Is it possible to visually get illustrated which constraint stops a dimension move?

bård_olsen

Sometimes I try to use dimension to snag a collection of several objects which is related to eachother with other dimensions, and i get constraints errors.

Like i have 15 objects, and all linked, and i want to align it to 0 mm to a line on the left, then it gives an error, but it does not show me which constraint i need to remove or modify for my action to go through.

Is it possible to visualize this?

NeilCooke

If multiple constraints show red there are multiple solutions and deleting any one of them will fix the sketch, so no. 

bård_olsen

When you have a big model, with lots of relations, and you try to move 1 object, deleting any constraints on the object you want to move do nothing, or show no changes, you have no way of knowing which constraints are stopping it from being moved. So if the constraints stopping it is in the main collection of objects you see no changes. There should be like all shown in red and white, and then blue lines towards the actual constraints stopping it to easier make it possible for people to troubleshoot. Internally Onshape must be listing up all the constraints errors, it would just help if the constraints were showing as 1,2,3,4,5 in order that they are locking an object. Having 100'reds of constraints showing up in red, and you have no idea which one fixes the problem, is a nightmare to troubleshoot. Often it is a horizontal or vertical alignment that holds it, and when you remove it it snaps into place, all other objects left alone.

But it is hard to find that 1 constraints holding it.

NeilCooke

Therein lies your problem - you need to keep sketches simple so that they are easier to troubleshoot when things go wrong - keep sketch entity count low and create multiple sketches/features to make your model (parametric modelling 101). 

There isn't any one constraint that is failing - the sketch is a system of simultaneous equations that has multiple solutions and any one of the red constraints can be deleted for the sketch to be solved.

Also - hold Shift when dragging to prevent additional constraints from being accidentally added.

Evan_Reese

I agree with what Neil is saying here in general (favor multiple simple sketches over one complex one), but I also remember Solidworks having a really good tool that addresses this issue. It would let you cycle through solutions, previewing the result of deleting constraint(s), until you got one you'd like. So it's at least possible to do something like that.

@bård_olsen a trick I use a lot when I have things broken and I'm not sure what's locking it up, is to select everything I need to move, and use the sketch transform tool to move it. This will break any constraints that are needed to complete the transform, while keeping the ones that are internal to the selected shapes. 

bård_olsen

@Evan_Reese That would have been a great tool to have in onshape too.

I like the transform tool, problem is it sometimes does not work with Dimension.