Hi All,
My K40 was starting to reduce its cutting performance the last 2 days. I decided to do a beam alignment just in case things were a bit out of wack. I didn’t adjust anything yet, but instead of getting a nice fine pinhole when I press test I got what looks like 2 lips about 4mm wide.
This is typical of a tube that has shifted to a higher-order transverse mode. TEM01 is the most common mode to shift to; it’s sometimes called the “donut mode” and in theory is donut-shaped but in practice seems commonly to look like the two dots you see here. [Edit: TEM₀₁* (donut) is different from TEM₀₁, which looks like two dots.]
Poor cooling control can lead to this happening earlier, but as far as I can tell it’s a common failure mode for even well-cared-for tubes that are just used up.
Thanks for the reply.
Not the answer I was after but spidey senses were saying this to be the result. Its not an old K40, having done less than 50 hours but they are made to a cost not quality I guess. The water temp has never exceeded 25 deg Celcius when cutting, but I might lower the water temp more with some freezer bricks in the water container.
Regards,
Mitch
If the tube have the strongest possibility of failure, You should also have a look to the lens (& mirrors) for a possible crack, that happen to me as I reported many years ago.