Author Topic: Grayscale engraving with 2.5W cheap and not TTL laser.  (Read 541 times)

vernerl

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Grayscale engraving with 2.5W cheap and not TTL laser.
« on: January 16, 2017, 12:59:36 PM »
It was long story how this all started, because previously (and still) I use Mach3 with my big CNC.
First software what I use for testing when I build my laser table was Benbox. It looked very understandable for my children to make small pictures but… what I really do not like is how it engraves curved contours.  It divides these curves in small vectors and looks that these vectors are sent to arduino separately – it makes cnc jogging and sound from motors are terrible. Here is some video how all was built and how Benbox works.
Then I happy found this forum, friendly person ZAX and great T2Laser forum  8)
After many tests and Zax assistance I found how to get something similar grayscale. The whole problem, why was it so hard is that the laser has not a TTL input. That laser has a built in current driver and it is not linear. Its mean, that it cannot open laser circuit when TTL/PWM is less than 150. If TTL is <150 laser only lights and not burning. Other problem ( I think) this driver cannot switch fast – when switch on impulse is to short  It not switch on the laser.
Problems, problems… Everyone who think to buy diode laser – please buy TTL laser and later will not have problems like me.
Gray scale solution:
T2laser: open image -> switch Mode to Dithered -> Velocity mode ON -> Photo mode ON -> Settings Resolution = 0.1mm for smaller images, 0.15mm for bigger images -> running man icon press left mouse button Feed Rate=1000 (for example) -> running man icon press right mouse button Rapid Feed Rate = 2000 (for example)
These Feed rate and Rapid Rate settings are for my laser. You can test and check your image by yours federates for better results. For testing You can use this picture:

What happens with these 2 different feed rates: when area of image is dark laser moves at slow federate, when image area is light – it moves at high speed. And it looks that it changes feed rate between these two settings: lighter=faster, darker=slower. How it is real, need to ask Zax  ;) It helps laser get a time for switching on/off.
Here You can see my some tests when Velocity was not switched on and when is ON:
Velocity OFF Dithered mode, two lower picttures with border switched On :)

Velocity OFF and many tests, when we change laser power PWM limits and feed rates

Velocity ON, some black dots on my daughter ;) face are interesting problem with my computer, and I will ask about it later..

« Last Edit: January 16, 2017, 01:10:41 PM by vernerl »

nottingham82

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Re: Grayscale engraving with 2.5W cheap and not TTL laser.
« Reply #1 on: January 16, 2017, 07:15:08 PM »
Wow great work!!!!!!!! Thank you for sharing.
Laser: 2500mw A5 eleks maker
OS: Windows 10 all in one pc
Software: T2
http://www.gearbest.com/3d-printers-3d-printer-kits/pp_290386.html Paid $160 in 2016