Adjusting action on bot-on neck K acoustic

[Theleman]

I got this old K guitar 6 string acoustic with bolt-on neck with 3 screws on the joint. This K guitar is probably from early to late 1970s, and the top has lot of cosmetic blemishes, but the rest seem solid.

The action is very high on the high frets, so I am thinking of taking off the neck, and putting shim underneath the neck lifting the neck a bit when it is bolted back on, so that it would give lower action.

Is this right way to do it? Anything to watch on this job? Would it work ok? Because I have never done this type of work, so it is just from my imagination just now, but would be nice to get some advice and info or any tips?

Thanks.

[Monsoon1]

That will work fine. I have a 60's Fender Villager and that's what I did.
It plays like a well setup electric now.

[Theleman]

Great to know. Thanks for your input and confirmation.
Will embark on the project with confidence.

Thanks.

[Monsoon1]

For what it's worth, it doesn't take a lot of shim to make a big difference. I used a piece of that super tough plastic that comes on items like small electronics. It's tough stuff and won't compress like a wood shim might.

[Theleman]

Yes, I was going to ask what material would be best for cutting the shim.

I have some wood lying around, but come to think of it after reading your post, maybe it would be better to go with hard plastic?

[mirwa]

Fit a shim with a slight taper to it, makes a huge difference and very easy to make, any hardwood is best, softwoods work okay too.

An example, a shim .4mm one side and 1.2mm on the other, can drop an action height of 140 thou

Steve

[Monsoon1]

Originally Posted by Theleman

Yes, I was going to ask what material would be best for cutting the shim.

I have some wood lying around, but come to think of it after reading your post, maybe it would be better to go with hard plastic?

That's how i've been doing it, and i've owned this guitar for 35 years. Not only that, but the original body had a big chunk missing from it, so I eventually found a replacement body on ebay for cheap, and put the neck and tuners on it. Then I did the setup with shims again, and it worked perfectly.

The strings are on a fulcrum from the nut, so when you push the neck up vertically, the string swing into place along the neck.
So unless the neck pocket has warped up at an angle somehow, a flat shim will work fine. However if the neck pocket has actually been warped in an upward angle somehow, then a tapered shim would be a better fix, although not necessary. (this all assumes that the neck is straight!)

Another good reason to use plastic is that it's very easy to cut the piece to completely fill the neck pocket so that it's fully supported from the bottom of the neck.

[mirwa]

I start by using scrap in the socket of different thicknesses, until I get the desired action height



Then I sand / plane a full piece of wood to match those measurements



And then glue the shim in place

[Theleman]

Great photos of the project. Thanks for sharing mirwa.

I am still not decided which to go with, plastic or wood shim. Does the shim needs be glued? Because it will be squeezed by the 3x long screws between the body and neck after.

[mirwa]

Gluing stabilizes the shim position, not needed but helpful.

Sent you a pm