Carving a new bone saddle

My good friend (and longtime Tonefinder client) Vince came to me with his Yamaha acoustic guitar with a very common issue; it was breaking strings at the saddle on a regular basis. Not great when this is your gigging guitar.

So let’s take a look at the saddle and bridge.

The offending saddle

We can see where an old string has been left in place due to a rapid string change after a breakage on stage. It also looks like necessity has dictated that at least electric guitar string has been used too (the A string?).

Let’s take the strings off and see what’s going on.

The strings are now off so we can see what’s going on

You can just about make out in the photo above some groves appearing in the saddle. The G string saddle point is particularly visible. This plastic saddle is too soft and allowing the strings to cut in. This would go a long way to explaining the string breakages.

Removed from the guitar

And in this photo, we can see that groove in the G position. You can just about make out a groove being cut in the B position too.

Old and new

After a chat with Vince, we agreed that the best way to proceed was for me to carve a new bone saddle and set the guitar up plus fit new strings. In the photo above we can see the old plastic saddle and below that the new bone ‘blank’ which I’ll use to make the new saddle with. What follows is the steps I go through to make a bone saddle. Making a bone nut is similar but I’ll write a separate blog article covering bone nuts at some point in the future.

Using the old saddle as a template

The old saddle was absolutely fine in terms of dimensions so I’ll use that as a guide to shaping the new bone one. You can see here that I’ve marked roughly the length I need to make the new saddle.

Marking the length using a set square

When making bone saddles and nuts it’s important to ensure that everything is as square as possible. I used my adjustable set square to mark the bone using the bottom edge as the reference. I also put a small cross in the area that’s going to be removed which helps remind me which end to remove.

Roughing out the shape of the new saddle

Here I traced out the shape of the old saddle on the bone blank and marked the material for removal. It’s only a rough guide at this stage at once that excess material has been removed the new saddle will be slightly oversized until I shape it properly later.

Getting ready to sand the saddle to the correct length

So here we can see that I’ve set my sanding wheel up ready to sand the end of the saddle and remove the excess material. Now I suspect I know what you’re thinking. Why don’t I just saw the excess away instead of sanding it away? Well, bone is actually quite brittle. I’ve tried using a fine blade on a hacksaw, various Dremel cutting attachments etc and I’ve very been happy with the results. Minor chips and even splits can occur when sawing. Sanding has proved to be quick, reasonably effortless and gives good/consistent results. And if you’re going to try this then please ensure that you use a good quality face mask (because bone dust stinks and lines your lungs for days afterwards) plus use a good dust extraction method because bone dust gets everywhere given the chance.

Getting close to the correct length

The saddle is almost the correct length now but I’m going to double check. A good rule of thumb is ‘measure twice, cut once’.

Checking the length of the old saddle

Using my calibrated digital Vernier gauge I’ll check the length of the old saddle. Here we can see it’s just a gnat’s tadger over 75mm.

Checking the new saddle’s length

And after checking the new saddle we can determine that just under .9mm still needs to be removed. ‘Delicate’ is the word you need to keep repeating to yourself at this stage.

Now we’re bang on the right length

Happy days. The saddle is now the same length (albeit 0.01mm shorter than the original, that’s 0.0003937008 inches in old money).

Using a vertical belt sander to rough out the shape of the saddle

Now it’s time to shape the curve of the saddle. I’ll use the vertical belt sander to remove most of the waste material and then use files to finish shaping.

About halfway through the shaping

Above we can see that I’ve started removing the excess material. I really can’t stress enough the need for decent dust extraction.

The rough shape of the new saddle is really starting to show now

The new saddle is starting to take shape. As you can see in the photo above I’ve marked the old saddle ‘old’ because it might start getting a little difficult to tell the difference between the old and new soon.

The new saddle is almost double the thickness of the old one

So we’ve worked two of the three dimensions so far, those being height and length. Thickness is the next thing we need to tackle and as you can see in the photo above the new saddle on the left is almost double the thickness of the old one on the right.

Setting up the Dremel Routing Table

The Dremel Routing Table is one of the best purchases I think I ever made for the workshop. It’s so versatile and for getting bone to the right thickness and intricate shaping it’s proved it’s worth more times that I can remember.

Let’s check the thickness of the old saddle

Using the Vernier gauge we can see that the old saddle is a smidge over 3mm thick. I’ll set the routing table up and test.

Testing on an old offcut of bone

Once I’ve set the routing table up I’ll perform a test run on an offcut/scrap piece of bone to double check my settings. I forgot to take a photo of the test piece after running through so apologies.

The new saddle is now the correct thickness

The new saddle (left) is now the same thickness as the old one (right). Notice that you can see the grooves that have been cut but the strings much more clearly in this photo.

Still some way to go – It’s time to shape up

We’re not done yet. We’ve got a lot of shaping to perform first. The top of the new saddle needs a nice smooth curve adding, the ends of the saddle need rounding off and I also need to introduce an offset for the B string. I’ll use bone nut files from Stew Mac. They’re double sided so I have rough, medium, fine and extra fine filing surfaces to work through in that order.

All nicely shaped

I used the camera on my phone to take all these photos and as I’m writing this blog I’m kinda regretting that choice. The new saddle is below the old one in the photo above. You can just about make out the nice rounded edges and if you squint a bit you can see where I’ve filed the B string offset.

Final polishing before fitting

Using some Scotchbrite I now polish up the bone saddle ready for fitting to the guitar.

It fits like a glove

The new saddle fits perfectly. The next step is to fit strings, set the guitar up and check intonation.

New strings fitted – she’s ready for another gig

So after installing strings and making some initial checks, I found the action was a touch too high for my liking. That’s easy to fix and simply involved removing the saddle and removing some material from the base of it. Intonation was checked and found to be spot on for all but one string. This was corrected and the guitar is now ready for another gig.

If you’d like to know more about bone saddles, bone nuts or indeed anything relating to guitar then please contact me and let’s talk. I hope you found the above article of some interest.

Cheers,

Rich