How is this possible? circles, snapping, getting things to fit for shape builder

[AspiringPerson]

There are some issues I've been experiencing with designer iPad. One of them is snapping. I might not understand the program well enough, but some things seem confusing.

I'll have snapping on, with all "snap to" options activated. I'll move an object near a line, and it'll glide right by it. This frustrated me for a while. I tried selecting the line I wanted to snap to and tried again. That worked. Why do I have to select a geometry first in order for snap to work? This inconsistency with snaping happens so often I don't really understand when or why it does or doesn't work. 

Anyway, my question today is related. I spend an embarrassing amount of time trying to get geometry, specifically circles to fit perfectly in order to use the shape builder tool. I'll think the circles are touch the lines on either end, but I'll be stuck on this for so long that I'll sometime just give up. 

Here's a video where I try to solve my problem geometrically. I have no idea why I'm having issues using the shape builder tool. 

Everything in this video is a perfect circle. The smaller circle is touching the ends of both circles so I can use the shape builder tool to cut the shapes as I please. I need to move that circle at an angle and cut somewhere else. I am unable to do that. Even when I rotate the smaller circle around the center. I don't understand geometrically how this is happening. The circles are the same distance apart at every angle, so how is rotating around the center not keeping it flush on either end? 

I feel stuck and have been trying to do this for idk 30 minutes but can't move on with the rest of drawing. Is the best way to work something like this just to fiddle around in wireframe mode, moving inch by inch to get the alignment perfect? Even when I do this, and I believe both sides are touching. The shape builder always tells me there's a gap. 

 

 

[NotMyFault]

Hmm.

First, the circle shapes are not perfect in Affinity when based on ellipse tool. They use only 4 nodes, and you get about 1/5000 deviation.

 

[NotMyFault]

second, only activate the absolute minimum snapping options. Otherwise you risk getting wrong candidates, which is difficult to detect.

 

[NotMyFault]

Third, there is no snapping option to perfectly match 2 curves along the curvature. 

[AspiringPerson]

Ohhhh, gotcha. Makes perfect sense. I knew I wasn't using this app right. 

[NotMyFault]

Never the less, I succeeded with perfect planning:

1. grid - triangular, 150px
2. snapping - grid, shape key points
3. move tool - alignment handles
4. helper object - circle between large circles to snap center points. This works better than trying to match circle edge.
5. helper object - star 8 to
6. use alignment handles to perfectly align all objects

then I was able to use shape builder tool and get all parts individually

 

 

shape builder tuorial.afdesign

[NotMyFault]

[lepr]

On 6/13/2023 at 7:26 PM, AspiringPerson said:

Everything in this video is a perfect circle. The smaller circle is touching the ends of both circles so I can use the shape builder tool to cut the shapes as I please. I need to move that circle at an angle and cut somewhere else. I am unable to do that. Even when I rotate the smaller circle around the center. I don't understand geometrically how this is happening. The circles are the same distance apart at every angle, so how is rotating around the center not keeping it flush on either end? 

As NotMyFault has pointed out, an Affinity ellipse/circle is a cubic Bezier curve which is not perfectly elliptical/circular.

Your method using Point Transform Tool (PTT) was good except for one missing step to compensate for the imperfection of the large "circles". After doing the 45 degree rotation, you should have continued using PTT to slightly scale the small circle toward its pivot point and snap it to one of the large circles. PTT has poorly labelled snapping options in the context toolbar on macOS - they should be available on iPad (but if not, just use 'snap to object geometry' in the general snapping options). See attached video.

 

Edited June 14, 2023 by lepr