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Show"N"Tell ( What you have made with your CNC machine.) / Re: Mirror Lasering With Shades
« on: January 30, 2013, 07:46:07 AM »
Thank you for your kind words John!
I do have to say, excellent image to g-code creation software to you!!
A little detail of the laser diode I am using, it's a 445nm 1W with a 3 element AR coated focusing lens. I able to focus the beam down to .007" and when I engrave Birch Ply, I use a .008" pixel resolution (stepover) and can run at 50IPM.
I use a 3.33 ratio from the stepper motor to the MA3 shaft encoder and since my Z axis screw being a 2.5MM pitch (.0984") then dividing that by 3.33 gave me .0295" to work with on the 0-5V range on the encoder without changing any steps to the motor. I start out at Z-.0038" for Z zero (just before it starts to burn the wood) This is almost 1V to the modulation input on the laser driver. I set PEP4 to cut at Z-.0255" depth, that gives me 255 .0001" incremental moves (theoretical shades) from white to black. This also gives me a .0002" safety below full depth before the encoder will jump back to 0V. My Z axis only moves half the total g-code travel since it's a 2-1 ratio from the stepper to the screw and does not effect the focus of the beam.
Mirrors are harder to burn so the starting zero point is Z-.0095" more then I used for the Birch Ply, about 2V to the driver. I have PEP4 go Z-.016" more for full power. I can run these at 40IPM with a .007" pixel resolution. I found out that full power to the back of a Dollar Tree mirror it turns white. I'm loosing shades with this setting, but how many shades are there from white to mirror anyway?
Thanks again to John, I am really excited about laser engraving mirrors. I have done several Lithophanes in Corian in the past and never got the detail like I am getting with laser engraving on a mirror. Besides, Lithophanes don't look the same when back lit or not like the mirror does, which is a really cool effect in itself.
Jeff
I do have to say, excellent image to g-code creation software to you!!
A little detail of the laser diode I am using, it's a 445nm 1W with a 3 element AR coated focusing lens. I able to focus the beam down to .007" and when I engrave Birch Ply, I use a .008" pixel resolution (stepover) and can run at 50IPM.
I use a 3.33 ratio from the stepper motor to the MA3 shaft encoder and since my Z axis screw being a 2.5MM pitch (.0984") then dividing that by 3.33 gave me .0295" to work with on the 0-5V range on the encoder without changing any steps to the motor. I start out at Z-.0038" for Z zero (just before it starts to burn the wood) This is almost 1V to the modulation input on the laser driver. I set PEP4 to cut at Z-.0255" depth, that gives me 255 .0001" incremental moves (theoretical shades) from white to black. This also gives me a .0002" safety below full depth before the encoder will jump back to 0V. My Z axis only moves half the total g-code travel since it's a 2-1 ratio from the stepper to the screw and does not effect the focus of the beam.
Mirrors are harder to burn so the starting zero point is Z-.0095" more then I used for the Birch Ply, about 2V to the driver. I have PEP4 go Z-.016" more for full power. I can run these at 40IPM with a .007" pixel resolution. I found out that full power to the back of a Dollar Tree mirror it turns white. I'm loosing shades with this setting, but how many shades are there from white to mirror anyway?
Thanks again to John, I am really excited about laser engraving mirrors. I have done several Lithophanes in Corian in the past and never got the detail like I am getting with laser engraving on a mirror. Besides, Lithophanes don't look the same when back lit or not like the mirror does, which is a really cool effect in itself.
Jeff
