Violin “purfling”

[Quickstep192]

I’m hoping to build an archtop guitar one day and I’ve been thinking about details. Today, I was looking at an upright bass and while I was thinking about the similarity to an arch top guitar, noticed that the top on the bass and violins overhangs the sides and is rounded. There’s also a narrow inlay inside that overhang.

I’m wondering how these are both done and if there’s a reason we don’t see this on guitars. Anybody know?

[mirwa]

Traditionaly the purfling is there to reinforce the edge from splitting, its done with a scraper thats offset from the edge, can take a photo of mine tomoz if you want

Steve

[Cincy2]

Originally Posted by Quickstep192

I’m hoping to build an archtop guitar one day and I’ve been thinking about details. Today, I was looking at an upright bass and while I was thinking about the similarity to an arch top guitar, noticed that the top on the bass and violins overhangs the sides and is rounded. There’s also a narrow inlay inside that overhang.

I’m wondering how these are both done and if there’s a reason we don’t see this on guitars. Anybody know?

It takes a lot of carving on the binding. Steve Holst did this for me on an archtop he is building to my specs. See photo. The double line inside the binding is done using a special tool. Violin makers use them also.

Cincy

[charles Tauber]

As Cincy points out, there are a few arch top makers who have used overhanging top and back plates with purfling, violin-family style.

Channels are cut with a purfling cutter.

I have not played one, but I'd expect the "lip" created by the overhanging top plate would be unpleasant to rest one's arm upon. This isn't done while playing violin-family instruments. The overhanging lip of a softwood top won't provide much protection against bumps, one of the reasons for using hardwood bindings.

On the up-side, it makes removing tops or backs much easier.

But for the neck and fingerboard, making an arch top is a different animal than a "flat" top and involves different skills and some different tools.

[JonWint]

https://www.internationalviolin.com/...ls-router-bits

[Howard Klepper]

We don't see it because:

Violin and viol family instruments are intended to be easily taken apart for repair by removing the top and back. It's very easy to slip a knife into the glue joint on a fiddle. Guitars are designed not to come apart.

Guitars have binding to strengthen the joint of the sides to the top and back, and protect against injury. Violin/viol family instruments are easily chipped and separated when bonked on their edges.

Guitarists rest their arms on the edge of the instrument (as Charles said) and also rest the instrument on their upper leg. The overhanging edge would be uncomfortable.

The purfling channel on a fiddle is cut with a gramil--not a scraper.

[Alan Carruth]

One way to make it easier to disassemble an archtop guitar is to have the binding the same depth as the edge of the top. If the glue line at the lower edge of the binding is the same height as the joint between the top and the liner it can be relatively easy to remove the top.

There's also no real need to have an overhang when you use violin style purfling. On a violin the center line of the purfling channel is supposed to be just over the inside edge of the sides; in line with the joint between the liner and the side.Violins use a relatively narrow liner; a couple of millimeters wide on the top/back surface. If you put the purfling line in too far you'd be in past the inside of the liner. The top is about 3 mm there, and the purfling goes down to within 1.5 mm of the lower surface. With no wood inside of the purfling channel that would make the top edge very weak. As it is, the purfling line acts as a sort of stiff hinge out at the edge of the fiddle: it's more flexible that it would be without the purfling, but does have some stiffness. This affects the sound.

With a guitar using 'normal' linings, say 1/4" wide on the top edge, you could move the purfling line in from the edge a good way without making the top edge too flexible. Many archtops use a lot of B/W lines around the top edge which takes the purfling in nearer to the inside edge of the liner, and may well have a similar acoustic effect to violin purfling. At any rate, a simple B/W/B purfling line could be set in from the edge far enough to allow it to be trimmed even with the sides.

With the pufling line moved in, you'd have enough space on the edge to do a 'half binding', such as was common on lutes. A narrow piece of hardwood veneer was inlaid around the edge to about half the depth of the thickness of the top. This is enough to protect the edge against some wear and tear, especially where the arm and hands rub on it. If you look at the end of the top you can see the end gain of the top wood below the half binding.

In short:
a) there are reasons behind tradition, and
b) all of these issues have been dealt with at one time or another.

[mirwa]

Originally Posted by Howard Klepper

The purfling channel on a fiddle is cut with a gramil--not a scraper.

Well what do you know, I must have been doing it wrong these last 20 odd years, lucky my customers never realised .

[Howard Klepper]

[QUOTE=mirwa;6144017]Well what do you know, I must have been doing it wrong these last 20 odd years, lucky my customers never realised .

Clearly you are being sarcastic. Yet I wonder if we are not just disagreeing about the name of a tool. Please show your "scraper" that cuts a 2mm or so dado. If you wish I will find photos of the tools for cutting the purfling channel shown on violinmaker supply sites that are called gramils.

[mirwa]

Originally Posted by Howard Klepper

If you wish I will find photos of the tools for cutting the purfling channel shown on violinmaker supply sites that are called gramils.

So, let me clarify, your not referencing the tool you use as you do not cut them, but are referencing something you have read on a website

I only commented as you corrected me with they are not done with a scraper, yet clearly they are done that way, as I do it that way, many other ways to do it as well including a gramil and a router and a purfling cutter etc etc.

Originally Posted by mirwa

done with a scraper thats offset from the edge, can take a photo of mine tomoz if you want

Originally Posted by Howard Klepper

The purfling channel on a fiddle is cut with a gramil--not a scraper.

Steve

[Howard Klepper]

Originally Posted by mirwa

So, let me clarify, your not referencing the tool you use as you do not cut them, but are referencing something you have read on a website

I only commented as you corrected me with they are not done with a scraper, yet clearly they are done that way, as I do it that way, many other ways to do it as well including a gramil and a router and a purfling cutter etc etc.






Steve

So no photo of your tool? You concede that a gramil is used for this job. Apparrently it can also be scraped, in which case I said something wrong. That has actually happened before. I would venture that a gramil is more commonly used than a scraper--at least from what I have seen it is. I can picture using an offset scraper, but I cannot picture how this would avoid excessive tear-out on spruce. I'd like to see how that could work, but I can live perfectly well without it.

Steve, I am trying to keep this exchange polite and informative. I am not a violin maker, but I have known several and pay attention to what tools they use. I never saw the channel being scraped. I only have seen a gramil used, and only seen a gramil offered by suppliers, or described in books. I think talking with and watching violin makers, reading books, and looking at violin tools, is a valid source of knowledge. You seem to be saying that I am disqualified from offering that by not being a violin maker, and thus not worthy of seeing your scraper.

I myself try to avoid pulling rank (e.g., "I've built more for a longer time than you, so I am right and need not talk with you about it") as a means of convincing othrs, since it is not what really makes one person right or another wrong, and smacks of an elitism I find distasteful. I come here to offer what I know, and learn what others know. If you are among those who view this forum as a place to win contests of one-upmanship we have nothing more to discuss. I'll regret that, for a few minutes.

[redir]

I think arch tops with the violin type top look very cool. I'm not sure it would bother me resting on my leg or on my forearm but I have never tried one either. I king of rest the corner edge binding of the guitar on my lap leaning it back to my chest anyway so it's sort of like the same knife edge. A strap of course would solve that problem too.

I do wonder what purflings have to do with tone too. I am building one now that has very wide purfs. the top is only about 3/32nd inch and the purf channel is almost as wide as the binding leaving behind about 1/32nd of top wood to rest on. Seems to me that weakens the top and maybe even makes it more responsive... I know it's different in this case but just thinking out loud.

[Alan Carruth]

I've been making fiddles since 1980 or so, and I've never seen or heard of a scraper used to cut the purfling channel either. There are several different tools that can be used, and the traditional gramil is not my favorite. I agree that it's hard to see how a scraper could be used here, unless it's a part of something like a traditional rabbeting plane, with marking knives and a blade that removes the material in between. It would be nice to see a picture of that tool so that we can understand it better.

[mirwa]

Originally Posted by Howard Klepper

So no photo of your tool? You concede that a gramil is used for this job..............................I myself try to avoid pulling rank (e.g., "I've built more for

All good, totally okay, my initial comment was only as rebut to a point you made a scraper is not used.

So its Saturday, I will show you my journey to take this tool photo for you

Hello from Australia

Leaving home




Steve

[mirwa]

Stopping for coffee