Four string fretless acoustic/electric (chambered)

[Jisch]

It's probably early for me to start a thread about this as it will likely be months in the making, summers tend to be busy.

The general idea for this build is to use a natural knot hole in a board as the sound hole for a bass. I'll be putting in a piezo, and yes I know the volume of this instrument when not plugged it will likely be pretty low, that's not really the intention of the build.

The body will be a single piece of mahogany, the neck will be bolt on, bookmatched mahogany, with perhaps a walnut stringer in the middle (haven't decided yet). I'll remove as much material from the body as I can and still have structural integrity. I have a slotted ebony fingerboard with a 34" scale.

The top is where I'm struggling a bit right now. I found a nice piece of black walnut with a good knot in it - the knot is split with multiple cracks in it, my first issue is getting that knot knocked out without cracking the other wood, I think I can do that, but there is risk. While it's black walnut most of the board is fairly white in color as it's the outer edge of the log.

The piece of wood I have for the top is not large enough to be the whole top, so I have two options:
1) cut it straight on either side of the knot hole and make a five piece top (walnut with the hole, black walnut then figured maple - all wood I have on hand)
2) leave the edge with it's natural edge - I'd square it off so I could join it, but the jointed edge would be curved.

I really like option two right now as it kind of enforces the natural theme that the sound hole will create. It would mean the lower part of body would be one piece as the board with the hole in it is big enough to cover the lower horn etc, and the upper part would be completed with something else that contrasts the light color following that edge (probably black walnut).

I'm having a hard time putting it into words, maybe this picture will make it clear.

Here's the board in question laid over the bass design - so you can see the parts that aren't going to be covered by this board on the left hand side:

 

[Jisch]

I cut the wood for the neck today. I'm going to bookmatch it which, based on the way the wood pinched as I was cutting it, is a really good idea, there was some tension in there. I found a piece of black walnut I could use for a stringer, but the more I think about it, I think I'm just going to use the mahogany alone. I like the grain and I'm thinking I want this one to be more low key.

 

[michaelwayneharwood]

Not sure how I missed this - sub'd!

 

[charlie monroe]

To get that knot cleaned out, I would drill a hole clean through it and pick away at the rings, kinda letting it collapse into the clearance hole.

Direct localized heat may help with this process.

 

[Jisch]

I should have put everything in one thread. If anyone is interested I posted a discussion about mahogany as neck wood here and one about the pickups I will use here. I'll make any further updates to this thread alone, but it will be slow going until I switch into obsess mode.

 

[Jisch]

Ok, I think I'll get some time to work on this build this weekend. Being my first bolt on, it will be strange to get to work on the body and the neck independently.

I am still up in the air on the front piece design. I've consulted with both of my design consultants (wife and daughter), and haven't gotten anything definitive back.

So I'll ask my question here again - should I make the sides of the wood with the hole in it straight, or use the natural curve as the join point between it and another piece of wood? Right now I'm leaning heavily towards cutting the board straight on either side of the knot and making it a five piece top. It would have the walnut with a hole in the center, a strip of black walnut, then a piece of maple on the outside.

 

[scottyd]

I love that knot.. if the wood is nice and dry CA the tar out of it and fill in any voids with some walnut dust.. If its good enough for buckeye its good enough for walnut.. Lots of good figure in knot areas. Here's one I did that had TWO knots.

 

[Jisch]

Yeah, there's lots of good figure and grain in that area, pretty excited to get this one moving.

 

[Jisch]

I knocked some of the knot out today. I made a bunch of holes with a drill then hit it with a dull screwdriver. It broke along the grain of the knot pretty nicely. Rather than push it and cracking something I don't want to crack, I stopped before it was completely knocked out. I'll resaw it tomorrow and then use a grinding wheel to take out material to leave a good side to the hole (or that's my intent). I'm about 90% sure I'm going to cut this square (see lines) and not use the natural edge of the board. It would be about 100% easier to resaw after I cut it down square and to size, so it's decision time on that front.

 

[Jonny5bass]

I've got to follow this. An acoustic/electric is on my bucket list of builds..

 

[Rôckhewer]

So if the walnut is thick enough to resaw... You will have TWO pieces, half as thick as the original (minus the saw kerf)... So you can rip one of the pieces down the middle and fold them out to create two bookmatched joints... on either side of the knot... giving you a top that is plenty big enough...and a cool double bookmatch effect!

 

[Jisch]

Holy Krap! I did not even think of that! Definitely happening. I was on my Saturday mountain bike ride and I kept running this through my head trying to figure out how I was going to make it work. That is perfect! Off to measure to make sure there's enough wood.

 

[Jisch]

It looks like if I move the hole down 2" or so, this will work. I didn't get to the shop today (yard work) tomorrow for sure.

 

[Jisch]

Bookmatching this thing is giving me fits. I ran it through the table saw on both edges with the blade all the way up, it went great. Usually I'll then run it through the bandsaw. The bandsaw blade kept pinching and running out of the cuts into the sides. I was rushing, never rush. I put it down, I'll go back to it another time.

 

[Rôckhewer]

Bookmatching this thing is giving me fits. I ran it through the table saw on both edges with the blade all the way up, it went great. Usually I'll then run it through the bandsaw. The bandsaw blade kept pinching and running out of the cuts into the sides. I was rushing, never rush. I put it down, I'll go back to it another time.

I frickin hate when that happens!
I was trying to re saw a teak board that I did the same way. Almost 3" up on both edges on the table saw & only had about 4" left in the middle. But the grain just wasn't helping me at all & the blade kept following it. Teak is somewhat ....problematic at times though.
You got a lovely knot in the center and all the weird grain that goes with it!
Are your bandsaw blade guides all in good shape & set up properly? Blade tight enough??
Good luck man.

 

[Jisch]

I need to take a step back and go at it slowly. I didn't have time to check everything, just saw it going a bad direction, probably good to walk away when I did.

 

[Jisch]

I decided manual was the way to go here. While I have a hand saw it's old and dull, it works ok for ripping wood when I don't care, but it didn't seem to be putting a dent in the walnut (which is honestly not that hard!). I went to the hardware store and bought a brand new saw - yep, it's a ton sharper!

It's fairly warm here today, I'm sure I'll get to the blood and tears soon enough, but today I got the sweat part out of the way, whew.

Here's what the end looked like after several aborted attempts with the bandsaw (you can see why I stopped with this approach). None of these are deeper than an inch or so and I don't need this end of the board (I don't think):

Here we go (French Bulldog for scale):

Made it to the knot - I kept putting shims in to keep the sides apart and theoretically keep the blade in the groove - it didn't work entirely:

And here's the finished board - as you can see I ran off the line once. How is it possible for me to not feel that? I don't know, but if I'm planing down to 1/8" I think I'll still be ok.

And here's the good side:

So now it's over to the sanding planer to see what size boards I'm going to end up with and what I can possibly do with them.

And just as an aside, I have been building basses for the last five or six years, I really wish I found this forum earlier! I love seeing all these projects and especially love seeing all the mistakes and recoveries. I'm trying to contribute in the other threads when I can - paying back if you will. Again, thanks everyone for making this a great place.

 

[Jisch]

I wasn't really paying attention to how thick the boards were as I was running them through the sanding planer, just trying to sand out all the saw marks, they ended up being a bit over 1/8", so it's just about perfect. It looks great, I'll look at it over the next few days and decide how I am going to join it up. The prevailing thought is to leave a bit of a taper on the lower end, but I'll stare at it and make a thousand chalk marks before I do the cut.

Here is the sides that were hacked after bookmatching - looking good.

And I glued up the neck - I'll get two necks out of this wood:

It feels great to get moving on this, but as I've said before it is the summer, so this will be slow going.

 

[Jisch]

I cleaned out the sound hole - my design consultant/wife didn't know I was doing this, she thought I would leave it rough, I like it cleaned out - even though it looks a bit less rustic. I think I have the top worked out, it will be three pieces, the middle being this, the outer edges will be pieces of the bookmatch. I don't think you'll know it's bookmatched, but it will be obvious it's the same piece of wood. This configuration (which is impossible to show) will maximize the figure on the top.

I cut one of the necks out of the blank - it came out great so this will be the one for this build - good to know I had a second chance if needed - this is a pretty rough cut with probably close to 1/4" of extra wood for me to mess around with as I carve it:

It should look pretty cool from the back:

 

[Rôckhewer]

I cleaned out the sound hole - my design consultant/wife didn't know I was doing this, she thought I would leave it rough, I like it cleaned out - even though it looks a bit less rustic. I think I have the top worked out, it will be three pieces, the middle being this, the outer edges will be pieces of the bookmatch. I don't think you'll know it's bookmatched, but it will be obvious it's the same piece of wood. This configuration (which is impossible to show) will maximize the figure on the top.

I cut one of the necks out of the blank - it came out great so this will be the one for this build - good to know I had a second chance if needed - this is a pretty rough cut with probably close to 1/4" of extra wood for me to mess around with as I carve it:

It should look pretty cool from the back:

Sweet !
I really dig the look of the knot hole cleaned out!