Ok I've read until I can't read anymore on studding so I thought I'd post how to get 24 scratch lines avoiding the center 3.75" (.125 safety margin on both sides of louver) on a 137" track. Sorry if this has been posted. I'm not a first time poster but I lost my old account and can't reset it because that email is no longer valid.
Outside Webs
These are 2.5" wide. Leaving .125" from edge of backer to edge of track. Stud boy backer is 1.375" wide.
2.5 - .25 - 1.375 = .875" studable area. 6 scratch lines means 5 spaces. .875/5=.175 between studs or scratch lines.
Because of the 6 stud pattern don't stud in an exact V. This would give you .175 x 2 between consecutive studs.
Inside Webs.
This is a total of 7.75"
One side half is 3.875. Half of the 3.75 louver area is 1.875 so you start with 2" area.
2" -.125 from edge - .6875 half backer width = 1.1875 studable area. 6 scratch lines means 5 spaces. 1.1875/5= .2375" scratch lines.
Because of the 6 stud pattern don't stud in and exact V again. This will give you .475 between consecutive studs.
What I do then is take a piece of 1/8" by 1.5" x 15" flat and put it in my mill with a small drill bit. I use the digital layout to space the holes exactly. Mark the track and drill according to the pattern. Reality is this could be done with a piece of firm cardboard and get close enough. This is leaving .125 from edge of track to spacer which some might want .25". Its easy to calculate and change the scratch distances to accommodate this or different backer widths.
Outside Webs
These are 2.5" wide. Leaving .125" from edge of backer to edge of track. Stud boy backer is 1.375" wide.
2.5 - .25 - 1.375 = .875" studable area. 6 scratch lines means 5 spaces. .875/5=.175 between studs or scratch lines.
Because of the 6 stud pattern don't stud in an exact V. This would give you .175 x 2 between consecutive studs.
Inside Webs.
This is a total of 7.75"
One side half is 3.875. Half of the 3.75 louver area is 1.875 so you start with 2" area.
2" -.125 from edge - .6875 half backer width = 1.1875 studable area. 6 scratch lines means 5 spaces. 1.1875/5= .2375" scratch lines.
Because of the 6 stud pattern don't stud in and exact V again. This will give you .475 between consecutive studs.
What I do then is take a piece of 1/8" by 1.5" x 15" flat and put it in my mill with a small drill bit. I use the digital layout to space the holes exactly. Mark the track and drill according to the pattern. Reality is this could be done with a piece of firm cardboard and get close enough. This is leaving .125 from edge of track to spacer which some might want .25". Its easy to calculate and change the scratch distances to accommodate this or different backer widths.
