25.4mm lens for cutting?

[namara]

Hi,

im working with 1.5mm plywood and using a 50.8mm lens for cutting.

just wondering if anyone has experience cutting with a F.L
of 25.4mm and if it would be a better suited lens for cutting 1.5mm plywood,

the 50.8mm lens is leaving burn marks,i dont have the option of being able to use an air compressor and thinking the 25.4mm lens has a smaller spot so less chance of a flame appearing but i dont know if its depth of field is
suitable for cutting 1.5mm plywood,

thanks,

[Exsecratio]

same power focussed onto a smaller spot = higher power density = more chance of fire

Without air assist you won't be able to get much improvement on the staining / scorching. You also run the risk of damaging the lens if you use a short focal length. a 1" (25mm) lens isn't really designed for use on anything other than surface marking at high resolution.

best wishes

Dave

[namara]

thanks Dave,

[GWEIKE-LASER]

even the shot focus lens can not solve the problem of burn edge.

do not suggest use shot focus lens for cutting.

[namara]

thanks GWEIKE-LASER,

i found this great calculator for laser optics;

Laser Optics Calculators

[GWEIKE-LASER]

namara, good sharing

[Rodney Gold]

What you can try to minimise charring is 3 fold in your case
1) go to a 40mm lens for higher power density but more or less the same depth of focus
2) Mask the top and bottom surfaces with cheap self low tack adhesive paper (get it from a vinyl sign supplier , called application tape)
3) More importantly , depending on what laser you are using , adjust your pulses per inch downward or use dot mode on some chinese machines
Basically you want to "just perforate" the cut line but with enough overlap between perforations to give a smooth edge but not too much to heat damage the edges.
You will never get a clean edge but can minimise charring