Large litho question

[large519]

I am currently making litho's to a size of approx 8x6 (200x150), and wondered if I made a litho that is bigger than my machine limits out of a few pieces of corian, by using the tile toolpath option in aspire, how would you join the finished pieces together?? to get a seam less join and would you see the join line once lit. has anyone done this before??

[Jozua]

The only possible solution may be to use corian glue which is in fact “liquid corian”.

I am no expert to say that one will not see the seams, but I think this would be your best option.

I would try it on 2 pieces of scrap first before committing to a project like that and waste material and machine time.

Joz

[martin54]

what sort of size are you talking about just out of interest?

As for the joins yes you will be able to see them, there are a number of factors that will determine just how prominent they are & the viewing distance will also make a difference. Important to make sure the edges that meet are perfectly square or you will get light showing through the join which generally looks worse than a darker coloured line. Not sure if it is possible using photovcarve to rebate them & if it is how you would go about it.

[large519]

Yeah, Ive heard about the corian glue, and I did think that the joins would have to be absolutely perfect.

Had no specific size in mind, just thought what would the possibility be of.... A large litho bigger than my current machining limitations.


But then again I suppose I'd just get a bigger machine,:-D

[NormanAlbert]

The seam would have to be made prior to machining for it to not be visable. Or at least, as invisable as possible. Of course your saying the size would be bigger than your machine so that's out. A very good mating joint and thin super glue may work but the problem you'll have is warping of the machined Corian. Yes, it does warp slightly from heat. Also,as the litho gets bigger, you really need a vac clamping set-up to keep things flat. Then there is the time factor, a big litho takes a lot of time, I don't care what kind of machine you have, the z axis dictates all in litho's. Norm

[ChrisInEstes]

I thought I'd chime in on this... I don't think there's anything you could do to seem your pieces that wouldn't be seen. So, how about making it look intentionally tiled... Call it "art" 'cause that's what it is anyway.

Chris

[large519]

I've just had my last litho warp and ruin the piece, so machining a large one complete would have its issues, also I agree the run time would be asrtronomical.

My thoughts were of sub frame to hold each piece, like a stained glass window.

[manfish]

I have done a few 11" x 17" and its a huge run time , had to upgrade my post processor memory to handle the file and the photo carve time rolls over post 24 hours... I would tell you to tile your pics and maybe go to 1/2" material , I will post a project like this soon I am preparing for an art exhibit.... Look for a posting on large lithos from me in the near future....
Earnie

[Jozua]

I have done a few 11" x 17" and its a huge run time , had to upgrade my post processor memory to handle the file and the photo carve time rolls over post 24 hours...

If I understand this correctly, are you saying that the run time for the 11” x 17” was over 24 hours?

Are you sure about the 24 hour carving time or is it only the software estimate?

Your example of 11” (280 mm) by 17” (432 mm)

I cut one recently that was 460 mm (18”) by 420 mm (16”)

Roughing with a 6 mm (1/4”) end mill and Finish with a 3 mm (1/8”) ball nose with an 8% step over

Total (actual) running time 3 hours 13 minutes (as per running times on the Mach 3 screen)

Joz

[martin54]

I have done a few 11" x 17" and its a huge run time , had to upgrade my post processor memory to handle the file and the photo carve time rolls over post 24 hours...

If I understand this correctly, are you saying that the run time for the 11” x 17” was over 24 hours?

Are you sure about the 24 hour carving time or is it only the software estimate?

Your example of 11” (280 mm) by 17” (432 mm)

I cut one recently that was 460 mm (18”) by 420 mm (16”)

Roughing with a 6 mm (1/4”) end mill and Finish with a 3 mm (1/8”) ball nose with an 8% step over

Total (actual) running time 3 hours 13 minutes (as per running times on the Mach 3 screen

Joz

You must be cutting these using Aspire as a program rather than PVC, you don't get the option to run a roughing pass in PVC so everything is done with the one bit using what ever setting you have selected for that bit.

[Jozua]

You must be cutting these using Aspire as a program rather than PVC, you don't get the option to run a roughing pass in PVC so everything is done with the one bit using what ever setting you have selected for that bit.

My Bad!!!

Even so, this eliminates the time for the Roughing pass but have no effect on the Finishing pass.

All it means is that the finishing bit is doing a little more work but at the same feed rate, same speed and same time.

Therefore the cutting time should be even less.

In my case the 3mm Ballnose time is 1 hour 43 minutes for that size litho.

Joz

[Jozua]

In my case the 3mm Ballnose time is 1 hour 43 minutes for that size litho.

Correction

3mm Ballnose Finish @ 8% stepover: 2 hours 41 minutes

Joz

[martin54]

You must be cutting these using Aspire as a program rather than PVC, you don't get the option to run a roughing pass in PVC so everything is done with the one bit using what ever setting you have selected for that bit.

My Bad!!!

Even so, this eliminates the time for the Roughing pass but have no effect on the Finishing pass.

All it means is that the finishing bit is doing a little more work but at the same feed rate, same speed and same time.

Therefore the cutting time should be even less.

In my case the 3mm Ballnose time is 1 hour 43 minutes for that size litho.

Joz

Not sure I follow that as it depends on your final depth of cut for one thing, instead of doing a roughing pass & a finishing pass depending on the tool settings you could end up doing the equivalent of 3, 4 or 5 finishing passes to get the right. I can't speak from personal experience as I haven't managed to do one in wood that I have been happy with (at any size) but have read a lot & it would seem that the larger you make then then the deeper you need to set your maximum depth.

Having said that your machine must be working far faster than mine, really need to go back into mach3 at some point & look at tuning the motors again.

[Adrian]

The finishing path in Aspire is always one pass to the full depth required. The pass depth on the tool is ignored.

[Jozua]

Not sure I follow that as it depends on your final depth of cut for one thing, instead of doing a roughing pass & a finishing pass depending on the tool settings you could end up doing the equivalent of 3, 4 or 5 finishing passes to get the right.

Martin, you are clearly missing the point.

I ran the test in PhotoVCarve and here are the results.

A Lithopane is done in a “Solid Surface” type material which is resin based and has translucent properties.

Do not confuse this with wood.

No matter what you set in the tool database as a maximum or minimum cutting depth for the tool, the software only works on the “Carving Max. Depth”.

In this case I used 6mm Corian and left 1.2 mm at the bottom. This implies that the bit will plunge to a depth of 4.8 mm and start cutting despite the setting what you had in the tool database.

So there is no 3, 4 or 5 finishing passes. There is only ONE pass at minus 4.8 mm.

As you can see running at a modest 150 inches per minute the “Estimated machining time” is 1 hour 57 minutes.

Do a test yourself and see how it works.

See the PhotoVCarve pictures attached

Joz