Laser Build (Based on 2.x)

[karsten]

Hi!!

This is my first post, and first of all.... english isnt my native language so, if i begin to talk like Yoda please understand me haha

Im 24 years old, studying Industrial Design, and well, as the title says, that is my intention. Do a home build CO2 Laser for cutting and engraving. Its in the school where i start using laser cutters (i didnt operate the machine, just arrived with my files to cut )

This are two of the projects i made with Laser.








And... as a fan of Star Wars....






Arrived to this forum a few months ago, looking for information about how to build a machine of this type, now i think i understand enough to start... buying at least hahaha

Dimensions of the machine... i would like at least 60x45cm of cutting area (same as the machine in school) still planing...

This is my Buy List until now, incomplete but i have a few questions

Switching Power Supply 400W 24V 16.7A for CNC Router Kits 115V/230V S-400-24
http://www.omc-stepperonline.com/switching-power-supply-400w-24v-167a-for-cnc-router-kits-115v230v-s40024-p-240.html

0.9deg Nema 17 Bipolar Stepper Motor 2A 46Ncm 17HM19-2004S
http://www.omc-stepperonline.com/09deg-nema-17-bipolar-stepper-motor-2a-46ncm-17hm192004s-p-122.html

0.9deg Nema 17 Unipolar 12V 0.4A 32Ncm Double Shaft 17HM19-0406D (Question: affects too much that this motor is Unipolar? its for Z axis, the table)
http://www.omc-stepperonline.com/9deg-nema-17-unipolar-12v-04a-32ncm-double-shaft-17hm190406d-p-121.html

50-60W CO2 Laser Power Supply for CO2 Laser Tube Engraver Machine Professional (Question: it would work for 40W Laser Tube? How much Power i need to cut MDF 6mm thick for example)
http://www.ebay.com/itm/50-60W-CO2-Laser-Power-Supply-for-CO2-Laser-Tube-Engraver-Machine-Professional-/221545310032

Set Co2 Laser Head +Mirror + Lens Intgrative Mount Cutter Engraver FL 1.5" to 4" (Question: From China, Is it good? )
http://www.ebay.com/itm/Set-Co2-Laser-Head-Mirror-Lens-Intgrative-Mount-Cutter-Engraver-FL-1-5-to-4-/331329488393?pt=LH_DefaultDomain_0&var=&hash=item4d24c6c609

AWC608 Commercial DSP CO2 Laser Engraving/ Cutter Controller
http://www.lightobject.com/AWC608-Commercial-DSP-CO2-Laser-Engraving-Cutter-Controller-P321.aspx

About the drivers... I am looking to this two, is much difference?

Bipolar Stepper Motor Driver Max 3A Current 128 High Subdivision ST-7128
http://www.omc-stepperonline.com/bipolar-stepper-motor-driver-max-3a-current-128-high-subdivision-st7128-p-244.html

Leadshine DM422C Digital Stepper Driver 20-40VDC with 0.3-2.2A
http://www.omc-stepperonline.com/leadshine-dm422c-digital-stepper-driver-2040vdc-with-0322a-p-75.html

Its all i got for now, i will prepare my next questions hehe, thank you so much forum

[rsm5178]

With a higher wattage power supply, you just can't use full power. There is a current limit of the laser tube. I run a 60w power supply for my 40w laser tube. I can only use 38% of the power supply since my tube'S maximum current is 18.5mA.

I know there are people who cut 6mm mdf with a 40w tube. May need 2 passes.

A bigger machine would be much easier to stuff a 60w tube into though....

Rich

[sshwarts]

I do 6mm MDF in one pass but very slow and PPI set to 1000 to make the edges decent. One thing I've really learned of late, is how important it is to keep the tube cool to get maximum power out. I ended up putting a small air conditioner in my "laser room" and use a radiator with fan to below the chilled air across.

[karsten]

thank you for the answers!!

With a higher wattage power supply, you just can't use full power. There is a current limit of the laser tube. I run a 60w power supply for my 40w laser tube. I can only use 38% of the power supply since my tube'S maximum current is 18.5mA.

I know there are people who cut 6mm mdf with a 40w tube. May need 2 passes.

A bigger machine would be much easier to stuff a 60w tube into though....

Rich

So, its the same as it is with a PSU for a Computer, i cant put any PSU for the laser, lets say, 100W for example, and use it with a 40W tube without problems, the PSU just deliver the power needed for the tube


Another Question, i want to use a custom water cooling system from a Computer for the laser tube, but im not sure about the tubing, the laser tube its made from glass, how strong is the tube or how you connect the tubings at it :/

[sshwarts]

You can use say a 100W power supply on a 40W tube, you just can't run it at 100%. Remember this is about controlling current not voltage. The voltage is constant, the current is adjusted for power. For example, I have a 40W tube but an 80W power supply. So at 35% laser power (as set on my DSP controller), that is the maximum current for my 40W tube. With the AWC and it's ilk you can set the maximum so you never go over by accident.

So people have put voltage dividers on the output of the DSP so that it scales the control voltage down giving them a full range of 0-100% (the power supply is controlled by a 0-5V signal where 5V = maximum output current). Other than for convenience, I'm not sure what this would do for you.

The tubing that connect to the laser tube is usually silicone tubing (can't remember the diameter right now) that slips over the fittings (a simply cable tie adds security)--it is glass so you have to be careful.. A PC cooler is great, just make sure you have plenty of coolant to circulate. I use a 5 gallon bucket with perhaps 4.5 gallons in it).

Scott

[karsten]

thats a lot of water!! xD

the laser tube generates that much hot? i planned to put a 360mm Radiator with a Push-Pull configuration to cool it

[sshwarts]

You have to consider a few things in cooling. One is that any radiator system can only cool to ambient temperature, you'll never get below the room temperature. Second, on some of my jobs, the laser is running for over an hour so a small amount of coolant gets warm quickly.

Scott

[cvoinescu]

You have to consider a few things in cooling. One is that any radiator system can only cool to ambient temperature, you'll never get below the room temperature. Second, on some of my jobs, the laser is running for over an hour so a small amount of coolant gets warm quickly.

That's neither here nor there. A larger bucket will not cool below ambient temperature either. And, if you have enough cooling to dissipate the amount of heat produced by the tube (with an acceptable temperature rise), the amount of coolant does not matter.

That said, a continuously running tube produces some 200 watts of heat (possibly more for the larger tubes), and you need to keep a pretty tight temperature control; a radiator that dissipates 200 watts with only a 10°C rise over ambient would be pretty impressive (several times what's needed for a single-CPU PC). This is why a large bucket is actually a very attractive option: it allows you to operate with less cooling than needed for steady-state heat dissipation, as long as you don't use your laser continuously for many hours at a time.

[sshwarts]

Well said...

[karsten]

thank you cvoinescu, sshwarts for your answers

Questions!

-- The stepper motors are ok? one is unipolar the one for Z axis with double shaft

-- The belt for Z axis is continuos in the design of the 2.x, modifying the size of the machine affects the lenght, where i can buy it, or what options i have

-- Searching Laser heads in ebay, some of them give this options:

Mirror diameter

Lens Diameter

Focal Lenght

I dont really understand the laser optics calculator of this forum :/ my only guess is it depends of the tube and size of the machine ??