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Hi,

The rotary valves on my Amati helicon are leaky ...

If I pop a tuning slide off, seal off the air passage and blow, air leaks out of the top of the valves.

Is there anything I can do about this?

I realise it's not an amazing instrument, but it does a decent job - I suspect this may be a fundamental problem with this instrument. It plays OK, but I feel it's got potential ...

I'd consider dropping new valves on the instrument if I could find some cheap enough that would fit. Jinbao tubas are cheap enough ... couldn't I get a valve set on the relative cheap (nudge nudge Neptune ...)?

An Amati with Jinbao valves would be at least similar quality (if not better ... discuss ...)

It could be that your rotors just aren't seated properly. Tap on your back caps with a small wood, plastic, or leather mallet and then see if you can turn the caps a little farther on. If so... tap again, and again until they are screwed on tightly.

Report back.

Hi folks,

it's been a serviced several times, by the good folk at FH Lamberts here in the UK. That are excellent, but they haven't quite managed to sort these valves out.

I'll give them a tap (caps are on tight though).

I think there was some discussion that the valves weren't a great fit, or something like that. There seem to be so few people in the UK that have the skills who are willing to invest the time on a lower quality instrument for a reasonable price ...

So many people try the 'I don't want to do it, so I'll charge really high'.

I'm sure we've all done it as musicians, but it kind of sucks in this case.

My suggestions (in terms of what I see as affordability):

1. Sell the horn and buy another one, like this one:
viewtopic.php?f=4&t=52679" target="_blank" target="_blank

2. Have your local tech remove the valve set and send it to Anderson Plating in Indiana, US. (The shipping for just a valve set would beconsiderably less than for a whole horn). Alternatively you could have the valve set send to some one in the US, like The Village Tinker, who could inspect the valveset and then determine whether it needs re-plating or whether the damage is elsewhere.

3. You could have someone try to install a Jinbao valve set. I doubt that it would be a wise move to just buy rotors and try to drop them in the current casings. The problem with the current rotors might also be in the casing themselves or in the front or back bearings among other things. I am not sure that jinbao makes a complete valve set with branches that you could buy and just paste on the horn. The cost of having your current valve set removed, having all branches and braces removed and then pasting the whole thing back together would probably outweigh what one of these horns costs (see no. 1)

Haha, the ones on Bruce's helicon will be just as bad! Why do you think he wants to sell it?

I'm probably the 'other contacts' he mentioned when talking about gig bags ...

I'm pretty sure FH Lamberts have the skills and tool to plate up the valves, I just need to articulate to them what I need doing ...

The third valve actually moves up and down ...

PaulTkachenko wrote:.... The third valve actually moves up and down ...

That's pretty much a firm indication that the rear bearing plate is not seated properly.

Very good to know ... I suspect I need to find someone with more expertise with rotors.

Anyone know anywhere on Germany, perhaps?

As I said, FH Lamberts here certainly have the skills and equipment to do this kind of work - I'll ask them why they missed it.

Thanks for all this - very handy.

The rear plate sits in a notch on the rear inside of the casing. It has two bearing surfaces, the round bushing for the rear shaft, and the face bearing for downward thrust. The shaft bearing on the front side is likewise. If the valve is tight "top to bottom" (or, in to out if you grasp the stop arm and push and pull), but the valve rattles, then it's the round bushings that are worn. They can shrink the bushing on the casing using a swaging tool.

If the valve rattles in and out, but not side to side, then the face surfaces have worn and the rear plate needs to be seated more deeply in the case. This can be done by turning it down just a bit along the inside edge so that it will press into the casing a bit further. That's a lot easier than turning the notch in the casing deeper. This should be an easy repair for a shop, I would think.

The screw-on rear cap is just a dust cover. It does not hold anything in place. Miraphones sometimes have little screw-in pins for fine adjustment in the thrust direction, but that pin does not a face bearing make. If the rear bearing plate will not stay tight in the casing, then it needs to be replaced. These are fairly simple things to machine from scratch on a lathe if necessary. It will then require a lot of honing to fit, but that should not be foreign to any competent shop. But you may need to bring your checkbook.

My worn rotary valves tend to the side-to-side sort of wear more than the in-and-out wear, but it somewhat depends on the linkage geometry.

There should be no wear on the face of the valve, or at least not much. In a properly fitted rotary valve, it does not actually touch the casing. The seal is made with a film of oil and moisture.

Rick "not seeing any occasion to want to plate a rotary valve" Denney

Hey Paul - when I lived in London, I found an excellent repairman named Luke Woodhead at Paxman's near Waterloo - although they are horn specialists he was willing to work on my tubas. Luke has now got his own operation:

http://www.woodheadhornrepair.co.uk/" target="_blank

I would definitely recommend running your Amati up to him as he is a rotary valve specialist as well as being a very honest and talented repairman.

Best,

Alex Kidston

Hold on here....

I just noticed something, thanks to the Resident Genius.

Plate the rotors?

NO! NO!

Well, unless you want to totally bugger the instrument. First off, I hope the shop would laugh at you for asking that.

But, that's not how they work. At all. They aren't pistons.

Hi,

well worth knowing.

Mainly due to the price, I'm going to give Lamberts one more go.

Looks like they would do a killer job up in Ampthill ... that may well be my next port of call.

This is all gold dust - thanks.

My only experience with rotors is on high end instruments and they just 'work'!
I've yet to have the discussion with Lamberts - now I'm considerably more informed.

Plating rotors is sometimes required but that is typically reserved for valves that have been excessively worn from years of playing with improper fit and /or worn bearings at both spindles and thrust bearings and is nothing like plating and resizing a piston valve. The big problem being the body or ported section of the rotor and the inside of the casing have been worn out or round and leaks between the ports. This is a very involved process that few shops can undertake unless they have a good understanding of what is involved and have proper plating and machining facilities at there disposal. Unless other problems exist, your horn would most probably require just a rotor-bearing refit; Swaging of spindle bearings after removal of lateral play by recessing the back bearing a bit to eliminate the hop. Not super difficult but its not a process that most shops are really up on.


Daniel C. Oberloh
Oberloh Woodwind and Brass Works
http://www.oberloh.com" target="_blank

So ... reply:

'Sorry for the late reply been really busy in the spray booth, I’ve had a word with a fellow repairer who had a similar problem with an instrument, we nickel plated the valves and then he honed them back and it sorted the problem out. When we took apart the first valve last week, I pulled the slides out and then pushed them back in to see if there was compression... upon doing so we could hear the air rushing over the valve and out of the first casing. The bearing plate is seated down on the valve casing but it is loose and would need tightening up hence the reason why it moves up and down, we can fix this either with a bearing cap compression tool (which we do not have and I would need to ask around to see if I could borrow one) or to nickel or copper plate it to fit and then hone the bearing true. The valves will need nickel plating as well and then honed back in to improve overall compression. We fitted a oversized silicone bung into the casings and then pulled the slides out and then pushed them back in to check for compression and they ‘popped’ very well which indicates that it is a valve problem. Please let me know what you want to do if you need it pretty quick.'

I'm going to take it in on Thursday. These guys have a really great 'we can do it' vibe and the price is very come competitive.

Obviously, not seeing the tuba is tricky, but any comments welcome.

Hey Paul

Another possible repairer who may be able to help.......

http://roycoxbrassrepairs.com/page1.html

Roy has done wonders with my instruments & is also Paxman trained. He used my helicon as a test bed to get to grips with dent magnets & did a superb job on it. He's an extremely affable guy & would be worth a call to discuss your problem/possible solution. I can totally recommend him as a good man & brilliant brass technician!

Best of luck with getting your horn back on it's feet.

Russ

Thanks for this ... top tip.

The tuba is now at Lamberts ... I have great faith in them - they know what they are doing.

Well, I got the helicon back yesterday. It's (obviously) much better now it isn't leaking.

I also had the lead pipe extended so that the mouthpiece sits better in relation to my mouth. This had a dual function as the horn always blew pretty sharp (so I pulled the main slide out quite a bit).

Well, I've yet to gig the thing (that's tomorrow), but my ear and a tuner say it's in tune at A=440. Sounds perfect, except that the ma in tuning slide is all the way in.

Should I have it shortened there, now that the leadpipe is in a good position?