I'm going to try repadding an Armstrong 104 flute that I purchased off of ebay for fun. Anyway, just wondering if it is absolutely necessary to clamp the keys when you are done? The "complete guide to the flute and piccolo" only touches on it briefly.

IDK but go take it to a pro.

It depends upon what type of pads you use. On student level flutes, softer woven felt pads often used. The factories do this as a short cut, because often the tone holes are not perfectly level and a softer pad can be (must be) clamped to give the pad an impression so that it does not leak. The pads still must be shimmed and checked with a feeler to get proper tone hole coverage before moistening and clamping.

It takes a lot of time to do a proper repad. A better quality repad job will use firmer pads made of needle felt and those are not usually clamped. Instead each pad is installed, checked with a feeler gauge for low/high spots, removed, shimmed, and those steps are repeated as many times as needed to get a perfect seal. On many flutes (especially student-level flutes), the tone holes require leveling to use this technique and that task is best left to the professionals.

The flute I got is merely for experimentation purposes, I wouldn't repad my own flute until I had a few under my belt. I think the pads I ordered are 2.6mm think. I would have to go back and check my order. I was going to play around with shims. So, if you use the shims and the feeler gauge do you still have to clamp?

The need to clamp depends upon several variables. If you have soft pads, unlevel tone holes, or don't do a good job shimming the pads, they will need to be clamped.

To eliminate clamping, requires firm pads, level tone holes, and lots of patience with the feeler and shimming.

James Phelan's "Complete Guide..." book that you have is an excellent resource, but IMO, it does not go into enough detail for a novice technician to learn to pad. I recommend "Servicing the Flute" by J.L. "Jeff" Smith.
http://www.jlsmithco.com/Home/BOOKS/SERVICING-THE-FLUTE-BY-JEFF-SMITH
This book has more of a step-by-step approach that is well suited to the novice.

Thanks for the suggestion, I have looked at that book online, I'll have to order it.

I've been doing this myself - I'm on about flute number 6. I've had lots of advice about pads and techniques both here and at saxontheweb. The professional techs have been very helpful. I have found that I am spending 20-30 hours on each flute, and end up with quite good, reasonably stable results. It's quite satisfying taking a flea-bag flute from a completely disgusting state to one in which it looks ok and plays well.

One obstacle seems to be getting your hands on "good" pads. I have been using MusicMedic pads, mostly 2.7mm. They are fairly forgiving, i.e. firm, but not so firm as to be hard to get to seal. I've tried the prestini thin and medium pads from votawtools, and found the thin pads tough to work with and the mediums a little easier. I'm going to try lucien delux pads from JLSmith next. I'd like to know which pads you are trying to use.

I have not needed to clamp the keys, at least not using key clamps. I have found that once I get the pads touching fairly evenly all the way around using a .0005" feeler gauge (use an inch or so glued to a toothpick) that I can dampen the pad and hold it closed lightly with finger pressure while I heat/dry/cool it with a hair dryer. That's been enough to put the final tonehole impression on the pad and make a positive seal point necessary to get the key regulation correct.

My take on the process is that I spend 10 times the time that a professional would, getting results that are initially probably not quite as good, but more stable over time. Since I carefully shim rather than clamp, I don't seem to get leaks from pads recovering from the clamping un-uniformly.

Padding, by the way, is infuriating for me at the best of times. There are shortcuts involving bending keys, which I also find to be black magic.

Do read the burkart-phelan book, keeping in mind that it is geared mostly towards professional flutes. The process in the book is as I have done and described. I believe professional techs treat student flutes very differently, bending keys, using soft pads, key clamps, and padding ovens to get the pads to seal with less labor. -- Jim

<Added>

sorry, should have been "(use an inch or so of audio cassette recording tape glued to a toothpick)"

I ordered the medium pads from JLS. Still waiting for them to be shipped. All I've done so far is turned a almost completely black flute back to silver which was fun.

You will absolutely also need some shims for under the pads. I recommend 17.0, 18.0, and 19.0 mm diameter, .001", .002", .004", and .008" thickness, and maybe even thicker if available. I have been using paper, but plastic might be good for the thicker ones. I typically find I need between 2 and 4 of the .008" shims under each pad depending on the flute and pads I'm dealing with. The idea is to shim the pad up so that the front and back hit evenly on the tone hole as the key is closed.

For some reason, I frequently find that a key might need too few shims or too many shims than the pad retainer system can handle. In these cases I bend the key to get close to a number of shims which fit comfortably. I have also not found the original pad/shim thickness to be particularly useful in predicting the shims I need, which seems confusing. The technique I use to bend the keys is to put the key cup in a padded vise and use a very light hammer and short wooden dowel as a punch to lightly tap the key arm where it joins the hinge tube. Do this with the rod inside the tube. Look out for key cups which are not aligned parallel to the tube/rod. If they look out of alignment, the same vise arrangement can be used to correct the situation by applying some torque on the rod/tube to twist the key arm. Easy does it! Armstrongs seem to be made of stiffer metals than Gemeinhardt in my limited experience.

For the small pads (C#, and the trills) 11.5mm seems to be the most common diameter. Pad thickness has not been a huge problem. I use hot glue pellets (from JLS) to glue them in and then level them to the tone hole while the glue is flexible. No shims involved there.

I use a common pin for a padding needle to pry the pads out for adjusting shims, and an old pair of stamp tongs, basically tweezers with rounded ends, to handle the shims and pads.

There's tons more...

Ironing the pad surface to eliminate wrinkles

Partial shimming to accommodate wavy tone-holes or pads (partial shims are controversial, but I have found them necessary)

Proper venting, which I have found really improves intonation

key regulation, especially the B - Bb arrangement

I guess I've come a long way from where you are starting, thanks to many who are responding to your questions. The Burkhart-Phelan book has been very helpful.

I was mistaken they will be pads from Votaw tools medium.

Thanks for all the advice. I'm enjoying reading all the suggestions!. Can't waite to begin. Unfortunately pads will arrive before everything else. So I will have to wait.

"Clamping is not a substitute for this accuracy, because otherwise when you take the clamps off, the pads will gradually revert to their poorly adjusted state, as is often the case with new student flutes 9 months after purchase. "

Micron makes a very good point here. I think that there is a tendency for many (not all) repair techs to go with the quicker solutions. This also serves their cause as they can then recommend a COA to coincide with the leaky pads that have inevitably deformed from humidity variables. I do believe that a pad iron can help a great deal for a better seal over heavy clamping.

Pads and a couple other things arrived today. But my shims and other supplies are coming from another place so I must wait.

In respect to the learning curve, oh dear. We will see.

I may have just been slammed... not sure