Knocked out a 7075 first-article at 7:10 a.m. — 1.2 mm walls around a 20 mm deep pocket, getting corner chatter on a Tormach 1100M at 12k, 800 mm/min with a 3 mm stub. Before I lock rev B, would you bump the wall to 1.6 mm or add two 0.5 mm ribs to tame it without killing airflow?
Given the ‘corner chatter’, I’d bump the wall to 1.6 mm and add a 0.6–0.8 mm corner relief fillet so the 3 mm stub isn’t slamming full engagement; two 0.5 mm ribs will just sing like guitar strings. If you can live with >=0.6 mm corner radius, that change plus a light spring pass will calm it down without killing airflow.
With those 1.2 mm walls, I’d definitely consider bumping up to 1.6 mm to minimize that chatter, but don’t forget to account for airflow around the ribs. Having machined parts at 7:10 a.m. means you’re in the zone; maybe try a quick test cut at the higher wall first before locking rev B. What’s the tolerance you’re working with on that pocket?
Since you mentioned corner chatter on the Tormach 1100M, I’d suggest bumping the walls up to 1.6 mm, but also consider experimenting with reducing the feed rate a bit. Sometimes, just slowing things down a little can help with stability without losing efficiency. Have you checked the tool’s condition?