Repair or Replace: Pads

We thought it might be interesting to look at a few components of the flute over a series of posts and examine whether they get repaired or replaced when a flute is sent to the repair shop.  Of course, we stopped in to see Powell's Repair Technician, Rachel Baker, to help us begin this series.  We wanted to start with pads, so we asked, "When a flute comes in, do you repair or replace the pads?"

Well, in the case of pads it's an either/or situation.  Pads can be "repaired" or replaced.  What would constitute a pad "repair?"  Shimming!  Rachel says that the type of repair most commonly done with pads is shimming.  Shimming is done to correct leaking pads.  When it comes to replacing pads, there could be a couple of things that would lead to this solution.  Obviously, if a pad is torn, it needs to be replaced.  Also, like anything else, pads age over time.  As they age, the skin on the pad can get brittle, and the pad would need to be replaced.  Brittle skin is more likely to tear, which (as we know) is certainly cause for pad replacement!

When it comes to pads, a "matching set" is very important as well.  Felt pads and Straubinger pads have different compression rates, so it is important to make sure that all the pads are the same type (or rather, "match") on the flute.  You don't want to mix the pads and have a few felt here and there and then a few Straubinger.  Definitely not a good thing.  If a flute comes across Rachel's bench and has "unmatched pads," well, some of the pads would need to be replaced.

So, in the case of pads, they may need to be repaired, or they may need to be replaced.  Visual inspections, play tests, and checks with the feeler gauge can all help determine whether the pad should be "repaired" or replaced.

This pad's edge has been "lifted up" and definitely needed to be replaced.

This flute has matching pads and is good to go!

Close-Up on Shimming

For those of us in the flute world who are not repair technicians, the concept of "shimming pads" seems pretty straightforward.  All you have to do is take out the pad and put a circular shim in the cup, and you'll be set -- right?  Well, not exactly.  Shimming is a repair skill that takes a lot of practice and a very careful touch.

Shimming is used for pads in two scenarios: pads that are "leaking," and pads that are "light."  Repair Technician Rachel Baker tells us that there is a distinctive difference, and she can determine whether a pad is leaking or light by using the feeler gauge.  When a pad is "leaking," there is no "drag" at all on the feeler gauge.  In other words, you can close the pad down on the gauge and pull the gauge through without any resistance.  Technicians check the pad all the way around its circumference, so it is definitely leaking when there is no drag at all completely around the pad.  When a pad is "light," that means that the pad seal is not even, and you can determine this (again) by using the feeler gauge at different points around the pad's edge.  In the case of a light pad, there will be some drag on the feeler gauge when you close the pad and try to pull out the gauge.  As you check around the pad, if there is less resistance or "drag" on the gauge in certain points, the pad is considered to be "light" in some areas.

So, given the different scenarios of light and leaking pads, shimming may require the technician to use layers and partial sections of shims of varying thicknesses.  Rachel tells us that she uses adhesive to secure the shim in the cup and for holding shim sections together when layering.  For a full shim, she said that shims of any of the varying thicknesses may be used.  For partial shimming, she most often uses the thousandth or half-thousandth (of an inch) thicknesses. These shims may be seen in the photos -- orange for the thousandth, and silver for the half-thousandth.  The silver shim is the thinnest -- and it is also the same thickness as the feeler gauge.

As we can see, shimming definitely takes time and a careful hand.  How does one know where to shim, how big of a section with a partial shim, and which to use?  Well, it all takes practice and a careful hand... 

Frequently used for partial shims -- orange and silver.

Using the feeler gauge to check for "light" and "leaking" pads.

Cutting a partial shim.

Adding adhesive.

Positioning the partial shim.

Close-up on partial shim.