Valve maintenance

[MartyNeilan]

This weekend I decided to perform full maintenance on my pistons to try get them running as smoothly and quickly as possibly, to alleviate hand issues since my son broke my right hand last year instead of his Taekwondo boards last fall. Synthetic felts were chosen to prevent the deterioration of natural felts or corks that can cause sluggishness due to bits becoming stuck between the piston and casing. Wide lightweight fingers buttons were used to help allow lighter springs to function effectively. New plastic valve guides were installed to insure optimal smoothness and reduce side-to-side movement that had begun developing due to worn valve guides. The work was performed on a first generation Meinl Weston 2165 piston valveset (aka "small piston" valveset) that has been grafted into my large early 1900's German tuba formerly known as BART. The previous owner of that valveset had Martin Wilk make up some lightweight valve caps to replace the extreme heavyweight valvecaps; the top caps now are closer to what would be found on a newer MW valveset, possible even lighter.

1. Remove all pistons and thoroughly clean pistons and valve casings.

2. Tap new metric threads in piston stems using a 4 x .7 (metric) tap http://www.amazon.com/High-Speed-Steel- ... B0006G4MCA My specific pistons originally used an SAE thread, unlike the MW "large pistons". Thoroughly wash off any filings. This step is only necessary if replacing the buttons with BlokeButtons™.

3. Replace worn plastic valve guides with new MW plastic valve guides. This involved using a very small pair of needlenose pliers with the points pointed AWAY from the piston to carefully start unscrewing the old guides. Then thread in the new valve guides snugly but not too tight - if overtightened the ends start to stick up. Screwing in the new plastic valve guides requires a LOT of patience to get them started, it is critical they go in straight and not get crossthreaded. Since neither of my index fingers work very well any more (my left hardly at all since putting a butter knife through it a year and a half ago) this was made even more challenging. Put a few drops of oil on each piston and test for valve guide fitment. I had to gently file down the plastic with a fine file until the valves moved up and down smoothly. On two of the valves, the plastic was just a little too thick for the channel in my valve casings and they did not want to easily slide in. The side-to-side fit was perfect (on a previous MW horn, I had to slightly narrow one of the valve guides to fit the channel.) Be sure to rinse all plastic filings off after each filing before testing the piston, and file as little as possible.

4. Slide bottom BlokeWashers™ over the valvestems, then top valve cap, then top firmer BlokeWasher™.

5. Firmly screw BlokeButtons™ onto valvestems. I was concerned that after tapping the new threads I might need to use a little bit of threadlocker, but once tightened all the way down (fingers only, don't overtighten) the buttons remained firmly in place and showed no signs of loosening up. Although not inexpensive, these stainless steel finger buttons are extremely well made and worth every penny if you are looking to lighten the pistons and have a broad flat surface on top, vs. the uneven or concave surface of many finger buttons. This allows me to keep my right index and middle fingers close together, instead of being drawn to the center of each piston.

6. Liberally cover the piston with valve oil (I currently like La Tromba T2) and reinsert into the casings. After working up and down several times, I removed, recoated, and reinserted them since everything had been completely dry.

7. Insert Yamaha euphonium plastic coated valve springs in the center of the back of each valve, and then screw bottom valve caps on. The pistons should be light and smooth enough that the tuba springs are not necessary. I prefer inserting the springs from the bottom after the piston is already in, instead of from the top before inserting the piston. This keeps the spring centered in the bottom of the piston instead of being off to one side.