Lithophane

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Joe Duplessis
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Model of CNC Machine: CNC Shark Pro Plus HD

Lithophane

Post by Joe Duplessis »

Machined a lithophane out of cast plexiglass using a rough cut ball nose .125 and then finishing cut with a .625 ball nose but the image didn't come out as the image didn't stand out like some lithophanes that I had seen. Also had to pause the machining cause of buildup on the finish cut or is there a way to stop the build up on the bit. :( Joe D

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dwilli9013
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Re: Lithophane

Post by dwilli9013 »

Slow down your spindle speed and try to keep air on the bit to keep it cool. This is very common when cutting Acrylic.
I'm certain a number of people will weigh in on this. It is a popular topic. Not without many different views and techniques. :lol: :lol:
D-Dub
Dwayne
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NormanAlbert
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Re: Lithophane

Post by NormanAlbert »

Hi: You'll find that Corian is by far the best material to use for lithophanes. I've done some white acrylic pieces but even with a brand new .0625 ball nose if the piece is over a couple hours run time there's a good chance of material sticking to the bit. Norm

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Xxray
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Re: Lithophane

Post by Xxray »

You for sure need corian, plexi is useless and worse than nothing.
Buy some on ebay if you have to, there is a guy on shopbot forum selling loads cheap too.

Basics: Import photo, set material size and thickness [ideally will want around 8x10 .25 corian]. Measure with digital calipers, ",25" corian is nominal, its usally a little less.
Next is cutting parameters, very important.

You want to cut as deep as possible without going through and there is not much margin for error. Not deep enough the image will be too dark, too deep then obviously you go through the material, project is ruined.
All depends on perfectly level table and very accurate measurements of material and Z. If it actually is .25 thick, I would set it to cut at .22 or .23 if you are feeling lucky.
Line spacing - 10-14%. Less = better detail, more time.
Line angle - Usually leave it at 0, sometimes 45. I don't use a roughing pass for these, if your hold down is secure, not necessary.
Check the "invert light/dark", else the litho will come out as a negative.
Contrast usually set around 20

Thats it, calculate and save tap file.

Once material is perfectly centered on machine, take a piece of paper, place it on material and slowly lower the bit, sliding the paper back and forth until the bit touches it, zero it there.
Start cutting and hope for the best.
Some guys zero on the spoilboard, I zero on material. So make sure you have that straight in cutting parameters.
If it comes out washed out because you didn't go deep enough, easy solution, and just how easy depends what kind ot sanding tools you have. just sand the back until it is thin enough to your satisfaction. I have a drum sander making it easy, too easy. Belt sanders can work, along with hand held orbital and mouse sanders, just takes more time.

Thats about it, once you got a few successes under your belt they are pretty simple. An average 8x10 with 10% line spacing can take up to 5 hours.
Also, it often helps to edit photo prior to importing. Crop out anything unnecessary, and if there are really bright whites, try dulling them out a bit. If there are large areas of white, these will be the deepest cuts leaving the darker colors a bit too dark.

As always, the better resolution photo, the better the results. I have transferred details as fine as raindrops and individual strands of hair to corian. But if you have a mushy, low resolution pic, the inferior details will be transferred as well.
Doug

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dwilli9013
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Re: Lithophane

Post by dwilli9013 »

As always, the better resolution photo, the better the results. I have transferred details as fine as raindrops and individual strands of hair to corian. But if you have a mushy, low resolution pic, the inferior details will be transferred as well.[/quote]

I knew the master would weigh in on this. Thanks Doug your work is some that I follow the closest. :lol: :lol:
D-Dub
Dwayne
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Xxray
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Re: Lithophane

Post by Xxray »

If I am a master, its only because my scrap pile is bigger than yours !
Doug

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