Great features but some of the basics need looking at.

jrs_spedley

There are some very powerful, time saving features but then I try and select a sketch obscured by another part then it's gone from a few clicks to menus and scrolling.
I also find selecting partial lines very annoying.  If two lines cross and I change my mind and want to select part of a line I have to delete it, then redraw it in two parts but all the geometry associated with the original is lost!  If I could just put a point there and select split from a menu all would be well.
Construction lines.  Surely the point is to draw over the top of them when constructing your drawing so why do they always get selected first when I try to change something?  Oh, and being light grey instead of blue would be awsome!

Thanks for listening (not sure how to write these things without sounding rude .. perhaps this will help )

philip_thomas

jrs_spedly - no offense taken and we always want to learn how to improve the product. 
That said, I am struggling with understanding these questions. Is there any way you could share a document or post screen shots or post a video to help us understand what you are trying to do?

Many thanks  - Philip

Jake_Rosenfeld

jrs,

You're in luck!  You can absolutely use a point to split a sketch curve:

https://cad.onshape.com/help/Content/sketch-tools-split.htm

Trim, extend, and split all share the same position on the sketching toolbar, so you may have to click the dropdown next to the pair of scissors to find the split tool.

As for your second issue, I'm a little bit with Phillip here on not being sure what you are asking, could you go into more detail about what you mean by "draw over top"?

AnthonyKM

Hi jrs,

Yes split curve is exactly the tool you need for what you are describing. 
Always best practice to avoid deleting and re-building things if possible because you will need to re-define all the 
constraints to make sure your sketch is fully defined. 

For you second point if you are constantly re-drawing over your construction line perhaps you dont want a construction line 
you want a solid line. It is quite easy to convert an existing construction line into a solid line, by hitting the construction button
(short cut 'q'). Remember in OnShape it doesn't always make sense to have your sketches closed loop, and you can quite easily
choose to only apply an operation to a closed loop section of the sketch, and have a sketch with multiple open and closed loop sections. 

If you are drawing over the construction line you can always draw your entities off the line and then constrain it how you'd 
like (for example I will often define an arc off of the entity I want to constrain to and then add in coincident constraints exactly where I want them). If you draw it in place OnShape will auto-constrain the entity, but sometimes it makes more sense to manually add them.

Which leads to your last point about line colour. It actually makes sense that the construction line is blue, because that signify that it is under-constrained, this means it may move accidentally. Once the construction line is constrained it will turn black like other fully defined sketch entities. The colour scheme is as follows:

Blue - Under defined sketch
Black - Fully defined sketch
Red - Over defined sketch (conflicting constraints)
Grey - Visible sketch but not active

For my construction lines I always fully define them usually referencing the origin, vertical/horizontal, and relate the end point to another entity. 
Define the line however you'd like, just make sure you don't leave it under defined or things may not behave as you'd like. 

Hope this helps.