Steels -- What Are They? What Do They Do?

Steels are not visible from the outside -- they are inside the mechanism tubing.

We've written several posts that include the term "steels," but have you ever wondered what "steels" are exactly?  Well, steels are a very important part of the flute mechanism, but, once the flute is finished, you really won't see them -- because they are inside the mechanism tubing.  In a previous post, Powell's President, Steven Wasser, summed up the function of steels quite nicely:

The “steels” for a flute mechanism are the axles on which multiple keys rotate so that tone holes can be opened and closed. If, for example, there are 4 distinct keys on the right hand of the flute, we don’t want all these keys going up and down at the same time, yet it would be impractical to have 4 separate steels, one for each key. There are different ways of creating independent motion of multiple keys on one steel, which include building pinned and pinless mechanisms.  (Follow this link to read the full post, "Pin Pals - Part I.)

We stopped by flute finisher Matt Keller's bench while he was finishing a 10k yellow gold Powell Custom.  This gave us the opportunity to see the steels completely separated from the rest of the mechanism.  In the photo below, you will see the complete set of steels for the 10k flute taped together with scotch tape in the flute kit:

As one might imagine, the steels are made of steel and are small rods that run through the inside of the outer mechanism tubing. As you can see from the photo above, there are several keys, and these keys are soldered to the outer mechanism tubing.  The keys (with tubing) must be aligned and positioned properly for the mechanism to function.  So, the steels are threaded through the tubing and then held in place at the posts.   Pinned mechanisms have pivot screws that screw into the posts and then into the ends of the steels to hold the steels in place.  For pinless mechanisms, steels have a screw-type head at one end of the steel to hold them in place at the posts.

The steels are inside the mechanism tubing, so when you press the keys, the keys are rotating on the inner steels.  How can you tell the difference, visually, between the steels and outer tubing? Well, the steels are steel, and the outer tubing is made from the same metal as the rest of the keys and key mechanism.  So, in this case, the outer mechanism tubing is 10k like the keys.  In the photo below, you will see a green arrow pointing to the steels, and yellow arrows pointing to some of the outer mechanism tubing.

As mentioned in the top of the post, you won't see the steels since they are inside the mechanism tubing, but they play an important role!  Steels are cut and fitted to each flute individually. They must be straight and run smoothly through the posts.  For more on steels, follow this link to watch as steels are cut and fitted to a 14k white gold flute in the previous post titled, "Building the White Gold Flute - Part 4."

Fitting Keys - Part I

One of the tasks that our flute finishers have is that of fitting keys.  The mechanisms involve several parts that must fit together in order to function properly, so the keys need to be "fitted" first.  Fitting keys takes several steps, but we had a chance to catch up with flute finisher Lindsey McChord to talk about some of the very early steps in the process.

Lindsey begins by taping the keys so that they do not get scratched in the finishing process.  Then, Lindsey begins the key fitting process by checking the mechanism tubing on each key.  When the key mechanism is assembled, a steel rod (or "steel" as it is commonly called in the shop) runs through the inside of the key mechanism tubing.  In order for the keys to move smoothly on the steel, the inside of the tube must be a perfect cylinder.  Sometimes, the inside of the tube still needs a bit of tweaking when it arrives at the finisher's bench.  So, a small gauge that looks like a double-ended screw driver is used to check the inside of the mechanism tubing.  This gauge is referred to by finishers as the "go/no go gauge."  This gauge has a green end and a red end.  If the green end of the gauge fits smoothly and evenly into the mechanism tubing, the key is a "go" and does not need any further work.  If the green end does not go in smoothly, there is a problem at hand.  If the red "no go" end goes into the tubing, the key is overly reamed and must be returned to the stringing department (which supplies key mechanism components to the finishers).

The "go/no go gauge" is used in a few different ways to help determine what might need to be adjusted on a key's mechanism tube.  If the green end goes in smoothly at both ends of the tube, the key is "good to go."  If it does not go in at all, or if it is extremely difficult for it to go in, the mechanism tubing needs to be reamed.  When reaming the tube, material is removed from the inside so that it is smooth and cylindrical, with an even diameter throughout.  If the gauge goes in but feels a little loose or a little tight in one area of the tube, the tube is "spun" by the finisher -- which is essentially a step used to even out the inside of the tube.

To spin and ream tubes, the finisher uses the bench motor with a steel that has a flat end and a pointed end.  To ream a tube, the steel is placed in the bench motor with the pointed end facing outward.  The motor is turned on, and the reaming tool spins very quickly.  The finisher runs this reaming tool through the tube to remove excess material inside.  A very straight motion is used in the reaming process.  In the "spinning" process, which evens out the inside of a tube, the same steel is placed in the bench motor -- but the flat end of the steel is facing outward.  The key is place on the steel, and the motor is turned on.  The finisher is then able to grab the end of the steel and "spin" it in a circular motion to even out the inside of the tube.  The finisher may use a tissue or paper towel to grab the end of the steel so that s/he does not hurt her/his hands.

There are several additional steps to fitting keys, but checking the mechanism tubing to make sure the steels run through smoothly is one of the first steps to key fitting.  Stay tuned for future posts as we explore more on the topic of key fitting.

Taping keys so they do not get scratched.

The "go/no go gauge" -- red for no go, green for go!

The red "no go" end is not going in, so this is good!

Testing the green "go" end.  It should fit in smoothly throughout the tube.

Pointed end of the steel used for reaming.

Steel in the motor, getting ready to ream.

Reaming the key mechanism tubing with a very straight motion.

Changing the steel for spinning.  A longer portion is used, and the flat end faces outward.

The steel is "spun" in a circular motion during the key "spinning" process.

Key placed on the steel, getting ready to spin the mechanism tube.