Symptoms of Excessive Valve Wear

Abraxas · Posted: Sat Jul 20, 2019 8:57 pm Post subject: Symptoms of Excessive Valve Wear

The title says it all: I'm wondering what the symptoms are of valves that are getting badly worn out ? Thanks.

JayKosta · Posted: Sun Jul 21, 2019 3:18 am Post subject:

Very smooth and 'non-interrupted' valve slurs.

Less precise 'resonance' capability with some valve combinations. Can you can get (when really trying) a good 'pure' sound with all valve combinations? If 'yes', is there some other symptom that you notice?

Jay
_________________
Most Important Note ? - the next one !
KNOW (see) what the next note is BEFORE you have to play it.
PLAY the next note 'on time' and 'in rhythm'.
Oh ya, watch the conductor - they set what is 'on time'.

Abraxas · Posted: Sun Jul 21, 2019 3:33 am Post subject:

Thanks for your time jay but I'm not quite at the stage where I can rely on subjective metrics for the things you mentioned. Since I no longer have a teacher and my last one was in fact a trombone player, I don't have a point of reference for these characteristics. I do have half a dozen horns which should work in my favor as if one or more are worn out, then surely i have some that aren't and perhaps I can do a comparison or find a more objective observation to solve my question. For example : Is slotting affected ? Is longevity of notes... ie long tones going to be affected ? An airy sound to notes played ?

I'm noticing one of my 80A's , after I did a lot of work on it.....chem cleaning...fine lap ... just to get the valves moving after almost destroying it, doesn't , as best I recollect, slot as well. I'm not sure as i only used it a few times, a year ago before going to town freeing slides with excessive heat and without getting the valve oil off first...... ie learning experiences. I think the oil burned onto the valves and it seemed a good chem clean and light bit of fine lapping compound was the only FINANCIALLY RATIONAL way to make it playable again. I'm saying I don't drop $600 on a valve job for $100 horns.

HaveTrumpetWillTravel · Posted: Sun Jul 21, 2019 3:48 am Post subject:

I think some of the repair folk here have mentioned a test they do for compression, which is de facto a test of valve tightness, right? If you search the forum, I know there are discussions of this.

Abraxas · Posted: Sun Jul 21, 2019 5:05 am Post subject:

shofarguy

JayKosta · Posted: Sun Jul 21, 2019 5:14 am Post subject:

From your description of the work that was done to the horn, I'd only worry if the horn does NOT seem to be adequately 'playable' - i.e. if the sound is overly 'airy' / 'fuzzy' (compared to the sound from your other horns).

Precise measurement of air leakage can be done with test equipment. But for DIY, it's limited to subjective measures such as:
1) pull a valve slide out a bit, depress that valve, release the valve.
2) with ear near the mpc receiver push the slide IN and listen for the amount and duration of hiss. The time duration measurement of the hiss might be a way to describe the valve condition.

If water drips from the bottom valve caps, that's a definite sign that there is leakage around the pistons. Using the heaviest valve oil that allows acceptable valve action would probably help reduce that leakage.

Jay
_________________
Most Important Note ? - the next one !
KNOW (see) what the next note is BEFORE you have to play it.
PLAY the next note 'on time' and 'in rhythm'.
Oh ya, watch the conductor - they set what is 'on time'.

Abraxas · Posted: Sun Jul 21, 2019 5:57 am Post subject:

Shofarguy.... thanks.

I can say, as a retired machinist that seeing any movement in the piston would be a sign that it is well past the need for rebuilding as I've been told and seen in several publications that the ideal or expected valve clearance is about 0.0002 inches. About 1/15 the thickness of the average human hair.

I had always been told, as a part of my training, that holding a square or precision straight edge up to a part, with a light source in the back, the smallest gap or crack of light that can be seen would be 0.0001. Being that a valve does not have the benefit of being back lit and being in a hole, I'd say any observable movement would have to be 0.001 or greater to be seen. About 5 times the tolerance of a good horn and I'd say far more likely close to a human hair 0.003.

Thanks Jay for your additional advice.

I have a little bit more work to do to rule out valve wear. My notes sure are not slotting very well but hey, I heard Committees don't either.

JayKosta · Posted: Sun Jul 21, 2019 7:46 am Post subject:

For 'testing' you could oil the valves with a very heavy oil (such as straight pharmacy Mineral Oil). Valve action would be very poor (sluggish), but the oil would likely seal air leakage between the piston and the casing. Also carefully inspect the piston passage tubes to determine if they have any internal leaks due to cracks, missing solder, etc.

Then try your 'slotting' tests using all the valve combinations.
I believe the taper in the leadpipe (and mpc backbore) has a large influence on note 'slotting'.

Jay
_________________
Most Important Note ? - the next one !
KNOW (see) what the next note is BEFORE you have to play it.
PLAY the next note 'on time' and 'in rhythm'.
Oh ya, watch the conductor - they set what is 'on time'.

James Becker · Posted: Sun Jul 21, 2019 8:00 am Post subject:

As others have stated, loss of pitch center (particularly in the low register) indicates excessive leakage.

With our in shop pressure tester we subject each valve to a load of 1lb of static air pressure. New professional trumpets typically score 95% or better while student trumpets on average score 85%. So when a Bach trumpet drops below 85%, it's a candidate for a rebuild.

Our valve seal test is provided free of charge to customers while they wait, and is the most efficient means we've found to determine which instruments will benefit from our piston or rotor rebuilding services.

A simple DIY play test involves applying gear oil (or similar) to your valves and play test the bugle tones. If you experience significant improvement in articulation and pitch center, again paying close attention to the low register, will give you a good idea what your trumpet/cornet might play like after a rebuild.

It's not unusual with older trumpets to also see reduced mouthpiece receiver gap, which also contributes to poor pitch center but more so in the upper register.

A proper valve rebuild combined with restoring original receiver gap specs (i.e. Bach) results in a more responsive, agile and energetic sounding instrument.

As for "slippery" Elkhart Martin Committee trumpets, it's more the result of the bell taper more than anything. It certainly is NOT receiver gap as these tend to have very generous gaps anywhere from 3/16" and 17/32", compared to a Bach at 1/8". Kenosha Martins on the other hand gap around 1/8". But it may be a moot point when these decades old trumpets likely have worn valves.

I hope this is helpful.
_________________
James Becker
Brass Repair Specialist Since 1977
Osmun Music Inc.
77 Powdermill Road Rt.62
Acton, MA 01720
www.osmun.com

Our workshop is as close as your nearest UPS store https://www.ups.com/dropoff?loc=en_US

yourbrass · Posted: Sun Jul 21, 2019 8:02 am Post subject:

The valve casing will generally wear faster than the piston. So you have irregular areas which will only reveal their leaks while playing the horn.

If you have played a horn before and after a valve refitting, you know what a radical, and positive difference it makes.
_________________
"Strive for tone." -John Coppola
Edwards X-13
ACB MV3C /ACB A1/26 backbore
https://yourbrass.com/

James Becker · Posted: Sun Jul 21, 2019 8:19 am Post subject:

Abraxas · Posted: Mon Jul 22, 2019 11:05 am Post subject:

Very insightful replies. Thanks guys.

James Becker, is it true what I've been told, that the ideal clearance is 0.0002 inches and if so, is that per side or on the diameter ?

James Becker · Posted: Tue Jul 23, 2019 5:22 am Post subject:

Proper clearance can measure as little as .0003” per side or .0006” total diameter difference. My very good source at Yamaha informed me they relaxed their professional trumpet pistons by .0002”, or .0001” per side.

FWIW oiled vs dry pistons gain 5% points on our static air pressure test.
_________________
James Becker
Brass Repair Specialist Since 1977
Osmun Music Inc.
77 Powdermill Road Rt.62
Acton, MA 01720
www.osmun.com

Our workshop is as close as your nearest UPS store https://www.ups.com/dropoff?loc=en_US

Abraxas · Posted: Tue Jul 23, 2019 9:40 am Post subject:

yourbrass · Posted: Tue Jul 23, 2019 5:06 pm Post subject:

James Becker · Posted: Tue Jul 23, 2019 6:26 pm Post subject:

No printed instructions, just a few tutorials from the Sunnen rep and school of hard knocks. Measuring to the 4th digit past the decimal point is plenty accurate. And “relaxed” means less tight by .0001” per side.

Kinda like “relaxed fit” blue jeans, less tight in the legs and seat.😉
_________________
James Becker
Brass Repair Specialist Since 1977
Osmun Music Inc.
77 Powdermill Road Rt.62
Acton, MA 01720
www.osmun.com

Our workshop is as close as your nearest UPS store https://www.ups.com/dropoff?loc=en_US

Abraxas · Posted: Tue Jul 23, 2019 7:47 pm Post subject:

If I want to measure something that is 1 inch in diameter, I'd need an instrument that has finer increments than that to measure it. As an example, If I used a rule that only had 1 inch increments and the bore was 1.995, I would be stuck with calling it 1 inch, as inch increments was the closest measure. So if we are talking about tenths of a thousandth of an inch clearances, I would think that , as a rough guide, we would need to measure the bore to a quarter of a tenth of a thousandth of an inch or finer. I can do that with a good digital micrometer on outside diameters, but I'm not aware of any method to do that on bores. Someone told me quite convincingly, that they had some privileged insights and access at Yamaha and they weren't even measuring their bores and that makes sense as I don't know how they could do that. They were simply lapping them together.

LittleRusty · Posted: Tue Jul 23, 2019 7:47 pm Post subject:

JayKosta · Posted: Wed Jul 24, 2019 4:07 am Post subject: