Billet baskets with holes that actually go all the way to the edge!

Traditional baskets are economically mass produced by stamping thin sheets of metal which require a large radius at the bottom edge. The thin material combined with high pressure extractions place the holes away from the outer edge for stress/deformation issues. They also have curved bottoms because it would deform permanently after the first few uses anyways as the material work hardens.

In my design, I set out on a no compromise approach with holes all the way to the edge - not just close enough! If this was done on standard 300 series stainless steel, it would deform and eventually crack. Rather than simply making the basket thicker and heavier, I use 17-4 stainless steel, a martensitic precipitation hardened material that is traditionally reserved for turbine blades, food processing equipment, gears/shafts or rocket engines which require high strength, hardness and corrosion resistance. To put this in numbers, the tensile yield stress of hardened 17-4 can be >190,000 psi whereas 316 is only ~35,000 psi. Stainless steel grinder burrs have a hardness rating of ~50 HRC. 17-4 can be hardened to >43 HRC while 316 is so soft, it doesn't even register on the HRC scale. Another important difference is that while 17-4 has excellent corrosion resistance, it's magnetic! Something that is important to the home barista. Not only will your magnetic accessories like funnels and my PorcuPress continue to work, they will now work even better.

Why am I telling you this? Because if you followed me this far, you might find this interesting as I am trying to bring my aerospace experience to the world of coffee! You probably also want to know where all your money is going...

The manufacturing process is long and extensive. It starts with a nearly 1kg solid block of 17-4 (which the raw material alone cost more than a high end stamped basket) and hogged away in the hardened state leaving just ~45g behind - the metal removed is recycled into raw material. Due to the complex processes involved, these baskets have an unconventional flat lip and take many hours to produce each one.

Paper filters are not required but available here if you prefer to use them

• Due to the straight side wall, these baskets will be a tighter fit going into your portafilter. You can loosen the grip by relieving the bends on the portafilter spring
• Baskets flex when under pressure. They all do. However, these high strength baskets will spring back to the original flat state while others deform permanently
• 49mm, 54mm, and 55mm will be made available to pre-order at a later time
• Pre-orders are expected to begin shipping in April