Why am I having such difficulty just getting three sketches to completion?

Reece_Isaac

I have been trying to generate some new parts from imported parts that were originally produced by Blender. These parts were very inaccurate in flatness and alignment and dimension.  I was using points from these intending to extrude new, straight, flat aligned and accurate parts .  Three weeks now and I have had continual errors pop up, service help and even a recognised fault. 
The  sales pitch has been that your work is never lost as it is continually backed up yet this evening the one sketch has reverted to it's starting start while I was trying to execute an export to dwg.  This not the first time a session of work has failed.
So where am I going wrong?  One video talks of generating multiple parts from fewer sketches yet I'm being to I should be breaking my big sketch into smaller ones because the system can't handle them.
As the sketches got closer to completion the response each change took longer and longer.

NeilCooke

Hi @Reece_Isaac - do all those sketch entities have constraints and/or dimensions on them? A sketch that size will cause any 2D constraint-based sketcher to struggle as it tries to solve so many simultaneous equations. The best technique is to create many, smaller sketches as you suggest - perhaps one sketch for the outside, then a sketch for the dovetails, etc. Alternatively, once you have positioned each sketch element, box select everything and fix it, so the constraint solver doesn't have to do any work.

tarek_mustafa

Hi @Reece_Isaac, please can you post some screenshots about the problem or share a copy of your file so that it might be easier for people to see what the problem is.

Reece_Isaac

tarek_mustafa said:

Hi @Reece_Isaac, please can you post some screenshots about the problem or share a copy of your file so that it might be easier for people to see what the problem is.

These were created from another document by copy workspace.
Sketch 1 (darker-front) was edited prior to sketch 2 (back-lighter).  Additions were 1.5mm circles on corners of rectangles and dovetails.  Sketch 1 was completed before sketch 2.
All appeared to be fine until after sketches were closed for editing to be extruded.
It was then that the alterations on sketch 1 reverted to the as created state.
Alterations to sketch 2 and 3 perpendicular(not shown) intact.
Also sketches 1 and 2 no longer aligned on the vertical centre line.

 

NeilCooke

Hi @Reece_Isaac - do all those sketch entities have constraints and/or dimensions on them? A sketch that size will cause any 2D constraint-based sketcher to struggle as it tries to solve so many simultaneous equations. The best technique is to create many, smaller sketches as you suggest - perhaps one sketch for the outside, then a sketch for the dovetails, etc. Alternatively, once you have positioned each sketch element, box select everything and fix it, so the constraint solver doesn't have to do any work.

Reece_Isaac

Hi,  @NeilCookeI've discovered today the one of the derived parts did not install flat to a sketch plane and the sketch that was placed on that parts surface are not inline with the plane.  The difficulty of breaking the sketch into smaller ones was that I needed to see features of one sketch in relation to equivalent points on the second sketch and adjust the measurements. After loosing a session of alterations on a sketch I have finally moved to extruding the parts and working on those. I would have still needed the sketches to confirm measurements.

noa

Hi @Reece_Isaac, 

Note that while in one sketch, you can use the "Use" command to project entities from another sketch into your current sketch and then make relations off of them. By only projecting the entities you need, you can keep performance nice and fast.

-Noa