How Can I Draw a Centerline Between 2 Lines?

[cbcnc]

What I am trying to do is to draw a centerline between outlines of a font. It's not really a problem if the stroke of the font is parallel. But, if the font outlines converge or diverge or are curves, then you need to measure the distance and half that for each point of the centerline. Then on curves you have to measure perpendicular to a tangent.
Secondly, I am going to cut the font with a V cutter. So, the Z depth is dependent on the width of the stroke.
Tedious, to say the least. By the way I am using Acad 2K.
So, can I automate this some?
Ideas please.

Thanks,
Chris

[ger21]

Buy VCarve Pro.

Actually, before I got VCarve Pro I had an idea to do what you want to do, but it was still tedious. Ridiculously tedious.

Anyway, here's what I was doing. First, I used the Express Tools to explode the fonts and get the outline. If two lines were parallel, it was easy. After all the straight sections were drawn, I'd start in the corners and draw a circle tangent-tangent-tangent. Then I got the radius of that circle, and entered it in a little lisp routine I wrote that would let me pick two edges as I worked my way away from the corner and draw tangent-tangent circles, increasing the radius by a small amount for each circle. So all I had to do was keep choosing the two edges, and progressively larger circles would be drawn until I got to the next TTT circle.

Once the letter was filled with all the circles I needed, I used a little VBA macro to draw a 3D polyline from the center of each circle straight down, with the length being the radius of the circle. I'd then delete the circles, and draw my toolpaths with 3D polylines by snapping to the bottoms of the perpendicular lines.

My plan was to make blocks of each letter, and write a VBA macro to place the blocks in the write location when I typed in the text I wanted. I was going to do a couple different fonts. I only ended up doing a few letters and forgot about it.

If you don't need 3D V Carving, just draw the tangent circles and the toolpath will run through the center of them.

[cbcnc]

3D was what I was hoping for. I'ld like to make a complete alphabet so I could copy and scale the letters. I wish VCarve was in my budget. If this was business I could look at it in terms of cost vs. time. I'll have to make a few more signs first.

Chris

[ger21]

This is what I was doing. The resolution was high so I'd be able to scale it up a bit bigger and still be fairly smooth.

[cbcnc]

Gerry,

That's a lot of circles!
Extending the length of the radius down for the Z depth works for a 45° bit. In my case I want to use a 60° bit. So, there's an extra calculation;
Tan30 = Radius / Z depth. Ughh.
Can you get a lisp routine to recognize and draw a circle between the outlines? Unfortunately I'm not really familiar with AutoLisp. I would try if it was possible. That would make doing fonts easier.

Chris

[ger21]

Originally Posted by cbcnc Can you get a lisp routine to recognize and draw a circle between the outlines? Unfortunately I'm not really familiar with AutoLisp. I would try if it was possible. That would make doing fonts easier. Chris

I tried that first, but couldn't get it to work. But I'm not really a programmer, so there might be a way to do it.