Welcome to 3DCADForums

Join our CAD community forums where over 25,000 users interact to solve day to day problems and share ideas. We encourage you to visit, invite you to participate and look forward to your input and opinions. Acrobat 3D, AutoCAD, Catia, Inventor, IronCAD, Creo, Pro/ENGINEER, Solid Edge, SolidWorks, and others.

Best Practices - Fix contraints


Quick question: I consider using the Fix constraint in general bad practice, akin to a blunt tool or duct tape solution, and a last resort.

Whether it's a sketch or an assembly, when do you condiser using the Fix constraint GOOD PRACTICE vs taking the time to actually constrain properly in the long run?

A little personal experience context:....

I know in some places I worked, for assemblies, they prefered to snap items into place and then fix (Catia v5) them because it was easier than putting in the extra thought/effort (and time) to constrain, but this also created problems where items would be out of place. Not a good thing when they are the support for exps-enive multi-axis CNC machining (shifted origin - tooling in the wrong place...)

Another example was that for performance it was mentioned that it may be better to position parts, then just fix them (Solidworks). Maybe justified, but if you need to do any edits (eg add a part), you risk losing all the other positions because you have to delete the fix constraint

Lastly another pet peave of mine is opening sketches to fiding fix constraints, particularly with models imported from other systems as a fast fix. Later down the line if you want to edit the part it's just a nightmare

(I'm definitely in the do it right first time belief camp. I also understand on occasion it may be counterproductive in the short term (time time time), but belieie it always affects you in the long run.)

Got any valid arguments to convince me otherwise? Or do you agree with me?



Super Moderator
I agree with you.

I also like to see the actual constraints which often show how the part was designed (the design intent).

But I have to admit to using FIX sometimes to prevent accidentally moving or resizing things, especially geometry that I've imported.

Articles From 3DCAD World