Negative 3d Finishing Tool Path for Acryllic

[JohnAdcox]

Good evening, hopefully someone can help point me in the right direction. I'm trying to carve a 3D relief into the back of a piece of acrylic. Since I'm cutting into the back of the acrylic, I need to flip the image horizontally and...invert the 3D carving (make it a negative of the original). It's a face and the nose needs to be close to the front and the back of the head in the back. I have Vcarve Pro and a Shark HD4 CNC machine. I've adjusted the Vcarve Pro file to fit the acrylic so the relief will not be nearly as deep as the original carving (see pic). The original was carved on the Shark to about 90% complete. I did some hand carving and finishing to add the final details. Thanks in advance for your insights!

[ryadia]

The process you are trying to achieve is called 'inverting'. According to Vectric's blurb for Vcarve Pro "Vectors can be easily scaled, moved, mirrored, distorted, grouped, welded, trimmed, extended, offset, smoothed and joined together." There is no mention of creating a vector from any other type of image or drawing. I.E. Scanning a hand drawn logo outline.

So the first thing (if you haven't already done it is to vectorise your drawing. I'm at this stage by saving the file as a SVG (vector image) from the drawing program I scanned my sketch into. Something I've not been able to do with Vcarve. I can't find any instructions in the VCD help documentation on how to import a vector drawing and kep it as a vector.

From what little I know about VC Desktop, to invert a vector is not just as easy as Click a menu item. After 2 days (on and off) of trying to discover how to invert my drawing, I've reached the conclusion that either the Desktop version doesn't have that ability of if it does, its not documented.

I've created my design in a drawing program (Corel Draw) and saved it as a .svg file which is a vector image. To get it to open in Vcarve Desktop I had to save it as a .DWG Autocad file. It is now totally useless because it is just a bunch of lines that can't be selected for editing.

I'm thinking now that I should have exported my art as a .jpg file and used a different program like photo Vcarve or a similar, cheaper application to create a Vectric file I can edit. That would let me invert the file in Photoshop (A trivial process) before saving it and importing it into Vcarve Desktop (if it can be imported) and converting it to usable vectors.

The more I use Vcarve Desktop the more I keep going back to AutoDesk to achieve what I need to do. I make LED internally illuminated signs by engraving text and logos onto Perspex. It took me 2 weeks with Vcarve to get it to carve a 10mm x 10mm step in a length of pine. I still have not had any success carving a round edge down one side and around a corner. The Vectric sales people told me this was the program I needed to do this with... So I bought it. I've been far more productive using AutoDesk Fusion which I used for 12 month before I found the need to carve lettering. Asking for help from support didn't result in any instructions about importing vector images or inverting them so I'll be watching this thread like a hawk

[JohnAdcox]

Thank you for the insights. Keeping my fingers crossed on a Vcarve Pro solution; however, I'll check out AutoDesk Fusion in the meantime.

[Rcnewcomb]

John,
Do you already have the image as an STL file?

[Adrian]

The process you are trying to achieve is called 'inverting'. According to Vectric's blurb for Vcarve Pro "Vectors can be easily scaled, moved, mirrored, distorted, grouped, welded, trimmed, extended, offset, smoothed and joined together." There is no mention of creating a vector from any other type of image or drawing. I.E. Scanning a hand drawn logo outline.

In VCarve you would use the Trace Bitmap function to create vectors from a scanned image. There are a series of short tutorials on it here - http://support.vectric.com/tips-and-tricks/select.php

You can also hand trace using the drawing tools over the bitmap.

Not sure what all the talk about vectors has to do with the original problem though. It's a 3D model which is a different thing entirely. You don't invert vectors, they only exist in a 2D plane. It's the toolpaths that do the "raising" or "lowering".

With a 3D model it's the model itself that is inset or raised and the toolpath follows the model.

[JohnAdcox]

I have the STL file and was able to machine the original (regular relief cut on a piece of Mahogany) perfectly, albeit very slowly. Used both the roughing and detailed 3D tool paths. Would like to take this STL file & invert it & flip it. The acrylic machining I want to do is from the back, not on top of the piece. For the effect I want, the machine has to do the exact opposite of the current toolpath (at least I think that is what needs to be done.). I'll check out the link above tonight and see if it provides any insight. Thanks

[highpockets]

See if this works for you.

Open a new project.
Set Job Dimensions and Origin.
Add Zero Plan

Import the model (I used the Bass from the clip art)

Use Mirror Selected Object to flip the model Horizontally

From the Models tab select the component and enter a negative value for Shape Height.

[TReischl]

What I am getting is that you want to take a positive model (your carving) and create an intaglio carving (negative). Think of cookie molds.

There seems to be some carping about the software not being able to do it. I have no idea since I run Aspire and I can certainly do exactly that.

This is the exact same model, the one on the right is subtracted from the material, simple as a mouse click, no gyrations, no messing around. Sounds to me like you are trying to get your software to do something it might not have been designed to do?

[TReischl]

Looks like HighPockets has your solution.

When I reread your OP, you sort of said exactly what you needed to do. But I think using he word "invert" may have got you off on the wrong track. Negate may be a better way to think about it?

At any rate, looks like you have a good solution! And without buying Aspire!

[JohnAdcox]

It looks like Aspire has this capability built in to it where Vcarve Pro will take some creativity to get the negative image. The cookie cutter analogy is a good one to help visualize what I'm trying to do. The solution from Highpockets sounds like it will do the trick. I'll give it a go tonight & report on the results. Thanks to everyone for taking time to look at this and for providing much appreciated direction.

[Rcnewcomb]

It looks like Aspire has this capability built in to it where Vcarve Pro will take some creativity to get the negative image.

Actually, in either program you would change the combine mode to SUBTRACT, done.

[JohnAdcox]

Even better. Thanks!

[JohnAdcox]

Kudos to Highpockets!! Setting the negative height worked! I'll give it a whirl and see how it turns out in real life. Thanks to everyone for contributing. Best, John

[JohnAdcox]

***Update - Not quite there yet***

I (believe) I followed the protocols above and this is what happened. Rather than the 3D image inverting, it effectively was pushed down into the acrylic. Think about it this way, if you had a solid piece sitting on top of jello (face up) and pushed it down (as is) into the jello, it would be down in the jello but it would still be face up. That's what happened in my case. What I want to do is turn the piece upside down and then push it into the jello (so to speak). Then it would be down in the jello and face down. Sorry for the lame analogy. I'm having trouble attaching an image of the acrylic. I'm going to post this and then try a subsequent post with the pic. Thanks in advance for your thoughts.

[JohnAdcox]

Sorry, no luck with attaching the pic.