Saturday, April 28, 2012

Bass Horn Part 7


I didn't buy the right wood. I should have spent the money on actual timber, instead of the particle board. But it was cheap and I still have a 6' x 4' piece (cut into 2x2).

Anyway, bending the crooks was interesting.

The first valve crook took me about 4 hours in order to make it look right, it still isn't right and I have no desire to fill it with Cerrobend again, Dan thinks I should be able to slightly bend the tubing with a drumstick or mandrel. It's off by like three millimeters from parallel, it won't run inside the slide as smooth as needed.

The third slide was bit more involved but took less time as I had some practice bending the right curves. plus I had to make another tool and had to screw down more board to support the tube during the bending process.

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I didn't think I could bend the tubing in a close enough curve (2.5 inches) without using an entire 30" tube (I have 6 left for the leadpipe/main-slide and the fourth valve), so I only bend the outer portion and used parts from my huge euphonium to complete the inner curve.

Oh, and I had little accident in filling a tube - didn't hold on to the cork...

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Friday, I spent the day making ferrules and tacking the body together. I may need to flip the valves after-all...

Here are some pictures:

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Tuesday, April 24, 2012

Bass Horn Part 6

Working on the valve block today didn't go quite as planned. I had hoped that the valve caps could be on top like they are on the French horn, but with the paddles flipped and the relatively short paddles, I couldn't fit the tubing around where needed, but most importantly get the correct height for the linkage to move freely.

I'm sure if I had more time I could machine a solid rise to sit between the two supports and the linkage bar, but trying to shim the two spots and still not achieving the right height was leading to more headaches than necessary. The work-around was to flip the section back over like you would find on a tuba... Sure you can still have access to the rotors for maintenance, but it loses some of it's Professional-Quality-Appeal. This does move the valves down and up a little, and should give me enough clearance to still depress the paddles. It should, if I wanted to and had better skills in the future, allow me to flip the valve section over again and use a new linkage set - maybe even strings!

I also filled the first branch after the valves with Cerrobend and bent the end toward the valve block. In draining the oil from the tube before filling with Cerrobend, I noticed a small crack in the seam. It's a little worrisome as this might lead to more crack, but it's in such a spot that I can cover it with a brace. Found a ferrule to fit the tube that I had torn through (old stupid mistake...) and made a ferrule for the two new inner branches. Then I cut the ends of the new inner branches and fit them together, then cut the first branch connecting to the valve section to the proper length to bring the tubing around as it should.

The current total estimate length, through the valves, leadpipe, two branches, body, throat and part of the bell (maybe) is around 178.5", this leaves me with about 37.5" to add between the leadpipe and the to inner branches. This is where it gets tricky....

I need to add the main tuning slide, but leave enough room to either cut tubing out to adjust the pitch up, or add a longer tuning slide to adjust the pitch down. This of course means I need to figure out the bell situation...

At the moment, the bell is in two parts. I have a throat from a euphonium/baritone bell, it fits the body collar perfectly and is just about the right length to fit with the design. The bell is the flare from the mini sousaphone - 19", again a near perfect fit for the design. The only problem is that the tapers of the two are different, meaning that I either have to make a new throat and mate it to the bell, or add a right of brass around the section where the two ends meet. The former would involve serious brazing and cutting tabs to join the main throat and then more tabs to join the ends with the bell - possibly more trimming of the bell inner throat. The latter would probably involve less work, but would look much worse (in my head). Of course if I could find a small 5.25" sousaphone collar, I could have a removable bell.

This is the next goal, although I could always start on bending the first and third crooks.

Of the parts I still need:
Braces (I should have the right ones)
Possible second valve crook from a King tuba/sousaphone
Possible trigger mechanism for the main slide and a thumb lever
Some other things I might think up...

Finish-wise, I buffed the leadpipe, though it has been drained of pitch as I still might need to bend it more or bend it back. When I'm done with it, I'd like to get it bead-blasted with bright trim and then a coat of lacquer, but that's just wishful thinking at the moment.

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Sunday, April 22, 2012

Updates all around!


Lots of progress made on the Bass Horn. My tubing showed up sometime in March and I purchased some Cerrobend - then found the paint can full of pitch.... Bought a pitcher, thermometer, pan, and electric hot plate to melt the Cerrobend. Also bought some wood and made the big jig and some drawings of the approximate sizes for the valve crooks.

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In bending the tubing, I had to first fill each pipe with vegetable oil, drain it and then fill it with Cerrobend. Then let it sit in a cold bath for 30 minutes, before bending it into the curves I needed.

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The first part didn't go to well, I over-annealed on 30+" tube and burnt two holes in it.... ugh.... Second and third try were much better, the the second tube suffered a kink during the bending process. So I had to hammer out the marks and then will have to sand the hammer marks off before buffing and assembly.

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The next issue I ran into, was that I couldn't get the ends to be as curved as I wanted. I have a 17" circle by which I'm bending the tubing, but because I have about a 1/2 inch or so where I plugged the ends, I couldn't get the extra bit to be as curved. The solution was to take a smaller diameter circle and bend the ends around that. This helped especially for the tube leading into the valve section and will help when I bend the branch after the valve section (so that it meets up with the fourth valve).

I also bent the leadpipe and cut the end to match the receiver. Just need to buff it and burn out the pitch, then buff again...

On Friday, I got two of the inner bows in relative positions, although I may need to refill them in order to get the exact position... Not much time left. Still need to address the bell and the paddles for the valves.... OH and bend ALL THAT OTHER TUBING, though I might not have enough for the fourth valve if I screw up another 30+" tube. AND I need to find braces!

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Finally, I'm almost done with my King Jumbo econo-overhaul. Just need to solder on the last two guard wires and do a final buff/polish/cleanup. I've buffed the bell with rouge two weeks ago, even got inside the back of the bell! I think there's some gold plating left back there. The body should look just as nice once I get around to polishing.

Before and After (almost)