Question: On a drawing, when adding a callout to a simple through hole or thread, SOLIDWORKS will sometimes add “THRU” and other times add “THRU ALL”. Why does SolidWorks sometimes add “THRU ALL” in such cases, even though the hole is obviously just “THRU” (“THRU ALL” being through multiple features and “THRU” being through just one feature.)
Two words: Design Intent. SOLIDWORKS has powerful modelling tools that allow the user to establish design intent. In the case of through holes and threads, this design intent is created by the user’s choice on how to make that hole through (its End Condition).
Notice, if a hole is added to a model where the end condition is blind, but the depth of that blind hole cuts through the part, the hole callout on the drawing will show stated depth and not the fact that the hole is through. Here, the design intent is that the hole shall be cut to a particular depth regardless of the fact that the hole ends up being through the part.
By instinct, many of us pick “Through All” as our end condition for a hole. However, SOLIDWORKS interprets this as the user’s design intent to make the hole through every feature, so the drawing’s hole callout is “THRU ALL” even though there is only one feature being drilled through. To capture design intent of “THRU”, the end condition of the hole must be “Up to Next”. This tells SOLIDWORKS the design intent is that hole is only through the immediate feature regardless of how many features it may intercept.
For threads, both end conditions may be set to “Up to Next” for the design intent to be fully captured so that both bore and thread are called-out as “THRU” on the drawing. A side note, thread callouts may still show depth, even if “Up to Next” is selected. Be mindful of this.
If drawings already exist with non-modified hole callouts, simply updating the model will usually update the drawing callouts.