Offset per face
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Shop estimate. Measure your stock and cut a test on scrap.
How to use it
- For a taper, enter the width where the taper starts, the width at the foot, and the length of the tapered part. That length is not always the whole leg.
- Read the amount per face for a two-sided taper, and the full amount if you taper one face only.
- The angle is the lean of the cut edge away from the original straight edge.
- For splay, enter the width at the top, the width across the feet, and the height. The kick is half the difference, per leg.
- The splay angle is measured from vertical. It is not a miter setting for the taper jig.
The formula
Per face = (start − end) ÷ 2. Angle = atan(per face ÷ length). Kick = (foot width − top width) ÷ 2.
- Two faces. The usual leg, tapered on opposite sides so the heart of the leg stays centered.
- One face. The whole difference comes off one side. The leg’s centerline shifts.
- Kick. How far each foot moves outward from where a vertical leg would land.
Worked example
A leg that goes from 2 inches at the top of the taper to 1 inch at the foot, over 20 inches, loses 0.5 inch on each of two opposite faces. The edge leans 1.43° from the straight side. Tapered on one face only, the whole 1 inch comes off that face.
A stool 12 inches across the top and 14 inches across the feet, 16 inches tall, kicks each leg out 1 inch. The leg leans 3.58° from vertical. That is the stance of the leg, not the taper of its thickness. They are different cuts.
What it will not decide
- It does not set a compound angle where a splayed leg is also tapered. Do those as two operations, and cut a test.
- It does not tell you the rake of a chair that has to fit a person. Comfort is not an angle formula.
- A negative taper means the foot is wider than the start. The page allows it and shows the sign.
Questions
Do I set the splay angle on the taper jig?
No. The taper angle is the edge of the leg against its own side. The splay angle is the leg against the floor, from vertical. Using one number for the other makes a leg that looks drunk in a way you did not draw.
What length do I enter for a taper that starts below the apron?
The length of the tapered portion only. The straight part under the apron is not part of the rise of the jig.
Is the kick the same on a round seat?
Only if you are measuring across a diameter and the legs sit on that diameter. A rectangular stance uses the width you measured on that axis. Do the other axis as a second splay.