Kay Pinless Bridge Conversion

Image Credit: Reverb - Hippie Holidaze

Pinless guitar bridges are the designed so that the strings loop through the bridge and then over the saddle eliminating the need for plastic pins and holes drilled into the guitar top. Kay started using them more in the early 1960s on their flat top guitars.

This design has the strings come in through the front of the bridge (saddle-side) and out through the back where they wrap over the bridge and onto the saddle. I consider these bridges to be less stable for the high tension of steel-stringed instruments and with subpar sound. The strings are held in place solely by the bridge and so the pulling tension is counteracted only by the strength of the rosewood bridge and the top is merely glued to this bridge. The top doesn't contact the strings nor offer any direct support but instead holds the bridge which is trying to be pulled away from it.

I set out to convert this bridge to a pinned one.

 My first step was to cut some Indian Rosewood to fit in the rectangular channel cut into the bridge. I rounded the corners to match the corners of the bridge and got a snug fit after trial and error. I used a plastic circle tracing sheet to get a good radius and then sanded to it using my belt sander. I glued the piece into the bridge using thick Cyanoacrylate, because this patch is permanent, and filled any small gaps with thin CA and rosewood dust which form a surface that is very similar to real wood after sanding.

 The other side of the bridge includes a similar rounded, rectangular channel cut into the side with 6 string holes drilled through it. I filled the holes with maple dowels (thin Rosewood dowels aren't something you can easily find and this is structural, nobody will see it) and cut another piece of Indian Rosewood to fit in that channel and filled using the same methods as above.

 Then I took the bridge to my belt sander to sand the grafted wood flush with the bridge. I had to be careful to not hit the base of the bridge and change the footprint because that would be very difficult to hide on the top of the guitar. This picture was taken after I sanded the patch and oiled the wood.

I used LMII's bridge drilling jig to place 6 perfectly spaced holes through the bridge for the strings about where the old strings came through. You can see the grooves that the strings left in the bridge which were filled with rosewood dust and thin CA. 

Then I hand sanded the bridge from 220 to 2000 grit to expose fresh wood which slightly alters the color of the wood because of the removal of the oxidized layer. Now the bridge should age and color uniformly which will help disguise my patch work

This guitar did have a spruce bridge plate so I drilled my holes, capped it with a piece of maple, and drilled through again. The maple cap helps protect the bridge plate from the ball ends of the strings hitting it and causing it to chip which compromises the integrity of it and leads to warped tops and lifting bridges.

The bridge area was properly prepped and the bridge is glued using fish collagen glue.

This is the front part of the bridge showing the other side that was filled, its barely noticeable but you can see the darker rosewood if you look close enough.

I ramped the saddle slots using a Dremel and a set of diamond bead reamer bits. Then I used an old bone saddle and some white plastic pins to complete the look of the instrument. The bridge is stable and should hopefully stick together for another 50 years!