Where to get fine grinding paste ??

ttf_marccromme · Post by **ttf_marccromme** » Wed May 24, 2017 2:56 pm

I have an 1.st valve on my Eb tuba I would like to grind to make it free moving. Does one use the same kind of grinding paste as when honing car valves?

ttf_JohnL · Post by **ttf_JohnL** » Wed May 24, 2017 3:54 pm

Maybe this stuff?
http://www.votawtool.com/supplies/lapping-compound.html

ttf_Doug Elliott · Post by **ttf_Doug Elliott** » Wed May 24, 2017 4:01 pm

BTW, casings are honed with a brass lap, not using the piston itself. You don't want wear both down, only take off the high spots that are causing problems.

ttf_Euphanasia · Post by **ttf_Euphanasia** » Wed May 24, 2017 6:06 pm

Generally, on older instruments you don't lap at all. Sticking valves are usually due to distortions in the casing. Often, it's pressure on a valve slide or even a dent. Generally, the best way to fix that is to get a mandrel of the proper size (Ferree's sells them) and insert it into the valve bore. Putting abrasives into a valve casing isn't the best way to repair a sticking valve.

Or are you saying you'd like to lap in the valve slide so it can be used for tuning?

ttf_marccromme · Post by **ttf_marccromme** » Sun May 28, 2017 3:03 pm

Quote from: Euphanasia on May 24, 2017, 06:06PMOr are you saying you'd like to lap in the valve slide so it can be used for tuning?

Yes, I think I was un-precise in my question. It is not about the piston valve itself. My 1.st valve slide works fine for general tuning, but is too sticky to be used as a trigger. I want it free-running, as it is easily pulled using the left hand. My 4th valve slide works very free and fine for fine-tuning, but it would be nice to have the same possibility on the 1.st valve slide.

ttf_BGuttman · Post by **ttf_BGuttman** » Sun May 28, 2017 3:47 pm

Quote from: marccromme on Yesterday at 03:03 PMYes, I think I was un-precise in my question. It is not about the piston valve itself. My 1.st valve slide works fine for general tuning, but is too sticky to be used as a trigger. I want it free-running, as it is easily pulled using the left hand. My 4th valve slide works very free and fine for fine-tuning, but it would be nice to have the same possibility on the 1.st valve slide.

You can get fine grinding compound in the pharmacy. It's called "toothpaste". Avoid the gel types as these tend to create their own grit when in contact with waater. The more old school stuff like Colgate or Crest is more appropriate.

For working on a tuning slide, sometimes 0000 (4 nought) steel wool works well also.

ttf_marccromme · Post by **ttf_marccromme** » Mon May 29, 2017 2:10 pm

Bruce - that is an excellent idea with the toothpaste. I could only find a car grinding compound here, at grade 320 (= 320 grains per inch, I guess). If it is the same numbering as sand paper, I would believe it's too coarse. So I'll try toothpaste. Thanks!

ttf_Doug Elliott · Post by **ttf_Doug Elliott** » Mon May 29, 2017 3:34 pm

Toothpaste on a slide could pretty easily get it stuck. I'd work on just the inner with 400 or 500 sandpaper, wet, just until it's close to the way you want it.

ttf_CharlieB · Post by **ttf_CharlieB** » Tue May 30, 2017 6:32 am

Remove the tuning slide, clean it with alcohol, and coat it with black Magic Marker. Reinsert the slide, remove, and note where the Magic Marker has rubbed off. Sand only those areas with very fine grit sandpaper.

ttf_timothy42b · Post by **ttf_timothy42b** » Tue May 30, 2017 7:41 am

I'm glad it's not the valve.

I had my Martin euph with a tech for a leaky receiver. While he had it, he took it upon himself to use abrasive on the valves. Well, they work, but it affected the tuning and the partials. It doesn't take much sloppiness in a valve to affect the response. Only with heavy oil sealing the leaks can you center the pitch.

Needless to say that guy hasn't had any other work from me.

ttf_bonearzt · Post by **ttf_bonearzt** » Tue May 30, 2017 8:45 am

United States Products specializes in lapping & polishing compounds.

https://www.us-products.com/

The Garnet at 1200 grit works well.

Valve problems are either dirt & corrosion, damage to the valve or casing, or either is worn & not perfectly cylindrical.

My thoughts are to rarely, if ever, use something other than the parts you are trying to fit together as a lap.

Eric

ttf_timothy42b · Post by **ttf_timothy42b** » Tue May 30, 2017 11:45 am

Quote from: bonearzt on May 30, 2017, 08:45AM
My thoughts are to rarely, if ever, use something other than the parts you are trying to fit together as a lap.

Eric

I've tried it a few times, though not on a trombone. It has never worked.

ttf_bonearzt · Post by **ttf_bonearzt** » Tue May 30, 2017 11:49 am

Quote from: timothy42b on May 30, 2017, 11:45AMI've tried it a few times, though not on a trombone. It has never worked.
\]

What were you trying to fit?

US Products has a pretty extensive write up on lapping. Worth a read!

Eric

ttf_marccromme · Post by **ttf_marccromme** » Wed May 31, 2017 3:19 pm

Quote from: bonearzt on May 30, 2017, 08:45AMUnited States Products specializes in lapping & polishing compounds.

https://www.us-products.com/

The Garnet at 1200 grit works well.

Thanks Erik - this was what I was looking for and could not find. Grit 1200 (or even 1000) sounds much more what I need than the grit 320 I did find in the local shop.

ttf_BGuttman · Post by **ttf_BGuttman** » Wed May 31, 2017 3:35 pm

I used to use some REALLY fine polishing compounds for making microscope cross sections. Sold by Buehler. They come as a slurry to use on a polishing wheel.

https://www.buehler.com/final-polishing-suspensions.php

I believe we used to use a suspension that was even finer than 1200. We used 1200 grit sandpaper disks before the final polish.

ttf_simso · Post by **ttf_simso** » Thu Jun 01, 2017 1:29 am

Quote from: marccromme on May 24, 2017, 02:56PMI have an 1.st valve on my Eb tuba I would like to grind to make it free moving. Does one use the same kind of grinding paste as when honing car valves?

I use hetmans grinding paste, 1200 is a nice paste and is water soluble, so you can wash it clean with warm water and detergent.

My website. Half way down you can see the paste being used to lap freshly replated pistons into a valve chamber.

Good luck with it, Water soluable is imo the most important thing to be looking for whatever compound you end up using.

http://www.mirwa.com.au/Piston_rebuilding.html

Steve

ttf_marccromme · Post by **ttf_marccromme** » Wed Jun 07, 2017 2:55 pm

These : http://www.hetman-eu.com/html/e_hetman_lapping_compounds.html thanks for the pointer, looks good.

ttf_marccromme · Post by **ttf_marccromme** » Wed Jun 07, 2017 3:17 pm

For other european trombonists: thomann has it: https://www.thomann.de/dk/hetman_uni_lap_compound_10h.htm

ttf_afugate · Post by **ttf_afugate** » Thu Jun 08, 2017 4:46 am

Quote from: simso on Jun 01, 2017, 01:29AMI use hetmans grinding paste, 1200 is a nice paste and is water soluble, so you can wash it clean with warm water and detergent.

My website. Half way down you can see the paste being used to lap freshly replated pistons into a valve chamber.

Good luck with it, Water soluable is imo the most important thing to be looking for whatever compound you end up using.

http://www.mirwa.com.au/Piston_rebuilding.html

Steve

Without derailing this thread too much, can someone provide a little more description of how you pressure test the valves? I couldn't deduce from the pictures what's going on.

--Andy in OKC

ttf_simso · Post by **ttf_simso** » Fri Jun 09, 2017 12:29 am

You need a flow jig, in the picture you can see the flow jig, you can set it up to apply between 1 and 3 psi of pressure, on a good trumpet, the loss indicated on the gauge is negligible to non existent, when connected to a bad trumpet the valves are so worn that the system cannot hold pressure and indicates loss.

Steve

ttf_timothy42b · Post by **ttf_timothy42b** » Fri Jun 09, 2017 5:09 am

My monitor didn't show the photos clearly enough but what I think he does is apply 1 to 3 psi of pressure to one end of the trumpet and plug the other end. If both ends measure the same there is no leak.

FWIW, I just read a study on trumpet pressure. For an ff Bb3, they measured .39 psi intraorally; for an ff Bb5, they measured 1.31 psi.

So those leak tests cover and exceed the range of normal trumpet pressure.

ttf_afugate · Post by **ttf_afugate** » Fri Jun 09, 2017 5:15 am

Thanks, both Steve and Tim.

So, one takes the flow jig, and hooks it to both ends of the trumpet (or points before and after the various valves in the cluster) and then measures for pressure drop. And, I assume one removes the various tuning slides as well?

Is this basically what's happening?

--Andy in OKC

ttf_simso · Post by **ttf_simso** » Fri Jun 09, 2017 6:01 am

Quote from: timothy42b on Jun 09, 2017, 05:09AMFWIW, I just read a study on trumpet pressure. For an ff Bb3, they measured .39 psi intraorally; for an ff Bb5, they measured 1.31 psi.

So those leak tests cover and exceed the range of normal trumpet pressure.

Interesting info.

I personally don't go by other tests, I found using local professionals / teachers / students that a range existed when playing the trumpet, 1-3 psi set pressure replicates this range fine. Have used this unit for testing easily 1000 plus trumpets now, works pretty good and shows people any leaks that happen during the Pistons travel, leaks that occur with pistons all up and pistons all down and various combinations in between.

When someone tells me they have a problem wi a certain note, we can finger that note and find if the instrument is at fault, when we do on those occasions identify it as the instrument after a valve rebuild we test it again and problems gone.

Steve

ttf_simso · Post by **ttf_simso** » Fri Jun 09, 2017 6:05 am

Quote from: afugate on Jun 09, 2017, 05:15AMThanks, both Steve and Tim.

So, one takes the flow jig, and hooks it to both ends of the trumpet (or points before and after the various valves in the cluster) and then measures for pressure drop. And, I assume one removes the various tuning slides as well?

Is this basically what's happening?

--Andy in OKC

Close, the bell is sealed off with a plug, the second gauge in the picture is connected downstream of the restrictor, it reads directly what exists within the trumpet, also note flow is always happening, you cannot just pressure the instrument, we need flow, the trick is identifying the amount of flow that exists in a good trumpet around good pistons, once we have worked out how much flow is always needed we can then apply added pressure to simulate playing within the instrument, if a leak occurs anywhere in the system greater than the flow that exists around a piston on a good instrument, be it a valve leaking or bad spit valve cork it will register a drop in the gauge as flow is greater and a pressure drop is registered on the gauge.

Example, puff your cheeks out with air, block your lips with your thumb, tilt your thumb so air slightly leaks, we now have flow with a small amount of pressure, try and maintain that same pressure and flow, now kick your fthumb to create a larger leak, the flow will increase and the pressure within your mouth drops further..

Steve

ttf_timothy42b · Post by **ttf_timothy42b** » Fri Jun 09, 2017 6:09 am

The highest intraoral pressure I measured on myself was about .5 psi, on an ff high Bb.

That measurement was done with a DIY manometer, with the tube stuck in the corner of my mouth while playing. (It's not easy to play that way, but it can be done.) It's been years, I should build another one and try for more accuracy.

Is that similar to how you measured trumpet players?

ttf_timothy42b · Post by **ttf_timothy42b** » Fri Jun 09, 2017 6:14 am

The study:

http://articles.ircam.fr/textes/Freour10b/index.pdf

ttf_simso · Post by **ttf_simso** » Fri Jun 09, 2017 6:25 am

Does not negate what I found with local tests, we created the flow system restrictor and everything about the unit in house, we then calibrated the unit with known quantities / good / bad / average condition valves.

You should conduct your own study with a group of say 60 people to start with and post back your findings

We attached a digital gauge to spit valve on main tuning slide using a Bach 37 as the test unit.

Trumpets / trombones work on bernoullis principle of velocity and pressure this is relative after the mouthpiece, not a measurement taken from internal mouth pressure.

Steve

ttf_timothy42b · Post by **ttf_timothy42b** » Fri Jun 09, 2017 6:42 am

Now you have me curious.

This study:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1501025/

says the maximum air pressure generated by women was .9 psi and that of men was 1.4 psi.

Wiki says 1.4 psi is the maximum air pressure of a "typical" human.

My measurement was taken inside my mouth, at .5 psi, and this is looking low.

BUT, remember there is a pressure drop at my lip aperture, and a second pressure drop at the mouthpiece throat.

In my case, I measured 13 inH20 in my mouth, and 1 just past the mouthpiece.

ttf_simso · Post by **ttf_simso** » Fri Jun 09, 2017 6:47 am

I feel some people just want to be right and feel the need to constantly disregard the findings of others.

I feel this sums your responses up.

i will continue doing it my way, and I will also continue rebuilding pistons and trombones.

Thanks for your input

Steve

ttf_BGuttman · Post by **ttf_BGuttman** » Fri Jun 09, 2017 9:12 am

Even at the low pressure of trombone playing (or trumpet playing, or French Horn playing, etc.) a leaky valve will cause intonation problems and in extreme cases can cause tone problems.

While a borescope can show problems with valve alignment (piston or rotor) it may not be cost effective to put into the process of making lower cost instruments where an extra half hour of labor can horribly upset the margin. On the other hand, a high level shop like Rath or Shires might use it to preserve their reputation for quality.

Osnum Brass has been doing pressure tests for at least 20 years and if they find the instrument leaky, it will generally have problems for the player. Repairs are rather straightforward if sometimes expensive. After all, plating up a valve core and honing it back to size is not a simple task and needs some attention to detail.

ttf_timothy42b · Post by **ttf_timothy42b** » Fri Jun 09, 2017 9:18 am

Quote from: BGuttman on Jun 09, 2017, 09:12AMEven at the low pressure of trombone playing (or trumpet playing, or French Horn playing, etc.) a leaky valve will cause intonation problems and in extreme cases can cause tone problems.

Yes. I gave an example earlier, where a tech used abrasive on my euph valves and made them leaky enough to be near unplayable.

I don't have any experience with axial valves but I've heard they are harder to keep from leaking than rotaries. I wonder about rotaries versus pistons.

ttf_timothy42b · Post by **ttf_timothy42b** » Fri Jun 09, 2017 9:42 am

https://www.rit.edu/cla/finearts/sites/rit.edu.cla.finearts/files/images/moreair.pdf

One more interesting study that shows different pressures for different instruments on the same pitch.

The only relevance here is that none of the intraoral pressures exceed 1.4 psi.

I did not find any measurements taken within the instrument. It is however hard for me to imagine a mechanism where instrument pressure is higher than mouth pressure.

ttf_afugate · Post by **ttf_afugate** » Fri Jun 09, 2017 4:33 pm

Quote from: simso on Jun 09, 2017, 06:05AMClose, the bell is sealed off with a plug, the second gauge in the picture is connected downstream of the restrictor, it reads directly what exists within the trumpet, also note flow is always happening, you cannot just pressure the instrument, we need flow, the trick is identifying the amount of flow that exists in a good trumpet around good pistons, once we have worked out how much flow is always needed we can then apply added pressure to simulate playing within the instrument, if a leak occurs anywhere in the system greater than the flow that exists around a piston on a good instrument, be it a valve leaking or bad spit valve cork it will register a drop in the gauge as flow is greater and a pressure drop is registered on the gauge.

Example, puff your cheeks out with air, block your lips with your thumb, tilt your thumb so air slightly leaks, we now have flow with a small amount of pressure, try and maintain that same pressure and flow, now kick your fthumb to create a larger leak, the flow will increase and the pressure within your mouth drops further..

Steve

Thank you, Steve. This makes sense!

--Andy in OKC

ttf_Lawrie · Post by **ttf_Lawrie** » Fri Jun 09, 2017 7:32 pm

Quote from: simso on Jun 09, 2017, 06:05AMClose, the bell is sealed off with a plug, <snip>
...also note flow is always happening, you cannot just pressure the instrument, we need flow, <snip>
Hi Steve - it isn't clear. How is the flow achieved? Does the plug sealing the bell have a port in it or something?

ttf_simso · Post by **ttf_simso** » Fri Jun 09, 2017 9:57 pm

Hi Lawrie, flow is always happening as pistons sitting inside a chamber are not a perfect seal, air moves around the pistons at all times and escapes through the bottom and top caps, a perfect piston to chamber relationship is a tolerance of around 1/2 a thousand of an inch.

If we were to seal the top and bottom caps then we would not be able to identify small minute leaks that exist past the pistons., as we are literally pressurising a closed circuit.

The calibration process is making a restrictor that allows this exisiting loss of air on a good trumpet become our base line, then all further leaks affect the pressure indications.

I apologise if I am not explaining it properly, but it took us about 4 weeks to get the system built right and that was after bringing in a mechanical engineer that specialises in flow dynamics.

Having now made and built the test rig, to me it seems incredibly simple, but I can tell you when we started we could not solve the problem or understand how to quaniify a leak that equates to a deviation of 2/10 thousand of an inch material loss.

I personally built this test rig as I needed something to quantify my before and after rebuilds apart from test playing, it also was required to be able to show a client why they were having a specific problem, as nothing in the market existed for doing this we had to start from scratch.

I believe a commercial product did exist many years ago that was distributed through allied parts that did the job, however for some reason it dis-appeared off the scene 20 odd years ago so I cannot really comment on how it worked.

Steve

ttf_Lawrie · Post by **ttf_Lawrie** » Sat Jun 10, 2017 2:16 am

Hi Steve,
thanks mate - that's cool. I felt it might be something like that but when you made such a point about flow it made me wonder if I was missing something.

ttf_afugate · Post by **ttf_afugate** » Sat Jun 10, 2017 5:10 am

So, back to the original poster's (Marc's) issue...

It's possible that the casing is distorted in some fashion and that should be checked first. If one laps valves, it's quite possible (almost certain) that it will negatively affect the valve compression unless everything is mechanically perfect first.

And then summing up what I understand about checking pressure...

Simso's (Steve's) process uses a compressor and a jig. The compressor provides air which is metered at a rate of between 1 and 3 pounds of pressure. The horn is stoppered and the air line is attached to the horn. Leakage is measured by having a flow meter gauge inserted inline between the air compressor and the horn itself.

This has been enlightening for me!

I hope I got this right. And I hope Marc resolves his issue.

--Andy in OKC

ttf_Euphanasia · Post by **ttf_Euphanasia** » Sat Jun 10, 2017 9:17 am

Quote from: afugate on Jun 10, 2017, 05:10AMSo, back to the original poster's (Marc's) issue...

It's possible that the casing is distorted in some fashion and that should be checked first.

The OP amended his original post to state that he was looking to lap the valve tuning slide, not the valve itself. If a valve ever worked and stopped working, lapping is probably not the answer. You'd end up removing metal in far more areas than the spot in the casing that's distorted.

ttf_simso · Post by **ttf_simso** » Sat Jun 10, 2017 6:42 pm

Quote from: afugate on Jun 10, 2017, 05:10AMSimso's (Steve's) process uses a compressor and a jig. The compressor provides air which is metered at a rate of between 1 and 3 pounds of pressure. The horn is stoppered and the air line is attached to the horn. Leakage is measured by having a flow meter gauge inserted inline between the air compressor and the horn itself.

This has been enlightening for me!

I hope I got this right. And I hope Marc resolves his issue.

--Andy in OKC

Spot on

ttf_afugate · Post by **ttf_afugate** » Sat Jun 10, 2017 7:19 pm

Quote from: Euphanasia on Jun 10, 2017, 09:17AMThe OP amended his original post to state that he was looking to lap the valve tuning slide, not the valve itself. If a valve ever worked and stopped working, lapping is probably not the answer. You'd end up removing metal in far more areas than the spot in the casing that's distorted.

Thanks, I missed that.

--Andy in OKC

ttf_afugate · Post by **ttf_afugate** » Sat Jun 10, 2017 7:19 pm

Quote from: Euphanasia on Jun 10, 2017, 09:17AMThe OP amended his original post to state that he was looking to lap the valve tuning slide, not the valve itself. If a valve ever worked and stopped working, lapping is probably not the answer. You'd end up removing metal in far more areas than the spot in the casing that's distorted.

Thanks, I missed that.

--Andy in OKC