Venture into Lithos

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Kym
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Model of CNC Machine: Home built
Location: Tasmania Australia

Venture into Lithos

Post by Kym »

Hi,
Have just completed one of my first Lithos,(could get hooked on this :D)...It is a gift for a friend, for his baptism.
I have done it using Aspire.

I would like feed back on my proceedure...not sure if I am producing it the best way.

I opened the picture of the Dove in Photoshop Elements 2.0, cropped then turned to greyscale, then inverted.
Brought into Aspire scaled it to the size required and then Create a component from a selected bitmap and then scaled z height (2.5mm).

Cut with 2mm Ball nose... Time 55mins.
Panel 165mm x 140mm x 12mm Corian type material.... Machined a pocket in the back leaving approx 2mm thickness of litho.

Are ball nose bits the preferred use or are V bits used?

Sorry the pic's are not the best.

Cheers,
Kym
Dove lite.JPG
Attachments
Dove un.JPG

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Alan Male
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Joined: Sat Feb 23, 2013 11:31 pm
Model of CNC Machine: heiz 400T
Location: Stevenage - UK

Re: Venture into Lithos

Post by Alan Male »

Hi Kym,
It really looks nice and clean.
I'm no expert yet but I tend to use 6mm Corian and cut leaving 1mm material ( no need to pocket the back then).
Like you, I turn my image to greyscale but I don't invert it, I tick the box to 'invert' in PhotoVCarve.
It is addictive though.
Well done.
Alan
CNC m/c - Heiz 400T
Software - Aspire, VCarve Pro, Photo VCarve, WinPC-NC
CAD - Catia V5

kaartman
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Joined: Sun Sep 21, 2008 6:41 pm

Re: Venture into Lithos

Post by kaartman »

Hallo Kym
Your Litho looks so nice, smooth and I like the wax look to it, what did you apply to the carved surface to protect it from finger marks?
Also no pro but I would love to share the way do it and this is what I have read on the forum.
For me I don’t use photo editing programs, to dumb for that, I ask a friend,
I do not invert or change the picture to greyscale in other programs, Aspire sort that out for me
I prefer to use 6mm Corian and it I get hold of 12mm then I first mill it down to 6mm
I use the scale function in Aspire to scale the photo to fit my prefer carving size,
Create the vector boundary for carving parameter or even the odd shape I want the litho to be.
For tool-path calculation I select a 1.5mm ball-end with a 10% step-over but the tool that I use to carve is a 60deg V cutter, ( with the V cutter the surface is not so nice and smooth like your carving but instead it show fine wormy markings but you need to look real up-close for that, I do not use a roughing tool-path – direct Finishing tool-path.
I have never tried a ball end for litho’s, I am the type that stay with what works for me
Happy carving!

Kym
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Joined: Mon Sep 22, 2008 8:03 am
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Re: Venture into Lithos

Post by Kym »

Hello Kaartman,

Thank you for your reply....I do not have any finish on the corian, it is just sanded.

I have only been able to get 12mm offcuts, so I pocket out the back leaving approx 1.5 - 2mm after model is cut.

I have been scaling the z height of model to 2mm...what is your preference?

What tool do you use in Aspire to achieve the invert?

Do you have a picture of one of your works done with the V bit method?

Cheers,
Kym

kaartman
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Re: Venture into Lithos

Post by kaartman »

Hi Kym
At the component settings you need to select U this invert (subtract) the component and if you then look at the imported picture it reverts to greyscale
Z height - my settings range from 2.5- 3.5mm depending on how much concentration of Black is in the picture if the picture
The gap below the model I set from 1.5 to 2 mm,if the picture has allot of bright white, then prefer to set it at 2mm
As a protective cover I prefer to use PU Clear finish that I apply very thin layer with a brush, I do not use the aerosol type because I could never get it on evenly and end up with distinctive spray lines
Attachments
IMG-20121111-WA0000.jpg

Kym
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Re: Venture into Lithos

Post by Kym »

Hello Kaartman,
Thank you for showing me the invert instruction....saves me going into photoshop.
The sample of your work is amazing :mrgreen: ...was it machined with a 60 deg V bit?...what size is the panel?
Is it the light scource behind that is giving it the brown colouring?
Kym

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zeeway
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Location: SC, USA

Re: Venture into Lithos

Post by zeeway »

Very pretty work, Kym.

Angie

kaartman
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Re: Venture into Lithos

Post by kaartman »

Hallo Kym
the back light in the above carving is provided by LED enclosed in a light box, the light of the carving with the men enjoying tee is by fluorescent tubes, note the change in colour with exact same material and carving settings. Yes I use 60 deg V bit here is the link to the type http://www.cmtutensili.com/show_items.a ... ~7/8/958~2
The size of the panel is about 75cm x 58cm, feedrate 40mm/sec, average carving time is 24hr`s per carving, I have carved 6 Litho`s of this size for the customer with various scenes

The detail is amazing, if you zoom in on the man pouring the tee you can notice the decor on the tee-cup and the fraying of the other man`s head dress, ( this is better visable on larger format picture)

Happy carving
Attachments
IMG_6959.JPG

Kym
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Model of CNC Machine: Home built
Location: Tasmania Australia

Re: Venture into Lithos

Post by Kym »

Hello Kaartman,
This will be my next learning curve, how to back light the lithos...do you use a light diffuser on the back of the box to project the light onto the litho?
I guess with the clear PU finish that you use, it gives the carving a sharper shiny look.
If you are using 6mm thick panel and your carving is around the 2mm Z height this would leave approx 4mm....Have you experimented with thinner material left for the light to get thru?
I have one of those CMT 60 deg V bits....I am also using engraving bits, they work very nicely for engraving fonts. I have also now used a 60deg V engraving bit on a litho using your settings and it machines beautifully.
I buy them on Ebay...link- http://stores.ebay.com/Supermario-Blade ... 2426005017
I have just ordered some 30deg bits to try, as I have noticed that one of the other members reccommends that size for lithos.
Kym

kaartman
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Re: Venture into Lithos

Post by kaartman »

Hi Kym
For the light diffuser - i just paint the complete box white on the inside, the PU that i use is matt or satin finish this has no shine to the surface. I guess the sharper the angel of the cutter the crispier the detail, on small lithos i may leave 1mm material but for biger panels in increase the material leftover. I had a oops before by cutting through the material on a large panel
Have funn with the carving

kilrabit
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Location: Uvalde Texas

Re: Venture into Lithos

Post by kilrabit »

Hello Kaartman,

I was looking at the size and time of carving of the 75mm tea litho, and was wondering how much step over you used for the carving with the V bit?




Roy

kaartman
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Re: Venture into Lithos

Post by kaartman »

Hi Roy
It is 75 centimeter, my settings is the same as mentioned in the above post
10%
Kaartman

Roy50
Posts: 11
Joined: Wed Aug 07, 2013 5:09 pm
Model of CNC Machine: cnc3040

Re: Venture into Lithos

Post by Roy50 »

Hi kaartman

You said that the Litho carving took 24hrs ..did you mean 24hrs ?

Do you leave the machine running then .... is it safe to do that ?

I always sit next to the machine in case of problems ...I like to watch the magic of things appearing as well :-)

Cheers

Roy

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