[Fertito]

Hello there!
I'm french hobbyist specialized in kite and paraglider building, I can make up to 10 wings (all discipline included) per year.
Some time ago (nearly 6 years) I started building plotter/cutter for such materials, I've got 2 proto plotter working (1 at a friend house, and 1 in a hangglider factory), and now I'm using a pizza wheel cutter to cut the materials.
here is some pictures :



I'm planing on buying a 20w CO2 laser tube to do the job, and mount it on the plotter instead of the cutting wheel.

thanks to this forum to make it possible...

[zax15uk]

Hi, I would suggest you try on a laser first, if you haven't already. Nylon cuts clean but in my experience some Polyester melts and does not like to cut very well.

It could be you just need more power for a good clean cut, 80W CO2 may work ok.

Zax.

[Fertito]

Hello,
I spent some time gossiping with the manager of a paraglider factory, He told me they were using a 28W (synrad) laser at nearly half power for nylon, a little more for Dacron (polyester) and that they also cut fiberglass with it (in fact these are thread of fiberglass between 2 layer of mylar).

Maybe I'll try to buy a 25W laser or so, try it and after that I'll try to implement it on my plotter.

I forgot to say that I develop my own software for my plotters

[zax15uk]

I haven't tried fabric, it was Polyester (Mylar) sheet. So a woven fabric is probably much easier to cut since each fiber will seperate.

Are you using a step/direction driver and your software or have you developed a PLC design?

Zax.

[Fertito]

when I started building my first plotter, I was using a simple ULN2003 to drive the stepper and was working coil by coil...
Now I'm using L297-L298 or so step/direction driver and this is easier...

[Fertito]

juste received a price from Eclaser:
25w laser tube : 127$
40w psu : 172$
lens : 28$
shipment & insurance : 209$ (ouch!)

thinks I'll go for this...

[zax15uk]

The glass tube is fragile, so they probably expect a few aren't going to make it. Don't forget the mirrors, unless you already have them.

Keep in mind the 25W Chinese tube is not near equivalent to the 28W Synrad, you'll need at least a 35W and probably 40W to compare.

Zax.

[Fertito]

I don't need mirrors, I want to put the laser head in a vertical enclosure with the lens directly in the path.
my plotter is 2 meter x 3 meter and will soon become 2x6 so I don't want to play with focusing...

I'll first do a try with a 25w laser tube, what I found is only a few watts are needed to cut such fabrics (less than 10) at a fast speed.
My plotter is not going that fast, only 10cm/s and I don't need it to go too fast.

Aeronaut has a 40w laser head that can go up to 1.2m/s... I don't need this.

And I don't want to cut steel, I just want to cut low temp melting fabrics.

[zax15uk]

Mounting a glass CO2 tube to your Z-axis is not a good design, I know it seems like the easy and logical setup but it isn't. The motion and vibration will result in a cracked center tube (it is basically suspended within the outer water cooling tube). Even though the machine isn't moving fast, it still changes direction quickly which is where the stress comes from. If you have steppers there is also resonance to consider.

Not to mention the water supply, HV connections etc.

Mirrors aren't that expensive and would make a much more robust system.

Zax.

[Fertito]

I was thinking of doing something like Aeronaut :

with the water also on the head, the only things was to bring the HV to the laser.

My software integrate a speed correction algorythm to avoid fast direction changing, the speed decrease has the curvature of a curve is prononced.
And my head is already nearly 4kg, I let you imagine the torque needed to stop it when it run at full speed (I can go up to 40cm/sec).

But I'll reconsider my design, you are right.
I would have prefered the laser on the head for more safety, and to avoid a focusing system as the minimum lenght of the laser beam will be less than 40cm, and the maximum will be 8m...

thank yo very much Zax for your suggestions

[dar303]

maybe you should try a small diode laser? a 10W 808nm ir laser can be found cheap on ebay and optics are not especilly complicated either. no watercooling, hv or fragile glass parts and only a hekto or so of extra wheight. just remember to have some airflowto keep smoke away from the lens.

[Fertito]

Hello,
Yes, I understand that a laser diode could do the job, but...
I don't know which one to choose, there is so many, with so many specification (bar, ...)
I would like to do other things than fabrics cutting, I would like to try to cut eva-foam too...

Well, just have finished my own plotter, a "T" style one :



I'll use it for plotting only for now, but I would like to try laser-cutting with it soon.

[Fertito]

Hello!

Sorry for long time no speak...

Was waiting for extra money before buying the laser tube. Now that's done

I was finishing my plotter, here's some video :


and

[Fertito]

Hello folks,
I just received my laser tube from eclaser,
everything's ok, except I had to pay 170$ of extra taxes for a amount of 560$ :
25w laser tube, 40w psu, 4 mirror and a focusing lens.

thanks to eclaser, they are great, the package was well done (a box inside a bigger box filled with newspaper sheets).





I'll try it next week, when my safety goggles will have arrived

[yngndrw]

Fertito, that's really cool, I didn't expect to find that the 25W laser tubes were so big. I'm sorry to hear that you ended up with extra Taxes - It always annoys me a great deal to buy something and then find out that I have extra to pay on top of that ! I'm also glad to see you mention about safety goggles.

Regarding the Aeronaut, I'm assuming that they have used a solid state laser for that (I.e. No glass tubes.) and that is how they have been able to do that.

About focusing, (I have no hands-on experiance with lasers, what I am saying is from college and what I've seen on other CNC lasers.) laser tubes emit a parallel(ish) beam of unfocused light. This means that while the "spot" is too large to cut with, it will not get much bigger when sent over a distance. What I've seen other lasers do is to have a mirror on the end of each axis to send the laser light to the focusing head. From there it is focused into a nice dot. The thing required to send the light to the head is alignment, not focus. Assuming that all of the mirrors are aligned correctly, the focusing is done on the head and will be the same regardless of where the laser is mounted.

Good luck.

[Fertito]

yes, 25w laser tube is 700mm long... and 40w, 1m...

I'm not really sure Aeronaut is using solid state laser, I asked them several month ago, they told me they were using 40w CO2 laser, and the paragliding firm I know is using a synrad module directly plugged on the router...

But I've heard what you told me and brought mirrors and focusing lens too.
Regarding focusing, yes, I know it need to be focused but the router will soon be more than 7m long for 2m width, so the max lenght would be of 9m, even if the laser beam is accurate, at that lenght it won't stay at 3mm, and my alignment has to be really accurate.
Maybe I'll try to put it on the Y carriage, parallel to the Y axis so that it would have less stress, and I can embed the psu and the water too.
This way the max lenght would be of 2m.

I made test this week-end, the router can go up at 300mm/sec, nice...

[yngndrw]

Mounting it to the gantry could work, in fact depending on the design of what you're cutting to could possibly just slow down the acceleration of the X axis and keep the Y axis' acceleration high. If a lot of the X axis' cuts are long with few direction changes, you could still get a high speed.

If you can I'd suggest testing how the spot size changes over such a difference. You may find that it won't be a problem over 9 meters.

300mm/s is really nice ! I'm only getting 20mm/s rapids on my small router. :P

[Fertito]

Yes, and I can change the laser power according to the speed.

I had to do lot of test, things I'll have no time to get lazy this end of year...

[Meduza]

I am pretty sure that Aeronaut uses a CO2 Laser, but not of the Glass tube variety but of the Synrad or
Coherent Variety (RF Excited CO2 Laser tube instead of HV Excited CO2 Laser tube) wich uses high
frequency radio waves to make it lase instade of using a high voltage.

This type of tube is made of metal, have a lot longer life and is refillable with gas when they starts to
degrade, they are also smaller, more effecient and is in most cases air cooled, in higher wattages
sometimes watercooled, and due to that they do not have a large glass tube but rather a shorter
metal one they can also be mounted like Aeronaut have done in their machines.


The downside to this is that they are much more expensive...

[Fertito]

thanks to this precision,
the other inconvenient in using RF thinks, like laser and plasma is the disturbing you can create on your driving chips.
A friend of mine spent lot of time (and money) finding a plasma that don't have HF.