Constraints - Sketching

sean_richards499

Greetings,

I am very new to CAD sketching.  I'm trying to create a model I will be using to as a template.  I'm trying to create a button and I can't seem to get it properly constraint.  I was wondering if you take a look and give me some suggestions.  To create the button I created to rectangles 2mm x 9mm and two 2mm circles.  I trimmed the inner circle out.  I created the line in the middle because the mid point kept floating all over the place.

matthew_stacy

@sean_richards499, share the document.  I'd be happy to look at it for you.

bruce_williams

@sean_richards499

Welcome to Onshape & the Forum!  You have begun a great adventure and there are many on the formu who will help along the way. 

You have a few basics to master with sketching.  Please see the Learning Center - https://learn.onshape.com/catalog?query=sketches

A few tips for now -
1) use construction lines for your reference geometry. Then your areas will work out better for features.
2) you can make centerlines that are vertical from midpoints to help center things
3) use the slot tool instead of rectangles and circles
4) try the different constraints and use as few dimensions as possible (for example you have 3 mm from top to both buttons. Instead use a horizontal constraint between the centerlines.
5) sometimes construction lines with an equal constraint will help for some positioning
6) As you probably know, it is best to fully constrain your sketch - all will turn from blue to black

Besides the help from Onshape, just try all the buttons in sketch and see how they work.  Turn the 'view constraints' on and work at knowing what every symbol means.  Practice and it will come together quickly.

sean_richards499

Ok, so I figured out how to constraint the half circle.  I used a coincident on the point and the arch.  That locked down the sketch.  So the piece I can't seem to figure out is if I remove the horizontal line at the arches how to constraint that?  The body stays back but the half circles return to blue.

sean_richards499

Thanks guys.  My posts seem to be on pause until an admin approves them.  I'm not sure if its the images.

sean_richards499

@matthew_stacy Here is the link you requested.  I got the button's figured out.  It might be a bit janky but not to bad for nooblet.  Now I have question.  I need to modify the original geometry of the iPhone model.  While it is a just a sticker in real life there are 4 black stripes at each one of the corners.  So I need to add 1mm section right after the fillet for a black stripe.

bruce_williams

@sean_richards499

Your post did not have a link.

For the stripes - split the fillet face with plane or sketch and then 'add appearance to face'

sean_richards499

Sorry, I'm still trying to get use to the forums.  It seems they either hold onto posts or because I'm new they require admin approval prior to being submitted.  I was able to get the template for the iPhone completed.  Thank you to everyone who's helped me grow as much as I have today.

https://cad.onshape.com/documents/44ca95563d024484458d405e/w/8ae8967a55e8ca797007cdf8/e/61067cb0463cc355da1f2a9b

sean_richards499

@bruce_williams I am watching the video's now.

sean_richards499

@bruce_williams That worked like a charm.

matthew_stacy

@sean_richards499,  when trying to identify degrees-of-freedom that need to be constrained, a handy trick is to click on various entities (end points, lines, arcs, etc) and try to drag them.  Any entity that can be moved is still under-constrained.

I'm looking at Sketch 3 (buttons).  The Ø1.5mm circle needs to be fixed in space.  Make it concentric with the R1 arc, or make their centers coincident.  The slots also need to be constrained horizontal.  And finally, dimension the elevation of the slot relative to some other sketch entity.

There is ample opportunity to replace dimensions with geometric constraints.  For example, constrain two (or more) arcs equal rather than dimensioning both R1.  It's less work and more importantly captures design intent.

And the training videos that @Bru@bruce_williams highlighted are a fantastic resource.