Archtop #5: Bridge

Over the years, I’ve given a great deal of thought to my bridge’s design and, looking back, at my early mandolins, the design has evolved considerably. So, here is the current incarnation.

The ebony blank is roughly fitted to the top plate: by marking out the curve on the base of the bridge from the templates used to carve the top plate it can be done quite quickly and accurately.

Then the slot for the saddle is routed. This allows the saddle to be fitted and by using a simple jig, the bridge’s location can be accurately found.

Then the base of the bridge can be sanded to fit the top plate perfectly and then worked to its final shape.

There is always a tendency for this type of bridge to tip towards the fretboard, so to compensate for that, I now make my bridges a tad wider at the base and set the saddle slot a few mil back. Also, at this stage the saddle is roughly shaped for intonation compensation and slots cut for the strings. The final refinement of the saddle is done once the mandolin is strung up.

Here’s the bridge, you can see that I scallop out the front of the bridge; this is to remove some of its extra mass which is gained by making the base wider. Also, I like to have “feet” on my bridges rather than continuous contact. The feet are directly over the top plate’s tone bars.

Make the nut and then………………..

Archtop #5: Neck Shape

The mandolin’s neck has been shaped and I think we’re now beyond the ugly ducking stage that I mentioned a while back!

Here’s a video showing my approach to the neck shaping process. I must admit, it does take me quite a long time to do and is best described as an iterative process: going back, again and again, continually refining until the desired profile is reached.

Archtop #5: Fretboard

The carbon fibre’s epoxied in and then the fretboard glued on.

I always sand the fretboard flat and then sand the compound radius (the white pencil marks act as a quick visual guide when checking progress). I was taught that a craftsman should always use edge tools and that sanding or filing was somehow a substandard practise. But when you’re working to very tight tolerances, on an unforgiving species of wood and seeking a perfect surface, abrasives are the best solution!

With the fretboard finished, the dots (black Tahiti pearl) can go in. The black pearl is very subtle and, in some lights, the dots appear to disappear! Not a problem as I put markers down the edge of the ‘board and I’m sure most players would agree that side markers are of much more use than the dots on the front surface. And then we’re on to the frets……….

Now the frets have been dressed, the neck finally gets carved.............

Archtop #5: Fretboard Extension

Next, the fretboard extension has to be painstakingly fitted. The tricky part of this is due to having a gap between most of the extension and the top-plate, giving an elevated section to the end of the fretboard. Why do this? Well to my mind, it frees up the area of the top plate, underneath the fretboard to vibrate.

To add to the complexity, I also like to fit threaded inserts, for the finger rest attachment, at this stage.

The fretboard extension is glued on and although I have faith in glue, if you know my work, you’ll know that I’m a belt and braces man. So, I put a dowel through the extension into the neck block to give some mechanical strength. Although it’s another task, if it makes it better, why not do it!

A couple of months ago, I bought one of these 25 quid mini lathes on eBay. I was a bit sceptical, but once it arrived, I was impressed by the quality and what it’s allowed me to do is make my own dowel from some walnut.

Here’s the dowel in place and you see what I mean about the ugly duckling phase!

And finally, all cleaned up and the slots for the carbon-fibre routed. The carbon-fibre ties everything together nicely! All the small holes are for wooden pegs that locate the fretboard whilst it’s being glued on.

Archtop #5: Neck Joint

 

With the mortice section of the neck joint already routed in the body, the next step is to carefully mark-out and cut the tenon on the neck itself. My rule is always to do any adjustment on the neck and leave the mortice well alone as it’s been routed accurately.

After a bit of fettling, the neck is glued in to place and left overnight; gravity does the clamping!

The protruding part of the tenon is then cut-off. It would, of course, be easier to cut it off before the neck is glued on, but that protruding part helps support a straight-edge whilst checking alignment.

After the bindings had been glued on and the body of the mandolin cleaned-up, it was looking quite pretty! However, with my method of building it will now under-go, what I call, an ugly duckling stage. You’ll see what I mean! The beautiful swan shan’t emerge until the neck has been shaped in a few stages time. 

You can also see one of the reasons why I like to leave the neck square and unshaped: it’s far easier to hold the mandolin firmly in a vice whilst doing this work.

Four 6mm dowels then go in to the neck joint to double lock it in place.

The first part of the fretboard support is fitted. As it’s wedged between the top plate and the neck, any possibility of future movement should be eliminated.