Mainstock ferrule and cup taper

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SeamusRua
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Mainstock ferrule and cup taper

Post by SeamusRua » Mon May 09, 2016 8:24 pm

I'm looking into rolling ferrules from sheet and am wondering about the mainstock cup and ferrule. On some 19th century examples it appears, though it's quite hard to be sure, that the ferrule is tapered just like the drone slides. On the other hand, I really can't find decent enough pictures or data on the cups to see if they are tapered. Would tapering of these components be standard on sets from the 19th century makers such as Coyne, Kenna, Egan, and Harrington?

The only measurements I have on these components are from the Hannan Coyne and O'Hannigan Coyne plans from NPU and from the Kenna C set on the Sean Reid Society webpage. The Kenna is the only one which provides a clear answer, giving two differing measurements on either end of the ferrule, showing a taper of about 1/100 which was suggested by Geoff Wooff in his article on rolling ferrules. This rate of taper is very close to what is displayed on the Hannan Coyne drone slides as well as the Kenna. The O'Hannigan drawings don't provide measurements to indicate a taper on either the drone slides or the mainstock ferrule. Would these truly not have been tapered? The Hannan mainstock is of course known to be a replacement and does not have tapered ferrules.

Photos on NPU's source section have proved to be difficult to glean information from, as the tapers are normally so slight. However the Séamus Ó Rocháin Coyne set's mainstock ferrule appears to have a tapered ferrule. Gay Mckeon's Coyne as well as the NPU Coyne set look like they may have a taper to their ferrules, however the shots provided for these make it hard to say for sure. There are also pictures of Geoff Wooff sets elsewhere which also appear to have this feature.

So, all that being said, would tapered ferrules be common for sets of this era? Would the cups also have been tapered(sloping the opposite way)? Would tapering these pieces offer any distinct advantages over using straight tubes? Maybe this would have to do with the design of the hollow chamber, or with the alignment of the bass regulator, or be purely aesthetic?

Séamus

billh
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Re: Mainstock ferrule and cup taper

Post by billh » Thu May 12, 2016 11:09 am

Anyone who has rolled a few ferrules can tell you that it's easier to roll a tapered ferrule. Fitting a few will also convince a person that a tapered ferrule makes it easier to achieve and maintain a tight fit to the stock and binding, whether bound purely with thread, or thread plus shellac. So there are practical issues that become obvious with a bit of experience, aesthetic considerations aside. I do think they look better, too.

Modern seamless tubing of that diameter tends to be quite thick walled, so there is weight to consider as well.

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Re: Mainstock ferrule and cup taper

Post by billh » Thu May 12, 2016 6:14 pm

I should add, to comment on the stock cup, that most of the surviving examples of mid-19th century stock cups which I've seen have been made of horn. They didn't seem to be tapered, but I don't know of anyone making horn stock cups today.

The timber or metal cups which I've encountered have seemed to be replacements, though it's sometimes hard to be sure. A tapered socket in the cup may offer some advantages to fitting, but the risk of the socket "letting go" suddenly seem high to me. I think in that case a cylindrical inner socket bore gives more warning when things are getting loose.

It was certainly common to see a slight taper in the outside diameter of the timber section of a 19th century stock, for instance those of Kenna and Harrington, and sometimes Coyne... Less so Egan. Tapered stocks seem less common in later makers' work.

SeamusRua
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Re: Mainstock ferrule and cup taper

Post by SeamusRua » Mon May 23, 2016 5:35 pm

On a related note, when bass regulator bars are curved slightly to splay out nicely, especially when fit to a tapered stock, how does this work with the wooden insert inside the metal tube? Geoff Wooff briefly touched on this in the video where he talks about his Harrington set but I'm still not exactly sure what he meant and exactly how this works.

chris bayley
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Re: Mainstock ferrule and cup taper

Post by chris bayley » Mon May 23, 2016 11:49 pm

The bass bar/separator section is a straight metal tube so no problem fitting the internal wooden part. The fold/bend is done on the metal tube connecting the Separator section to the keyed section and was the preferred method of the old masters and some of the modern ones. By doing this the Bass regulator keyed section is closer to the Baritone regulator. If you go for the wooden Tenon connection then this is not possible and Bass regulator can have a larger than ideal gap from the baritone regulator
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billh
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Re: Mainstock ferrule and cup taper

Post by billh » Tue May 24, 2016 2:58 am

Actually the splayed 'dog leg' bass regulator can be done with the wooden tenon method - since less than a degree is generally required. It requires bending the regulator tube with two mandrels, but I have done it with good results. The resulting kink in the bass bar was/is very hard to spot, and the tenon fit and seal were fine. It does require a subtle mitering of the keyed section's tenon to eliminate the resulting gap (small as it is).

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Re: Mainstock ferrule and cup taper

Post by wooff » Tue May 24, 2016 6:36 am

Taking a look at the angle between the upper and lower bass regulator sections on my Harrington set and a new set I am making , I have measured the off set from straight at about 2.5° on both instruments.

This has been achieved on the Harrington, I think, by bending the connection tube whereas my method is to glue the 'straight' connection tube into the upper wooden section at an angle. The reason I do it this way is because the metal connection tubes I make are tapered on the inside but not on the outside... these being rolled from a heavy gage sheet and it is eaiser to control without putting a kink in it. As Bill says there then has to be a slight mitre on something to fill the gap and I do this on the decorative mount between the upper and lower sections of the regulator.

The other problem I have with Bill's idea to put a kink in the upper section cover tube and use the tennon-in method of joining is because I also roll a tapered tube for the cover tube ,so I would need to redesign the whole thing to provide a parallel socket.

The reason why I come up with a far greater angle of offset is because all the ports in the mainstock are drilled to 'splay' the pipes, perhaps 1 or 1.5° out from the axis... so, combining this with the external taper of the mainstock which brings the upper end of the keyed section of the bass regulator closer to the middle regulator it needs more angle so as to lay nicely alongside its splayed neighbour.

Whilst we are on the Mainstock; I not only drill the ports at a slight splay but also taper those holes very slightly outwards (larger diameter at the outside end) because wood will shrink and the effect of moisture leaving the end grain of the stock will often be responsible for making those holes smaller at the outside edge than further in.Poor drilling technique can also have the drill bit wandering off centre and making the hole larger the further in the bit goes. The effect of this 'tight edged' hole is to make it virtually impossible to achieve a good joint between the drones and the stock.... a wobbly /leaky joint is not desirable... and I have seen plenty like it!

Geoff.

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Re: Mainstock ferrule and cup taper

Post by billh » Tue May 24, 2016 10:50 am

Thanks for weighing in, Geoff.

I confess to having guessed when I said less than one degree in the bass reg bend. It could have been more,
I didn't measure it. It's also true that my regs had a bit less splay than yours. My main goal was to reduce the gap between bass and baritone regs, using a tapered mainstock, and it seemed to accomplish that ok.

I am currently rolling a straight bass regulator bar, when I roll it (I have been known to use 3/4" tubing, when working with brass). Getting a rolled cylindrical tube off the mandrel can be a bit of a pain.

I take your point about the tapered drone sockets, it seems like a good idea.

chris bayley
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Re: Mainstock ferrule and cup taper

Post by chris bayley » Tue May 24, 2016 3:31 pm

To illustrate here are some photographs and a brief description of my method which is slightly different to Geoff's - it is still in the rough and wrappings are temporary just to allow assembly and checking angle

I tend to make up parts in batches so have a number of the connector tubes to hand. Photo below shows the keyed part and separator sections together with the connector tube and two further ones on end to show that inside is tapered and outside is parallel. A very thin saw cut is made around 3.4 the way through which is carefully tapered out to allow the tube to be folded and soldered to the desired angle which in this case is between 2.5 to 3 degrees.

Image

End on view with connecting tube installed - note the cavity formed by the bead on the separator which serves to hide the join as the angular connection does not allow a good butt up between the two parts

Image

Assembled

Image
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SeamusRua
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Re: Mainstock ferrule and cup taper

Post by SeamusRua » Tue May 24, 2016 8:18 pm

Thanks for such detailed explanations.

One other thing: When making a tapered hollow mainstock would it be best to use a boring bar to cut a tapered bore on the inside, in order to keep a uniform wall thickness, or is this unnecessary and a parallel bore could be used?

wooff
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Re: Mainstock ferrule and cup taper

Post by wooff » Wed May 25, 2016 1:00 am

billh wrote:


I am currently rolling a straight bass regulator bar, when I roll it (I have been known to use 3/4" tubing, when working with brass). Getting a rolled cylindrical tube off the mandrel can be a bit of a pain.

Agreed! Perhaps this is the main reason why Harrington made the seperator tube tapered. it certainly is why I do it. Not to say that making a rolled seperator tube, which can get to nearly 15" long on a Bb set, is at all an easy job. When it is conical the practicality of drawing it up to size and roundness, on the mandrel is more controlable. This is true for all ferrules.

On SeamusRua's original point ; the mainstock ferrule taper I use is 20 thou. per inch ( 1 in 50)... on the Cup I use a parallel ferrule.

On your latest point SeamusR; the wall thickness of the hollow stock has some bearing on the sound emmitted by the slapping of the drone reed tongues. Whilst a gentle ticking is pleasant and can add nicely to the overal sound of drones, too much of this can become annoying. The hissing of a Tennor drone reed might not be too pleasant for the player. This can depend on the type of wood used for the stock and whether a bass regulator is screwed to it. Generally a parallel sided cavity is seen in Classic period sets.


PS: regarding things like tapered stock ferrules and regulator seperators, splay angle Bass regs. etc.... reviewing my drawings of sets from the Classic makers I do not find these features in the work of the other makers before or after the Famine and not all of these things were done by Harrington either. That I do them is because of the encouragement and suggestions created in my head from a long study of this particular Harrington set which I think of as the last flowering of the golden age, made at a time when the full effects of the Famine were devastating the musical life in Ireland. So it would appear that the set went off Gold prospecting... possibly sold for a 'grub stake' in Australia and, like Bilbo's ring, knowledge of it was lost untill its timely discovery in the early days of the current traditional music renaisance .

SeamusRua
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Re: Mainstock ferrule and cup taper

Post by SeamusRua » Thu May 26, 2016 7:56 pm

Alright. So the slight change in wall thickness may actually help to produce a steady hum rather than distinct ticking.

Thanks

wooff
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Re: Mainstock ferrule and cup taper

Post by wooff » Fri May 27, 2016 12:42 am

SeamusRua wrote:Alright. So the slight change in wall thickness may actually help to produce a steady hum rather than distinct ticking.

Thanks

A wee bit of ticking is pleasant, preferably coming from the Bass or Baritone reed , but the overall effect depends on several factors; type of wood, thickness of wall, presence of bass regulator and drone reed material. Though I'm not sure that the "slight change in wall thickness" will help anything. I'm imagining someone scraping away at their hollow stock ,like a violin maker, thinning the walls untill the tone quality of the drones sound best..... I doubt that would be practical.

good luck,
Geoff.

SeamusRua
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Re: Mainstock ferrule and cup taper

Post by SeamusRua » Fri May 27, 2016 1:18 pm

Thanks Geoff

Let me just say that it's very encouraging hearing from all three of you

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