This is a long shot, but it has worked for me. Assuming your plane iron is thick enough for the job, chatter can result from the blade not having enough support. It looks like your plane is sand cast iron so check the area wherever the blade is supported. Sometimes, in sand cast frames, a grain or more of sand remains embedded in the iron frame, gets by QC, and keeps the plane iron from bedding perfectly flat and supported. It only takes one grain of silica to lift the iron slightly or bow it even and cause chatter. If you spot any sand sticking up chip or grind it down carefully. There's two cents. Are we up to a dime? -- Steve
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