(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.

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.

 

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.

 

This is a high resolution lithophane of a wonderful white tiger.

 

The GCode file (which was kindly given to me by a fellow ‘Mach 3 forum’ member) contains more than 342,000 lines of X Y Z instructions and it took more than 8 hours of machine time to cut. The end result was, I think, well worth the wait.

 

This photograph does not fully do justice to the actual lithophane which really does show the reflections in the tiger’s eyes - It is quite stunning.

 

Lithophanes are an art form, extremely popular in the mid 19th Century, which have mainly been superseded by the advent of photography and are now almost extinct from common use. They were generally cast in fine porcelain from handmade wax carvings and like all art forms required a great deal of artistic talent and skill to produce.

 

Modern computers, suitable software and CNC machines have entirely changed the emphasis of the skills involved and today, quite stunning, lithophanes may be produced with little or no artistic skill at all. Software is available which will convert almost any image or photograph into a ‘depth map / height map’ whereby shades of light and dark from the image are translated to varying depth of cut for the Z axis of a CNC machine. The actual machining is not necessarily a quick process (depending on the resolution required for the final image) but CNC machines can be left unattended to get on with the job and only revisited occasionally or when the work has been completed.

 

Many people I have shown lithophanes to are truly surprised at the detail and depth of image that has been created when they see one for the first time. For my part I am fascinated by every one that I produce.

 

The following is sort of ‘step through’ guide to illustrate the basic process from start to finish.

Think ahead, plan things and always make provision for the unexpected.

A first aid kit and a dry powder fire extinguisher are so basic yet often lacking in the home workshop. Why ?.

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Some Laser cut lithophanes.

 

The parliament building is probably the most photographed structure in Hungary. Not only is the architecture so superb it also exhibits perfect symmetry.

 

This lithophane is just 50mm square and is perhaps a good example of the detail that can be reproduced by laser techniques.

 

The big advantage of using a laser is of course speed as this little example, cut into Corian, took less than 20 minutes to complete, including cutting the blank to size.