Coincindent constraint fails on some vertices from imported DXF

daniel_melendrez

Hi guys

I recently started learning the most basic features of Onshape and I am really liking it. Thus, please bear with me.

I am designing an enclosure for a PCB based on the exported DXF from the EdgeCuts of my design. However, I am having issues constraining some of the vertices to make them coincident.

Here's the failing version: https://cad.onshape.com/documents/ab100f04c52ffe52817d3952/v/4b657f6a9e48b2a5e37f0ff7/e/5dc67bbbd845771b9ba3a853

(please let me know if you are able to edit it)

I am making the selection of the vertices following the recommendations from another discussion on how to select two vertices (right-click |> select other |> vertex).

Some of my constraints successfully work but others fail:



I have added some fix constraints to the rest of the vertices and segments

Is there any workaround to this?

My goal is to extrude this profile and then offset it outwards to create a gap between the PCB and the enclosure for the final extrusion

Thank you for your help and thanks for this fantastic CAD solution

Cheerio

steve_shubin

@daniel_melendrez

https://cad.onshape.com/documents/0e75e46f34181069b6123295/w/cdb2e371f43cd12cd882f7e4/e/62f9b091a39a68515daaaf24

The document was functioning fine when I was using it on my iPhone

In part studio MAIN ENCL SS, look at SKETCH 1 SS.    Everything is properly constrained

The way I would do it is make sure your scan is vertical and horizontal — — It was in this case

You correctly put the scan on one sketch by itself

Then in a different sketch, start at one point and work either counterclockwise or clockwise

You could start by making points horizontal and vertical where logical, such as where you would want the center of a radius to be horizontal with part of the radius and vertical with another part of the radius to create a 90° angle

Make sure that lines are constrained horizontally or vertically where it makes sense

But the main thing is is start at one point and work your way around  the scan so to speak

And in order to tell if your work has been fully constrained up to a point, to do that you need to select a vertex or a line and wiggle it. If it wiggles, it means it needs to be constrained

steve_shubin

@daniel_melendrez

i’ve added another part studio.
MAIN ENCL SSv2

In this part studio, you’ll find SKETCH 1 SS to be a more accurate tracing of your  image.

To do this I used six splines and four arcs across the top. With the splines I was able to follow the outline more accurately

But doing it this way is more work. It’s more work to fully constrain the sketch. You may have to deal with the sketch going red more times. As a result, there will be a bigger effort to make it all black

One thing I do is I suppress inferences quite a bit when doing sketches like this.

Suppressing inferences will turn off the snaps and the semi auto alignments. So if you suppress inferences, and you want to have two points join together, you’ll have to select those two points and go up to the toolbar and select coincident

To suppress inferences on the iPhone, there’s a contextual menu you access by doing a double tap on the screen. On the desktop I believe you hold the shift key down (to suppress inferences) while doing your sketch

A key thing about suppressing inferences is that it helps you avoid going into the red in a number of cases

daniel_melendrez

Guys, I think I have figured it out!

The solution was to first remove some of the fix constraints then apply the coincident constraint and go back to the fix ones.

Is this normal behaviour or something's kinda fishy here?

This is my progress so far:



Having TONS of fun!

steve_shubin

@daniel_melendrez

Well one thing you did have was a ton of fix constraints.

First thing I did when I got to your Sketch 1 was I removed every single fix constraint.

Then I fixed the large line on the left and the point at the top of that line and that acted as an anchor and from there I started applying dimensions going around the perimeter in a clockwise manner.

I did apply a few fix constraints but very few. And sometimes when I did apply the fix constraint, I just used it temporarily

But typically I don’t use as many fix constraints as your sketch had, because it’s more time-consuming to get everything fine-tuned. You’ll have to release certain fix constraints before you can move something else. Whereas if you use dimensions as SKETCH 1 SS had, you can just double click on the numbers and make adjustments real fast

And being as you could type into the thousandth of an inch or millimeter, well you’re gonna be able to really fine-tune much faster by tweaking dimensions rather than manually dragging around points and fixing. And then unfixing, dragging and fixing again

That’s my opinion and method

S1mon

Typically fix is something you only use for quick and dirty sketches. Perhaps in a case like this one might fix one entity and dimension everything else off of it, but dimensioning one thing to the origin or other datums is better for design intent.

Occasionally I will use fix when I want to get an intersection for some reference ID surface but then remove the connection to the surface to simplify the model (e.g. remove an assembly context or delete a derived feature or import). In that sort of case, I will make the reference a dashed curve that is fixed, and then make my real geometry with dimensioned sketch entities.

If the goal is to leave the sketch undimensioned for ease of manipulation, I might just leave things unconstrained (all blue). Every now and then when I'm early in development I might fix a few points or lines in a sketch and drag others, but as the sketch becomes more "real" I will remove the fix constraints and dimension everything. I will also sometimes make a dimension driven temporarily so I can drag it and then switch it back to driving.

steve_shubin

@S1mon

Great insight to a well rounded approach of the matter

I knew my explanation came up on the light side. But the words just didn’t come forth. I think part of my brain is on hiatus. LOL

Thanks for jumping in

daniel_melendrez

@steve_shubin

Thank you so much for your multiple comments and help.

I actually managed to properly constrain my sketch by removing additional ones that were unnecessary. 

Funnily enough, I figured it out before getting your reply. It proves that I am not that lost with this fantastic app.

In the future, I will follow your general recommendations.

Best wishes to you

daniel_melendrez

steve_shubin said:

@daniel_melendrez

https://cad.onshape.com/documents/0e75e46f34181069b6123295/w/cdb2e371f43cd12cd882f7e4/e/62f9b091a39a68515daaaf24

The document was functioning fine when I was using it on my iPhone

In part studio MAIN ENCL SS, look at SKETCH 1 SS.    Everything is properly constrained

The way I would do it is make sure your scan is vertical and horizontal — — It was in this case

You correctly put the scan on one sketch by itself

Then in a different sketch, start at one point and work either counterclockwise or clockwise

You could start by making points horizontal and vertical where logical, such as where you would want the center of a radius to be horizontal with part of the radius and vertical with another part of the radius to create a 90° angle

Make sure that lines are constrained horizontally or vertically where it makes sense

But the main thing is is start at one point and work your way around  the scan so to speak

And in order to tell if your work has been fully constrained up to a point, to do that you need to select a vertex or a line and wiggle it. If it wiggles, it means it needs to be constrained

From your kind reply, my main takeaway point is this:

"Then in a different sketch, start at one point and work either counterclockwise or clockwise

You could start by making points horizontal and vertical where logical, such as where you would want the center of a radius to be horizontal with part of the radius and vertical with another part of the radius to create a 90° angle

Make sure that lines are constrained horizontally or vertically where it makes sense

But the main thing is is start at one point and work your way around  the scan so to speak"

this methodology makes a lot of sense to me. I will definitely keep that in mind and try to improve my workflow. I am taking baby steps with Onshape

Cheers!

steve_shubin

daniel_melendrez said:

Funnily enough, I figured it out before getting your reply. It proves that I am not that lost with this fantastic app.

It always makes me feel good when I’m able to figure something out by just playing with the program — so I can relate. That’s a testament to those who have designed this intuitive interface/program. So thanks to the Onshape folks for that

It’s good to hear that you’re on your way with this app

Don’t forget all of the free learning courses that Onshape has to offer