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I have an older horn that is a little stuffy so I would like the best possible valve alignment. Using a dental mirror I can see that the pistons are not perfect. In the open position the near port looks exactly right but the far port looks a little off. I had this idea for finding the optimal position.

With only the piston in the housing (no spring or felts). What if I tied a small weight to a long party balloon then threaded the balloon through the valve. If necessary using a small magnet on the weight to help it along. Inflating the balloon would force the piston into the position of maximum air flow. Take measurements or mark the stem and repeat if possible for the down position.

A good technician with a snake scope could do the job faster and easier but what do you think of this idea for hobbyists who enjoy tinkering with their horns? I am thinking in the worst case scenario the balloon pops and I have to flush it out of the horn.

My guess is the alignment on two or three valves might be off by 0.025 in. Is that enough to notice any difference? If no one thinks of any obvious downfalls I will give it a try and let you know how it goes.

DuckCallDan wrote:... My guess is the alignment on two or three valves might be off by 0.025 in. Is that enough to notice any difference?....

In my opinion.... YES!

A little mis-alignment on one piston might not have very much affect .... But.... with all pistons off a bit, the impact on the open partials can be huge. Likewise.... in the down position, a little mis-alignment might not be very noticeable but with multiple of all pistons down... the results can be quite dramatic.

I just went through this with a Marzan (Willson) 'Solo' BBb tuba. The alignment was about .030" high in the 'up' position and was about .030" low in the 'down' position. The horn was difficult to center and played like a waterkey was half open.

There is usually always a bit of compromise with valve alignment due to basic manufacturing tolerances.

Also... don't neglect the radial alignment. Worn guides or guides that are made offset can cause the same problems.

Spot on, Dan. AND with a compensating instrument the problem rapidly compounds as the air column goes through valves again. Try getting a 982 with odd lengths of actipn rods as well set up right. Throw in a botched "Fletcher cut" as well and you have some real fun!

Dan covered it. There are almost always compromises to be made in valve alignments because of manufacturing tolerances. One extra thing. It's common enough on very old 4 valve tubas for the 4th piston to use different felts for correct alignment. I get trade-in's that don't play well when in fact the 4th valve was way out of alignment.

I might also add that it's very important that the length of the valve stems are correct. Time and time again... I see valve stems that are either incorrect altogether or the lengths vary from one piston to another.

As Matt mentioned... I've also run across occasions where the 4th piston takes a different combination of felts and corks and may even have been manufactured with a different length stem.

Indeed critical!

I found that most older euphs I've collected were fitted with modern day bigger felts when slim, but noisy ones were the norm.

Many 4v euphs that have suffered broken/replacement valve stems were just not even measured before being repaired.

It's so simple on the 4th., just look down the main slide and you can get it perfect. Yet I had a 1990's Miraphone that was way off line, it needed much bigger felts under the finger button to line-up and looked silly, but worked!

There are some very old model cornets around with different height valves to match the curve of the hand.

I played a Besson 4v comp euph (made in the 1940's) with the 2nd. valve reach further out (forward) than 1 & 3.

CB

Does it make a difference? Yes.

Enough to notice? Depends on the player.

+1. Each of my tubas has had valves get out of line, which made them noticeably stuffy. The fix was easy and quite effective.

bloke wrote:rule of thumb:

If the space between a valve and its casing is wider than the thickness of the felt required for proper alignment, don't bother.

I haven't had a chance to try my balloon idea yet but I have used the dental mirror to make adjustments. All of the valves needed adjustments ranging between .01 and .065 in.

Yes it makes a difference! My horn is much less stuffy now. There is room for improvement. The valves are off radially and there is a lot of play in the valve guides. Is there anything a do-it-yourselfer can do correct radial alignment? I don't suppose Home Depot sells a plastic bolt that will replace the valve guide of a 95 year old Conn.

For those wondering how I fit a mirror down the valve casing, Target sells a DenTek Oral Care Kit with a dental mirror. The mirror itself is plastic not glass so you can trim or sand the sides until it fits. Place the mirror in the valve casing and use a rubber band on the exposed handle to hold it in place. Now you have both hands free to work the flashlight and press the valves.

DuckCallDan wrote:..... The valves are off radially and there is a lot of play in the valve guides. Is there anything a do-it-yourselfer can do correct radial alignment? I don't suppose Home Depot sells a plastic bolt that will replace the valve guide of a 95 year old Conn....

Most of the valve guides on domestic tubas screw in to the side of the piston. The screw threads are #3-48. New guides are available in two widths (.100" and .130") from Allied. Ferree's sells a guide that's basically a large round head with the threads on the backside. Those have to be filed to shape. These two types of guides require some 'fitting' The guides from Ferree's are good for making minor corrections to radial alignment by simply filing the head off-center.

I don't know of any plastic screws from Home Depot that would do the job.

Properly fitting valve guides is sort of an art. You never know what you'll run in to. Some repairmen think a good fix is to just put a glob of solder where the valve guide should be and file it down.