Laserscript user forum

I am suddenly getting very poor results cutting 3mm Birch ply sourced from HPC. I have been putting it down to poor, sinewy wood. However after wasting yet another sheet - using the settings I have used for nearly 2 years now - I wondered if the beam is off centre - even though it cuts Perspex fine.

When I make single shots onto a piece of card the first shot hits the card and then I make a second shot that is nearly 4mm apart from the first. If I continually shoot the laser I end up with quite a uniform burn, but is nearly 4mm in diameter. I suspect tis is not correct - but why does the laser shoot at two different spots without changing anything?

Any input would be well appreciated.

Regards

Rick

Is the card you mentioned placed before the first mirror? What sort of pattern do you get after the 2nd mirror before entering the head?

If so - the dimension is about right as the lens focuses the beam but the double beam doesn't sound right - check be the output coupler lens on the tube, it may be damaged or the tube could be on it's way out.

Best
Dave

Thanks for that. If I place the card in front of the first mirror it is central and singular and strangely, further shots after the next mirror now seem singular as well! I haven't opened the lid on the laser for a while and am surprised how much muck is in there so will give this a clean and see how things progress (I am pretty meticulous at keeping the working area of the machine clean!)

Best regards, Rick

PS Any hints at a method of cleaning the radial fan?

Yes worth cleaning the mirrors and check for any cracks etc.

The extractor fan can be a bit tricky - I take it apart but would not recommend doing so unless you are used to doing similar, have a lot of time and patience!

Best way without taking apart is a long stiff brush and a vacuum!

Best
Dave

HaHa! I didn't really think there was a simpler way!

- yep best not to get it dirty in the first place!

I am now experiencing an issue that is really only apparent when cutting Perspex in that the cut is slightly bevelled - only a small amount, but when it comes to glue-welding pieces together there is only marginal contact.

It would seem obvious that the laser is not exactly square with the table, but I use a spirit level on the honeycomb and shim the ends to ensure it is level. Is there a way of testing and adjustment of the laser and if so, is it a job for am amateur please?

Best regards, Richard

the laser beam focus is cone shaped, coming to a point at the focal point and then spreading out again after that.
try getting the focal point half way through the material, or use a longer focal length lens, or both

Good thought. Just to clarify, if I am cutting 3mm Perspex and my focal distance is normally 73mm I should increase this to 74.5mm?

Best regards, Richard