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I have recently been replacing cork every other week. I went through 3 pieces of cork in a week in my 5th rotor. I got frustrated and swapped it for rubber. I dislike the bounce of rubber with my rotary valves. It seems that the new corks like to "settle" at rates that differ from rotor to rotor. Is there a more consistant product? or is there a "better," more durable material that is available to people not "in the know?" I have used the search feature and have not found a difinative place to purchase or title for such an item. FWIW I did have the first set of corks professionally installed and I learned how to do it from that repairman. (I just want to eliminate the possibility of "error" on my part).

Inquiry:

Do you have any idea why are cork bumbers are failing on you? This happened to a friend of mine last year, and I believe it was because he was drench the entire linkage system at the rotor in oil. If some of your oil is leaking out, that may be causing the cork to become brittle.


Either that, or restrain yourself from smacking them so hard, Kong!

That's a good idea I'll take 'em all apart and wipe the whole outer setup off with a cloth. On the last one I replaced I took the stopbar u shaped piece off and it was oily underneath. This might be a good solution.

Where are you getting your cork? Cork tends to get 'crumbly' when it gets old.... or maybe the cork you are getting is just a low density. Not all cork is the same. There are probably six or seven types of rubber available. If you don't like the 'bounce' from rubber, you might experiment with different durometers (hardness) to get the feel you are looking for.

Tubatom, I hang around Aurora sometimes (in fact, I had an absolutely fabulous non-musical job there) and bought the rubber for my rotors from these guys:

http://www.musicarts.com/" target="_blank

Apparently they have a store in Naperville, but I went to their warehouse in Itasca (where they do repairs, cleaning, etc.) and got the rubber from a very nice guy there named Dana, who is a tuba player. If you don't feel like driving to Itasca, you could probably call them up and talk to Dana about getting some rubber sent to the Naperville location.

Isn’t part of the problem, that what the music industry calls cork isn’t real cork. Far too often I have seen a useless mass of crude cork chunks held together with some glue, which cannot hold up against oil.

Hobby making of wine used to be widespread here. Hence our equivalents of drugstores sell real corks for bottling. I cut oversize blocks out of cork slices and press them into the horseshoe slots by means of a screwdriver.

Klaus

Some shops use black neoprene rubber. My 186 has them and I'll never go back to cork.

Belltrouble wrote:What about that stuff wich is used for industrial O-rings ?
It´s normaly available from industrial seal and gasket supplyers and is available in several diameters,also useful for waterkeys............. Kurt

Hi, Kurt! You are so correct. Probably the most diverse industrial supplier here in the US is McMaster-Carr in Chicago. They carry many diameters and at least five or six durometers of rubber cord. Nitrile, Viton, Buna N, and silicone are three that come to mind that aren't affected by oils. Some rubber materials are more prone to hardening and need to be replaced more often than others but they hardly wear out.

I'll second the Buna N as the best bumper material for most people. Order O-Ring Cord Stock from McMaster-Carr. Order about a foot each of the various METRIC sizes near what you need to get the best size selection. Buna N gives minmal bounce, minimal compression, good longevity, and reasonably quiet. After about 2 years it starts to get hard so no sense stocking up on it.
Most people like the feel of Buna N bumpers, but then again the story of The Princess and the Pea tells us there is always someone out there that will need somthing softer.

I believe mine has the black neoprene mentioned above, works great for me.

As for cork, I know a guy who would go to Olive Garden and ask for wine bottle corks when they were done with them. I guess you could do the same thing at a bar.

Or treat yourself if you're old enough....

So now, what is better Buna N or Neoprene? I really am not worried about replacing this stuff within resonable time frames of 2months or so. I am just worried about the "bounce factor."

Yes, if you like cork you just need a better cork. Champagne cork is smaller ground and dense-I have a few coasters that are extremely hard-pressed cork. Too hard, in fact, so I glue a thin rubber pad to the end that provides a soft landing, yet the whole setup never shrinks or deteriorates over time.

And I love the clear white rubber stuff on the downstroke-soft & quiet.

My two cents

Rotaryclub wrote:Yes, if you like cork you just need a better cork. Champagne cork is smaller ground and dense-I have a few coasters that are extremely hard-pressed cork. Too hard, in fact, so I glue a thin rubber pad to the end that provides a soft landing, yet the whole setup never shrinks or deteriorates over time.

And I love the clear white rubber stuff on the downstroke-soft & quiet.

My two cents

Would Rotary club you, if you played a piston instrument?

K

I was browsing some cork suppliers and found items that caught my eye. On company, Jelinek, offers a specialty music cork. And another cork company offers synthetics. I am wondering if these items would be oil resistant. Anyone "in the know"?

I can tell you that after a couple of years, even neoprene starts to compress. It's about time for a new fitting for my 186 as well.

You could use rubber for the compression side and cork for the return or "at rest" side that way you get the strength of the rubber when you push the valve but when you release it you don't get the bounce. That being said , what about leather?

kingconn wrote:You could use rubber for the compression side and cork for the return or "at rest" side that way you get the strength of the rubber when you push the valve but when you release it you don't get the bounce. That being said , what about leather?

That's what Miraphone currently does with their horns (the 186, at least). I really liked that system.

I get various-durometer density and diameter neoprene cord from J.L. Smith & Company of Charlotte, North Carolina, a fine supplier to repair technicians. They may also sell to the general public, but I cannot confirm this.

I keep my stock of bumper cord in ziplock bags, to limit its exposure to the environment. Neoprene should last for several years under normal usage. Different instruments need different diameter bumpers, and different density, due to differing spring tension and lever-to-stop arm ratios of motion.

I do also use cork on certain applications. In my earlier days, I tried wine corks, hardware store cork stoppers, just about anything you can imagine, and most of it was pretty disappointing. If you have an instrument with moderate or low spring tension, cork will last quite a while. When feasible, I like to use cork, as it is an earth-friendly renewable resource. The cork-oak trees, primarily found in Portugal, live much longer when their bark (cork) is regularly harvested, so we actually do the environment a favor when we use cork. High-quality stick cork, when dampened, compressed and fit into the bumper channels, and allowed to dry before use, will give virtually no bounce whatsoever and should last for a year or more under non-abusive use. High-quality stick cork is available from major instrument repair supply houses, such as Ferree's Tools in Batlle Creek, MI, and Allied Supply in Elkhorn, WI. I believe that Ferree's may now sell to the general public, also, but I'm not sure about that. What I am sure of, is that your local repair technician can get what you need for your instrument. All you have to do is ask. If they refuse to take care of you and your instrument, find another repair technician. No one should have to play a poorly-performing instrument.

I had a semi-emergency situation today with one of the existing neoprene/rubber bumpers on my horn today. I've now ordered several sizes of the "Buna-N" cord that Matt Walters recommended, but I needed a solution until they arrive. (A chunk fell off of my 1st rotor stop, and the rotor was extending well past it's intended alignment)

My wife and I hosted for Thanksgiving this year, and we had a few empty bottles of wine still sitting in the recycle bin. I grabbed the corks off a couple bottles, and my x-acto knife. The first two corks were completely useless... Very coarsely ground, and would only crumble as I tried to cut them to size.

The third and final cork I tried worked perfectly! Less than 5 minutes with a pair of needle nose and the knife and I was back in business! I can't comment on how long it might last, but I'm guessing it will get me through the next few days until my order from McMaster-Carr gets here.

For those concerned, the cork that worked came from this bottle: