A Closer Look at Spuds

Last fall, we took a look at what "spuds" are and how they work.  If you didn't have the chance to see it, take a look at http://www.repairmyflute.com/2012/11/spuds.html.  In that post, we highlighted the change in design from soldered spuds to spuds that are "machined" or built into the cup.  Both types have the same function, but what are the differences?

Well, the major difference is in construction.  Soldered spuds are made from brass and are soft soldered into the key cup.  We see these in the repair shop on older flutes, although the change in Powell was made just over 13 years ago.  So, a flute with soldered spuds is not necessarily "old," and other brands may have soldered spuds as well.  A machined spud is built into the cup and is, literally, part of the cup.  The cup's design includes the spud,  so when the cups are made, they are made with spuds!  Unlike the older brass spuds, these machined spuds are made from whatever material the cup is made of -- silver or various types of gold.

The construction also can give you a clear expectation of a spud's "lifespan."  Solder wears over time, so a soldered spud may become loose or ultimately completely detached from the key cup.  There is pressure on the pad from the screw and washer, which in turn causes the pad to pull on the spud.  With a machined spud that is part of the cup, well, the spud is not going anywhere!  It can take as much wear and tear as you can give it, and it will not be pulled out of the cup over time!

So, for those of you with machined spuds, rest assured that your spuds are secure!  For those of you with soldered spuds, do not despair.  Our repair technician re-solders every spud on an overhaul.  They can be easily fixed if you have any problems, and they can be replaced as well.

Soldered spud -- the bottom gets soldered into the key cup.

Close-up - we see the threads where the screw would go in.

Soldered spuds can be replaced.  There is a whole tube of them in this photo!

Machined spud -- will not get pulled out!

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.

The G Disc

It has several different names, but it all serves the same purpose -- the G disc, G donut, or high E facilitator.  Some flutes have a G disc, some have a split-E mechanism, and some flutes have neither.  We recently saw two Powell flutes in the repair shop with G discs that had different shapes.  The "donut" shape is an older style, and the "crescent" shape is the design that Powell switched to about 20 years ago.  The G disc helps facilitate the high E by limiting the amount of air that comes out of the tone hole -- because the key cup is open when you are playing the high E.  If you have a split-E mechanism, when it is engaged, the mechanism lowers the key cup slightly to help limit the amount of air coming out of the tone hole.  Reducing the amount of air coming through the tone hole via a G-disc or split-E mechanism is often times referred to as "venting" the high E.

As mentioned above, some flutes do not have any additional type of device or mechanism to facilitate the high E, because it is really a matter of the player's preference.  However, if one is in place, your flute would either have a G disc or a split-E mechanism -- not both.  If your flute does not have any type of high E facilitator and you are interested in getting a G disc put in, that is not a problem at all.  The repair shop at Powell can add one to your flute for roughly $70.  We realize there is debate on the G disc.  Many people find it very helpful in venting a high E.  In the case of intonation, some people find that it is an improvement, and others have the opposite view -- yet there are so many additional variables in what can effect intonation, so it all depends on the player and his/her equipment.  If you are interested in having a G disc installed, or if you have any additional questions, feel free to contact Rachel Baker in our repair shop at rbaker@powellflutes.com, and she'd be happy to help!

Red arrow points to older G disc design, yellow arrow points to current design.

Yellow arrow points to key that has a G disc in the tone hole.

With the G disc in place, the yellow arrow points to the open area of the tone hole. 

Alto Repadding

We stopped by Rachel's repair office here at Powell and were pretty excited to see something different -- an alto flute!  It's not every day that this instrument crosses her bench, but we lucked out, because she was in the midst of repadding the instrument.  Straubinger pads are not an option on the alto, so the Powell Sonaré alto uses felt pads.  Brand new felt pads have never been in the key cup, so once they are screwed into place, the skin can wrinkle a bit from the new amount of tension.  How does one solve this problem?  Well, oddly enough, it is quite similar to a wrinkled piece of clothing -- it gets ironed!  Rachel has a special "pad iron" to iron the pads.  She takes it, dips it in water, and then uses it to wet the pad skin.  She then heats the pad iron with an alcohol lamp and irons the wet pad with the heated iron.  This is repeated on every pad.  Since the pads are already wet, Rachel then clamps them to get an impression of the tone hole crown on the pad.  She lets it dry overnight with the clamps in place, and then in the morning, the impressions will be set.  The impressions help Rachel seat the pads, because she can see where they may be a little closing too lightly or too heavily on the tone hole -- and then she can shim the pads accordingly.

As usual, if your flute needs repadding, it is best to take it to a professional.  Obviously, there are many steps in the process from taking a brand new pad out of the bag to making it fit and function perfectly in the cup!

Getting ready -- pad iron is the metal device to the left of the flute.

Dipping the iron in water.

Going to wet the pad.

Heating the iron after wetting the pad.

Ironing out wrinkled pad skin with heated iron.

Clamping pads to get impressions.

Spuds?

We were in the flute finishing area, and the topic of "spuds" came up.  Although it may seem as if we were talking about potatoes, we were actually talking about a part of the key cup.  The "pad spud" is the part of the key cup where you secure the screw that holds the pad -- because obviously, the screw has to go into something!  This spud is a very small piece of metal as you can see from the photos below.  The spud can come loose after a while, especially on a key cup with an older solder joint.  There's actually quite a bit of tension on the spud from the screw and pad pulling against it when the flute is assembled.  If the spud comes unsoldered, the pad could then fall out.

When you send your flute to Powell for an overhaul, all pad spuds are resoldered as a precaution.  It's not good to wait until the spud is loose to have it resoldered.  With all the work that goes into an overhaul, it seems logical to make sure that these spuds are solidly in place as well.

Currently, pad spuds are part of the key cup with Powell flutes.  This started in the early 2000s -- toward the end of the 2100 series.  Powells with serial numbers 11,000 and above will have pad spuds that are part of the cup.  Our repair technician reminded us that this is a good thing because it is "one less thing to worry about!"  However, if your flute has separate spuds, and they come loose -- do not worry.  Send your flute in, and our repair technician will take apart the key and resolder the old spud (if you still have it) or replace it with a new one.  As she says, "Don't worry -- it's definitely not the end of the world!"  We were happy to hear that!

Pad spud (upside down).

Blue arrows point to pad spuds soldered in place in key cups.

New key cup with built-in pad spud