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I own a PT-20 with piston valves and for some reason the a couple of the pistons stick for no aparent reason that I can see. I have gotten the casing cleaned and I oil them frequently, but the problem has no gotten much better.

I was just wondering if anyone else has had this problem and how did you fix it?

I had problems with all of my valve guides, one by one by two they were replaced and now the horn is perfect for me.
Good Luck.
Peace.
ASG

Everybody focuses on the valves. How about the casings? Have you had the valve casings burnished? Then put the valve in and see if when you get it inserted almost to the valve guide, will it spin freely? If so, problems probably solved on the next cleaning and oiling. If not, you have out of round problems that will probably never go away.

Forgive me, my strong opinion is that stainless steel has no place in a brass musical instrument, when monel does the job much better, has just as much corrosion resistance, has a thermal expansion factor closer to brass, is not inherently harder than the casings, which will eventually cause wear, and has been confirmed as THE metal for valves from its use for about 3/4 of a century.

If I had a horn with stainless pistons, and I just loved the sound and playability of it so much I couldn't quit, I'd have Dan Oberloh make me a set of custom monel valves for it.

Cost. Stainless is basically iron, a bit of carbon to make it into steel, and nickel to make it stainless. Monel is a rather complex alloy of mostly nickel with iron and other metals, and was a patented, then trademarked alloy. The higher percentage of nickel, 63% or more, also makes it more expensive, as nickel is more expensive than iron. So, MW started using the cheaper alloy steel instead. For further information:

http://www.lenntech.com/Monel.htm?gclid ... GAodayZyiQ

Okay, I have read enough.

For the record:
Total bs about the metals and there quality that are being used in valves. Thermal expansion??!! give me a break. You guys playing your horns in a blast furnace? Monel is an copper/nickel alloy, not my favorite material. Yes, it is very durable before it is made into a valve but the processes used to create the piston (silver soldering in the ports) has an annealing impact on the metal and this makes it not as hard, additionally, it has an oxidizing issue that can cause the piston to stain and drag. Monel also has a rougher surface that is covered with micro abrasions. This roughness and an oxidized cylinder wall can cause drag or occasional stickiness of the valve. The inexperienced repair person will often hand lapp the valve (wrong approach) sometimes to excess, making a minor problem worse. Stainless works every bit as good and is every bit as durable as monel, if not more so. It does not stain and is easy to clean but the jury is out with me on its rebuildability. I very much doubt that the cost difference in materials is the reason for there use considering that the labor in making the valves by far over shadows the cost of material. The true ideal material for piston valves is hard-nickel, plated onto a nickel-silver substrate. Most manufacturers do not use this design because it is much more costly to produce.
Many that do use the nickel-plated design tend to have more slop then I prefer and have there drawbacks but they still work reasonably well. The nickel plated valve is hard, very smooth (feels wet even when dry), can be honed to a very close tolerance and has excellent corrosion resistance. Those of us who actually work on such components understand this all to well. I rebuild Holton 345 pistons that are arguably some of the most fragile of there type and from them, I am able to produce mechanisms that are second to none in there smooth action and light feel. I regularly rebuild monel pistons that are only ten years old and that are worn out beyond belief. I also routinely see nickel plated pistons that are 70 years old and still holding good compression. The tolerances of a piston valve do not allow for rough handling or poorly executed repairs and because this is the case, I always say "Its a good idea to understand what the real problem is before you attempt the repair".

By the by, my 18 year old HB-2P has stainless pistons and they are fantastic. The only problems my stainless pistons give me is when I fail to give them a cleaning every other year. Thats my fault not the horns. Good quality valves will give little in the way of problems as long as they are properly maintained and undamaged, where the lesser quality design will have issues almost from the first day they are put to use. The good thing about the monel piston is that it can be rebuilt and made into a far more superior functioning valve then it was when it was new. This can even be done to much of the new junk that is sold on e**y, though it can't do mush about there very poor acoustic properties. Thats another issue all together.

If your valves are sticking, remove the guides and test the action. The guides are often not fitted as well as they should and may need some fine tuning. If the piston has drag with the guides not in place, there is an issue with the cylinder or piston. if it is a cylinder issue then the horn has possibly been damaged and it is manifesting itself in the casings. if it is the piston, it probably has been dropped and is slightly bent or out of round. Both can be corrected with the proper approach and a bit of care. Polishing a piston should only be done by an experienced professional through block-lapping.

Daniel C. Oberloh
Oberloh Woodwind and Brass Works
Seattle, WA
www.oberloh.com

I stand corrected by the master.

Of course, the HBs with the plastic rotors laminiated with a metal coating did expand with body heat and stick, but that's a whole 'nuther kettle of fish.

So, with Dan setting us all straight, why is it we are hearing about all these sticking stainless steel valves, especially on Besson products? Were they just not made or put together properly, compared to other companies, or did we just have that unrealistically high expectation of Besson? or are the other companies just not up to speed, or taking the time, to mill them straight?

Dan, please enlighten us, yet again?!

As an example of what to do following bloke's post, when I took my Besson in to be de-dented from receiver to main tuning slide, I also had my tech work on the valves, even though they were in really good shape to begin with, because, like bloke said, they can get knocked off true very easily, especially when you are having slides unsoldered to be worked on. When he was "done," I went to the shop and we spent at least a half hour together making sure the casings were perfectly clean and burnished, the valves were perfectly clean, straight and buffed, and had to oil, assemble, and disassemble and re-oil several times to get them right. I don't know why people tolerate bad valves, either, when there is no reason for it.

I guess the same people who don't take their horn in periodically to get the valves gone over don't change their oil in their automobiles regularly, either.

One of the things that needed dents taken out was the arch off the 3rd valve slide as it goes back into the 1st valve for the comp loops. The knuckle going into the casing was concave, so it had to be unsoldered, and the port checked. After it was disassembled, using heat, of course, and the dent popped out, and reassembled, using more heat, of course, the heat soak and the change in tension on the metal reassembling it was just enough pressure on the casing to cause it to stick. We both knew it would be like this; that's why we allowed the time for it, and also double checking the valve slides for parallel, which also had a couple of dings taken out of the curves, which can throw the legs off parallel. Nothing major, of course, and nothing that was out of the ordinary or expected. Just the tech and myself being realistic about repairs on an old horn and taking the proper time to work with each other to the satisfaction of both of us. Am I going to spend big bucks "restoring" this horn? Of course not, having an initial investment at this point, including repairs but not including mouthpiece, of less than $600.00, and knowing it would cost more than the market will bear if I wanted to sell it later. Do I enjoy the horn? Yes, immensely! Will I spend a few bucks on it now and then making sure it doesn't lose its playing integrity? Of course, just like you do keep washing, changing the oil, battery and tires regularly on a $1000 car, and keep registration, license and at least liability insurance current, if it's all you have to drive.

This seems to be common problem with piston horns, esp. if you were a former rotor player. I've not read all the multiple posts to see what others are doing but I will give you a fix.
1. take a look at your valve guides. They need to be smooth with no burrs. You can even put some heavy oil directly on the valve guide and then play the horn. If the sticking stops, the problems is probably the guide.
2. take some 600 grit sandpaper. Sand the upper sharp edge of the valve. (I'm assuming that your valve is only sticking on the up stroke.) It would be like slightly rounding the top ede of a Coke can. That sharp edge is acting like a squeegee and pushes away the oil. This sharp edge is the only area that your sanding.. It's stainless steel and is faily forgiving with 600 paper. Just the sharp edge though..
3. wash the piston with warm soapy water. Shake water off, don't dry, oil and test.
4. If it feels good they you may want to consider this...
The synthetic oils are really nice, esp. with the problem valves. But most oils are too thin. I will use either Hetman OR I will use lamp oil. (once you find and oil that works, don't mix and match, stay with what works..) THEN... I apply (1) one, one, that's one drop of Mobil one 5W30 synthetic motor oil to the piston, AFTER spreading the valve oil on the piston. Don't try to mix them. This will increase the surface tension of the oil. The piston rides or hydroplanes on the oil. Give it just a bit more strength for supporting the piston.
Tiny burrs, sharp edges, calcuim, etc., break the surface tension and whoa, the valve sticks.
You may consider putting your pistons in a bath of CLR as well. Don't put your mother of pearl or those flattened water and oil soaked felts in it though! The calcium in the water that we drink is enough to gather on a piston and cause problems.
Good luck,
Alan Baer