Need help.. running cermark on ss and not getting good adhesion after about 40

Need help… running cermark on ss and not getting good adhesion after about 40 hours of running. Black rubs off the parts. If change to a new tube, it works well again. It cant be the tube getting weak that quickly, can it? Is there a water issue? Cleaning? Power supply?

Check the temperature of the cooling water. As the temp increases the power output of the tube decreases.

What ma you running

I think the ma is the problem. I just read last night about running no higher than 16. I have a machine with no meter on it. Been running this job at 95% power. Installed a meter last night only to find out that’s 30 milliamps. Looks like I’ve been frying the tubes and was not aware that I was frying them.

Has anyone put together a basic quick-and-dirty guide to these machines since they come with nothing?

@Mark_Harper

#K40DigitalPanel
#K40TubeFailures

…there are many “guides” linked in this community and my blog has info organized in an index. What kind of guide are you looking for? Perhaps we need to add something.

Did you see the “Getting Started” post?

What kind of machine?
Laser Power?
Controller configuration?
How many tubes have you used?

K40 stock machine, stock controller (M2), have used 4-5 tubes now. Currently running a CloudRay 40W tube. I poked around on here but havent gotten far as links were broken, ran out of time, etc.

@Mark_Harper
Wow, that,s a lot of tubes depending on what time span that includes.

If you get some time, letting us know what links are broken enables us to try and fix them.


Have you looked at this blog and where there broken links?:

I add some warnings about the impact of not watching tube current when using the digital meter, to this post.

Tube life has been horrible. 40-60 hours for each one. The tubes still fire and work for wood engraving and lighter operations, but not for Cermark which is what I need. Now that I installed the ammeter I can stop smoking the damn things. Thanks for the links - I will do some more browsing this weekend.

There must be something else affecting tube life than just the current, as I run tubes at 95% power and am into the hundreds of hours without failure. When running at high mA, adequate cooling is a MUST!

I am running in my garage (Chicago) and monitor water temperature (by feel) throughout the day. It never gets above luke warm… even then I will add ice just to be safe. Another part of this - it’s not 100% failure… I end up with lines that wipe away in the middle of the text. Not uniform by any means. When the tube is new, I get consistent black. 40+ hours later, I get streaks, and some peices may completely wash away.

I am using distilled water, btw. Is there a better alternative?

@Mark_Harper distilled water is the right choice… I would get a temp monitor though and interlock the laser power with it. Again, links on my blog.

@funinthefalls true that, but 30 ma is a lot for a 40W laser??? I did not think the LPS would go that high with a 40W.

@Mark_Harper you have a stock LPS?

Yes, stock PS. Put in the 30ma ammeter like in your blog, at 99% power it hits 30ma.

Even hits 30ma with the tube I am questioning. Is it possible the PS is not sending a good signal to the tube and giving me these inconsistent results? Controller? I have a spare PS and controller from a parts machine I picked up.

@Mark_Harper the reading of 30 ma, unless it’s not reading correctly, suggests the power supply is working. Albiet that higher than I have seen in normal operation.
Could there be an intermittent optical problem other than the tube, that is making the power at the surface change like this?
.
This is were a power meter would be valuable.

Not sure… I will try running some parts tonight with the new ammeter and watch it. Should I still try to run at 16ma?

@Mark_Harper have you done an optical alignment? I would keep the current below 20 ma until you figure out what is going on.

Try some wood cutting at 20 ma and see what it will do.

You could hold a piece of acrylic (1/4") in the path at various points and pulse the laser a fixed period to see if the beam penetrates the same amount in front of each mirror an at the table.

What are you using for the table?

Yes, I have aligned it. I made my own adjustable height table from expanded metal and made a height gage for setting focus.

I have past experience with a Trotec machine so I can make my way around ok… K40 is definitely a different animal though