Problem with laser power

[bobkeyes]

45 watt laser tube-New from LO.
Good mirror alignment.
Good clean mirrors.
Great water flow. Exit temp-68 F.

Cutting 1 1/2" circles from 3/8" clear plexi.
Running 1mm speed at 18 mA.
Using 3 passes with air assist.

First circle cut fine.
Second circle took 6 passes to cut.
Third circle took 9 passes.

All alignments and water are OK after running the 9 passes.

The more I cut the longer it takes. I can stop the machine for say 30 minutes and the first circle after that cuts in 3 or 4 passes. Then down hill again.

Seems I'm losing power. ANY THOUGHTS. I NEED SOME HELP HERE!!!

Thank so much.

Bob Keyes

[bobkeyes]

Here's some pics of the laser pattern. Same patterns when flipping the lens. Thought maybe I had it in upside down, but no.

[Tech_Marco]

Bob:

What was current setting on the laser tube? It seems that the current was very low somehow that's why you got a "donut" ring like burn mark
Check the connection on the HV laser wire to make sure high voltage is not "leaking" by lose connection or damaged wire somewher

Marco

[bobkeyes]

Marco,

Current is 18 to 19 mA. That's what is recommend for the 45 watt laser tube I have. I can move it up. I'm only running about 62% of power. At full power, 98%, I have 28 mA.

[bobkeyes]

No evidence of any leakage or bad connection. Connection to tube is soldered tightly. Ground is also soldered. Connection to PSU is plugged in and booted. No sound of HV leak to ground. No evidence of that on the wire either.

Bob Keyes

[Tech_Marco]

Try to power the laser tube with 18mA and let it firing for 5min see what's happening. Do it without lens/mirror. You need to remove the laser tube out from the machine and let it shoot on a brick or wood block.

3 pass cutting shouldn't take more than 30seconds so if the laser firing OK for over 5min, then the problem is not the tube. Double check the HV cable, check any 'spark' as I think that may be a cause.

FYI, last month two customer return a tube for me and claim to have the same issue like you did. We tested the tube and found nothing wrong by firing at 10mA and 18mA for over 15min. It burn very good.


Marco

[Tech_Marco]

You soldering the wire on the laser tip??
Send me a picture what you have done. You should NEVER soldering a wire to the laser tube. It will damage the bonding as glass and metal 'never' bond together well. You can wrap the wire on the pin and glue it with silicon glue.

Marco

[bobkeyes]

Here's what I did.

Cleaned post. Wrapped with soft copper wire leaving a tail of copper wire. Soldered with low heat soldering gun. Placed HV against post. Wrapped it with the tail of copper wire. Soldered in place. Did the same with the ground. Covered both with silicone, slid a piece of silicone over the joint.

Not sure I can get it in a position to shoot against a wall, but I'll try.

By the way, now it won't even cut thin shirt cardboard at 28 mA!

[Tech_Marco]

No! You don't want to set to 28mA. That cook the lens/mirror inside the tube! Over current won't get you higher power but it happen opposite
For a 40~45W tube, 18~19mA is the max.

Marco

[Tech_Marco]

Bob, when did you buy the tube? Got a picture of the tube?

Marco

[bobkeyes]

I paid for the tube on 10-13-2013. I received it on 10-17-2013. Installed on 10-19-2013.

Here's the best pics I can get right now. This is a big heavy machine. It sits against a wall and I have to move a table and other things to be able to get to the back.

I have to go to a play this evening so it might be later before I can get back on this.

Thanks for your help. Will you be around tomorrow afternoon?

[Tech_Marco]

Did you use different account to buy it as I couldnt locate your order. Can you send me order number please.
I should be around tomorrow. You keep posting here and I wil reply you promptly

Marco

[bobkeyes]

I can't locate my paperwork. May not have it anymore. I'm bad about that.

It would be under Robert W. Keyes OR Classic Impressions. Don't know which.

Ah Ha. I found it. Here's the info

Order Date: 10/12/2013
Order Number: 199123
Ship To: Robert Keyes
Status: Completed Items

1 of: 10L/min (158GPH) High Temperature (80 'C) DC12V Brushless Submersible Water/ Oil Pump
1 of: 45W CO2 Sealed Laser Tube (1M)
1 of: 12V 10mm Bright White LED 10pcs

[Tech_Marco]

Great!

Just in case the tube is bad and I can send you a new tube for exhange without you to pay

Marco

[bobkeyes]

Marco,

I ran the tube onto a 2 x 4 for about 25 minutes at 18mA. It charred a nice hole about 5/16" in diameter and about 3/16" deep. It was bright red the whole time. Nice purple straight line in the tube as well.