by ArtF » Sun Jan 31, 2021 8:04 pm
Mark:
Yes, the max power and MinPowerRad are used in doign photo's and such. Max power is usually set to 90% or
something just to make sure you dont overdrive your laser, some do not like 100%, its hurts them over time.
By setting to 90% or so you may lengthen the life of the laser.
Now, as to the range of grey scale in a photo, this is really particular to the laser as to how
this is set. This is how I do it.
First of all, there is a feedrate override button on the screen, I use this always in photo 3d engraving or
photo burning. Youll notice on the image import screen when creating an augmentation for a photo
burn there is a ramp size, I always set this to about 20m or so on my synrad laser system it runs slower
than my galvo. This is because my slow system conceivably needs a ramp to get up to a speed where
linear corrections work best. During initial start of motion the speed can be too slow for this linear power
curve to smooth things out. So make sure there is a ramp if your system has acceleration that might
be considered low or it takes a bit to get up to speed. On my galvo I use no ramp, but its speed is immediate
and its accel is very high.
Second, I control power with my power slider, not with S words, in fact I keep S words out of my
engraving power to make it all manual power adjustment, every material is different so they all need
to be individually set for power.
Now about grey scales. It is said that power and speed have a linear correlation. This is not true
in the context of greying or blackening wood in my experience. While it may be true that 10 watts
at 100mm'sec is the same in linear terms to 20 watts at 200m's per second in terms of radiation
produced, its my finding that time is the variable that affects these two from being the same. Wood
simply darkens at differing time rates based on actual power.
My advice is to use, as in most cnc, as fast a motion as you can while burning. I most always set to
a high power and adjust speed for the best grey scale. My lasers though probably dont react the way
yours does, so experimention is in order. I set my power to 90% or 95% and then do a test burn at a very
high overridden feed rate. I adjust it down till I get my grey scale. This usually works. With some
materials I lower the power as the grey scale is bad, I then start fast and slow down again.
Its worth havign a very small grey csalke augment to use as a test, I usually keep a small 75 x 5mm
test pattern of a full grey scale to use on scrap material to try to get the best grey scale before a
cut I want to keep.
Another technique to use, is to do 3d engraving runs with 0 as the step distance in height. This is essentially
a multi pass system , and they are better at times for a good grey scale..
Art
Mark:
Yes, the max power and MinPowerRad are used in doign photo's and such. Max power is usually set to 90% or
something just to make sure you dont overdrive your laser, some do not like 100%, its hurts them over time.
By setting to 90% or so you may lengthen the life of the laser.
Now, as to the range of grey scale in a photo, this is really particular to the laser as to how
this is set. This is how I do it.
First of all, there is a feedrate override button on the screen, I use this always in photo 3d engraving or
photo burning. Youll notice on the image import screen when creating an augmentation for a photo
burn there is a ramp size, I always set this to about 20m or so on my synrad laser system it runs slower
than my galvo. This is because my slow system conceivably needs a ramp to get up to a speed where
linear corrections work best. During initial start of motion the speed can be too slow for this linear power
curve to smooth things out. So make sure there is a ramp if your system has acceleration that might
be considered low or it takes a bit to get up to speed. On my galvo I use no ramp, but its speed is immediate
and its accel is very high.
Second, I control power with my power slider, not with S words, in fact I keep S words out of my
engraving power to make it all manual power adjustment, every material is different so they all need
to be individually set for power.
Now about grey scales. It is said that power and speed have a linear correlation. This is not true
in the context of greying or blackening wood in my experience. While it may be true that 10 watts
at 100mm'sec is the same in linear terms to 20 watts at 200m's per second in terms of radiation
produced, its my finding that time is the variable that affects these two from being the same. Wood
simply darkens at differing time rates based on actual power.
My advice is to use, as in most cnc, as fast a motion as you can while burning. I most always set to
a high power and adjust speed for the best grey scale. My lasers though probably dont react the way
yours does, so experimention is in order. I set my power to 90% or 95% and then do a test burn at a very
high overridden feed rate. I adjust it down till I get my grey scale. This usually works. With some
materials I lower the power as the grey scale is bad, I then start fast and slow down again.
Its worth havign a very small grey csalke augment to use as a test, I usually keep a small 75 x 5mm
test pattern of a full grey scale to use on scrap material to try to get the best grey scale before a
cut I want to keep.
Another technique to use, is to do 3d engraving runs with 0 as the step distance in height. This is essentially
a multi pass system , and they are better at times for a good grey scale..
Art