Double Bass Yet Another Kay Bass Bar Thread

[cykogrilla]

I have a 65 Kay M-1 with a bass bar that's disconnected on the bottom and a top that's flattening out. I've read up on how to fix the problem and have confidence in my woodworking skills to pull it off. Plus, it's already been painted (not by me) so touching up any mishaps isn't really going to be that difficult. Everything else is solid and the neck doesn't even need planing or anything.

Any suggestions on what to do to temporarily snuff the bass bar rattle until I get my garage back and have a workspace to pop the top and fix this? She sounds great amplified and you can barely notice the buzz except when acoustic so the main concern is structural integrity. She now has bumped Rotosounds so the string tension is a lot less than the steel strings that were on there before. From what I can tell with a mirror the bass bar is still intact.

Here's a pic where you can see the top sinking below the f-hole.

 

[KUNGfuSHERIFF]

Yikes. I'm amazed it holds tune in that condition.

When you pop the top, which you should do sooner rather than later, it's possible to re-arch the top by slowly and gently clamping the bottom of the bass bar back into place, and basically using the bass bar as a prybar to force the top back into round. It is critical to apply low heat and small amounts of moisture from a mist bottle to the inside of the top during this process, to avoid wrecking the top.

When I did a similar repair on an old King, this worked, but you're going to want to replace the bass bar, which is no small job.

Part of the reason that top got as bad as it is is because the bass bar is "sprung," or fitted under tension, kind of like a longbow with the bow string in place. It was thought at the time that a sprung bar was beneficial, but the current thinking is that a sprung bar is a ticking time bomb that causes caved-in tops even if the bar never pops loose.

You can use the original bar, glue it back in place when the top has been pressed back into round, and reinforce the ends and the middle of the bar with linen patches soaked in hot hide glue...but... in the long run you might be better off fitting a new unsprung bass bar accurately enough where you can't slip a piece of paper between the bar and the top.

 

[james condino]

Circa 1965 Kays have a tulip poplar inside layer that can be very prone to the outermost layer separating from the plys; the bassbar connection actually is holding well but the plys are separating. When rebuilding, adding an overlay to that area dramatically increases the surface area so it holds much better. Quite often on old Kays, the seeming bassbar noises are coming from the endpin and loose linings that can be very challenging to pinpoint and regularly with a deformed top the noises come from a funky soundpost fit- one of mine sounds great half the year, but gets a crazy soundpost rattle when the weather gets just so.

From what I can see in the photos, that top should hold up to a lot more gigs with a reckless punk band. When the time comes, you would be amazed how far gone a top can be and with the right person and the right jigs, it can be brought back to better than new with a perfect arch and a better voice. I have a full size original arch spec top mould that is in use almost every day of the year that gets used in combination with several heat blanket systems that can take an old Kay that has collapsed 3 or 4 inches and completely deformed all of the soundhole wings and with about 12 hours of bench time over a week period brings everything back to original spec and it is ready for another 50 years of hard use.

... if you put your location into your profile, we could recommend someone in your area .....

j.
kaybassrepair.com
condino.com

 

[cykogrilla]

Potential bass trigger alert... I decided to add a trap door on the C-bout. Even with the strings still on at full tension a gentle push got the bass bar half way towards the top and got the top moving back into shape. Removing the strings (obviously) with a little heat and moisture and I think she'll go right back into shape. This also gives me the added advantage of quickly adding a second sound post for bad feedback environments.

Waiting on some magnets for the trap door but it came out nicely with just some paint chipping of the white top coat.

I'm in CO but won't be in the market for a full restore anytime soon.