Tap Holder Design

WHY THIS PROJECT?

When I first got to bioMerieux Inc. as a Mechanical Engineering Intern, I was tasked with designing a fixture that would hold taps that attach to a pneumatic press. The current system had 11 taps and a drill bit holder sitting in a bucket which made it difficult to tell them apart, even though they had labels describing what tap was which. This slowed down the creation of prototypes and a solution was needed.

HOW MIGHT WE STATEMENTS

As I took in feedback and insight from the full-time mechanical engineer who gave me this project, I came up with a couple of “How Might We” statements to guide my design. They are as follows:

  • How might I design the fixture so that the taps and drill bit holder fits in the fixture no matter the order?
  • How might I design the fixture so that the fixture won’t fall over under normal use?
  • How might I design the fixture to also accommodate the drill bit holder with it being larger than the other taps?

PREPARATION/PROCESS

As I began to design what this fixture would initially look like, I first started to measure the taps as the maximum outside diameter of these tap fixtures was not consistent. To simplify the design and its use, I settled on the hole opening being consistent across all of the holes for the attachment to sit in, and having the maximum outside diameter be what influenced the distance between each of the holes. This would allow for the taps to be placed in any orientation making it easier for the end users. This also fulfilled the first “How Might We” statement.

Once I had figured that out, I wanted to make sure that whatever I designed wouldn’t easily tip backward if someone didn’t delicately place the tap or drill bit holder back, thus causing a bigger mess. In order to do that, I designed some “feet” that would make it much harder for the fixture to tip backward. These feet took the form of extra material on the back side of the fixture and also fulfilled the second “How Might We” statement

Another issue I had to overcome was figuring out what to do with the drill bit holder as it was bigger, bulkier, and wider than the rest of the taps. With that in mind, I decided that it would be better to have the drill bit holder sit lower to the ground so that its center of gravity would be lower and therefore would have less of a chance of falling over, or worse, knocking the entire fixture over if it was bumped. This actually went against the first “How Might We” statement, but it was a single exception and it allowed for the third “How Might We” statement to be fulfilled.

With these ideas in mind, I drew up a couple of designs and then took to SolidWorks to design my fixture.

Initially, I began with a solid 3D printed model that would have holes for each of the taps and the drill bit holder to fit in. However, after showing one of the full-time engineers, who gave me the project, what I had come up with, he said that what I had designed would work, however, he challenged me to make it out of sheet metal instead.

With that feedback, I went back to my design and began to make parts that could be fabricated out of sheet metal. Since I had never worked with sheet metal before, I needed to learn about the different processes, like water jetting and bending, so that I could determine how best to make this fixture. Once I had learned about the processes and the benefits and limitations of both, I decided to go with water jetting.

However, this created one more issue which was that I needed to determine how I would attach the pieces of sheet metal together and keep them together as well. I decided that I would have tabs stick through pieces that were attached together, and then with a hammer, I would flatten them so that they would flare out, causing the pieces to stay in place. After taking this idea to the engineers that gave me this project, they liked the way that it looked and gave me the green light to water jet the pieces of sheet metal. Below is a rendering of what the final product looked like.

Since this fixture has been made, it has been used by all that have gone to the machine shop to use the taps and drill bit holder. The labels on the taps can easily be seen and it is much easier and faster when finding the desired attachment to the pneumatic press.