actually 2 question for photovcarve

[wentzele]

First what is the best or minimum resoultion of a picture used to make a Lithophane?
minimum pixels or DPI.

Secondly, if I try a multiple pass for photo vcarve I set my mill deep to .1.
If cutting to depth of .18 I expect a 2 pass cut. Originally I was thinking that the bit
would cut one pass at .1 or .09 (1/2 max) then repeat same line at .18 dp.
What I am seeing is as the cutter moves across and area with greater then .1 depth then the bit backs up and recuts that partial pass a 2nd time to final dp of .18.
However what I ma seeing on my machine is the bit will travel past the >.1 depth area the back up to start of > .1 depth and do 2nd pass down to max .18 depth. The bit then claims back to areas .1 or less and continues down the line. However if there is a second area along the same toolpath it will cut that complete pass to full depth even though it may be greater the .1 deep cut.

As I said I would expect one complete depth pass of .09 then retrace that path at .18.
Didn't expect it to back up at any point along the path to recute. but then ignor the 2 pass command and cut to full depth rest of line.

[P.Passuello]

Hi wentzele,

I'm not sure of the best resolution but I find the program converts the picture a lot quicker is the size of the photo matches the final size of the carving. It doesn't seem to require a high resolution photo to produce a very good result.

As for the pass behavior you mention I can confirm what you have noticed of the cutter only obeying the pass depth at the start of each line. Should a deeper cut be required later on in the line it is cutting it will cut at full depth instead of doing 2 passes. If you are really unlucky it will break your cutter.
To get around this I do roughing cuts for Lithophanes and have now changed from ball cutters to engraving cutters which can make large cuts if needed and allow the engraving to be done in one cut.

It would be interesting to know if this is a software bug or the way it is meant to be.

Peter

[buck4]

Wentzele,
I believe good contrast is just a important as the resolution.
I use a somewhat different cutting style then some of the forum members. Alot of them are using a v-bit to cut the lithophane in one pass. And they are getting good results.
Max cutting Parameters at .100"
First off I cut the outline of the picture with a .125" bull nose .140" deep with a offset of .010" So if the picture is 5"x7", I offset it by .010" making it 5.010"x7.010" and cut on the line -.140"
Using the same cutter for the roughing pass, I reset my z-zero .070" into my stock. The machine thinks its only cutting a max of .100" , but is at times cutting .170" After the roughing pass, I use a .0625" bull nose with a .005 setover after lowering the z-zero another .010" and cut at 30 degree angle.
Apoint to remember is, when you set up the material, use bottom left cornor as x/y zero. Because when you start the rough pass, the cutter is going to plunge .070" below your stock height, and rapid move to the bottom right corner. By cutting the picture ouline .140" deep first, this gives the tool a path to rapid move in, where the stock has already been removed. Plus the outline cut (.140") makes a smooth edge for the finished lithophsne, and stops leaving tool marks around the outside.
Buck

[NormanAlbert]

I use a 1/4 shank 4 flute tapered to a 1/16 ball nose solid carbide bit made by Think & Tinker and available at Precision Bits. The tapered design gives great strenght and the 4 flutes means you can slow the router down for less noise. I've taken 1/4 inch deep cuts in corian without any problem with this bit. My stepover is 10 %. The straight bits in the 1/16th diameter range do need to take finer depth of cut. Norm

[Win Brayer]

I am confused. If pass depth is set to .1 and you program a max cut in pvc to be .2, I assume it will make 2 .1 passes automatically. Is this correct?

[rsetina]

Win,

That's correct.