How Do I Fill In A Cavity?

[jlarremore]

How do I fill in a cavity in a solid body I'm not using. I'm using the bridge and the middle of a strat. The bridge is a hum and the middle is a single coil. How do I fill in the unused cavity?

Thanks,

Jef

[avengers63]

There is always debate on if you really need to or not. I'm on the side that you don't need to. It won't cause any feedback and is extremely unlikely to make a noticable tone difference. Cosmetically, with it being under the pickguard, it'd never be seen. If you ever want to use the space in the future, you'd then have to open it up again. My suggestion would be to leave it alone.

But...

If you're set on doing it, you'd be best served by making the cavity square. That would make it a LOT easier to plug the hole with a piece of wood. Imagine making a square piece, then making a rounded-corner. Which will be easier to get exact? You'll want as tight a fit as you can reasonably manage. Cut the fill-in piece to the dimensions of the cavity to be filled. Unless you mean to refinish the body, you might want to consider cutting it just shy of flush with the surface - maybe 1/16". This will give you a small margain for error. If you leave it even a little proud of the cavity, you'll need to level it down somehow, which is very likely to monkey up your finish.

Simple version: cut the hole square, the glue in an appropriately sized piece.

[low end fuzz]

uhm. i dont know if you want to fill it for 'tone' or aesthetic purposes;

but the best way to deal with an unused pickup cavity (especially on strats) is to buy a new pickguard with only the pup spaces you want.

[jlarremore]

Ahhh, good questions by all.

I want to fill it for aesthetic purposes. I know it won't make any tonal differences. I am having a hard time with the balance between the pic guard and the finish. The finish is crackle so the pickguard will probably end up covering a large amount of the finish I want to come through.

If I fill the cavity I can make a smaller pickguard. But it sounds like you will always see something around the old cavity.

Hmmmm, At this point I think I'm going to go the easy way and just go pickguard, but I'll spend a little time seeing if I can make the plug to fit the shape. Good exercise for a long weekend I've already traced it and I have the spare wood ( thikness is 3/4" ).

Finding a pickguard that matches a H/S/Blank configuration might be tougher than the blank. Going pickguardless was an easy solution and just using pickup mounts.

Oh the conundrum!

Jef

[jlarremore]

There is always debate on if you really need to or not. I'm on the side that you don't need to. It won't cause any feedback and is extremely unlikely to make a noticable tone difference. Cosmetically, with it being under the pickguard, it'd never be seen. If you ever want to use the space in the future, you'd then have to open it up again. My suggestion would be to leave it alone.

But...

If you're set on doing it, you'd be best served by making the cavity square. That would make it a LOT easier to plug the hole with a piece of wood. Imagine making a square piece, then making a rounded-corner. Which will be easier to get exact? You'll want as tight a fit as you can reasonably manage. Cut the fill-in piece to the dimensions of the cavity to be filled. Unless you mean to refinish the body, you might want to consider cutting it just shy of flush with the surface - maybe 1/16". This will give you a small margain for error. If you leave it even a little proud of the cavity, you'll need to level it down somehow, which is very likely to monkey up your finish.

Simple version: cut the hole square, the glue in an appropriately sized piece.

Your work on the crackle finish is what inspired me to start this project. I never saw how your guitar turned out.

Jef

[Bryan316]

My brother bought a "Jackon" Randy-style flying V which used to have a front pickguard. The previous owner had filled in the electronics cavity with a block of wood, re-routed the backside for a rear cavity, and painted over the front afterwards. Looked like the front was never routed.

Heh! Oh yeah! I forgot!

Except the wood contracted horribly and ruined, RUINED, the paint creating an indented silhouette of where the cavity used to be.

Ugly. Awful. Amateurish. Retarded. It was like duct-taping a painted bumper to make it look chrome. The different, new block of wood behaved entirely different than the kiln-dried, aged, humidity-stabilized body wood. That block shrunk underneath the paint, and the whole block's surface now sits a millimeter below the rest of the guitar, and it is glaringly obvious that this hackjob looks horrible.

The simple nature of wood! It is organic. It is still alive. It still breathes, moves, shifts, reacts. And your guitar body will of course be more stable and steady compared to ANY block of ANY species of ANY age wood you put in there.

DON'T DO THIS TO YOUR GUITAR. YOU WILL HATE YOURSELF IN THE NEAR FUTURE.

[jlarremore]

Well, Brayn, looks like I know what I have to do. Thanks!

Jef

[low end fuzz]

stew mac has a whole bunch of combinations of strat guards

[Bryan316]

I simply want you to be spared the heartbreaking experiences, man.

There's a difference between screwing something up because you experimented, and screwing up cuz the idea was bad from the start. I don't wanna see you throw away a project cuz of this!

Oh, and another suggestion.

Do your crackle finish, by including the pickguard. Screw it in place, and do the paintjob over the pickguard itself. Then pull it off and assemble.

[zyonsdream]

I took this BCR NJ series Warlock and turned it into a 1 pickup 1 knob guitar

I plugged the hold with dowels using regular Elmer's glue leaving the dowel sticking up a little and simply sanded it flat. I then used a little wood filler to fill in any imperfections.

To fill the pickup cavity and the Kahler cavity I used a piece of card stock and traced the inside lines of the cavity and transferred it to a piece of rock maple that was a little thicker than the cavity was deep. I made the pug really tight. I had to use my dead blow hammer to hammer them into place. I also used a liberal amount of Elmer's to ensure it stayed in place. I gave it a few days to dry and then sanded it flat with the face of the guitar. Once that was done, I went over it with a touch of filler to take care of any imperfections.

Since it was getting a solid finish I went over the whole body with grain filler and then painted it. There isnt one person who could tell that this guitar had been modified like this.

Here is a close up of it in primer

When It was done, I was able to sink a BCR wrap around into the old bridge cavitiy with no problems.

Edited July 2, 2008 by zyonsdream

[avengers63]

Your work on the crackle finish is what inspired me to start this project. I never saw how your guitar turned out.

Jef

I'm flattered. I just wish I had been able to pull it off. The craclke I had wouldn't crackle. I was pretty disappointed. I'm currently painting the whole thing blue.

[Bryan316]

Zyonsdream! GRAIN FILLER! Never... ever... EEEEEEVER thought of using it that way!!! That's almost, like, GENIUS!!!

Seriously!

If you glue that wood in, and just soak that sucka with grain filler, it'll be like injecting epoxy hardener right into the fibers of the wood!!!

[Setch]

And your guitar body will of course be more stable and steady compared to ANY block of ANY species of ANY age wood you put in there.

Why?

If you choose a piece of the same species, well dried and seasoned, and with the grain oriented correctly, there is no reason why your guitar would be more stable and steady than your repair.

If you're going to use block capitals to stress a point, best make it correct.

[Bryan316]

Zyons' is the first example where I've seen it work correctly. I'll take take my words back, because his method worked.

No one I've ever seen do a woodblock fill-in, has ever had success doing it. I've seen it done in alder, mahogany and maple. With blocks of the same species. That's my base for my comments. I'm pretty sure it wouldn't work in ash, or oak, or even pine.

But overfilling it with grain filler... that's a totally different technique.

[jlarremore]

I thought I would add some pictures of the project. I was inspired by Avenger63's attempt to do a crackle finish on a guitar. Little did I know that it was going to consume me. I decided to post some pics of the whole process.

I started with a free guitar a former relative left in my mom's garage. Specifically a Peavy Predator or Raptor or something. It was made in Korea. it was like all the other guitars I have found at a low price, black and a white pickguard. There are tiny deposits of rust on the pickguard screws probably from it's time in Pascagula where they lived before Katrina. I'm guessing it was left there and then collected later. Still don't know if it plays.

I decided to try a heat gun to strip it, then thought again after leaving a burn through the sealer under the wood. I went with aircraft stripper. Worked much better but left tons of pock marks in the sealer. Hey, it's a cheap Korean guitar.

Then I put wood filler in it to smooth it out. Love/hate that stuff. It's like clay but does a great job. I did a better job just using my fingers to smooth it in.

After a coat of poly to seal it all up, I used Krylon red and black to do the solid colors underneath.

Now here's the most important part. I couldn't find the crackle combination in the colors I wanted. Most mediums are for water based paints. I found one from Rockler Woodwoking called General Finish Crackle Medium out of Wisconsin that would work with enamels. It was VERY specific that it had to be enamel paint. I have no idea why. I tried with the Krylon - which must have some kind of latex in it, and it only worked with cheap black enamel paint.

So I need to get the pickguard right so that it will blend in well with the finish.

Jef

[jlarremore]

I apologize for not updating this topic. I am finished with the guitar, but I think staining the neck ebony would really help. I had to modify the pick guard tremendously as the tail section was too narrow and the middle pickup had no spot. I'll post pics as soon as I can.

Jef

[kpcrash]

I took this BCR NJ series Warlock and turned it into a 1 pickup 1 knob guitar

I plugged the hold with dowels using regular Elmer's glue leaving the dowel sticking up a little and simply sanded it flat. I then used a little wood filler to fill in any imperfections.

To fill the pickup cavity and the Kahler cavity I used a piece of card stock and traced the inside lines of the cavity and transferred it to a piece of rock maple that was a little thicker than the cavity was deep. I made the pug really tight. I had to use my dead blow hammer to hammer them into place. I also used a liberal amount of Elmer's to ensure it stayed in place. I gave it a few days to dry and then sanded it flat with the face of the guitar. Once that was done, I went over it with a touch of filler to take care of any imperfections.

Since it was getting a solid finish I went over the whole body with grain filler and then painted it. There isnt one person who could tell that this guitar had been modified like this.

Here is a close up of it in primer

When It was done, I was able to sink a BCR wrap around into the old bridge cavitiy with no problems.

Sound how flamed am I going to get if I wanted to say, fill a floyd cavity this way? Especially on a body I plan to sand back and add a veneer top on?