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Has there ever been a 'fix' offered for the plastic/brass composite rotors on Hirsbrunner tubas? I am fully aware of the 'why' of the sticky problem. Are replacement rotors available to replace the composite ones?

Curmudgeon wrote:The official "fix" was to lap them in while slightly heated.

Brass rotors can be had. Peter has supplied them on occasion. Entire valve sets have also been supplied and swapped.

The 5th rotor on this horn has been lapped twice. Once a few years ago and again by me last week. All of the rotors cause problems once in a while but you can depend on the 5th locking up when the horn is warm. This last time... the lapping was done under warm conditions and tested with heat when I cleaned and put it back together.

Too bad Hirsbrunner used Nylon instead of Delrin or other plastic that resists moisture absorption.

I'm going to try to source some brass rotors.

Relevant thread ---> viewtopic.php?f=2&t=32122&start=0" target="_blank

Hi-
Just a FYI...some Alexander's of that period also had those same tryplen rotors...they were usually identified by having TRYPLEN stamped on the rotor bridge/bar....
Mark

Thanks for the info, guys. I'm going to take another shot at lapping this one. I just hate to keep taking material off!

bloke wrote:What about a set of rotors/casings harvested from a badly bitch-slapped (cheap to buy) jimbo model 192 knock-off ?

"cheap crap"...?? maybe, but they're not leaky...and they don't stick.

+1
Mark

bloke wrote:What about a set of rotors/casings harvested from a badly bitch-slapped (cheap to buy) jimbo model 192 knock-off ?

"cheap crap"...?? maybe, but they're not leaky...and they don't stick.

Joe... I have four REAL Miraphones and two York 'masters' on the bench right now. I don't want to piss them off by introducing foreign stuff into the shop.

Mirafones are American. Right??

Dan, I also had a problem with my Hirsbrunner's rotors but only in very hot conditions. I had to strap an ice pack to the bottom of the rotors to keep them cool in the hot conditions. It worked. I had my rotors lapped twice but it only helped a little. About 3 years ago I contacted Peter Hirsbrunner about the valve issue. I returned the valves to him and he had some shop that makes the valves for his horns make a duplicate set in brass. I had to pay for the new valves and they have been working fine. I do have to old set of valves. Would you want to try them to see if they are a good fit for your horn? I believe Mark Mordue also had new valves made for his Hirsbrunner shortly after I had mine made.

tubabill2 wrote:Dan, I also had a problem with my Hirsbrunner's rotors but only in very hot conditions. I had to strap an ice pack to the bottom of the rotors to keep them cool in the hot conditions. It worked. I had my rotors lapped twice but it only helped a little. About 3 years ago I contacted Peter Hirsbrunner about the valve issue. I returned the valves to him and he had some shop that makes the valves for his horns make a duplicate set in brass. I had to pay for the new valves and they have been working fine. I do have to old set of valves. Would you want to try them to see if they are a good fit for your horn? I believe Mark Mordue also had new valves made for his Hirsbrunner shortly after I had mine made.

Do you remember the cost?

tubabill2 wrote:
Dan, I also had a problem with my Hirsbrunner's rotors but only in very hot conditions. I had to strap an ice pack to the bottom of the rotors to keep them cool in the hot conditions. It worked. I had my rotors lapped twice but it only helped a little. About 3 years ago I contacted Peter Hirsbrunner about the valve issue. I returned the valves to him and he had some shop that makes the valves for his horns make a duplicate set in brass. I had to pay for the new valves and they have been working fine. I do have to old set of valves. Would you want to try them to see if they are a good fit for your horn? I believe Mark Mordue also had new valves made for his Hirsbrunner shortly after I had mine made.

Do you remember the cost?

+1

What is a good cost consideration in valuing a horn that has the composite rotors? In other words, would you expect to pay more or less for a model with the composite rotors?

Those troublesome rotors might not be difficult to fix. Peter Hirsbrunner recommended heating the rotors with a hair dryer and then lapping them

-F

I've played my HB-2 in direct sunlight on a 95 degree day. I've never had issues with the valves locking up. Any time they feel slightly sluggish, it's because I forgot to oil a spot.

michael_glenn wrote:I've played my HB-2 in direct sunlight on a 95 degree day. I've never had issues with the valves locking up. Any time they feel slightly sluggish, it's because I forgot to oil a spot.

I have to concur! I have never had any problem with my HB-2 (composite) valves.

Perhaps relevant to this thread, perhaps a hijack:
My Mirafone 186 BBb from 1972 has rotors that are gray. No one who has ever worked on this horn has any idea what they are, other than they have never seen anything like it. They are tightly sealed, and work terrific. They never bind, and require minimal maintenance. But, they are a battleship gray. Are these some sort of plastic? They weigh about the same as would a regular brass rotor [by feel, not on a scale] Is this a plastic coating? Or something else? I realize you would need to see and touch them to come up with a real answer, but has anyone seen something like I describe? Something carbon fiber?

Ferguson wrote:Those troublesome rotors might not be difficult to fix. Peter Hirsbrunner recommended heating the rotors with a hair dryer and then lapping them

-F

I used to have an HB6 with the Nylon Rotors and it would hang up on very hot days at the Hollywood Bowl (95 plus degrees). Al Baer hot lapped them for me (he said he used a torch) and they never hung up on me again. I was worried the rotors would be ruined but they still had good compression and were very fast after he finished the job. The playability wasn't affected at all. Al did the same lap job on his personal HB6 as well.

I had a second HB6 for a while that had replacement brass rotors and, although they fit well, the tuba did not play well since the ports were much larger than the Nylon rotors. I ordered a set of Nylon rotors from Hirsbrunner and had Kevin Powers fit them to the casings. That tuba tuba played much better, almost as good as my #1 HB6. Never any sticking problems with those valves either.

FWIW

Norm Pearson

Quit messing around with those crap European tubas and buy Chinese.

Ferguson wrote:Those troublesome rotors might not be difficult to fix. Peter Hirsbrunner recommended heating the rotors with a hair dryer and then lapping them

-F

Yes... I DID resolve the problems with the composite Hirsbrunner rotors by elevating the temperature of the entire rotor assembly to perhaps 120 degrees (or so) while lapping it. It's just a shame to have to resort to removing material from the rotors of an expensive horn.

I have an HB2. The valves were lapped under heat for the previous owner, but on 95+ degree days, they bind after a bit of playing.

My solution is to pour a few oz. of water down the mouth pipe (the mouthpiece makes a wonderful funnel). I then slosh it back and forth through the valveset while wiggling all the valves. When I'm finished I pull the tuning slide and dump the water. This takes some heat out of the system, and unbinds the valves. I can do it in under a minute.

I now do this between pieces as a preventive measure every half hour on those really hot days.

Perfect, no, but good enough.

Warming up an old thread......

To all those, that have had replaced theyr tryplen valves with brass rotors. Did the sound of the instrument change? If so, les or more overtones; more or less core to the sound?

Thanks and greetings basshorn