Anyone know how the holes are formed in baskets? I'm learning metal spinning and making the basket isn't hard, but I'm wondering about the holes. I think I read somewhere that they are dimpled and ground the way a pinhole (as in camera) is made, which makes some sense.

However, if a laser or waterjet would work, I'd prefer to go that route.

Thanks,

dan

The descriptions that I've read say that the baskets are stamped and the holes are punched. This makes sense as punching would be a lot less expensive than drilling the holes.

I'm sure that they could be done with CNC (drilling). Waterjet, etc will also work if the tool has sufficient resolution and may make sense for low volume runs. For large scale manufacturing, you'd want to have punch press tooling made.

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Seems amazing to me. I can make tooling, but making something like that is way beyond me. Spinning the basket to tight tolerances is easy. If I get around to it, I'll check out a local laser shop and see if they could do it.

Are you simply looking for the satisfaction of being able to make a basket, or is there a particular customization you have in mind?

I would like to make my peppina basket maybe 12mm longer.

They stamp a pattern in it on the outside and grind that down from the inside.
At least, I'm pretty sure my La Peppina baskets are made that way.

I have to admit, I had always thought the holes were perforated by the way they looked. On closer inspection, the hole diameter to the thickness of the metal, they may very well be dimpled then ground. I can guarantee you they are not laser or water jet.

Whether they are perforated or dimpled then ground, the process for making the dimples or the holes is basically the same process. It's a tool and die to form the dimples or perforate the holes.

The baskets will all start on an oversized sheet of metal. There's a few methods that would cut and form the baskets. I suspect it's done in one step with a tool and die that presses the shape and cuts the perimeter at the same time.

If you're just trying to do one basket for yourself, I don't know that there's a practical way to get the hole by hand with any consistency both in hole size and pattern/open area.

The baskets will be stamped out of sheet steel. Almost certainly it will be multiple stamping/forming operations. As noted earlier, the holes are punched from the bottom. The grinding or milling is a finishing operation to remove the punch burrs on the inside of the basket.

Laser/waterjet/CNC, etc would not be used for production runs, but may be viable for prototypes or short run manufacturing. When the tooling cost is amortized over larger runs, then stamp & punch will be much more economical.

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If you want to make the basket deeper (assuming you're using a bottomless portafilter), I'd first look at welding on a new sleeve to the top (or mid section insert) of the basket as opposed to making an entire new one. If you did a mid-section insert, you could cut your current basket in half (radially), add a mid-section, weld it, grind and that'd be it. Also, you could be sure the holes are the correct sized too.