It’s easy to see how “rope” pasta (like spaghetti, fer instance) is extruded, but I can’t figure out how the die for tube pasts (like macaroni or zitti or penne) works–how can you extrude a hollow tube?
I’ve looked and I can’t find a diagram of a tube pasta die. Any help?
Thanks!
(Specifically, if you have a piece sticking up in the center of the circle that the pasta’s extruded from, you’d have a seam where the stick is. But pasta doesn’t have that seam)
This photoshould help.
Think of a short tube with a rod running down the center. The rod is anchored behind where the dough enters the tube. The dough fills in around the rod and exits the tube as a tube. A knife then chops the pasta off in the desired length. I believe elbow macaroni is made by forcing the pasta out under differing pressures, one side slightly higher than the other, making the tube curve as it exits the mold.
Or just anchored sufficiently far back from where the dough exits - allowing the mixture to flow around the anchoring parts and rejoin before it is pushed out
Good question
I always assumed the support posts for the center ring on on the back half of the die. Then if you narrow the pasta wall gap toward the front it would squish it back together into one continuous round piece past the posts.
I’m not sure if that’s how most do it though.
The part of the die that supports the center is a called a bridge, in case anyone is wondering.
And the curling is probably accomplished by having the wall on one side slightly thinner than the opposite side wall causing the extrudate to “run” faster on one side. In other words, the bridge is not perfectly centered and balanced.
The also extrude gun propellant (models with perforations) in the same manner. Propellant grains with 1, 3, 5, or 7 perforations are the most common made. The number and size of the perforations affect the burning rate of the propellant (grain burns from outside in and from the inside of the perforations to the outside of the grain). I imagine the pasta perforations are to allow the shape to cook more uniformly. A solid elbow macaroni would be too mushy outside or the inside crunchy when cooked.
A slightly hijacky question, if I might.
Is there any other reason other than “Because we can!” for some of the 42,000 different shapes of pasta? I can see some of them - different sauces work better with different shapes. But bowties (farfalle)?
Because people like novelty.
That explains Franco-American, sure. 
Novelty explains some of it - but farfalle is actually a good choice for both soups and pasta salads.
Darn. I was hoping there was a story. Like one day in 15th Century Milan, the Duke’s life was saved by the Ducal Accountant. From that day forth, the court and courtiers ate bow-tie pasta to commemorate the actions of the bureaucrat.
My goal in life is to see this become such a well known legend that I see it on SNOPES
You need to flesh it out a little bit with colorful details. You know make it personal so it is a fun story that people want to repeat. It needs to be so good that it should be true.
Neat! I love watching things get extruded. I used to love watching “How It’s Made” for the same reason. Plastic, metal, food, whatever; if you extrude it, i’ll watch.
Alton Brown covered this in his pasta episode. It’s a matter of regional pride – even pride of individual towns – to have their own pasta shape.
Of course, some come about for practical reasons – you can’t interchange orzo with lasagna noodles or even spaghetti with penne and get quite the same effect. Different shapes are better for certain applications or even certain sauces.
In other words, you need a Play Doh Factory for your next gift?
I have used various pasta shapes as a base for lasagna type recipes…that is, if a recipe calls for a pound of lasagna noodles, I’m quite apt to boil up a pound of wagon wheels and mix all the ingredients. My dish won’t be layered like a lasagna, but on the other hand, I don’t have to fiddle with large strips of pasta, either. To me, the dish tastes about the same, I just find it quicker and easier to deal with smaller pasta pieces.
That’s not lasagna without lasagna, that’s Baked Ziti without Ziti. 
Some of the practitioners of the world’s oldest profession likely specialize in this.
