CNC fabric cutter setup - need some input before purchase

[Rokas]

Hey everyone,

I am preparing to build a CNC laser cutter for fabric cutting. Table size will be 150cm x 200cm (roughly 5 x 6.5 feet). The budget is rather tight, but I don't want to loose quality on critical components. Here are my initial considerations, kindly waiting for Your feedback/suggestions:

1. 40W CO2 tube: http://www.lightobject.com/40W-CO2-Seal ... m-P46.aspx There is also a smaller version with the same power rating - any difference worth knowing? Size doesn't matter for me.
2. Matching PSU with PWM: http://www.lightobject.com/40W-PWM-CO2- ... y-P71.aspx
3. Laser head and mounts. I was going for this kit: http://www.lightobject.com/Laser-Head-M ... -P741.aspx Will I be able to hook up air compressor to it? If not, which head should I go for?
4. Optics - lost here. I could match the sizes to the mounts, but which types of mirror/lens should I choose? Looking for something above average, but not most expensive.
5. Steppers. Would this one be strong enough for the cariage? And which one should I choose for the laser head? I understand there is not trivial answer, as the construction is not known yet, but some kind of guidelines would be much appreciated.
6. Stepper driver - http://www.lightobject.com/2-Phase-56A- ... -P455.aspx for the big one. Now is this one necessary, if I'll take the drivers anyway? http://www.lightobject.com/New-version- ... -P505.aspx DSP is out of budget this time.
7. PSU for steppers: http://www.lightobject.com/DC-24V-15A-S ... -P447.aspx
8. Goggles? http://www.lightobject.com/CO2-10600nm- ... -P133.aspx

Also, some more questions:

1. How do you guys measure the current fed to the laser? Just connect an ordinary multimeter to the negative high voltage line? I mean those multimeters handles those KV's?
2. How does tube power usage correlate to it's lifetime? If I would run my 40W at 50%, would it double the lifetime?
3. And how much power do you think it would need to cut an average fabric (like dress-shirts)?
4. Any experience shipping to Europe (Lithuania to be exact)? Duration?

Huge thanks in advance!

-Rokas.

[jblakes34]

Hi,
I don't know much, I'm still trying to get information myself from these guys. I just spent a chunk of money ordering parts from lightobject too. I have spoken with Jain at lightobject, and he has given me a little help.

Concerning the current measurement, you are measuring milliamps, not voltage. You should be able to use this amp meter:
http://www.lightobject.com/3-digit-Mini ... -P457.aspx

Jain told me that it is connected to the negative side of the tube. I haven't seen the components yet, so that's all I know about that.

By the way, my dad's family is from Lithuania. Good luck with your machine.

jb

[Tech_Marco]

Hello Rokas:

First of all, thank you for your interesting in our products and welcome to the forum

Back to the subject, I think the 40W for the table size is "too small to be useful". The 40W is good for small machine like 3040 (300mm x 400mm) or 6040 (600mm x400mm) machine. But since your stage is large at 1500mm x 2000mm, the weakness of laser power at the farthest point is significant, especially for cutting. By the way, what are you trying to cut?

Most laser tube power rating is proportional to the length of the tube assuming the diameter is the same. The K40 tube (700mm) is not really a full power 40W tube but it is a 32~34W tube instead with 50mm in diameter. For a true 40W, you need 800mm.

The setup of optics is usually in this format: 25mm mirror/20mm focus lens, 23mm mirror/19mm focus lens, 20mm mirror/18mm focus lens. It is quite common standard that is using in China

My suggestion for 50W or higher laser, use "Si" mirror. For 130W or higher, you may consider "MO" mirror where Si is still ok but I would suggest to add a heat sink to the back of the mirror. That is something I may carry later

For the motor/stepper, as long as the current rating on the driver is higher than the stepper than it is OK. Note that the current rating on those driver is "Peak" not "RMS". If the motor rated at 4.0A, you may want to get a 5.0A driver. FYI, I'll get 3-phase stepping motor and driver soon. It's more torque than a bipolar motor with a little more in cost

Standard laser tube usually rate 1500~2000hrs with 80% of full power. It doesn't mean that you lower the current by 50% and you will get double life-span. You may be able to reach 2000hrs or a little more but not double.

To cut cloths, even a 40W laser is good enough. However, the light beam travelling must be short. To accomplish this, there is a special setup on the XY stage. The tube is carry-on the X gantry. So the laser beam travelling distance is limited to certain length so that laser power is not affected too much. I will carry the system soon. The special XY stage is having useable area at 2000mm * 3750mm.
See attached images.

Note, the pictures seems small but the complete setup is big as the Y guider is not showing yet and the X is for a small setup. Plus, the pulley is much bigger than standard one and 3 phase motors will be used.


Marco

[Rokas]

jb, Marco, thanks for Your replies.

Concerning the current measurement, you are measuring milliamps, not voltage.

I do realize that I need to measure miliamps, but wherever there's electricity, there's always amps AND volts, and some measurement devices cannot handle higher voltages, even while measuring current.

Back to the subject, I think the 40W for the table size is "too small to be useful". The 40W is good for small machine like 3040 (300mm x 400mm) or 6040 (600mm x400mm) machine. But since your stage is large at 1500mm x 2000mm, the weakness of laser power at the farthest point is significant, especially for cutting. By the way, what are you trying to cut?

This machine will be dedicated to cutting only cloth fabric, so I suppose from Your answer that it is enough, if the construction will be based on moving laser tube on the X axis to minimize beam travel distance. So there's a question - any experience moving high voltage wires? Should they be separated from other wires (e.g. stepper's wires)? Can high voltage "+" and "-" wires be put close together?

For the motor/stepper, as long as the current rating on the driver is higher than the stepper than it is OK. Note that the current rating on those driver is "Peak" not "RMS". If the motor rated at 4.0A, you may want to get a 5.0A driver.

Understood. But if I purchase those standalone drivers, do I need something like this: if http://www.lightobject.com/New-version- ... -P505.aspx ?

FYI, I'll get 3-phase stepping motor and driver soon.

How soon is that? Tight budget is not the only constraint we've got, time is also critical

To accomplish this, there is a special setup on the XY stage. The tube is carry-on the X gantry. So the laser beam travelling distance is limited to certain length so that laser power is not affected too much. I will carry the system soon.

This looks insanely awesome, but even the smaller XY stages are way out of our budget...

And what about the laser head?

I was going for this kit: http://www.lightobject.com/Laser-Head-M ... -P741.aspx Will I be able to hook up air compressor to it? If not, which head should I go for?

Huge THANKS for Your support.

-Rokas