Angle, Pressure, and Speed
Trimming is a skill. The same leather-hard pot can produce beautiful clean cuts or a ragged, torn mess depending on your technique. These principles make all the difference.
The Angle of Attack
The loop tool must be held at the correct angle to cut rather than skip or dig.
- Hold the loop so it faces the direction of travel (into the clay as the wheel spins).
- Tilt the handle back very slightly from vertical, roughly 10–15 degrees.
- This angle means the leading edge of the loop shaves the clay rather than digging in perpendicularly.
If the tool chatters and vibrates, you are angled too steeply. If it skips across the surface without cutting, flatten the angle.
Pressure and Depth
- Start with light pressure and increase gradually.
- Never force the tool deeper than it wants to go in one pass. Make multiple shallow passes instead.
- Listen: a steady, even scraping sound is correct. A high-pitched chattering sound means too much angle or too much pressure.
Wheel Speed
Use medium speed for the bulk of trimming. Slower than throwing, but not so slow that the tool digs in between revolutions.
The Chattering Problem
Chattering (a series of ripples left on the clay surface) is the most common trimming problem. Causes:
- Tool angle too steep.
- Wheel speed too slow.
- Tool not braced by the support hand.
- Clay slightly too dry and brittle.
Fix: Check all four. Usually tightening the support hand and adjusting the angle solves it immediately.
Cut Control Drill
On one test pot, run three passes:
- Pass 1: ultra-light to set angle
- Pass 2: moderate pressure for material removal
- Pass 3: refining pass to clean surface
Layered passes are safer than deep single cuts.
Explore More
The chattering problem is a form of vibration that engineers call chatter, a well-studied phenomenon in lathe work where tool deflection creates a feedback loop with the spinning material. Mastering the angle and pressure of the cut is a skill built through muscle memory, and most potters find that consistent practice over a few weeks dramatically reduces chattering incidents.
