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paul mott
01-01-2013, 4:22 AM
Itís been some time now since Mike started the ball rolling for laser cut Lithophanes so I thought you may like to see this one, made yesterday.

I have used 3mm opal Plexiglas as it sublimates easily and has pretty good light transmission qualities, only illuminated with natural background lighting by being placed in a window.

I still have a couple of problems to be overcome but hey, thatís half the fun of it.

Paul.

Mike Null
01-01-2013, 11:26 AM
Paul

I like the look of it. Keith sent me some thin Corian a couple of weeks back and I'm going to try to make at least one lithophane.

paul mott
01-02-2013, 7:37 AM
Hi Mike,

I still have my doubts that laser produced Lithoís can match the quality of those that are spindle machined but they are certainly a whole lot quicker to make.

Paul.

walter hofmann
01-03-2013, 6:02 AM
Hi there
I did a few lithopane pieces and they turned out pretty well here are a sample
greetings
waltfl250005

Jiten Patel
01-03-2013, 7:35 AM
Hi folks,

really interested in doing some of these - can you possibly show some pictures with and without a light source so people can gauge what these are all about please?

Keith Outten
01-03-2013, 7:44 AM
Paul,

Laser engraved lithophanes are vary rare, not many people have been attempting to make them it seems so there is very little information available. Theoretically a laser should be able to produce a lithophane with much better detail than any rotary cutter could ever match given the diameter of the beam. I have only experimented with a laser lithophane once, the piece had some problems based on the graphic preparation not the laser work.

IMO the only reason that laser lithophanes are not popular is that most laser operators don't have access to the software that almost every CNC owner has that will easily process a bitmap for the intended purpose. Aspire, VCarve Pro and PhotoVcarve will process bitmaps to provide the necessary gradients and Vectric has advertised that these programs can also be used to prep a bitmap for laser engraving. It seems to me that the problem is that none of us who own a laser and any of the Vectric programs have had the time or the need to experiment as yet. I spent some time watching the Vectric lithophane training video last week and I hope to be able to devote some time to my next attempt in the next couple of weeks.

I see some very big advantages to using laser engravers to make lithophanes. Besides the pinpoint cutting capability you would never break a bit, never need a roughing pass and the time required can't take longer than CNC machining even if multiple passes are required. Someone is going to come up with a technique that works and when that happens I believe it will open the door to a whole new level of machining lithophanes. Mike Null or Walter Hofmann have already broken gound we just need someone to take the next step.

Those of you who have never seen a lithophane they are amazing. When an experienced CNC operator makes them they have the highest WOW Factor of any project I have ever seen. The down side is that lithophanes take many hours to machine on a CNC Router. A 5 by 7 inch can take 5 hours or more depending on the picture and other factors that have to be addressed. When you hold one up to the light and see the picture POP you will understand how absolutely Cool these things are, until then it is too difficult to try to explain what a high quality lithophane looks like IMO.
.

walter hofmann
01-03-2013, 7:51 AM
Hi all
the most important part is like all pifture engraving preparation of the picture.
it should be in 8bit grey, min 600DPi and a at least two to three run first with low power and then depending on the material a bit higher power
the speed plays a major role. the first run should be a bit faster then slow down to about max 100mm/s.
its a bit a slow process if it should come out right and quite a bit of practis is required.
greetings
walt

Keith Outten
01-03-2013, 8:21 AM
The Vectric Aspire training videos provide specific instructions for saving bitmaps that have been processed so they can be laser engraved.

Here is an excerpt from the Vectric web site about PhotoVcarve:

What is PhotoVCarving?

PhotoVCarve instantly converts photographs and images into high quality toolpaths that can be run on virtually all CNC routing and engraving machines.

What can it do?

The ability to permanently CNC machine pictures onto jobs has been a challenge to many machine users and although there are software products that appear to offer the facility, they often fail to deliver in reality.
PhotoVCarve is also perfect for machining 3D Lithophanes directly from photographs, that make perfect gifts, keepsakes and mementos that will last for generations.

The opportunities PhotoVCarve offers are endless and it can be used by all CNC machine users. From the hobbyists who build their own ‘home brew’ tables to professional engravers running high cost industrial machines, the software offers something for everyone.

walter hofmann
01-03-2013, 9:55 AM
Hi
I use only coreldraw and corel paint
similar to rodnes gold methode
greetings
walt

Dee Gallo
01-03-2013, 12:44 PM
I would like to know if someone can "translate" what "100mm/s" means on my Epilog 35. I don't know what Walt means by "a bit faster then slow down" - what is the starting point? Thanks for any clarification.

cheers, dee

Dan Hintz
01-03-2013, 1:09 PM
Dee,

That should be around 20S...

Mike Null
01-03-2013, 4:19 PM
I have a feeling that Walt meant 1000mm speed or about 40 inches per second.

Dee Gallo
01-03-2013, 6:03 PM
Okay, so Dan - how is 20 speed considered fast?

Mike - I don't know how many inches per second translates into speed numbers.

Walter - what do you mean by "low power"? I would consider 20 to be low power, but 20sp/20 p seems like it would not do much to a piece of acrylic.

Dan Hintz
01-03-2013, 7:16 PM
Okay, so Dan - how is 20 speed considered fast?

Oh, I never said it was fast, I merely did the conversion for you, as requested... 100mm/s is roughly equivalent to 20S on your machine.

paul mott
01-04-2013, 2:40 AM
Because my laser operates differently (GCode) I am not sure you can translate my settings but if itís any helpÖ

My Cat Litho (show above) is 100mm wide, it was cut in two passes and took just under 40 minutes to complete.
The maximum laser current was set at 12mA.
The X axis federate was 3500mm/min (constant velocity, with the acceleration and deceleration zones outside of the image area).
The X axis and Y axis step-over was 0.1mm.
I used an 8 bit colour image converted to greyscale where each pixel value was translated into a defined number of 40uS pulses, compiled (just one line at a time) and sent to the laser. These constant width (PWM) pulses were then triggered at a varying frequency (PRF) of between 0 (black) and 12.5kHz (white) during each laser line scan.

Paul.

walter hofmann
01-04-2013, 5:31 AM
Hi dee and dan
ok I am working with the AWC DSP and this is all in metric, sorry
now the starting point is about 10 inches?second and the last run should be around 4 inches /second.
the power I use is first run about 5mA ( 16%) on my DSP and the lastone around 8 to 10mA ( 24 to 26% on DSP)
I hop this clears it up sorry
greetings
walt

walter hofmann
01-04-2013, 5:38 AM
Hi dee
ok its very confusing with all the different machine values thats why I prefer to give real values like mA for power and mm for speed.
on acryl like on this picture, what is different from the corian lithopane I only use 6mA with one run and speed around 150mm or 6 inch/second

greetings
walt250154250155

Mike Null
01-04-2013, 5:44 AM
Walter

The problem with using mA is that it is totally meaningless to the majority of people on the forum. Watts would be more understandable. We can convert mm to ips easily enough.

Michael Hunter
01-04-2013, 6:31 AM
The magic of a really good lithophane is that there is absolutely nothing to see until light shines through from the back (the back being the side with the image).

The best example of this is a bottom-of-the-teacup lithophane which only appears as the cup is drained.

Given that lithos are time-consuming to produce, what do people think is the best way to display them?
It needs to be something that encourages people to pick up or move the litho so that the image appears and/or changes.

walter hofmann
01-04-2013, 6:38 AM
Hi michael
I disagree that the picture can not be seen without light, the original lithopane shows the picture without light as a 2D flat picture and with the backlighting it comes out like a sub 3D. see explanation here http://en.wikipedia.org/wiki/Lithophane
greetings
walt

paul mott
01-04-2013, 7:46 AM
The magic of a really good lithophane is that there is absolutely nothing to see until light shines through from the back (the back being the side with the image).


For best viewing results the back is actually the plain side - they are viewed from the machined or image side !

Paul.

Michael Hunter
01-04-2013, 7:50 AM
Hi Walter

Agreed that many examples are like you say.

The very best one I have seen was in a museum. It was a fairly large rectangular panel set at an angle as you approached it and well lit on the front so that all you saw was a flat sheet of glossy porcelain with a bit of a "glow" to it. When you got in front of it, the image suddenly appeared, as if by magic.
To get that effect is definitely worth the time and trouble, but difficult to set up at home.

Another fairly good type is the wall lights which are just smooth white in the day, but have images when illuminated at night. Not quite the same magic though.

Mike Null
01-04-2013, 8:02 AM
Michael

I agree with you. The best I've seen are the teacup examples you mentioned. It is not possible to achieve the same look with a laser but if we could find exactly the right material we might be able to show them smooth side out which would be my preference.

paul mott
01-04-2013, 8:29 AM
Walter

The problem with using mA is that it is totally meaningless to the majority of people on the forum. Watts would be more understandable. We can convert mm to ips easily enough.

I understand what you are saying in relation to RF Laser tubes but for Glass Laser tubes the situation is slightly different – a current setting (mA) is easily set and / or measured.
The actual tube used may well be rated at 40 Watts (manufacturer’s specification) but that may not be the power that is actually being applied to the work during the job creation thus mA is often used as the expression of output power.

Paul.

Scott Shepherd
01-04-2013, 8:41 AM
So are you supposed to look at them from the front or the back? In the wikipedia article, it's clearly showing them from the machined side. I did one last night in Corian and it's fuzzy, at best, from the back side, but from the machined side, it looks great.

I'm so confused :)

Mike Null
01-04-2013, 8:49 AM
Steve

My fault. They are viewed from the machined side. I wanted the other view as I had in mind to make a lamp shade which only showed the image when lit.

Paul

I appreciate your point but the entire industry has used watts as the measurement for equipment as well as material settings. The use of a percentage of wattage is more easily understood. If those working with glass tubes find mA to their liking so be it.

Dan Hintz
01-04-2013, 8:52 AM
You say tomato, I say toMAHto... look at it from whatever side you wish. Personally, I think they look best when viewed from the flat side... then it's magic when lit from behind.

If it looks fuzzy, you';re not close enough to the flat surface for detail... turn your power up or decrease your Z height (laser or CNC, respectively).

Scott Shepherd
01-04-2013, 9:12 AM
You say tomato, I say toMAHto... look at it from whatever side you wish. Personally, I think they look best when viewed from the flat side... then it's magic when lit from behind.

If it looks fuzzy, you';re not close enough to the flat surface for detail... turn your power up or decrease your Z height (laser or CNC, respectively).

Yeah, I can't do that. I processed the photo thinking a good contrast would be good. However, when engraving in 3D mode on the Trotec, it's made those peaks and valleys quite high and low. So while some is within .030" of being through the corian, some is still at the top level, never touched. On the contrary, it looks great in 3D. First time I've used that on the Trotec and it did an amazing job.

In the future, i'll try to make the image a lot more "flat" in it's contrast.

Mike Null
01-04-2013, 10:14 AM
Here's a link to that earlier thread on lithophanes. http://www.sawmillcreek.org/showthread.php?56128-Lithophanes-Way-to-Go/page2&highlight=lithophanes

Scott Shepherd
01-04-2013, 1:05 PM
Here's my first attempt. It's showing from the front. It's 6" x 6" done in 1/4" corian.

Click to enlarge
250178250179

Mike Null
01-04-2013, 2:05 PM
Steve

Very nice detail.

Dan Hintz
01-04-2013, 6:19 PM
Steve, looks good to me... what's the problem?

Scott Shepherd
01-04-2013, 7:57 PM
Thanks, the only problem was I kept trying to make it visible through the flat side. I engraved almost all the way through it and it's still not clear and visible on the flat side. The relief side, however, could have done with a lot less passes, if I only knew that's what I was supposed to be doing :) Probably about 1 hour to 1 hour 15 minutes to do a 6" x 6" photo if I would have stopped when I should have.

Andrea Weissenseel
01-05-2013, 6:23 AM
First of all, happy new year everbody (better late than never;) )




IMO the only reason that laser lithophanes are not popular is that most laser operators don't have access to the software that almost every CNC owner has that will easily process a bitmap for the intended purpose.


agree with you Keith, and you also have to have the time to experiment with and learn the software. I also think that the picture is the key to a perfect lithopane like these ones https://www.google.de/search?um=1&hl=de&tbo=d&biw=1241&bih=585&tbm=isch&spell=1&q=lladro+lithophane&sa=X&ei=oQzoUObAO9DgtQb4_IHICQ&ved=0CFUQvwUoAA

@Steve, that looks very nice and detailed

Keith Outten
01-05-2013, 8:11 AM
Andrea,

I agree that it is difficult for some to find the time to experiment with new techniques and to learn how to use new software. The software part is where I find myself lacking in skills, it seems to take me hours to learn what most can in just minutes when I install new software or even experiment with new features. Honestly if it wasn't for Aspire's capability to process photographs and provide the necessary gradients automatically I would pass on the idea of making my own lithophanes. The ability to process photographs into files for engraving is a very special skill that some have and some don't, sadly I fall into the second category :)

I saw my first lithophane when I was visiting ShopBot in Durham NC a few years ago. I picked up the piece and had no idea what it was, a few minutes later one of the ShopBot techs walked by and I asked him what in the world I had in my hand. He held it up tot he light and told me it was a lithophane and that it was machined on one of their CNC Routers. In 2010 I was at IWF in Atlanta, while wandering around the vendor booths I saw a group of people standing at a table at the Laguna booth. When I was close enough to see what they were looking at I picked up one of the lithophanes and held it up to the light......they were all amazed when the picture poped out of the Corian piece. At the same show I met one of our SawMill Creek Members who was carrying a lithophane he had machined, a picture of his mother when she was young. His lithophane was the best I had ever seen, machined with a 1/32" diameter bit and absolutely beautiful work.

Like any other technique there will always be different levels of success. A very high quality lithophane is rare to see but they are incredible eye candy that leave a lasting impression. I seriously doubt that anyone could take a picture of a high quality lithophane that would do it justice, you have to see them with your own eyes to appreciate the WOW factor.

My renewed interest in making lithophanes is based on the fact that I now own an 80 watt Trotec laser. My old Epilog 35 watt didn't seem to have enough power to provide the necessary depth in a reasonable amount of time.
.

Scott Shepherd
01-05-2013, 8:25 AM
Andrea,

I agree that it is difficult for some to find the time to experiment with new techniques and to learn how to use new software. The software part is where I find myself lacking in skills, it seems to take me hours to learn what most can in just minutes when I install new software or even experiment with new features. Honestly if it wasn't for Aspire's capability to process photographs and provide the necessary gradients automatically I would pass on the idea of making my own lithophanes. The ability to process photographs into files for engraving is a very special skill that some have and some don't, sadly I fall into the second category :)
.

Keith, when you get a chance, just take your photo and engrave it directly from the Trotec, using the "relief" option (where the stamp, standard, etc. options are). I think you'll be pleased with how well it does right out the box. I'm not sure all the tweaking is necessary. Maybe a little, but not much.

Mike Null
01-05-2013, 8:47 AM
I agree with Steve. Further, had I not used a material 1/4" thick my engraving time would have been far less. (I used translucent white acrylic)

Keith Outten
01-05-2013, 12:59 PM
OK, I will give it a try late this evening. I'm bending a sign hanger this afternoon so I should be able to engrave a test piece after I shoot the first coat of paint.
.