Unable to define sketch.

andrew_southen

Absolute noob user here. I've worked my way through the training videos/courses, up to a point where I'm experimenting with my own sketches. I seem to be running into issues when drawing basic sketches, & I can't figure out where I'm going wrong. I "think" it's something to do with when I offset lines & arcs. Here's an example of a sketch, I've tried to define all dimensions, yet the sketch is staying red, & giving me a warning it can't be solved. Can someone take a look, & tell me what I'm missing. Please. https://cad.onshape.com/documents/0c0b803967dcb44e84963886/w/fa7385ac3ebfce54e4c02c34/e/d807f0df43aac6ac10c191e1 If there are any more videos/tutorials on sketching techniques that anyone can point me in the direction of, I'm absolutely more than happy to work through it myself. Cheers.

steve_shubin

@andrew_southen

steve_shubin

@andrew_southen

NeilCooke

After you’ve deleted the duplicate dimension you should pick one of the blue edges/vertices and wiggle it around to see how it moves. That will give you an idea of what is missing. 

andrew_southen

andrew_southen said:

Absolute noob user here. I've worked my way through the training videos/courses, up to a point where I'm experimenting with my own sketches. I seem to be running into issues when drawing basic sketches, & I can't figure out where I'm going wrong. I "think" it's something to do with when I offset lines & arcs. Here's an example of a sketch, I've tried to define all dimensions, yet the sketch is staying red, & giving me a warning it can't be solved. Can someone take a look, & tell me what I'm missing. Please. https://cad.onshape.com/documents/0c0b803967dcb44e84963886/w/fa7385ac3ebfce54e4c02c34/e/d807f0df43aac6ac10c191e1 If there are any more videos/tutorials on sketching techniques that anyone can point me in the direction of, I'm absolutely more than happy to work through it myself. Cheers.

Here's a screenshot if that makes it any easier to spot the issues

steve_shubin

@andrew_southen

steve_shubin

@andrew_southen

NeilCooke

After you’ve deleted the duplicate dimension you should pick one of the blue edges/vertices and wiggle it around to see how it moves. That will give you an idea of what is missing. 

andrew_southen

steve_shubin said:

@andrew_southen

He he he. First off, thank you very much for the detailed answers. I reckon I've made a pretty good mess of it, to both under, & over define the sketches simultaneously Dummy award incoming I got frustrated, started again, and step by step added & deleted dimensions to watch the effect, & see when they (entities) turned black/blue. Little bit of a learning curve involved. As a fabricator working from shop drawings, to me the sketches look to have enough dimensions to be fully defined, obviously not I've got to use the program a bit more I think, to understand exactly what dimensions -and what they're related to, that the program is actually looking for. To me, it looks like I get some unexpected results when I start trimming excess/unwanted lines in my sketches at times, when cleaning them up after basic layout. Arcs/circles that are defined, turning blue when I trim sections out of them  where they pass over other lines in a sketch for example.
I see in your first example, you're getting a little drop down tab/menu, telling you exactly which entities are over defined, & allowing you to delete them from there. Is that only available in the phone? app, or is there something similar in the desktop environment? 
Once again, thanks for the help, cheers

steve_shubin

@andrew_southen

YOU MENTIONED — I see in your first example, you're getting a little drop down tab/menu, telling you exactly which entities are over defined, & allowing you to delete them from there. Is that only available in the phone? app, or is there something similar in the desktop environment? 

I don’t use Onshape on a browser, so I’m not sure, but I think if you hover your cursor over a constraint symbol, that a pop up will tell you if it’s over defined. Somebody who uses Onshape on a browser should jump in here and either confirm this or tell you how to find the desktop equivalent.

And the part you mentioned about getting unexpected results when trimming — sometimes you need to make sure that the endpoints of two lines that appear to be contiguous, actually have coincident points. Like @NeilCooke said above, see if you can move anything around. For example, in the GIF below, you need to make the two end points coincident. Then you’ll have a fully constrained sketch