GARCAD Laser System specs

Because the GARCAD laser is digital, it has these attributes:

+ Burn power is regulated as pulses per unit of travel.
  It can not overburn on acceleration or deceleration.

+ The dynamic range of the power settings is essentially unlimited.
  (but the very low end doesn't burn most materials).



The laser dot 'effective size' is @ 0.0025 square.  It really is not square or exactly that size,
but that's close enough for calculations.  It computes to 400 dpi with no overlap.

> The GARCAD digital laser is normally powered down to a safe level that will not burn.

> This dot is used to position the laser and to focus it.
  (The dot will appear as a dim rectangle with a brighter line across the long axis
    and a very bright speck in the middle of that line.  This speck is the hot.spot.
    If the rectangle is in focus, so will be the burning focus.)   [---*---]

> The GARCAD digital laser produces pulses whose frequency is controlled by signals
  from the stepper controller (the STEP signal of whatever axis is used).

> Burn 'intensity' is governed by overlap of the pulses.
  This is a function of the Dots Per Inch setting.
  Increasing the DPI (laser bun dots per inch of travel) increases the depth of the burn rather than the width of the line unless combustion spreads it.




Remember that the laser 'axis' is capable of infinite acceleration - set your parameters so.



The 2W model:

5V, 2W, 445 nm, water cooled, pulsed laser diode M140

water cooling allows continuous operation with no degradation:
output: 5V @ 2081 mW optical output

Measured optical output power @ 98% duty cycle:


Test results at various DPI settings:




The 6W model is coming soon!




-= BURNING TIPS =-

Material's Color Matters
color of the material affects the threshold for ignition.  
even the effect of smoke staining the surface encourages the burn
color inhomogeneities of a workpiece can cause erratic rendering of a burn image.

Priming Ignition
On very light colors, a blackened surface 'primes' the burn to get much more even burning.
black shelf paper is very thin and is easily removable.    
it also protects the surface from discoloration by smoke/resin

Combustion Widens Lines.
a coating of thermoplastic paint or lacquer or wax will stifle combustion and produce thinner lines.

Focal depth increases with distance, however the size of the dot also increases.
for close, fine work, e.g. photo rendering, keep the laser close to the work (as close as 0.75 inches)
for cutting, increase the distance for greater depth at the expense of getting slightly thicker lines

A puff of smoke will show the focal cone to help you get the best distance from the work.

The Laser takes a 5vDC power supply which may be a separate supply or a step.down converter run off the main psu.
If it is a separate supply, be sure it shares a common ground with the main psu.

The Laser board needs only 5vDC power and a STEP signal:



The STEP signal of E1 can be used conveniently.  Use Blazer Suite to set the corresponding axis name for the laser.

Shown here on the actual board:

You can download v0.432 here: http://s000.tinyupload.com/?file_id=50577727722307522476
Blazer Suite is a windows only app that helps prepare bitmap images for lasering.
The ONLY image format used is 24-bit bitmap.

Blazer Suite Functions:


Configuration for the GARCAD Cartesian machine is provided as an ini file. Changes are made via the Configuration button.


Creating the halftone image is done via the Halftone button.


Converting the halftone to g.code is done via the Pointillism button.


Files can be very large.  You can reduce the size by rounding off the laser code, e.g., 0.04375 might be fine as 0.044, saving lots of bytes.