Annother possibility is, that the laser ray is out of the optical center from the focus lense. You should check it burning a paper above the focus lense utilizing a tiny laser pulse, the test button, if you machine have one.
I have a question. I have two leses of 2" and 4" focal lenghts. I would like to cut acrylic of 10-15 mm thick. What lense I should use it and at how may passes I have to repeat ?
I would like to cut in 2-3 pass only. I have a few chinese machines with different watts and different sizes ( 40-60 watts.). But I would like to use in 1.0 M long 50 watt machine.
Thanks in advance.
My suggestion is use 4" lens, cut in 3-4 passes and move material 1-2 mm higher than usual focus. I think you do not have autofocus, so set material to focus manually as usual BUT AFTER move table UP 1-2 mm.
For the future
1" lens for ultra fine engraving - very thin details, security elements for stamp making
1,5" lens for fine engraving
2" and 2,5" lens - universal - engraving and cutting up to 10 mm
4" lens - for cutting
Have no idea for you as I sell GCC lasers with aluminium Synrad tube
BUT
1) You will not have problems with cutting 10 and possibly 15 mm, but for 20 mm quality of cut will not be perfect and you may be need do some finishing with flame polishing equipment
2) Be carefull with acrylic. Cast is much better for cutting than extruded (but expensive ). There is now dark material from China LOOKS like black/dark blue acrylic but in reality contain PVC - can damage your equipment.
3) Do not remove safety paper from acrylic before cutting as it will protect cutting area from residue.
4) Be careful with cleaning and painting after cutting. Very often on EXTRUDED acrylic appear cracks after cleaning with some liquids and painting
Hi Litografa
I did according to yor advise (moved little up 1-2mm) acrylic. It cuts fine. I have two little questions.
1- If we cut 1.5 cm round, from the top it is fine but at the bottom it is not round but irregular. Upto 3/4 the finishing is fine but rest of them is rough. I am using 2" focal lenght Lense and having 3 pass of 1 cm thick acrylic.
2- The sahpe of the final material is not straight from top to bottom. It is front side is more than forward and bottom also forward. It looks like little bend not like cylinderical.
May be the last mirror above the lense is not correct or ??
Regards.
Muqtadir
Yes, as I told you before both problems will be during cutting of thick materials - more or less but will be. There is two ways to improve cutting quality:
1) Use 4" lens
2) Did special edge finishing with flame polishing equipment.
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