Understanding Dividers and Glazing Bars

Key Points: Understanding Dividers and Glazing Bars

1. The timber cutting list editor
The timber cutting list editor has six loops - frame dividers, sash dividers and glazing bars use similar logic:

Frame dividers - Frame divider, partial frame divider
Frame divider, full or partial refers to any part added to the frame via the transom/mullion button.

Sash dividers - Sash divider, partial sash divider
Sash divider, full or partial, refers to any part added to the sash via the transom/mullion button, such as, door muntins.

Glazing bars - Glazing bar, partial glazing bar
Glazing bar, full or partial, refers to any part added to the glazing via the glazingbar button.

2. Full vs partial loops
The difference between full and partial loops is not whether the rule will trigger for a particular divider, but:

How many times the rule will trigger

What values it will calculate for its visible_length_in_mm variable (sightline_length_in_mm for glazing bars)

With no other conditions in place, transoms and mullions will always trigger rules on the frame divider and partial frame divider loops, regardless of transom length.

3. Example - Simple design
A simple design will trigger identically on frame divider and partial frame divider loops.

4. Example - When one divider intersects another
The loops behave differently when one divider intersects another:

Frame divider loop - Considers the full length of each transom and mullion
The rule triggers twice because the transom from jamb to jamb and the mullion from frame head to cill are both considered as a single divider.

Partial frame divider loop - Considers the length up to the intersection
The rule triggers four times because the loop registers two mullions divided by a transom and two transoms divided by a mullion.

Note: When writing timber cutting list rules for transoms and mullions, put mullion rules on the frame divider loop, and transom rules on the partial frame divider loop. For the given example above, this would trigger as a single full-length mullion intersecting two separate transoms.

5. is_partial variable
The is_partial variable available on full and partial loops checks whether the divider is the full length of the frame/sash/glazing. It will only trigger if the divider stops when it reaches another divider, instead of continuing to the other end. The given example below has a partial transom. 

If the condition below is added to the rules, they will only trigger for the partial transom, regardless of loop.