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Hey Tweakie. Blue Laser on 3D Images

Discussion in 'General Talk' started by GrayUK, Sep 15, 2014.

  1. GrayUK

    GrayUK Openbuilds Team Elder
    Staff Member Moderator Builder

    May 5, 2014
    Likes Received:
    You know I'm planning on carving faces and such, in 3D in wood mainly, and then to use a Blue Laser to burn the details into it. Well, let me ask about this burning.
    I know with the Co2 Laser burning, you yourself do, your Z is fixed, because your material is flat, and the Laser focus point is constant.
    Can you see where I'm leading? :D

    With a 3D image, say of a face, the surface is not a constant distance from the laser point, therefore I would need the Laser head to rise and fall as if it were cutting the last path of the previous carve. If you get my drift? :cool:
    So, to the questions.

    1. How much leeway is there in the focus point, any room to maneuver, and still get a reasonable burn? Or is it criticle?

    2. If, say, the focus point is about 100mm from the zero point of the work piece, should I be thinking of setting the Laser zero with a false point of 100mm from the surface?

    3. Can one get various shades, or degrees, of burn by going out of focus, in mm, and thereby reducing the concentrate of burn, I'm thinking of shading here?
    Can one reduce or increase burn by the rate of speed?

    I think of these things while I'm driving all day,
    and, I just know, you know the answers.:thumbsup: :D

  2. Tweakie

    Tweakie OpenBuilds Team

    Jan 18, 2014
    Likes Received:
    Hi Gray,

    I really don’t know all the answers. :)

    It is a law of physics that the ‘depth of field’ (a useful laser dot size) will increase as ‘focal distance’ increases (I leave you to Google the formulae).

    In my opinion, with 100mm focal distance you should be able to obtain a useful depth of field of at least 5mm and obviously it would be prudent to set the focal point some 2.5mm or so into the highest point of the work surface in order to average out the results.

    As the laser beam moves ‘out of focus’ the apparent power density will reduce and the ‘shade of burn’ will become ‘lighter’ which may or may not be a useful attribute for your intended application.

    As you suspect, this ‘shade of burn’ will also vary in accordance with feed-rate. (Quite a lot of work has already been done in this area by creating images using a constant laser power and varying feed-rate and the software G-ray was probably the first in the field).

    To my knowledge, little work has been done (at least in the hobby area) with lasers in regard to adjusting the focal point (Z axis) to allow ‘terrain following’ however, this practice is common with plasma work and ‘torch height control’.

    So it looks like you need to do a lot of research to get it all together but I am certain you will succeed. :thumbsup:


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