Laser Tube Bad?

[nlucomputers]

HI guys, i need some advice,
just finished building my diy laser, it is a 40w laser using the aw608 controller, the 40w PWM power supply, and a 40 watt laser tube i bought off ebay (before i found lightobject). it worked great all through testing and aligning. water cooling works great everything seemed fine. i went to make my first project on 1/8 acrylic (a raspberry pi case) it cut out the fist piece and and got halfway to the second piece and stopped cutting. the laser was still glowing and the motors were still moving but no laser was coming out of the tube. So i turned it off and checked connections and tried it again and the same thing happened, at the same spot. I even put a piece of paper in front of the laser and nothing was coming out. So i panicked and turned it off. I was concerned because i did not have a water flow indicator installed, so i spent a little time and installed the flow indicator. then powered up the laser and told it to cut. the power meter stays at 0 and the motors move, but nothing. Ive ran this laser for a total of like 20 minutes. Is this tube bad? did i do something wrong? I checked to make sure it was not getting too hot, the water stayed cool. Im at a loss. The only thing i can think is that this tube is shot and i should buy one from light object so i get a warranty. any advice would be appriciated.

[waltfl]

did you set your power settings above 11%?
push the test button on the laser PSU and see if the laser fires.

post a picture of the tube
greetings
waltfl

HI guys, i need some advice,
just finished building my diy laser, it is a 40w laser using the aw608 controller, the 40w PWM power supply, and a 40 watt laser tube i bought off ebay (before i found lightobject). it worked great all through testing and aligning. water cooling works great everything seemed fine. i went to make my first project on 1/8 acrylic (a raspberry pi case) it cut out the fist piece and and got halfway to the second piece and stopped cutting. the laser was still glowing and the motors were still moving but no laser was coming out of the tube. So i turned it off and checked connections and tried it again and the same thing happened, at the same spot. I even put a piece of paper in front of the laser and nothing was coming out. So i panicked and turned it off. I was concerned because i did not have a water flow indicator installed, so i spent a little time and installed the flow indicator. then powered up the laser and told it to cut. the power meter stays at 0 and the motors move, but nothing. Ive ran this laser for a total of like 20 minutes. Is this tube bad? did i do something wrong? I checked to make sure it was not getting too hot, the water stayed cool. Im at a loss. The only thing i can think is that this tube is shot and i should buy one from light object so i get a warranty. any advice would be appriciated.

[nlucomputers]

yes the power was at 98% I will post a picture tomorrow when i get to work. If i press "laser" on the display i can hear the power supply putting power to it but the laser does not light up. Im also going to try the led trick marco suggested in another post.

[waltfl]

hi there
did you watch the mA meter??? because if you had cut for 20 minutes with 98% you probably shot the tube .
with the DSP even the manufacturer setting should be at 98% but the cutting power shoud never go over 48% this equals to the max current of the 40W tube of 18mA and should never be higher.
how do you hear the power supply puttingpower to it ( what is "it")
greetings
waltfl

yes the power was at 98% I will post a picture tomorrow when i get to work. If i press "laser" on the display i can hear the power supply putting power to it but the laser does not light up. Im also going to try the led trick marco suggested in another post.

[nlucomputers]

so when your cutting you set the power to 48%? is that enough to cut? I understand what your saying about the amperage and i feel like an idiot, i see that my tube says operating current 18ma, and i was running at 20- 24. I guess i thought 50 is good but 100 is better. I really appreciate your expertise. I included a picture of the tube.

[waltfl]

hi there
yes it looks like the tube is already gone.
if you got room then exchange it against a 50mmx 850mm length 50W tube you can drive this with your powersupply but have much more cutting power.
greetings
waltfl

so when your cutting you set the power to 48%? is that enough to cut? I understand what your saying about the amperage and i feel like an idiot, i see that my tube says operating current 18ma, and i was running at 20- 24. I guess i thought 50 is good but 100 is better. I really appreciate your expertise. I included a picture of the tube.

[wctx1977]

Hi waltfl,

I damaged mine a few months a go due to overpower as well. It still engraves but when it comes to cut, it does very little. I know I need to replace it but I would like to know if you think that the 50mm X 1000mm tube can be installed in the k40. I know I have to cut a hole in the case and I have plenty of room in the side after the hole. If feasible I would rather using this one instead the 50mm X 850mm. Please let me know what you think. Thank you.

[waltfl]

Hi there
yes its possible to use the 1000mm length 50W tube but you need to check if your HV wire is long enough.
greetings
waltfl

Hi waltfl,

I damaged mine a few months a go due to overpower as well. It still engraves but when it comes to cut, it does very little. I know I need to replace it but I would like to know if you think that the 50mm X 1000mm tube can be installed in the k40. I know I have to cut a hole in the case and I have plenty of room in the side after the hole. If feasible I would rather using this one instead the 50mm X 850mm. Please let me know what you think. Thank you.

[wctx1977]

Thanks waltfl for your answer. Also, will the original power supply that I'm using now would be ok for the 1m tube?

[waltfl]

if you got a original 40W power supply like from marco ( lightobject) you can go with 50W tube. if you got a power supply others then I don't know.
greetings
waltfl

Thanks waltfl for your answer. Also, will the original power supply that I'm using now would be ok for the 1m tube?

[nlucomputers]

thanks waltfl
I'm pretty sure it is shot, the one i bought off ebay was a 750mm tube and i made the mistake of not leaving any room in the design for a bigger tube. I ordered a http://www.lightobject.com/40W-CO2-Seal ... -P208.aspx which is 700mm and will use that for the time being. I think next summer i will do a redesign and put the tube behind the main unit and upgrade to 80w 1000mm and 80w power supply. I had a blast building my laser cutter and will do it again i am sure. I learned my lesson about buying parts off ebay. The only parts i had problems with was my laser tube and the mirrors (wrong size sent) both bought from ebay. I am a lightobject lifer now.

EJ
NLU Computers

hi there
yes it looks like the tube is already gone.
if you got room then exchange it against a 50mmx 850mm length 50W tube you can drive this with your powersupply but have much more cutting power.
greetings
waltfl

so when your cutting you set the power to 48%? is that enough to cut? I understand what your saying about the amperage and i feel like an idiot, i see that my tube says operating current 18ma, and i was running at 20- 24. I guess i thought 50 is good but 100 is better. I really appreciate your expertise. I included a picture of the tube.

[nlucomputers]

Update, got new laser tube today, same problem. laser will run for a minute and then lose power. this time i took a video so you guys would believe me.

http://www.youtube.com/watch?v=TJIuX9M2pOc

I think this laser is going to drive me insane...

any chance i could be the power supply?

EJ

[waltfl]

Hi
your video shows that your beam is not aligned right. you need to make sure that the beam hits center of all three mirrors on all four corner of your work table.
it looks like your table is not level ether make sure that you got the same distance ( according to the lens focal length, which is from top of the lens to top of the material)on all four corner to.
general only 0.5mm is already to much out of focus
your manufacturer settings should be at 98%, but the cutting power should never be 17.8mA better 15mA ( equals on a DSP to around 48 to 52%)
if I see it right that's a 1/4 inch ply from the worst quality, you need a bit better quality. I use the 5mm ply from HD and cut this with 15mA = 48% and 3 to 4mm/s
greetings
waltfl

Update, got new laser tube today, same problem. laser will run for a minute and then lose power. this time i took a video so you guys would believe me.

http://www.youtube.com/watch?v=TJIuX9M2pOc

I think this laser is going to drive me insane...

any chance i could be the power supply?

EJ

[Tech_Marco]

I think the problem is the laser tube is gonna bad.
I got to send him another tube as he purchased from me about a week ago. Look like it is a defective laser tube
If laser tube grow (purple) but got no power output, the tube is pretty much 'done deal'


Marco

[wctx1977]

Hi nlucomputers,

Have you tried to follow the beam with a piece of paper while this is happening? I mean, grab a sheet of paper or wood and place it in front of each mirror between the path of the laser beam and see if the beam still strong. To me it looks like the beam is getting obstructed somewhere and more than likely this is happening inside the air assist nozzle. It possibly is touching the wall inside the air assist nozzle at the very narrow tip.
I had a similar problem before and I had to realign everything until I got it solved.

I hope you can find the issue, I know how frustrating can be...