ALright so i want to do a kerfed port on my next box... i read a thread and i am almost ready to give it a shot. However i have one question. when you do the kerf, do you use the port piece to kerf and then attach it to the front piece on the box or is the port piece and front piece one seemless piece with the kerf in it? if this doesnt make sence i will try to expalin better.

One continuous piece.

One continuous piece.

Thanks that helps alot....

I read in the other thread that for a 3 inch radius you add ~4.7 inches to the calculations...so say my port piece is supposed to be 20 and the front piece is supposed to be 25, then i would add those up and cut a piece of mdf at 49.7 inches and then kerf where i need it to bend?

Its been a while since I've done a kerf port, can't recall exactly, but its easy to draw in sketchup and figure out how long the board needs to be and where to start cutting. Thats what I did last time, when I made this.

Layout the kerf on a panel that intersects.

Like pictured above, the kerf would be layed out on the rear piece.

That way you can tell exactly where to start and stop the kerf.

The layout will also help you when it comes time to assemble because

you can maintain the smooth radius by following you're guide lines.

Its been a while since I've done a kerf port, can't recall exactly, but its easy to draw in sketchup and figure out how long the board needs to be and where to start cutting. Thats what I did last time, when I made this.

when using sketchup is there a way to enter the length of the arc you want to use...i can draw arcs but im not sure how long they are or how to tell how long the straight piece of wood would be before kerfing.

simple math will help out.

If a radius is 3" on the outer surface, then the diameter will be 6".

Multiply the 6 by pi (3.14)

This will give you the circumference. (in example 6 x 3.14 = 18.84)

18.84 will be the total distance around the outer side of the circle.

You need a quarter of a circle so, divide the 18.84 by 4 and you get 4.71 (4 and 23/32 of an inch.)

On the kerf add about 3/8" on each end to the overall length. (when cutting)

This will make things easier on you when you install the kerfed panel.

simple math will help out.

If a radius is 3" on the outer surface, then the diameter will be 6".

Multiply the 6 by pi (3.14)

This will give you the circumference. (in example 6 x 3.14 = 18.84)

18.84 will be the total distance around the outer side of the circle.

You need a quarter of a circle so, divide the 18.84 by 4 and you get 4.71 (4 and 23/32 of an inch.)

On the kerf add about 3/8" on each end to the overall length. (when cutting)

This will make things easier on you when you install the kerfed panel.

This is what im looking for....now just to clear it up....if i have a front piece that is supposed to be 25" long, a port piece that needs to be 20, and the kerf will add 4.71 inches, the strait board i need to cut for this will be 25+20+4.71=49.71" correct? or am i off track?