PT-20 piston problems
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iiipopes
- Utility Infielder
- Posts: 8580
- Joined: Tue Sep 06, 2005 1:10 am
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.
Jupiter JTU1110
"Real" Conn 36K
"Real" Conn 36K
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Alan Baer
- pro musician
- Posts: 127
- Joined: Sat Mar 27, 2004 12:10 pm
Sticky valves
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
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