McDonald’s Introduces Five Variations on the Shamrock Shake, and One Crazy New STRAW Reimagined with 3D Printing

Pure radioactive goodness.

It may be only the middle of February, but signs of spring are beginning to show themselves. I noticed a few daylily shoots poking out of the ground yesterday, the birds are getting more vocal, and, most importantly, McDonald’s is now offering their Shamrock Shake. I have to have one every year, even though it makes me feel like syrupy death for the rest of the day – it’s an important ritual to mark the coming of spring. I’m a bit of a Shamrock Shake purist, so I have mixed feelings about the new variations McDonald’s has introduced this year. There are now five varieties: the traditional green-dyed mint concoction; said mint concoction layered with a chocolate milkshake on the bottom; a chocolate chip frappe mixed with a Shamrock Shake; hot chocolate mixed with a Shamrock Shake; and a Shamrock Shake mocha.

I’m conflicted – I can’t deny the appeal of mint combined with chocolate, but I’m also suspicious of messing too much with a good thing. McDonald’s is getting fancy, and that alone is reason for concern – if they try to change their fries, I’m picketing. But the fast-food restaurant has caught the innovation bug, as evidenced not only by their Shamrock Shake hacks but by a new straw design emphatically named the STRAW, or Suction Tube for Reverse Axial Withdrawal.

What is this new devilry?

The STRAW was designed specifically for the new layered Chocolate Shamrock Shake, so that you can get the full mint-chocolate combo experience rather just feeling like you’re having two separate milkshakes, one after another. Of course, you could always just mix the two flavors together with your regular straw or spoon, but why simplify when you can bring in an entire team of electrical and aerospace engineers to leverage their combined expertise for the creation of a super-straw?

That’s right, McDonald’s enlisted the help of NK Labs and JACE.design to engineer the STRAW, a J-shaped contraption with a design resembling either a musical instrument or the pipes beneath your sink, depending on how you look at it. Designing it was a challenging process that involved a lot of CAD modeling, 3D printing of prototypes, and even fluid dynamics simulations. It seemed simple at first, said Seth Newburg, principal engineer and managing partner at NK Labs, but quickly revealed itself to be a complex design challenge.

The best minds of our generation.

Their first idea was to create a double straw, with one tube going all the way to the bottom of the drink and the other shortened so that it pulled from the top mint layer. However, the team quickly realized that as the milkshake disappeared, the shorter straw would be left pulling in nothing but air. Finally, one team member came up with an ingenious solution.

“One of our team members said, ‘How about we change this? Instead of drinking the bottom up, we drink from the top down.’ They drew a J-shaped straw,” Newburg told Fast Company.

Two strategically placed holes on the end of the J-curve allow the drinker to draw in mint shake from the top layer, while the end of the straw pulls from the bottom like an ordinary straw would. The key, however, is another hole at the bottom of the J, which prevents the drinker from sucking in air when the shake levels get low.

The engineering of the STRAW involved many, many prototypes, beginning with cutting and pasting at the beginning and progressing to 3D printing as the design got closer to what the engineers wanted. To test the flow dynamics and mixing capabilities, the team used the decidedly unpleasant method of sucking up oil and water with the STRAW and then spitting it out to measure the ratios of the fluids the STRAW picked up, while modeling the fluid dynamics in CAD software.

“At some points when you’re drinking it, you can get an exact 50-50 mix of the flavors,” said Newburg. “But with the different conditions: Full cup, nearly empty cup, depending how much it melted, you could get some slight variations. But we made sure that you’re still getting both flavors all the way through.”

McDonald’s will be distributing a limited number of 2,000 STRAWs in 80 cities over the next few weeks, with the possibility of mass-producing them in the future if they’re a hit. I don’t know if those 80 cities include my own, but I may just have to break down and get a Chocolate Shamrock Shake to find out. If you’re one of the lucky ones to get to try out a STRAW, let us know how it works in the STRAW forum at 3DPB.com.