the tap perfectly in line and tapping my m4 hole in there. Now what I’ve got is an
8:46o-ring, I could have used a small compression spring but I decided that
8:50people probably won’t have a spring, but you certainly might be able to get hold
8:54of an o-ring very cheaply and this will do the same job. So what I’m going to do
8:58is to snip a piece of that o-ring out, about a quarter of an inch long. It’s got
9:03to be approximately half the distance to this edge here. We’re now going to remove
9:12this,
9:16undo this, take it off remove the pen. Wow,
9:26so now we’ve really upset the settings, that were supplied with the machine.So
9:33hopefully, if I’ve designed this correctly that will be quite a nice
9:37slide fit in there, which it is and what we’re now going to do is to put
9:41the piece of o-ring into the hole that’s at the back there, that flat hole,
9:52and we’ll put in a m4 screw in behind it. We should see the o-ring just start
9:59to come through the hole. What we’re trying to do is to get this so that it
Transcript for Laser Machine Autofocus Pen (Cont…)
10:08is, when you tighten that screw up, you can still move it like this. It’s clamped
10:16but not clamped. It’s clamped but still able to slide around like that.
10:23Okay, so what we’ve done we’ve actually put a small compression system in there
10:27that allows you to adjust this very accurately and it will stay put and then
10:33through here we can now put a cap head screw. Because A:
10:40we’ve got a lot of material here and B: we don’t need much clamping load and we
10:44shall do the same in there. We’ll put a cap head screw in there. We’ve only got
10:48one clamp screw in here this time instead of two and that’s because
10:52basically what we’ve got here is a V block. I’ve changed the design so that
10:56it’s located here and here and clamped just there. So now when I slip that on,
11:03and put that back in there,
11:09like that. I shall be able to clamp that up and feel it snuggle up like that, put
11:17just a small amount of load on it and that will be really a nice stiff
11:22positive fixing for this. But bear in mind that this we can still move it
11:30around you could go back and look at session 10 to find out how you would
11:36find the exact focus for this nozzle. It really doesn’t matter where you do your
11:45location and reference from and we’re going to set it off a block, we could set
11:50it off this surface, but it might be too low. So the first thing we’ve got to do
11:57is we’ve got to raise the table so that we’ve got approximately seven
12:01millimetres under here well in this particular instance I know it’s exactly
Transcript for Laser Machine Autofocus Pen (Cont…)
12:04seven millimetres. 10, 9, 8, 7 is there, I’m gonna drop that down onto the gauge like
12:15that. Hands off, just so that there’s no pressure on anything and then I’m
12:20clamping it up. So that’s my seven millimetre position.
12:24This has to be switching exactly five millimetres above the same work surface
12:32and hey look I’ve got a five millimetre gauge here and I can now adjust this up
12:40and down until it just touches the step, but that’s not going to help me.
12:46So now we’ll come across to the keyboard and we’ll press the Z/U button and
12:52we’ve got to use the arrow keys to go right the way down to the bottom and
12:57down this list as well until we find diagnosis.
13:06Enter, and in diagnosis we shall find that we’ve got a series of basically
13:13indicator switches and just here we’ve got Z plus and Z minus. So if we now
13:22tweak very carefully the limit switch, the pen, what we should find is that at a
13:31certain point it will change. Pull it up and just gently put it down again,
13:38until you make the switch go red and there we go. Okay, so now we can tighten this one
13:45up, we can feel it now, snuggled up and what we can do is test it. We will just
13:55exit, escape from this screen and we get back to this screen here where we can
14:00press the up arrow until we get to autofocus. Now I purposely moved the block
Transcript for Laser Machine Autofocus Pen (Cont…)
14:07out of the way, just in case there’s any risk of
14:12something going wrong. Better safe than sorry, so if we press autofocus, enter
14:27and then it drops away five millimetres, which is why we used that five
14:32millimetre step,
14:37and now if it’s all worked properly we should find that we’ve got a seven
14:44millimetre gap underneath there, just like that. Look, absolutely perfect,
14:51seven millimetres. If all of a sudden I decide I want to do something, I want to
14:58clean my lens for example. So I need to take my lens out, well rather than take
15:04everything out we leave that behind, we shall often need to take that off to
15:10clean the end of the the actual nozzle itself to keep that nice and clear.
15:14Because that’s an, if you like something that people tend to overlook. Now we’ve
15:19done that, we put this back on
15:26and the first thing we do is push everything right to the top, push
15:32everything right to the top and tighten it up again.
15:35We’re guaranteed that our clamp is sitting down on this shoulder which is
15:39most important. Okay and from now onwards we’ve got the autofocus set. It doesn’t
15:46matter that we’ve had it off and put it back on again because this point, switch
15:53point here relative to that shoulder has not changed. We’ve got lots of space down
15:58below now we’ve turned the block over and let’s just do another autofocus. Run
Transcript for Laser Machine Autofocus Pen (Cont…)
16:04to the bottom of the list, autofocus, Enter.
16:28So we’ll just use the real world to check again five, six, seven, they won’t go
16:37on eight and it’s just a lovely slide fit under seven. So that switch is set
16:44absolutely perfectly, now you’ll need to do the same thing for every lens that
16:50you’ve got in your system. Check where it’s true focus point is and come back
16:56and do this same procedure. Now if you didn’t make these the first time round
17:00and these are made out of five millimeter material just so that they
17:03stand on their edge and are self-supporting. If you find they’re not
17:07exactly the dimensions that are shown on here either you can tweak them yourself
17:12or leave them as they are because you’re not interested in real-world dimensions
17:18what you’re interested in is the numbers that are on these here. So for instance I
17:25don’t know whether that dimension that I’ve just set there is exactly seven mil
17:29it may be 7.3 it doesn’t matter because whenever I set it up I’m using this
17:35gauge.
17:37Some very observant person is going to say, “yeah but look I’ve got a screw here,
17:45if I undo that screw I can adjust the micro switch from up here”, yes you can do,
17:54but it’s a lot more fiddly and you don’t have the same precision control that you
17:59do down here with my friction system that I’ve introduced. This will be very
18:05much more difficult to actually set, so I would advise you not to touch this one
Transcript for Laser Machine Autofocus Pen (Cont…)
18:11and just do your settings down here with this one screw. Now I’m personally not a
18:16lover of the laser autofocus system because it gets in the way of me messing around
18:22with the Machine far too much and I’m going to give you an example of that now.
18:27Look we’ve just set this up to etch for example on this surface, fantastic.
18:39If I want to raise the job and I go to Z/U and I try and raise the job, I can’t.
18:47I can lower it, but I can’t raise it. It’ll only come up to zero which is the
18:55autofocus position. So all it will ever do now is come back and set to seven
19:03millimetres IE zero Z. So if I want to for instance go and engrave something on
19:10there what I’ve got to do, is I’ve got to go all the way through to Z/U and
19:17down to autofocus again.
19:40Which is fine, but I now want to set up for another job and I want the table up
19:47how do I get the table up because it’s already at zero. So when you start the
19:52Machine up when you press reset, it automatically cancels your auto zero and
20:05now you’ve got full control of Z and that’s how I tend to operate the Machine.
Transcript for Laser Machine Autofocus Pen (Cont…)
20:11Because if all of a sudden I want to bring for instance that surface into
20:15play Z/U button, raise the job up, I just
20:18drop my gauge under there with the seven mil step, let that drop down onto it, job done!
20:27The only reason I could see, that you’d want an auto focus system, is if you wanted to
20:33do some sort of in-process change of height. Now I don’t know what the in
20:40process change of height would be, I’d not discovered anything in the work that
20:45I’ve been doing over the past two years where you have to change the focus
20:48height during the process. There is a myth going around that if you want to cut
20:54thick material you should drop your focus point to something like about a
20:58third of the way into the material. Well all the experimentation work I’ve done
21:03shows that I don’t get any advantage. I leave my focus point set always on the
21:11surface of the job and just adjust the speed to get the cut right. Now although
21:16I’m not a convert to this system, I’m very happy to make it stable and to show
21:22you guys how to set it up. If you have a real need for it within your process
21:27then fine. In theory this is a good idea, in practice it’s about as useful as this
21:35other thing that I have strapped up. This is the red dot pointer, so when you’re
21:41not looking I shan’t be using this laser autofocus system. I
21:45can leave it like this, it’s not dangerous like this and I will be able
21:49to set this up in a tenth of the time that it takes for the
21:53laser autofocus system to work and it gets even worse if I’ve got a very small
21:59product that I want to put on there for instance let’s just say I want to
Transcript for Laser Machine Autofocus Pen (Cont…)
22:03autofocus on that now. Let’s just see what happens. All the way down to autofocus,
22:11press the enter button.
22:21Ah it’s now hit the limit stop for the table and so what it will do it will
22:26find its limits position there and then it will drop down to a safe position,
22:32like that and now I can drop this down until it just about touches the
22:39surface and then I can lock it up and now I’ve got to go through the whole
22:43process again. So we’ve got to set the Z/U button, go down to autofocus and
22:51press Enter.
23:09I’ve just wasted a minute of my life and at my age I can’t afford to do that. Well
23:17here we are at the end of this session and I’ve got to make it very very clear
23:23that some of the opinions that I have expressed are very personal opinions,
23:29there is no criticism of Thinklaser and the product that they are selling. This
23:35is a well engineered product and it is in demand by the marketplace, so all that
23:41Thinklaser are doing is satisfying that demand. It’s just that the marketplace
23:46doesn’t realise that there is very little use for this lovely feature. If
23:50you’re going to do some acrylic origami work and I’ve seen some great stuff
23:54online well I was quite excited at the possibility, but I’ve never got around to
24:00it. The need has never arisen, I haven’t got a business that would require it, but
Transcript for Laser Machine Autofocus Pen (Cont…)
24:05maybe you’re in a business where you have got that specialist niche that
24:10really requires this laser autofocus system, but I hope today that are demonstrated
24:15that those people that think they need it probably don’t really need it. It would
24:19be a lot quicker to set the Machine up manually. I don’t want to take anything
24:23away from the quality engineering that’s been built into this machine. Well thank
24:29you very much for your time and your patience for listening to the rantings
24:32of an old man. I shall see you in the next session.
