Sketch of making self-secured joint

Grooved seam Total allowance = 3G ? 4 T shared: equally between limbs 1 and 2; or two-thirds limb 1 and one-third limb 2 where joint center position is critical. Double grooved seam Add W T to the edge of each blank to be joined.Allowance for capping strip = 4 W + 4 T, where L = 2 W + 4 T. Paned down seam Add W to the single edge 3. Add 2 W + T to the double edge 4. P = 2 W + 2 T. Knocked up joint Add W to the single edge 5. Add 2 W + T to the double edge 6.K = 2 W + 3 T.