After a large failed engrave I decided to try some grey scale.
The upper horizontal lines are from a slanted board test and testing smoothie is able to control power (pot at 15ma and 100%, 50%, 30%).
Grey scale mage set at 90 dpi on the left and 300 dpi on the right.
Various max settings from 50% to 100% and various speeds 20-300mm/s.
Question: why can’t I see any difference between black levels? It’s all engraved the same and then fades away quickly.
Any ballpark values for min/max ma and mm/s?
+Peter van der Walt That’s exactly what I was trying to do. I guess I need a LOT more patience to bump the parameters right.
+Peter van der Walt That tutorial is where I got the ideas for the tests but I guess I’m either jumping over the correct interval or I’m very far away from it. My machine has some issues with the belts which I’m too lazy to replace and I haven’t try to go faster than 300mm/s, maybe that’s why I have deep engrave and no difference between darker shades. Still waiting for Alex Krause to chime in. And by the way thanks again for the wonderful piece of software LW3 is.
@Mircea_Russu you will certainly have deeps engraves with a k40 specially on softer woods. If you can reach 300 mm/s you are good on speed. Try to lower the max power. I would say go 300 white- 200 black and power 5 or 10 to 30 on increments of 5
What pwm period are you using for the laser module
@Alex_Krause 200us that is 5kHz via a mosfet to the center tap of the pot. The mosfet is an IRLR7843PBF which should turn on/off under 100ns. Going 250mm/s is 10"/s going for 90dpi it has 900 “dots” for 10" so 900 points/sec so about 5.5 pwm cycles/dot. Should I change to 200us (50kHz)?
@Mircea_Russu I’ve been playing around with settings yesterday. I’ve tested white 500 & black 200, white 500 & black 250, white 800 & black 250. What I’ve noticed (& intend to test today) is that the higher I set the white, the less visible the white is in the image. I’m running at 10mA max currently (Ariel suggested that is high enough). If you look at the post I made with the pic of dragon on wood, I noted settings for each test on each picture’s comment.
@Mircea_Russu is your pwm signal 3.3v or 5v
@Alex_Krause my pwm is inverted, it grounds the IN pin from the pot. So the power % in LW3 is the % from the max power set on the pot. It works for cutting the horizontal lines show different powers, the ma meter shows power setting ok. For engraving power fluctuates too quickly to be read on the ma meter.
@Yuusuf_Sallahuddin_Y thank you I shall take a look.
@Mircea_Russu what wood is this? I have noticed not all woods are created equal for engraving. Also there is a minimum power required to enable the laser to engrave most people see it around 4-5ma but with a chiller can be seen as low as 1-2ma in power. the efficiency of your tube is effected greatly by the cooling water temperature. You can see this by going back a few days and looking at @Ariel_Yahni_UniKpty test on acrylic.that being said… I believe @raykholo has a 5k ohm resistor in series to help with overcoming the minimum power required faster. Please correct me if I’m wrong Ray.
