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TWEAKIE my CNC machine under construction. |
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CNC is only limited by our imagination. |
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Making stuff - Lithophanes. |
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(37) The original photograph, scanned and converted to monochrome which was used to create the height map for the lithophane.
(38) To get the best results it is essential to use a high grade, translucent, acrylic (such as 'perspex') and to get the spindle speed and feed rates correct.
(39) When it is being cut, the lithophane really does look rubbish, perhaps because it is carved in reverse (white is deep and black is shallow).
(40) The finished cut, it still doesn't look that good.
(41) When it is held up to the light all the detail and wonder are revealed.
(42) Placed on a hardwood stand, the finished lithophane. They are a lot easier to make than I had first envisaged. |
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This low resolution lithophane (comprising of 172 horizontal lines) was cut using a 2mm dia ball nose milling cutter. The material used is 3mm thick, white, opal, plexi-glass and the depth of cut ranges from zero to 2.5mm. The maximum step over was set to 0.5mm and the cutting was completed in a one depth pass with a total cutting time of about 45 Minutes.
If you wish to cut this lithophane yourself you can download the Mach3 G-Code file here eagle.nc. The actual image size is 100mm x 86mm and the start point (X zero and Y zero) is dead centre of this. The Z axis zero point is with the cutter just clear of the surface of the work.
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Depending on your spindle speed you may wish to adjust the feed rate that is currently set at F450.
To produce high resolution images a smaller endmill & correspondingly smaller step over dimension would be required. It would almost certainly require multi pass cutting (small dia cutters, cutting deep in plastic, tend to clog and overheat, resulting at best in a sticky mess) with a considerably longer cutting time involved. But there again, thats the advantage of CNC - you dont have to stand and watch it you can, for example, go and have lunch.
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