8’ bridges

Instrument Building
1

I am referring to French and Flemish style of 8’ bridges. Is there a consensus on how they were made 300 years ago? I mean: bent or sawn? (I am speaking of the treble portion, not the bass “hook”).
I have perused the archives, here and on the defunct hpschd-l list, and on the latter I found a couple discussions with no definitive response as the participants did only write about their own techniques and preferences with no reference to historical harpsichords. All of them but one preferred bent bridges vs sawn bridges.
As for historic records, I have found the following:

  • of course those bridges were all sawn (Martin Skowroneck, who was still alive, reported by his son Tilman).
  • of course those bridges were all bent (various listers).
  • of course most of them were bent but the parisians makers sawed them (William Jurgenson).
  • sure those bridges were all sawn, French and Flemish (Augusto Bonza, curator of Castello Sforzesco music instruments museum in Milan, in a couple private conversations).

So I am confused and am asking specifically: is there any knowledge on how the 8’ bridges were made, bent or sawn? (4’ bridges don’t need to be sawn or pre-bent as they are thin enough to be bent by hand while gluing on the soundboard, so they pose no problems)

2

Not really, You’d have to go to every museum and look.

Does it make any difference to anything in terms of final result?

Some bridges are scarfed.

3

I don’t think there is any difference in final result but there is in how fast and how simple is the work! :slight_smile:
However a few possible difference were mentioned:

  1. (sawn) If the soundboard cracks in the treble, the bridge could crack as well, due to its short grain (theoretically possible, but how frequent?).

  2. (bent) If the bridge is pre-bent a little less than its final shape, and then hand-forced in position, its spring-back force would counteract stringband force, effectively diminishing bridge rollover and improving soundboard flatness (there was a consensus on this, our own @owendaly among them. Again, a theretically acceptable hypothesis, but is there any real difference?)

Dom (who hates making Franco-flemish bridges and hates gluing them to the soundboard)

4

You need to build a go-bar deck. Then you will smile.

5

I have made one years ago and it works well. Still I struggle working fast enough while the (hide) glue is still warm and to have the bridge solidly in contact with the soundboard along its entire lenght. Last time I had to unglue and re-glue. The previous time it went much better but still not entirely satisfactory, no major failure but if you looked with a magnifying less you’d notice a couple spots where the bridge makes no contact to the soundboard. 4 mm and 6 mm long, both visible only from the bentside - not from the spine - so probably the no-contact surface does not go very far under the bridge. Still it’s disturbing.

Back to the bent-sawn bridges. At least in Ruckers they were sawn. Grant O’Brien writes im hos Ruckers book:
“[…] the 4’ bridge is made by a straight piece of wood which is bent and held in its bent shape solely by the glie and by the nails driven into it from underneath the soundboard. However, because of the thickness of the wood in the 8’ bridge and the sharp curvature of the bass end of the bridge, the 8’ bridge is sawn from the plank and not bent.“

I guess this is accurate. Augusto Bonza, whom I quoted in my first post, had studied and worked with GOB, so if GOB information is wrong, he could have inherited it. However, it’s consistent with both Martin Skowroneck’s statement (“all of them were sawn”) and with William Jurgenson’s (“bent, but the Parisians sawed them”). Parisians knew Ruckers harpsichords, “ravalé” them, purchased and sold them with or without a fake nameboard, so it makes sense they sawed their bridges just like the Ruckers.

6

As for gluing with hide glue, in the discussion about bridges I found a suggestion I am going to follow: to size the soundboard (with diluted hide glue) before putting any bridge or rib on (I used to size the whole only after having glued bridges etc.) This would simplify the gluing of the bridge.
Indeed I have learned that the trusted standard way of using hide glue is to pre-size every surface going to be glued. I had no occasion of trying this newly-learned technique to bridges, but I’ll do.

7

Well, I’m not sure if anybody can be interested in my amateurish endeavours, but I’ll trll you I decided to go for a bent bridge as opposed to a bridge sawn from a plank.

I started with a board 7 cm wide, i.e. about the height of three bridges, and 20 mm thick, i.e. a bridge’s width. Imagine three bridges one atop of the other. This way it’s easy to bend without twisting.
I bend by heat, provided by a curved iron form you can see in the pictures.
First, my wooden board (beech) is planed to get a taper from 15 to 20 millimeters thickness, 15 mm at the treblemost end, 20 mm at the bass end. This size leaves a bit of fat to be trimmed.

Then the board goes on my bending

IMG_8467
IMG_84673024×4032 2.26 MB

IMG_8468
IMG_84683024×4032 1.19 MB

IMG_8465
IMG_84653024×4032 1.42 MB

Inside the form there is a grill resistance which provides the heat.

This form I have copied by renowned makers. Bill Jurgenson has one very similar, and Darryl Martin portraits another one, again very similar to mine, in his book “The art of making a harpsichord”. And this design is used by this harpsichord maker: https://youtu.be/gsiNSEAew2o?si=kxwhQC-m_S2mXJ0G (minute 2:50). So, it’s not my design. I had it made for me by a blacksmith as I have no soldering tools nor am I able to solder.

I love bending wood by heat: very easy, very fast, the bent wood is immediately usable and stable.

IMG_8470
IMG_84703024×4032 3.44 MB

I am not quite home yet. Please note the “bridge” is still a three-bridges high batten. I’ll saw it in three parts after bending.

IMG_8471
IMG_84713024×4032 2.96 MB

I am almost done.

IMG_8473
IMG_84733024×4032 3.09 MB

I’ll stop here, I’ll force-bend that last centimeters while gluing down.

Now I will have to saw the batten length-wise and then I’ll give the bridge blank the usual tapered trapezoidal form.

All the procedure, after the initial planing, took me exactly 40 minutes from the turning on the grill to the switching off. In the meanwhile I stopped several times to take the photos and to check if the bend was similar enough to the drawing.

I think I prefer bending to sawing. The surface is smoother and there is no short-grain in the curve, resulting in a stronger bridge.

8

Bravo!

David

9

I think you point out something that is very important. Most harpsichord makers worked in a shop where there was help. The idea of the individual maker doing everything is a modern phenomenon. Kevin Fryer has had some recent posts on Facebook where he gets a bunch of friends together to all together do things like you are talking about or gluing in a soundboard.

So perhaps you need to enlist your friends! Teach them in a runthrough what needs to be done. Make a dry run or two so everyone knows what they are doing in the process. Then go for it! And treat them all to wine and food afterwards!

10

There’s nothing amateurish about this rig and your work @domenico.statuto !