Replacing old rotors (triplene core) - Hirsbrunner

[JB]

Replacing old rotors (triplene core) - Hirsbrunner HB-2

For a late-1980s Hirsbrunner HB-2, I am looking to replace the old, triplene core rotors that have lost their quality over a long period of time and now cause the common, well-documented problems.

The ideal solution seems to be replacement with solid metal rotors. (Purchase of a new instrument is not an option/consideration.)

I have been in direct contact with Peter Hirsbrunner, but while doing some additional research I also stumbled across the site of the company that produces and supplies the valves to Hirsbrunner (J.Meinlschmidt GmbH http://www.jm-gmbh.de/deu/produkte7.htm).

The valves below with the “New Lubrication System” caught my attention.


Does anyone have any first-hand experience with these “new and improved” rotors, either positive or negative? Any useful insights and opinions are welcome.

Rough Translation from German:

Operational principle: Bringing in the lubricant is made by a spiral groove at the upper and lower camp pin. At the lower camp pin the oil is supplied from the outside by an axial drilling. By a radial drilling the lubricant arrives into the lubrication groove. At the upper camp pin the oil is brought directly into the lubrication groove. With the rotation of the change the oil distributes itself evenly between the sliding bearing surfaces. The oil remaining in the axial drilling serves as reservoir and provides thus for a sufficient amount of lubricant. An overdosing and thus oiling the valve are prevented by this principle.

Advantages: For the musician the care of the turning valves is substantially simplified. For oiling, the lower cap must be only removed and the lubricant from the outside be supplied. The self cleaning effect of the lubrication groove provides beyond that for a very high Wartungsfreundlichkeit. When playing the instrument the new lubrication system becomes apparent by a still suppler run of the changes

This is the result of a homogeneous lubricating film which is formed between the sliding bearing surfaces. An optimized finishing technique makes it possible to us to offer this option with only small extra costs so that for our customers a very good cost-performance ratio is obtained. This innovation from the house Meinlschmidt is protected by a patent.

(And, although not what I am considering, the carbon rotor was also of interest – unless I completely botched my very weak German and misunderstood what I read/saw. Any experience with these? Anyone?)




Thanks in advance for the assistance.

Cheers

[JB]

In my experience, the sticking issues only occurred when the rotors were new and not broken-in. The fix was to lap them while warm.

If they are sticking now---when very broken-in--- you might have a very experience repair technician check and swedge the bearings. On older instruments this has worked very well in the past for me.

Thanks for the suggestion, but have already had that attempted. Didn't prove to be as successful as hoped. I have been in touch directly with Peter Hirsbrunner, and it is his solution to have the rotors changed. He wrote that the triplene has been discovered to deteriorate after a number of years, and then continues to do so. Thus, the only permanent fix is the switch to solid metal rotors.

The HB2 I owned never stuck. Not even in 100 degree heat. It was well broken in and had well fitted bearings.

I am very envious that you had one that didn't seize up. And the temp doesn't have to be anywhere close to approaching 100 degrees for this to happen -- it has gotten to the point that hot stage lights will set it off. Not quite what you want to have in the back of your mind when in mid-performance!

[JB]

The “latest” (an update of sorts, with thanks to Bloke and LJV for their valuable input thus far):

After written discussions with Peter Hirsbrunner, and specific questions about the precision of new rotors for 25-yr worn casings*, Mr Hirsbrunner writes his assurance that the solution is as described below. He explained that this has already been carried out for a number of folks that experienced the same problem, one with whom I have been in direct contact via telephone (and is a “very major” orchestra tubist and a trusted friend).

My original valve rotors, including the lower bearing plates, need to be sent to J. Meinlschmidt, where "they know the problem" and have made this “valve copying” several times. To quote Mr Hirsbrunner,

“The full metal rotors will be exact copies of the originals; they will fit your valveset like the originals. The rotors will be made with 0.01mm oversize, to compensate for wear on the current ones. Based on this oversize, your repairman has to lap the new valves to the corresponding valve case. This will take a little time, but then the valves fit exactly and are tight.”

(*One of the questions to Mr Hirsbrunner:

“Are you able to ensure that the rotors match the size and the spacing of the horizontal knuckles that go out from each rotor casing to meet the valve/slide tubing?”

)

When asked if he would recommend these "New Lubrication System" valves** by Meinlschmidt (mentioned in my original post, above), he answered,

"yes,"

and added that

"all the new rotary valve sets in Hirsbrunner instruments use these valves."

(**http://www.jm-gmbh.de/pix/pag.jpg and http://www.jm-gmbh.de/pix/prod_7a.jpg)

[So, at this point: while very pricey, according to Mr Hirsbrunner, this proposal is less expensive than purchasing the entire five-valve cluster; and provides a solution to the matter of my old valve/slide tubing lining up with new rotor casings – as this becomes (hopefully, and if believable) a mute point].

If anyone on this forum has had this specific procedure applied to your own instrument, I would appreciate learning of the results and your own experiences. I also encourage (and appreciate, with sincere thanks) further input and ideas from Bloke and LJV (and others who have meaningful input to offer).

Cheers (until the next “update”)

[Jesperiank]

Hello everyone! =)

I thought I would post this for the record. I own a Hirsbrunner HBS 192 3-valve Bb-tuba from 1985, whose rotors have the infamous sticky-rotors problem described in this topic: at first the three valves have great and quiet action, but the more you play, the more the triplene rotors tend to stick because of the heat. The third rotor is not affected by this phenomenon since it is a classic "one-floor", solid-brass rotor.

I found this post describing the problem, and got in contact with Meinlschmidt to discuss the matter. (They speak English very well of course, and reply quite fast using the email address on their website. You can also call them directly by phone.). I first proposed to send them the faulty rotors and their bearing plates to have them copied, and then sent back to me to be lapped by my repairman as JB stated. However, they told me they needed the whole instrument to work with, or at least the valve section. As my repairman told me that unsoldering the whole valve section and then solder it back would be quite pricey and hard to set it up as before, not to mention the damage done to the silver plating, I decided to send them the whole tuba (really thick cardboard + acoustic foam I got at my lab). I live in France so there is not much travel, reducing the risk of accident.

I paid 200€ to send the tuba to their factory, and 200€ again to ship it back to me. The invoice was 550€ in total, here is the details written on the invoice about the operations they performed on the tuba (I also attached a screenshot of it to this message):

Manufacture new inner valves, disassemble,
clean, measure, manufacture inner valves with
measurement (incl. lubrication groove), mill
pentagon, manufacture new lower bearing caps,
lapping, ultrasonic cleaning, assemble, leak test.

A valve costed 200€ to manufacture, so 400€ in total. They did as well:

Dismantle pusher and slides, grease and
reassemble after repair.

, which costed 62€. To all this is added the VAT, about 90€.

Because of covid cases at their factory, it took them a while to perform the replacement (3 months). Actually, when I got it back there was quite a lot friction in the valves, and it appeared that they did not clean it very well, as there was very some very thin black powder (lapping compound I guess) left in the tubing. Therefore I had to take it to my repairman to clean it completely, which costed an extra 150€. I reported the issue to Meinlschmidt, to which they answered:

The instrument was in perfect condition when it left our house. Unfortunately, we cannot guarantee that the instrument will be in perfect condition if lime deposits or contaminants come out of the pipes during playing or transport.

As a gesture of goodwill, we can send you a Hydro Jet M1 cleaning hose so that you can remove any minor impurities yourself in the future.

After the thorough cleaning the valves worked perfectly though, impeccable sealing and very quiet. Maybe Meinlschmidt are just better at manufacturing than maintaining.

The new rotors are now made of solid brass (or another alloy) instead of brass + triplene, so they may be heavier, but they feel almost as fast to operate than the third valve, which is the regular one. The best choice to have an even faster response may have been to order carbon rotors, but I have no informations about their price, durability etc.

So all in all it costed 1100€ to have two valves replaced. Also, if you live outside EU it would cost much more than 200€ to send your tuba to Germany I guess. If you insist a little, maybe they will accept that you send only the faulty rotors + bearing plates to have them copied, as JB stated in its first post?

I hope this post can help someone. If you have any questions, feel free to ask! =)