Aluminum knockdowns: what they're for

A dent doesn't end when the metal comes back out. Around the repair there's always a ring of high spots — crowns pushed up while the panel was stretched. A knockdown brings that ring back down to level.

You rest the knockdown on the crowned metal and tap its face. The strike spreads across the whole face instead of concentrating in one spot, which is exactly what a crowned panel wants.

Aluminum is softer than the steel you're working. The strike lands on the knockdown, not the panel, and the softer face is easier on the clearcoat while you flatten a crown. It's a working surface you can be firm with.

We machine two: an 8-inch and a 12-inch. The 8-inch gets into tighter panels and shorter crowns; the 12-inch covers a long, shallow high spot in fewer setups. Most benches end up wanting both.

Both are in the shop, machined from solid aluminum.