joining open and closed vectors

[Rarast]

Hi, my question is about creating svgs for cnc toolpaths and how to deal with open and closed vectors. I'm always trying to "join" the nodes where every open vector meets a closed vector at a T intersection: adding nodes, breaking the nodes, rejoining the nodes, all with the goal of making 1 unified vector. Having learned today that that does not make 1 closed vector (my incorrect thinking lol), I don't really see a purpose to keep doing that, and it adds a lot of work time for a detailed image. Incorrectly I thought if a number of vectors need a specific toolpath, say a profile, then all those vectors needed to be joined in the svg before importing into a cnc cam program. Could anyone explain if it's best just to leave the open vectors separate from the closed vectors and then select them as needed in the cam program, or if there is a reason to join them?

joining vectors.heic

[Paul Mudditt]

4 hours ago, Rarast said:

Hi, my question is about creating svgs for cnc toolpaths and how to deal with open and closed vectors. I'm always trying to "join" the nodes where every open vector meets a closed vector at a T intersection: adding nodes, breaking the nodes, rejoining the nodes, all with the goal of making 1 unified vector. Having learned today that that does not make 1 closed vector (my incorrect thinking lol), I don't really see a purpose to keep doing that, and it adds a lot of work time for a detailed image. Incorrectly I thought if a number of vectors need a specific toolpath, say a profile, then all those vectors needed to be joined in the svg before importing into a cnc cam program. Could anyone explain if it's best just to leave the open vectors separate from the closed vectors and then select them as needed in the cam program, or if there is a reason to join them?

joining vectors.heic 39.05 kB · 3 downloads

Try watching this video, the secret is to replace all curves with shapes by using expand stroke on your entire design. If all your lines become shapes then it is easy to join shapes using the geometry operations, so that your entire guitar outline and frets become a single shape.
 

 

joining vectors.afdesign

joining vectors.svg

[Rarast]

Thank you Paul, that really helped. When I first started learning affinity designer that was one of the videos I watched, and practiced, then filed the info at the back of my brain apparently, lol. If you're creating a profile toolpath, is there an advantage to having the bit go between two lines (say for the frets) vs having a single line for the bit to follow (stroke only so before expanding the stroke)? Just testing your file I don't really understand the advantage for doing that. Thanks again!

[Paul Mudditt]

1 hour ago, Rarast said:

Thank you Paul, that really helped. When I first started learning affinity designer that was one of the videos I watched, and practiced, then filed the info at the back of my brain apparently, lol. If you're creating a profile toolpath, is there an advantage to having the bit go between two lines (say for the frets) vs having a single line for the bit to follow (stroke only so before expanding the stroke)? Just testing your file I don't really understand the advantage for doing that. Thanks again!

 

SVG’s for CRICUT and other systems must be a simple closed paths not strokes. As you have found there is no way to describe a t-junction in vector graphics hence, we draw it, then expand to curves so that each stroke is a shape.

Once they are shapes we can add and subtract etc to create a simple SVG that other systems can work from. Not sure if that answers your question as I have only discovered this myself after a question in my facebook groups (in my signature) recently.

[Rarast]

Hey Paul, your explanation and the video really helped clarify things for me, I think I'm slowly beginning to see the bigger picture, now off to practice! Really appreciate your help and the people on this forum.

[Rarast]

Hi again, just a follow up question about the "expand stroke" function. How do you compensate for the change in dimensions when expanding the stroke? The 2 overlap each other identically yet give different dimensions. I understand that before expanding the stroke the dimensions are taken of the line only, not the outside of the stroke. What am I missing?

[Alfred]

4 minutes ago, Rarast said:

How do you compensate for the change in dimensions when expanding the stroke?

Why do you need to compensate for that? Before you expand the stroke, the bottom left and top right corners of the bounding box pass through the nodes at those corners, so the (centre-aligned) stroke extends beyond the bounding box. After you expand the stroke, the bounding box completely encloses the resultant shape, which necessarily means it’s larger than the bounding box for the unexpanded object.

[Rarast]

Hi Alfred, thank you. Sorry I'm still a bit confused. What dimensions would you expect when you export the svg? If it is the expanded stroke (larger) and you require the object to be the dimensions you originally drew it at, I can't seem to just scale it down proportionally, and if you change the dimensions individually then the object is no longer the same.

[Paul Mudditt]

For your example there is no real change in dimensions.

 

[Rarast]

Thank you Paul for the videos, they're really helpful! Sorry, am still confused. Could you do a drawing like that one, with curves, and make the measurement say 3"w X 2"h. Then expand the stroke and you will get a different measurement, even though they are identical objects, because as Alfred mentioned, the measurement is taken from the resultant shape. How do you draw that (before expanding the stroke) and obtain the 3"w X 2"h measurement that you need? From your initial drawing you don't have a 3"w X 2"h object, even though that is what you see in the dimensions, as it never was since it's only measured from the corner node points. If you try after expanding the stroke you can't always scale it down proportionally and changing the dimensions individually may result in a different shape, depending on what it is.

[Paul Mudditt]

 

On 3/25/2024 at 4:26 AM, Rarast said:

Hi, my question is about creating svgs for cnc toolpaths and how to deal with open and closed vectors. I'm always trying to "join" the nodes where every open vector meets a closed vector at a T intersection: adding nodes, breaking the nodes, rejoining the nodes, all with the goal of making 1 unified vector. Having learned today that that does not make 1 closed vector (my incorrect thinking lol), I don't really see a purpose to keep doing that, and it adds a lot of work time for a detailed image. Incorrectly I thought if a number of vectors need a specific toolpath, say a profile, then all those vectors needed to be joined in the svg before importing into a cnc cam program. Could anyone explain if it's best just to leave the open vectors separate from the closed vectors and then select them as needed in the cam program, or if there is a reason to join them?

joining vectors.heic 39.05 kB · 11 downloads

I must apologies I think I went down the wrong garden path here, I think for your CNC machine you have no need of the frets in your design since your CNC cuts out a solid object?

Returning to your original guitar shape my solution is to draw the outline to your correct dimensions with a minimal visible stroke, then use the vector fill tool to create a solid object, then set the stroke to zero. Export as a single solid shape SVG to your cutting system.

So in answer to your question no point in filling in all of the details unless they serve some purpose on your cutting machine.

joining vectors.svg joining vectors.afdesign

 

[Rarast]

Sorry Paul, I had to go for surgery yesterday so just seeing your post, I'll go over it today. I also have one more question when you have a moment. When I'm making an object (stroke only) larger the size of the stroke is changing as I do. It happens whether or not "scale with object" is on or off. The other day I messed with settings in the constraint panel so not sure if something there affected it. It only happens when I have one finger down to keep aspect ratio the same, if not then the stroke size stays the same. Thank you again!

[Rarast]

Hi Paul, hey I found my error. I had turned “show scale override options" on, oyyy! After turning it off it's working like it used to.