K40 Laser head w/ air assist

[uMinded]

I picked up the air assist head and a 38.1mm lense and is it just me or is it exactly 38.1mm from lense center to the tip of the air assist nozzle??


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If I put something with small print under the nozzle and look through the mirror I can read the letter clearly by only when the nozzle is physically touching the object. This is also a problem because the tip of the air assist is also essentially the gantry height so it snags the papers edges if not taped down.

Is something wrong here or is this lense too short for this assembly?

[brian257]

You are focusing a different wavelength of light for the laser than you are when you look through the lens. You can't focus it that way. Buy a cheap pair of 6" digital calipers from Harbor Freight and measure how far your lens is up in the head plus half of the lens thickness and that will tell you where your focal point is. With mine the focus is about .35" from the tip of the nozzle and I have a cut piece of wood I put under the head to focus.

[NickWL]

and the distance is from the centre of the lens to the workpiece (not necessarily to the end of the nozzle).

Best is to get it roughly right then lay a sloped piece of work material, draw (laser) a line up the slope, note where it is sharpest then pick a handy datum reference point and measure from there to the sharp focus. Then you've got it easily settable.
Nick

[BrianJenkins]

and the distance is from the centre of the lens to the workpiece (not necessarily to the end of the nozzle).

Best is to get it roughly right then lay a sloped piece of work material, draw (laser) a line up the slope, note where it is sharpest then pick a handy datum reference point and measure from there to the sharp focus. Then you've got it easily settable.
Nick

That's what I did. Mine turned out to be 23 mm from the end of the head assembly.

[AndyKunz]

I posted a design for a simple tool in this thread: http://www.rcgroups.com/forums/showthread.php?t=2292449

One of the guys converted it to a 3D printable thing. I made some at work, and have been using the ever since.

Mine is for the LO head for a 900x600 system, but the idea may help you.

Andy