Gibson j45ADJ #2. Gibson 's Gift to Luthiers

[Diane Kauffmds]

Like I said about the 1963 Gibson J45 ADJ, Gibson's gift to luthiers everywhere is their ill-conceived bridge.

This is a 1967 with the same bridge design, made of BRW. This one broke entirely. The wood that holds the saddle to the screw has also broken. My client is an avid originalist; he wants all original parts whenever possible. I explained to him that because of bad outcomes in the past, I will only replace bridges which have broken entirely. I don't try to fix them anymore.

So, I'll be using the BRW bridge blank in the photo to make a replica of Gibson's ill-fated bridge, along with the saddle. The blank is large enough for the bridge and saddle.

However, mine won't move and break like Gibson's. As you can plainly see, Gibson used a little glue and glued that puppy right to the finished too, a huge NO-NO.

For you new folks out there...never glue to finish. Always glue clean wood to clean wood. Even a little finish under a bridge will cause failure.

There's also a crack starting in the top that I'll fix.

I'll update as I go along.

[carld05]

I've got a couple of guitars with the dreaded adjustable bridge. My neighbor gave me a Yamaki 12 string that has a bridge that ripped up and took up a chunk of the top and plate broken along the pin line. I also have a bad eBay buy, a Stradolin, that looks sort of like a D35 but all veneer. It's bridge is also lifting. Both have the threaded inserts for the adjusting screws drilled through the x-braces! I hope the Gibson design is better than that!
Perhaps I'll pull the back off the Yamaki and rebrace the top, The pieces are all still attached and it would need a bridge plate but it's a nice solid wood "lawsuit" guitar.
The Stradolin on the other hand will get a bridge R&R and a couple of splints. There's a free group guitar class in town that will get a donation.

[Diane Kauffmds]

I've made the bridge out of my last BRW bridge blank. Gonna have to buy more to keep on hand for vintage guitars like Martin and Gibson.

I "drew" the bridge in the CAM software for the CNC to cut the bridge and holes. I'm excited to report that the bridge came out identical to the original. All holes lined up and the saddle slot was perfect. Since I have no idea on how to use CAD software, I shaped the wings and top of the bridge the old fashioned way, with my spindle sander, disk sander, and hand sanding.

I glued the bridge yesterday and removed the clamps today.

I made the adjustable saddle today. It fits great and should work well. But, I ran into a snag. Gibson installed the nuts that the adjustable saddle screws go into at an angle. So, the saddle wood pushes against the sides of the saddle hole on the bridge. It causes more pressure than I'm comfortable with, so tomorrow I'll do some sanding to accommodate this anomaly.

I think this is the reason the original bridge cracked like it did. I'll make sure this doesn't happen with the new bridge.

I've already fit the bridge pins by reaming the holes, put the now unnecessary bridge bolts back in, and glued the original mop plugs back into place.

Tomorrow, I'll clean the fb, recrown and polish the frets. It'll be ready to string up and set up.

[jread]

Very interesting post! I'm still not quite over being impressed at your cnc table and setup that you made yourself!

[Diane Kauffmds]

Thanks John. I'm kind of proud of the cnc too. I had to go back many times to make changes until I was satisfied. It's performing beyond expectations.