How does the Joseph Joseph spaghetti iris work?

Today we raid the kitchen draw and get to disassemble a spaghetti iris portion tool. The Joseph Joseph adjustable spaghetti measure cleverly makes use of an iris diaphragm’s aperture to give you the perfect amount of pasta on your plate, every time. It does this by closing the aperture and clamping around the spaghetti, giving an indication of portion size between 1-4 servings. Someone was clearly using their noodle for noodles when they came up with this idea!

Spaghetti iris up close

From the outside we can see the spaghetti iris operates exactly like any typical iris diaphragm you’d find in a follow-spot, or camera, etc. The body has the portion sizes clearly marked above the handle slot. Notches on the handle aid selecting the desired portion size, which by design help it stop at these particular apertures. Between these stops it’s silky smooth to operate this 6-blade iris.

Top-side shows the portion sizes

Handle notches

Materials

The whole iris is made of polypropylene – a thermoplastic polymer – making it both tough and food safe. As it’s a mass produced product, all the parts are injection molded.

Holding it up to the light shows the gray blades to be slightly translucent. This is likely due to the thinness of the material of this part. Even the body exhibits the same to a degree.

Bottom side shows the pivot pins

Translucent blades

Disassembly

Taking the spaghetti iris apart is a simple process. The two halves of the body are glued together, and so carefully prizing them apart easily opens up the device.

1. Pry open with a plastic tool

2. Lift the top off

3. Lid removed

4. Flip the iris over

5. Lift the back off

6. Blades on the actuator ring

7. Blades off

8. Parts laid out

The blades

The spaghetti iris uses the ‘banana’ type of blades. This design decision builds-in strength and robustness into the device. As it’s essentially being used as a clamping device, most other types of iris design would be prone to failure, or unintentional disassembly. Using blades that span across the entire aperture ensures the blades are always anchored at both ends, as well as providing added supported around the variable aperture – where the blades are meshed together.

Blade

Curiously there are no ejector pin witness marks anywhere on the blade’s surface. It has in fact been very well hidden on top of the blade’s pin itself.

Ejector pin witness mark on the blade pin

At the other end of the blade, you can see where the mold gate was connected to the blade.

Spaghetti Iris - Blade gate runner connection

Blade gate connection (and parting line)

Shape

You’ll of noticed that the ends of the blades are different. The pointed end is shaped that way to ease the pressure slightly at minimum aperture, by allowing the blade to naturally flex down at the back edge where the pin is located.

Blade top

Pin position

The pins are located 135° apart from the center of the aperture, with the drive pin (the one that runs in the slot) set back close to the outside edge of the blade. This ensures the pin is contained within an enclosed slot, preventing it from ever coming out – if there’s ever a moment when the blades bend due to too much clamping pressure being applied. Because of the way the blade flexes there are also small gains to this arrangement, as it helps ease the twisting in the array. Another reason to have it there would be if the minimum aperture were smaller, then you would need to set it back to give you enough travel.

Blade bottom

The body

One half of the body accommodates the pivot pin holes that allow the blades to rotate.

Pin holes

Pin holes inside

The other half has the portion sizes marked out, and the Joseph Joseph logo. On the inside there are 3 concentric raised circles (the inner one being the body wall) that the actuator ring slides on top of.

Body top

Inside the top half

Around the inner edges are location tabs and slots, to align the two halves correctly.

Body location slot

Body location tab

The portion pins are positioned within the handle slot to coincide with their respective aperture sizes.

Portion pins in the handle slot

Portion pin close up

The actuator ring

The slots are located on the actuator ring as pockets. The blade pin never traverses the whole length of the slot, so they could be shorter, but no doubt the slot is a length that minimizes material use.

The handle is offset so that when the iris is assembled, it is on the central plane, making the operation of the iris symmetrical. Lining the handle pin up with the measure on the body sets the portion size.

Actuator ring slots

Actuator ring underside

The cut-out, between two of the slots, gives the handle a little bit of flex in that area for when the location cup slides over the portion pins. The material either side of the cup is ramped to aid it’s transition.

Actuator ring portion location cup

Spaghetti Iris - Acyuator ring portion location cup 1

The location cup is ramped

Opposite, at the far end, there’s a pin… When the iris is closed, the blades ride up over one-another fighting for space, and act like a spring, pushing the actuator ring down firmly onto the portion pins. But when the iris is fully open the blades are slack, and the actuator ring is free to float up and down. This riser pin takes up this slack – in combination with a ramp inside the body – by tilting the actuator ring so that the portion pin is engaged firmly at the maximum aperture setting.

Close up of the riser pin

Close up view of the riser ramp

The underside is covered in many ejector pin witness marks. On the slot side, near the handle, there is evidence of where the injection mold gate has been removed and smoothed as a secondary process.

Evidence of a secondary process to smooth injection mold gate

Reassembly

Starting with the body half with the pivot holes, stack the blades all around.

1. Stack the blades

Spaghetti Iris - Reassembly blades stacked

2. Blades all stacked

Place the actuator ring on top.

Spaghetti Iris - Reassembly actuator ring install

3. Actuator ring install

Spaghetti Iris - Reassembly actuator ring installed

4. Actuator ring installed

Test that there are no issues with the blades.

Spaghetti Iris - Reassembly actuator ring test

5. Carefully test the operation

Apply some glue to the body, being careful not to get any on the other parts.

6. Glue the the body

Making sure the handle slot lines up, locate the top half in place.

7. Locate the top in the correct position

Done!

8. Reassembled

Conclusion

The Joseph Joseph adjustable spaghetti measure is a thoroughly thought out iris diaphragm design. It functions well as a measure, if perhaps a little tricky to operate one handed whilst holding spaghetti in the other.

The Joseph Joseph adjustable spaghetti measure was purchased from Amazon.

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How does the Joseph Joseph spaghetti iris work?

Spaghetti iris up close

Materials

Disassembly

The blades

Shape

Pin position

The body

The actuator ring

Reassembly

Conclusion

Design your own iris

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