PNG Laser System

This has been a long project for me starting over a year ago with the decision that if the business were to survive and grow, some sort of precision cutting would be required.  In today's world of technology, a laser was the best option. From there, the search for the "right" machine started. Turnkey systems with enough power to cut the materials I use and a large enough cutting table started at $30,000. Then I found Emission Technologies.  Don Winter and I had become good friends and coincidentally, Emission Technologies and Don lived within 30 miles of each other.  That was good enough to schedule a "visit".  While in Orlando, I took Don along and we visited Robert Conway's home to get a first hand demonstration of his laser kit. Very simple and a very impressive machine. In fact, the day my wife and I flew home, Don went back and purchased his machine.

While my machine incorporates the "look" of Robert's, I have added several "enhancements". So, this first picture is an overhead shot looking down at the table. The honeycomb vacuum table is 2' by 4' and the entire footprint is approximately 3' by 7'.

Poplar plywood can be purchased in 4' by 8' size and I wanted to be able to feed a whole sheet in from the side. Hence the "open" frame look.

This shot shows the controller, front left, air vane air pump, left rear, laser high voltage supply, center and water chiller on the far right. This type of laser tube is glass and requires water cooling.  The tube produces 50 watts of power but needs 500 watts to get that output. At only 10% efficiency, 450 watts of power go up in heat. The water chiller uses a peltier type of cooling element and is a closed system.   Even running the laser continuously, the water temp only goes up 8 degrees.  I used an air vane instead of an air compressor.  Air is needed at the nozzle holding the focusing lens for two purposes.  One is to keep positive pressure inside the nozzle keeping smoke and debris out and away from the lens.  Two, to blow away or through the cut, the carbon as the laser cuts.  The controller is of my design and build.  It houses 3 power supplies.  A 5 volt TTL (logic) supply.  A 24 volts utility supply for fans, hour meter and laser pointer used for mirror alignment.   And a 36 volt supply for the stepping motors.  It also house the stepping motor controller and two more circuit boards for optical isolation of all the computer parallel port pins and logic circuits that turn on and off the air vane, arming voltage and high voltage to the laser, laser pointer, hour meter as well as monitor the air and water safety cutouts to kill the laser in the event of a problem.

This is a shot of the "Y" gantry as hung under the "X" gantry. Visible in the third and forth steering mirrors and the focusing nozzle / lens assembly.  The red handle is to loosen or tighten the bracket holding the nozzle.   Depending on the thickness of the wood, the nozzle has to be raised or lowered to maintain the proper focus of the laser beam.  Like holding a magnifying glass out in the sun and focusing on a piece of wood to burn.  The hose is air from the air vane.

This shot is of the right end of the table. Visible is the first and second steering mirror and the "tinker toy" assemblies to support them.   Also visible is the end of the laser tube and the water hoses.

This picture shows the bottom of the vacuum table. The honeycomb is supported in 4 pieces of aluminum angle and screwed to a bottom plate.  This is all duct taped to air-tight the assembly.  The 4" hose goes to a common saw dust collector which provides the vacuum.  Vacuum is needed for two reasons.  One to hold down the wood while cutting.  The wood is typically slightly warped and vacuum corrects and holds the wood flat while being cut.  The vacuum also carries away the smoke and particles from the cutting.

This pictures shows the business end of the laser tube. The aluminum device hanging on the end is the housing for the laser pointer.  Just a simple hand held pointer found in most stores.  The batteries were removed and a special "core" was machined with an RCA jack for power cables to attach.  The barrel looking things on the wire from the bottom of the pointer are ferrite coils.   The laser puts out an enormous amount of RF when running and filtering is a must.   The brass "T" with a wire is a temperature probe for monitoring the temperature of the output water.  I run the chiller at 18C or about 64 F. 

This is a piece of scrap plywood under the nozzle.  I had the laser pointer on but the flash obscured the red dot so I "doctored" the pictured and added a dot.  Love that PhotoShop!!!

Here the laser is cutting. This is not a train part but only a souvenir for visitors.  The paper is freezer paper to cover all the unused area of the honeycomb to focus the vacuum to the wood.

Almost finished.  The six pieces snap together to form a 1" cube.