Does anyone know at what size litho you can go up to a larger tool? I remember reading a post by TonyMac to Jason that if a litho was say a 20" square you could use a 1/8" dia ball nose for the finishing pass, and still get perfect results. I am interested to know for future reference too, but currently wish to machine an 11"x14" family pic lithophane. I have been using a 1/16" ballnose with a 10-12% stepover on my small lithos with very good results (I have not yet purchased the conical engravers that I know will be stronger and smaller dia. yet like .04) I want to retain decent photo quality, but of course, would like to reduce the machining time.

Also, could someone better explain to me (I know I'm missing something basic) what Tony means by (also as shown in the PDF machining lithophanes file from Vectric) --Setting the Z0 origin 0.080"/2mm into the material for roughing? I understand the toolpath is still set to cut at a max depth of 0.10" Are you "cheating" the Z into cutting -0.180" total? If so, how do you set the Z0 into the material? Do you have to have an off edge material start? I was wanting to use the center of my design as X0,Y0 and carving into a machined pocket of .25 depth in .5 corian. Do you plunge in the .08" and then set your Z0 with the (router in my case) running and then start file? Or is the setting something you do in the PhotoVCarve or your motion control software? So far I've just done my lithos with a single finishing pass in 0.125" material using a 0.08" cutting depth.

I'm really into doing these now, and have all kinds of "tweaking" questions. I tried to read all the posts regarding lithos before I purchased my PhotoV and VCarve, but I am having trouble remembering and finding all those details.

Thanks in advance for any answers, suggestions, input, etc. I truly appreciate this site even though I don't thoroughly understand how to use it yet. Hope I submit this correctly. ---Sparkgirl

Hi Sparkgirl,

Sorry for the delay in getting back to you on this. The Z setting is a bit tricky and can be confusing so lets see if I can try to explain a little clearer.

The main problem is that the Corian is typically 1/2" thick and either needs to be machined to around 1/4" thick or an initial 1/4" deep pocket needs to be machined. The Lithophane is then cut into the pocket region.

When using the pocketing method, then you are correct about 'cheating the Z zero position'. This is because the Z0 position for the initial pocket is on the surface of the material - then run this toolpath.

In PhotoVCarve the 3D Lithophane toolpath is also calculated relative to the material surface. So you need to reset the Z0 on the machine to now be off the bottom of the machined pocket.

You should be able to do this with the XY Origin in the middle of the job by,

Cutting the pocket
Change the cutter
Return to the X0 Y0 point in the middle of the job
Drop the cutter to just touch the base of the pocket
Set this = Z0
Run the Lithophane toolpath

Very Important - In PhotoVCarve make sure the Rapid Clearance Gap (Safe Z height) is set to at least 0.280" so the cutter can move across the top of the material.

Note - When you get confident in using PhotoVCarve and VCarve Pro it is possible to setup the complete job in VCPro and not have to reset the Z0 origin off the bottom of the pocket.

Import the PVC file into VCPro
Double click / Edit the toopath
Edit the Start Depth to be 0.25"

This drops the whole toolpath into material by 0.250"

Save the Toolpaths using VCPro

If you calculate the Pocket toolpath 0.25" deep in VCPro then Edit the PhotoVCarve toolpath to have a Start Depth of 0.25". Then Preview the pocketing toolpath then the 3D lithophane toolpath. You will see that the lithophane detail is cut into the base of the pocket.


I hope this makes sense and help?

Tony

I am trying to figure out the answer to the first question too -- how to cut down on machining time without making reducing the quality. I tried drawing it out, but have decided to machine some samples.

I took a small portion of a lithopane that I like the results on (it is a face shot, and I am taking a section with one eye to outside the hairline to get the high contrast in the eye and the fine lines of the hair). The plan is to machine examples with all of the combinations of the variables: litho size, mill size, step size, etc. and see what the effect is.

Try a 8x10 with a .25 ball cutter, depth of .1 with a 6% stepover.
cut time at 40 ipm is about 1.5 hours.
the results will not capture the detail like a 40thou. ball would but it does give it a softer kinda look.
i start with images that have been ran thru PS to get rid of unwanted "high spots" .....with the image inverted in PVC the lighter areas will show up as a deep pocket.
plus i convert to greyscale and save as the same size has my corian blank.
These are quick cuts that sell for a lower price...some folks like em that way...some don't.
I guess it depends on the picture .....
I should note that I start with .125 glacier white corian (1/4" milled down)
and the image below is a photoshop image.

CR-

How are you pricing you lithopanes? I am just starting to sell them, and am trying to get a handle on pricing.

The same as all things...what the market will bear:)

actually since this is a hobby I just charge a flat rate....8x10 high resulotion 100 bucks.

A quickey is 45....
a framed and lighted 140

keep in mind that most sell for alot more...but this isn't my job and I would rather it never turn out that way...i have a job....i don't want another.

Chuck