Hi,

I've a triangular grid, and want to draw a 60 degree arc (270 to 330) that aligns with the snap points, but I can't seem to make it exact. I want a regular arc, so equal radius at both ends etc. Vertically, the first point I make is fine, but over to 330deg, there's no option to snap it to the grid when i draw it. I can then make the bounding box wider, but that then changes the angle of the line, I can adjust the line angle by going back to arc mode, but then it's still the same fixed length, just a touch of the exact same length as the vertical. just back and forth, nudge, nudge nudge...

What I want is a way to just identify the center of a notional circle, two points on it's circumference, all exactly snapped to grid locations and make those two edge points be an arc. Am I missing something?

Hi.

Only thing you miss is inkscape not being a cad program.
First you may need to increase the precision in the preferences at the svg output settings (Shift+Ctrl+P).

Then, hava a look at this:
primer on Béziers.

Svg may be able to save circular arcs as path segments but there is no gui in inkscape for that.
And if you perform a boolean operation like union or cut, they will be converted to cubic Bézier paths.
So preferably draw everything straight from paths -thing to keep in mind is path nodes can be placed preciesly but segment points rendered in between are with larger errors "misplaced" towards the middle.

Bottom line, if you want to snap an arc to such an isometric grid, draw it by using the * tool and set a node number of 6 or 12 preferably.
Draw the polygon by holding Ctrl, then convert it to path (Ctrl+C) and turn every nodes from cusp to smooth.

http://tavmjong.free.fr/INKSCAPE/MANUAL ... -Arcs.html

While the Ellipse tool isn't focused on drawing arcs, at least in terms of snapping (you can't snap the arc points while drawing the arc, even though you can create an arc, what snaps are the bounding box corners), you can create what you want in a bit more steps.

I created the grid and a circle snapped to a point on the grid. Then used the guides and arc handles to snap to guides to get the arc you described.

Hello:

The way I do it, is to make a circle. To do it from a specific point, the center, active in the snapping bar, "adjust to the center of rotation". With the ellipse / circle tool I click on the center that I want at the same time that, with Ctrl key I move about 45º. With this I have a perfect circle. I correct the size of the circle, selecting this one, and with the combination of Shift + Ctrl keys, I adjust the size of the circle. If I have a grid, I can adjust the radius of the circle exactly if I have activated "adjust to guides" in the snapping bar. I pass the circle to the path.

I take out two guides: one with an angle of 270º (or 90º) and another of 330º (or -30º).

I make a path with Bezier's pen following the guides that pass through the center of the circle.

Select the linear path and the path of the circle. We make Path> Cut path.

We have cut the circle in two parts. One with an arc of 60º, with respect to the center and another of 300º. You can separate them and delete the one that does not interest you.

You can check the 60º arc with the measuring tool.

I hope this, answers your question.

Fernando