A lithophane without a roughing toolpath on 1/4" corian

[BSImages]

That's right!
I cut this 10"x12.5" (actual cut area) Lithophane without a roughing toolpath on .25" corian using a 45 degree V-bit!
I took the picture of this huge sculpture/waterfall at the Jackson Rancheria Casino in Jackson California yesterday.
I have attached the PhotoVCarve cutting parameters page, as you can see I told the software that I am using a 0.031 ball nose bit.
I set the Z zero at -0.1" and cut it in one pass.
Cutting at a 45 degree angle is essential with this method as it is a deep cut.
With the V-bit once the first pass is cut each subsequent pass is only shaving the edge of the previous pass.
This is why the roughing pass is not needed.

Bill Schober
Pine Grove, CA USA

[CRFultz]

Outstanding Bill

Now you really have my interest!

You didn't mention about the time saved, minus the rough, is the finish pass quicker
since you are going faster? I see you have a 30/30 for your settings....can you go faster since you are using a stronger bit?

I usually run at 40ipm with a .04 ball with the router running at about 20k.

Another question...does the ball size you have for the settings have any correlation to a 45 degree cutter.

Or I should say if I was using a 60 degree...should the setting stay at 031?...
i have bought some very sharp solid carbide bits with a 60 degree angle, I'm anxious to try them out.

Thank You very much for the heads up on this new technique

Nice photo by the way...i kept trying to see the water source....reread your post to discover it was a sculpture

Chuck

[BSImages]

You can cut it at a much higher speed than the 30/30 I did it at, as I was experimenting at a lower speed simply to observe the cutting process.
Time saved would be figured by how much faster you can run a stronger bit, and time saved by not setting up for and then cutting the roughing cut.
I think that a 45 degree V-bit would cut better than a 60 degree bit if the detail is fine and a 20 degree would be best if it really fine detail...
The smaller that you tell PhotoVCarve that the ball nose bit is the more detailed the output will be.
But it you can use any V-bit as the tip is approximately 0.00" , but the angle of the bit is important if you have real sharp edges as the angle of the bit would be added to the edge.
Does that make sense?
Bill

[knight-toolworks]

You can do a single pass with a small ball nose too. I did it and it works fine. but a v bit is far stronger. I tried a large lith and it is a bit faster but all of the plunges slow down the process by quite a bit. the machine never gets to max speed. even with z set at 4ips and xy set at 8 it is still a slow process on larger pics.
photocarve gives pretty bad estimates I tried doing a 8x10 at my max machine speed it shows 2.25 hours but the machine take about 7.
the plunging slows the whole process down unless there are a lot of flat area's.

[BSImages]

I had the same problem too until I increased the acceleration in Mach II. Now the time estimates are less than a minute off for a job. The acceleration setting tells it how fast to get up to full speed and conversely how fast to slow back down to a stop. After increasing mine though I had to put more braces on the legs my machine table as the whole table would move with the sudden starts and stops.
I really like the way my homemade machine performs now!

Bill Schober

[denver]

Hello,

I was wondering about the V bits mentioned earlier here. Are those 20, 45, and 60 degrees included angles? If they are, where are you getting bits like that? I've seen 60 and 90 degree (included) bits, but nothing smaller.

Also, why is cutting at 45 degrees better than 0 or 90? You would be shaving off the same amount each pass in any case, wouldn't you?

And you could also manually edit the part file to reduce the speed on the first cut, then restore it for the remainder. Seems like I read someone else mentioning that somewhere....

Finally, from what I've noticed cutting a few lithophanes is that a lot of time is spent on the rapid clearance gap. It moves Z up & down that amount at the end of each line. I've tried reducing that by 1/2 and significantly reduced cutting time. Haven't had the nerve to cut it to zero yet.

Thanks,

Denver

[BSImages]

The smaller the angle the finer the detail...an example might be small white dots on a black background in an image. If the bit is too large it will make more of a bevel or gray area around the dot. A 60 degree should work okay though.
At a 45 degree angle the 1st cuts are very small and shallow, try it and watch it cut once and you will understand the reasoning.
The clearance of 0.125" is actually only 0.025" because you are setting the Z zero at -0.1 of actual Z zero.
I hope this clarifies things for you,
Bill

Hello,

I was wondering about the V bits mentioned earlier here. Are those 20, 45, and 60 degrees included angles? If they are, where are you getting bits like that? I've seen 60 and 90 degree (included) bits, but nothing smaller.

Also, why is cutting at 45 degrees better than 0 or 90? You would be shaving off the same amount each pass in any case, wouldn't you?

And you could also manually edit the part file to reduce the speed on the first cut, then restore it for the remainder. Seems like I read someone else mentioning that somewhere....

Finally, from what I've noticed cutting a few lithophanes is that a lot of time is spent on the rapid clearance gap. It moves Z up & down that amount at the end of each line. I've tried reducing that by 1/2 and significantly reduced cutting time. Haven't had the nerve to cut it to zero yet.

Thanks,

Denver

[denver]

Hmmm. I think I'm confused now. I understand that a smaller bit will result in finer detail. However, I'm talking about the "Line Angle" setting under "Set Cutting Parameters" in Photo VCarve. And I'm referring to the width, not depth, of the cut. It seems to me that the "Line Spacing" setting would dictate the width of material removed per pass. It shouldn't matter if you are cutting at 0, 45, 90, or any other angle to the X axis. I've noticed that if you have a rectangular image, cutting in the long direction can certainly speed things up. You end up with fewer total lines, and less time spent raising and lowering the bit at the end of each one.

Thanks,

Denver

The smaller the angle the finer the detail...an example might be small white dots on a black background in an image. If the bit is too large it will make more of a bevel or gray area around the dot. A 60 degree should work okay though.
At a 45 degree angle the 1st cuts are very small and shallow, try it and watch it cut once and you will understand the reasoning.
The clearance of 0.125" is actually only 0.025" because you are setting the Z zero at -0.1 of actual Z zero.
I hope this clarifies things for you,
Bill

Hello,

I was wondering about the V bits mentioned earlier here. Are those 20, 45, and 60 degrees included angles? If they are, where are you getting bits like that? I've seen 60 and 90 degree (included) bits, but nothing smaller.

Also, why is cutting at 45 degrees better than 0 or 90? You would be shaving off the same amount each pass in any case, wouldn't you?

And you could also manually edit the part file to reduce the speed on the first cut, then restore it for the remainder. Seems like I read someone else mentioning that somewhere....

Finally, from what I've noticed cutting a few lithophanes is that a lot of time is spent on the rapid clearance gap. It moves Z up & down that amount at the end of each line. I've tried reducing that by 1/2 and significantly reduced cutting time. Haven't had the nerve to cut it to zero yet.

Thanks,

Denver

[mjc117]

Hello

This is what I do and it seems to work very well. I use a 30deg vbit for all of my litho's. I set the depth to .130" in 1/4" corian with a speed of 45in /min, and the line angle set to zero. I then create the toolpath and edit it to remove all of the up moves to my rapid clearance depth, you can use notepad with the find/replace function - put the rapid clearance in the find (Z#.###) and one push of the space bar in the replace. Then click replace all and it will remove all the rapid clerance moves. Now go to the end of the g-code and on the last move that takes you to the home position put in a clearance for the Z or your piece will be ruined.
Removing the rapid moves saves time when making litho's.

When I set the tool zero in mach I zero the tool and then set it to +0.080" so my deepest cut is actually -0.210", I like the contrast it provides and the light does not need to be as bright (I use LED's). I also reduce speed on the very first cut.

I think although not sure, that the rapid clearance at the end of each line was used when using pvc for it's original intention. I understand that the litho carving was an added bonus.

Hope this helps someone

Mike

[lovebugjunkie]

Hello

This is what I do and it seems to work very well. I use a 30deg vbit for all of my litho's. I set the depth to .130" in 1/4" corian with a speed of 45in /min, and the line angle set to zero. I then create the toolpath and edit it to remove all of the up moves to my rapid clearance depth, you can use notepad with the find/replace function - put the rapid clearance in the find (Z#.###) and one push of the space bar in the replace. Then click replace all and it will remove all the rapid clerance moves. Now go to the end of the g-code and on the last move that takes you to the home position put in a clearance for the Z or your piece will be ruined.
Removing the rapid moves saves time when making litho's.

When I set the tool zero in mach I zero the tool and then set it to +0.080" so my deepest cut is actually -0.210", I like the contrast it provides and the light does not need to be as bright (I use LED's). I also reduce speed on the very first cut.

I think although not sure, that the rapid clearance at the end of each line was used when using pvc for it's original intention. I understand that the litho carving was an added bonus.

Hope this helps someone

Mike

Cute baby Mike and nice litho. Thanks for letting us know how you did it.

Do you buy a led kit or build the circuit? Mind posting the circuit diagram/setup of the led’s. I want to do some litho for a few friends and have been wondering how to “light” up the smaller ones when I get to them. (Waiting on my router)

George

[mjc117]

Hi George

I build my own LED light panels and they work great. I tried the cold cathode light tubes but they didn't have enough light for me. Four 80mcd Led's in series using 12volts works great, and no need for a resistor since they tend to be self regulating although they don't provide the the full 80mcd of light. I could use 3 LED's and a 33 ohm resistor but 4 lights provide a more even backlight light. I use the high power LED's with a 100+ deg light angle, don't use the ones that have spot beams. The litho in the actual pic above is 5.5" square in a box that is 7" square x 4" deep and 4 LED's lights it up really well in a fairly bright room. Now I'm working on one that will change intensity based on ambient light. The good thing about LED's is that they have about 60,000 hr life span and the leds only draw 80ma of power so you can leave it on 24/7.

One trade secret down the tubes, enjoy.

Mike

[denver]

That's great Mike. I've been heading in the same direction regarding editing the toolpath file. Cutting at either 0 or 90 degrees also helps locate the end of the first line - it's where either the X or Y coordinate changes - when you want to set the speed of the first cut lower. I've been orienting the images so the long axis is Y, and cutting at 90 degrees.

One of the photos I did recently was fairly dark, so I've also been experimenting with increasing the max. depth setting and also starting with the Z axis set a bit lower. So far the results have been good.

I just discovered that PVC doesn't accept a rapid clearance of 0.0, so deleting it from the file is the next best answer.

Mike, what kind of line spacing are you using? And are you specifying a V bit in the tool selection, or something else?

And it looks from your photos that you're doing something with the edges - perhaps carving them down? Or are my eyes playing tricks?

I would also be very interested in hearing more about how you package these - what kind of frame/enclosure, power for the LEDs, etc. Lithophanes are one of the things I would like to begin selling, but I haven't figured out a good backlit frame/holder that's simple, easy, and looks good.

Thanks,

Denver

[mjc117]

Hi Denver

I’m using the same setup basically as Bill showed at the top of this thread.

Thanks Bill, thanks to you I was able to accomplish this.

My line spacing is from .005 - .007, I have been trying to increase it as much as possible and still have the detail to cut down on total mill time. Tool specified as .031 ball mill as Bill showed and I use a v-bit to engrave in one pass. It still takes ~3 hrs to cut though at 45 in/min. The edges are just the natural depth from carving and it is recessed in the box around a quarter inch.

I use shadow boxes for the litho (check your local discount stores), wish I could find someone to make them in bulk at a good price since the availability is not always there or I will need to redesign things. My garage is packed full so my space is limited at this time for more tools and I'm not quite ready to rent a shop $$.

Mike

[denver]

I've been experimenting with this (cutting with a V bit instead of ball), and have noticed an odd side-effect. If you have a nice back light and you are reasonably far away, the resulting lithophane looks great. But when examined more closely - within 18 inches or so - it begins to look, well, dirty. I suspect this is because you don't get the same smoothing with a V bit as you do with a ball. Has anyone else noticed this?


Thanks,

Denver

[BSImages]

Yes I have. What I do to correct this is to scrub the finished lithophane with a stiff brush and soap followed by good rinsing of water. After it dries I give it a spraying of clear lacquer. The results are amazing!

Bill