G. Weike 1390 CO2 laser not cutting any more

[Byron Lu]

Maybe you guys can help me diagnose what the problems are for my Laser machine. I bought in August 2018 directly from the company in China. It has a 100W Reci tube. But I did not really use it until this three months ago. I mainly cut 1/2" plywood and it has been okay cutting although the speed was slow at 9mm/sec. But more recently, it does not seem capable of cutting through the plywood anymore even through I lowered the speed to 3-4 mm/sec and up the power to 78%. If I cut a circle, it would cut through part of it and then skip the next part (pretty random). I have been using the same plywood from the very beginning and was able to cut them in February.

So far I noticed:
1. the included ammeter shows stable 24 to 25mA when cutting at 78% power.
2. the laser beam has no issue engraving at 100mm/sec at power 25%.
3. The CW-5200 water chiller seems working with temp at 19 to 22 degrees celsius.
4. the table is even and lenses are focused as before.

Anyone can help what could be the problem?

Great thanks.

[Chris Thomason]

It sounds like you have two separate issues.

Skipping sections sounds like a controller or electronics issue. Check to make sure all your connections are tight and wires are not damaged.

Second issue seems to be an apparent loss of power. Check to make sure the lense and mirrors are clean and your alignment is still correct.

[Bill George]

Sounds like a tube power issue. Check your HV connection and the ground. What do the folks say you purchased it from?

[Byron Lu]

Sounds like a tube power issue. Check your HV connection and the ground. What do the folks say you purchased it from?

Well The customer service sucks big time. I sent wechat messages to two people who originally supported me in installation, but did not get anything back. (I also understand that China has a big May 1st holiday right now). I am not sure I will get anything back at all even during a non-holiday time.:mad:

[Byron Lu]

Well by skipping, I meant by look at the backside of the board, some sections of lines are cut through, but not some others. If I look at the front face, the lines are ALL cut, just not THROUGH for some parts.
I'm uploading two images here, one for the cutting face, the other the back of the 1/2" plywood. What you guys think the problems are?

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Also, for a while the machine room was very dusty with sanding and dremel cutting. How would dust play a role/contribute the problems? It has a RUIDA controller.

Thanks again.

[Wilbur Harris]

Clean the lens and mirrors and refocus. If that doesn't fix it your tube is going south.

[Kev Williams]

the 'skipping' on the back side isn't 'skipping', it a normal result of simply needing more power and/or less speed to fully penetrate the material. I don't cut plywood but based on what others say, it's a pain to cut mostly because of the glue- could be the plywood itself is part of your problem. Have you tried cutting thru 1/2" pine or alder or some other non-glued wood?

As others have said above, clean mirrors and lens(es), and run an alignment check. My Triumph was dead to rights when I bought it, around 2 years old I kept getting non-cut parts on the far right end of the machine while the left side engraved fine. A check showed the beam 'climbing' up the 3rd mirror the farther right the head went. The burn spot showed it was still hitting mirror, but since the incident beam is quite a bit larger than the burn spot I concluded part of the beam was likely hitting the top edge of the mirror hole reducing power. Once I got the beam back down all was well, and has been ever since...

[Byron Lu]

I know cutting 1/2" plywood is a pain in the a** but I could cut the same plywood three months ago but not any more, although I lower down the speed to 3mm/s and up the power to 82%. It gives a lot of burn soot yet still not cut through. I just ordered a new 130w tube and power supply from light object - Ouch that is more than $1700 including shipping!

I will realign the mirrors as well. I hope the new tube/PSU will fix this issue.

[Chris Thomason]

Since the laser is moving and firing in the correct places the controller should be fine.

Did you clean or inspect the mirrors and lense?
What about checking mirror alignment?

You can do those in less than 5 minutes for no cost. I always like free solutions. Given the tubes age what you use it for and the dusty conditions in the room it would be prudent to check those before your tube ships.

[Steve Utick]

Well by skipping, I meant by look at the backside of the board, some sections of lines are cut through, but not some others. If I look at the front face, the lines are ALL cut, just not THROUGH for some parts.
I'm uploading two images here, one for the cutting face, the other the back of the 1/2" plywood. What you guys think the problems are?





I have the exact same issue on our 100W machine with 1/4 Baltic birch sometimes. It's the wood. We got a bad batch here a bit back and had tons of problems. The best thing I've found, is to run your focus down a bit. I've played around with our one machine, and through experimentation, found out that focusing it down 1mm gives the best and most consistent results for our cutting. I had to just use trial and error to find out where the ideal focus was though. But, still run into random issues that are 100% related to hard spots or glue spots or something in the wood that just flat can't be prevented.

[Byron Lu]

I did more mirror alignments and bed leveling. And it seems to have more to do with the mirror alignments. I have had a hard time aligning the 3rd mirror (the one shoot down the laser to the cutting material. It is extremely hard to center the beam straight down. It seems that the beam may bounce inside the metal tube and only give weak beam. After I took off the the cone-shaped metal cover piece (so the entire beam force exposed to the wood surface), it can cut the 1/2" plywood now. But that defeated the purpose of nozzle air blowing a bit. Any one know an easy trick to adjust the 3rd mirror? (I have watched a few youtube videos).

Of course the plywood knots and glue spots contribute to the randomness of not cutting through as well.

Thanks you all for helping me on this. :)

[Chris Thomason]

What I try to do is to make sure the 3rd mirror is pointing the beam straight down. Otherwise your cuts will not be square.

I remove the nozzle and do a pulse into a scrap of wood at focus then move the table down several inches and make sure the out of focus beam lines up with the focused one. After that point all the mirrors are in line.

Then put the nozzle back on and adjust the laser tube itself slightly until the beam passes through the center of the nozzle. Put some masking tape over the nozzle and keep adjusting until the laser hits the middle. Then check each corner and the middle of the machine to make sure it is consistent over the whole surface. May not be the best method but works for me.

[Kim McIntosh]

The easiest way I've found to do the third mirror is take the lens out and replace it with a 3mm piece of MDF, or similar, the same size as the lens. Pulse your laser. Pull the mdf lens out and you now know exactly where your beam is travelling. Adjust until dead center.