Weld Button doesn't work on non-cancollide parts


Using the “Constraints - Create Weld” tool does not work if one of the parts has CanCollide set to false. Considering it is perfectly OK for non-collidable parts to be welded, I would consider this to be either a bug or just an undesired behavior.

Current behavior: The Create Weld button does not work for any parts that are not collidable.


  1. Create 2 or more parts in Studio
  2. Make at least 1 of them non-collidable
  3. Select the parts
  4. Use the Create Weld button on the toolbar (Model tab > Constraints > Create > Weld)
  5. Parts will not weld together

Desired behavior: Parts weld together even if any of them are not collidable.

I spent a lot of time thinking the button was broken before figuring this out. I’m sure it has confused many other people too.


It appears there may be other cases in which the button doesn’t work, but I have not figured out how to reproduce it.


For my Incubator project almost the whole world aside from buildings and terrain were physically interactable (in other words: unanchored). To keep the models together, I extensively used the Create > Weld tool, and every time I would have to enable collisions for the whole model, use the tool, and then revert collisions to what they were previously.


The water in this bucket has collisions disabled:

Anything that’s not blue on this cart has collisions disabled:

Ropes on this elevator have collisions disabled:

There’s only one collider (pink part) for this swinging platform:

This flag has tiny cylinders between segments to smooth joins – they don’t have collisions enabled:

If you have the RibbonBar minimized, clicking the “Weld” button will not work. You need to select it from the dropdown every time. This is a separate issue, and already logged internally.


Yeah we’ll call this a bug. We’re tracking this internally now and we’ll fix this soon as we can. We’ll post back here when it ships.



Awesome, thanks!