what is the formula to determine how much longer a port needs to be with kerfs? i intend to have 1 3" kerf on top and a 2.5" kerf on the port bend.

 

anyone have any links? thanks.

half the distance from the flare throat and mouth

thank you.   when building a center slot port box   O l l O  style.    torres does not have an option for this so i assume i divide all the measurements by half and then use torres. when building i double it up and it should work?

 

i tried winisd but they also do not have an option for the center port.

Edited October 9, 201311 yr by ncc74656

thank you.   when building a center slot port box   O l l O  style.    torres does not have an option for this so i assume i divide all the measurements by half and then use torres. when building i double it up and it should work?

 

i tried winisd but they also do not have an option for the center port.

I'd use a calculator and google sketchup, you will get better results calculating it all yourself. Plus you can use options like center port or kerfing, and be able to see every part.