TromboneChat

Those of you who have ever owned and used a Kanstul Bass...
I have my first one ever. Its a single valve version.
The trigger response is not quick and "snappy" or immediate. There is a bit of resistance on the return stroke, or release.
Yes, I have oiled it. The linkages and spindle too.
I am reticent to disassemble the CR valve because I do not wish to damage anything OR not be able to reassemble it correctly

Anything else I can try short of sending it for a professional cleaning??

Thanks,

Sam

I find the CR Valves on my Kanstul Contra need a lot of cleaning. It did take a couple of years to break them in.

I do use Ultra Pure light valve oil.

Everything needs cleaning. If that's not a job for you, it's a job for someone else.

I've had a Kanstul double valve for 8-10 years. I sent it back in the first week because the valves jammed up. I've always been able to disassemble my rotary valves (I've played an 88h and serviced it myself for ~50 years), but I could not get the Kanstul valves to go back together. So Kanstul cleaned and reassembled my valves. A couple of months later, same problem. I took it to my local tech. Same problem. The next time this happened (in a year or so), I just had the tech lap the valves a little bit to reduce how tight they were. I wasn't getting any benefit from the valves being so tight, and the horn was very unreliable As far as I'm concerned, if I (a mechanical engineer) can't reassemble my valves, there's a problem. So lapping them seemed like an extreme solution, but in the end, it's what worked for me.

It turns out that my saliva has a lot of junk that calcifies in my instruments with valves. My old instruments with a lot of valve slop never had a problem, but the new tight Kanstuls were a different story. This happens with tight piston valves for me as well, regardless how much I clean or oil the the horn. I own 11 trombones and 4 valve instruments, most of which are 50-70 years old. Only the new instruments valves stick for me, and the Kanstul was the only one I couldn't handle myself.

I'm not sure what to recommend to you, because lapping brand new valves is an extreme measure, but if it's keeping you from using the instrument, something has to give. Either clean the instrument every time you play, learn to work with the valves yourself, resolve to paying someone to do it, back off and use only 30 year old valves or in the extreme have the valve lapped. Those are your options as I see it. Especially if new valves haven't worn in within a year, that's a problem. My horn doesn't play any differently after the valves were lapped, but the valves don't stick now. I think Kanstul got carried away and just made the valves too tight because in a shop environment they could get away with it. But when you get out in the real world with a lot of variables, those tight valves don't always cut it. And they don't give you any advantages, except bragging rights "hey look at how tight my valves are", and maybe 150 years from now they'll still be functional, but maybe that's because they just don't get used because they stick too much.

Take from that rant what you will. People I play with love the sound of the Kanstul bass, but keeping the valves going around is a different story.

Hmmm, that is definitely not how it should be. I have two Kanstul Tenors, and the valves are definitely quick moving. Sounds like it may need a cleaning, as they are rather tight tolerances, as noted by others.

You purchased this horn as a used instrument? Was the valve always this way, or has it slowed as you've owned and played the instrument.

First thing is to get it properly cleaned and assessed. Tightly fit rotors can bind up from twisting, bending, or other damage to the bell section.

The next step would be to have the tech look closely at the fit of the rotor and make sure the bearing surfaces are fit properly, and they your lever spring has appropriate tension.

Once all of that is settled I would look at the lubricant you are using, how often you're applying it, and where you're applying it. It can be challenging to get oil where it needs to be on rotors, especially those with very tight clearances.

I would avoid lapping or otherwise removing metal to "remedy" this situation, personally.

A simple cleaning.
Buy a rubber stopper at the hardware store that fits in the receiver the slide goes in.
Plug it.
Pull the tune slides.
Pour in some white vinegar and water and a little Dawn detergent. 50/50 ish will do.
Activate the valve a few time so the fluid is on all sides of the valve.
Let soak for 4 to 10 hours.
Empty, rinse and oil.

You can get more aggressive with all vinegar or much more aggressive with diet coke for cleaning any part of the horn. Just rinse it out really good.

Take it to a tech. I had problems with the second valve. It did not return after pressed. It was stuck and it turned out it needed a clean. I usually can pick valves apart but this Kanstul valve was too tight and I did not want to use force. The tech had a special tool to do just that, so no problem. After the clean he also adjusted the fether. My valves are now much better than when I bought the horn ten years ago.

/Tom

The CR valves have what I call a “beehive” type construction. Since they are not a single piece of metal that is machined, they are more prone to misalignment. I had some Kanstul bass trombones come through the shop last year and all of the CR valves had some type of issue. I found that the best solution was place them on a lathe and keep working with them until they spun straight and true. Once they spun true from spindle to spindle, I found that they worked quite well. I am very impressed with how they play!

Just take it to a tech. You cannot effectively clean your valves without taking them apart. There's probably lime scale and sludge inside your valves that needs to be removed by someone who knows how to do that. Of course, you probably have already. I see this is an old thread that has been resurrected for whatever reason.

Crazy4Tbone86 wrote: ↑Wed Aug 09, 2023 7:54 am The CR valves have what I call a “beehive” type construction. Since they are not a single piece of metal that is machined, they are more prone to misalignment. I had some Kanstul bass trombones come through the shop last year and all of the CR valves had some type of issue. I found that the best solution was place them on a lathe and keep working with them until they spun straight and true. Once they spun true from spindle to spindle, I found that they worked quite well. I am very impressed with how they play!

Are you saying that you turned the rotor down, or were you making adjustments to the concentricity by bending/straightening the spindles?

No, I did not turn the rotor down. I twisted and lightly tapped on it with a small rawhide mallet unto it was concentric.

On a normal rotor, if you get the spindles straight, it will usually spin true. CR rotors are different in that the “beehive” construction makes the body of the rotor have a little flex. Thus, making the rotor concentric can require a bit more patience.