LeftyBassist.com

this thread is a detail follow-on to the LeftyBassist 4-string bass build discussion. in that thread, the discussion covers the entire process of specifying the details for a bass build, and the details of actually building the physical parts are covered at a more general level.

in this thread, all of the juicy details of making a solidbody bass body will be detailed for anyone who has interest in the subject.

here's the specifications from the other thread (the target for this build):

* Swamp Ash body core, bookmatched figured American Cherry top and back, Wenge veneer accent lines between the Ash and Cherry
* 1-5/8" (42mm) body thickness
* rear routed control cavity (no pickguard)
* carved arm contour on front
* carved tummy contour on back
* clear gloss finish

thanks for joining along!

all the best,

R

the first step in building a body is to choose the materials you want to build with. there are several ways to gother the materials, but most builders either purchase rough lumber from a lumber yard or they order from a reputible specialty dealer. in the case of this build both the American Cherry and Swamp Ash were purchased from a local hardwood supplier and required a significant time investment in sorting thru the available stock for material that had the right grain and or figure.

the Swamp Ash board selected was a 12' (3.7 meter) long 6/4 rough stock that had nice grain and was significantly lighter than anything else available. the American Cherry was a1 2' (3.7 meter) long 4/4 rough stock that showed significant promise of usable figuring. both came home tied to the top of my car.

once here at my shop, they have acclimated for nearly a year - the Swamp Ash was cut into body blank pieces about six months ago. each of these pieces were matched into sets and arranged for grain alignment. each piece had one edge run thru the Jointer so that there is a perfectly level and smooth edge for gluing to the other half. the two pieces were then glued (utilizing a hoarde of clamps) and allowed to dry for 24 hours

here's the resulting 2-piece Swamp Ash body core



next the top and back sets needed to be chosen from the larger Cherry board.



the board was cut into sections long enough to fit the length of a body, passed thru a Jointer to smooth and square the edge that will be glued, and then cut on a bandsaw across their width. here's an image showing the process for bookmatching a top (the image shows a Black Walnut top I cut the previous evening)



the results from the bookmatching reveal a great figure pattern for both the top and back sides



for reference, here's the bookmatched top with the Birdseye Maple fretboard blank. the two woods compliment each other nicely IMO



more to come ...

all the best,

R

the next step is to thickness the multiple wood pieces in preparation for gluing them together into a body blank. since the woods used for the top/back are highly figured a Planer is definitely out of consideration - using a Jointer on firgured woods leads to frustration and dispair because it has a tendency to tear out the figuring instead of leaving a smooth surface. so what to use for this??? enter the Thickness Sander ...



with this machine you simply sand the wood down to the proper thickness and flatness. the sanding grit is adjusted by wrapping different paper onto the drum, and the rotating drum sands the wood as it passes underneath. it is super easy to get the desired thickness perfect as each full revolution of the adjustment handle lowers the sanding drum just 1/16" (1.5mm)

here's the Cherry top and Ash body core being thicknessed




and here's the resulting bookmatched sides

Top


Back


Top (left) and Back (right) together


and a peek at what the sandwich will look like when everything is all glued together




all the best,

R

the next step is to glue all these wood pieces together into a body blank

the side that will be glued together is once again passed thru a jointer (if needed) to ensure that the glue edge is perfectly perpendicular to the top face and also perfectly flat. while the jointer can give a pretty good edge, it's not the best tool for using with highly figured and/or brittle woods.

I next clamp the two blank pieces together (body core pieces, or bookmatched top pieces) and lightly sand them with a machined straight edge (same one used for levelling frets) to ensure I have a nicely fitting glue joint. once I an satisfied with the fit I lay plastic wrap onto my workbench, add Titebond Original wood glue to each face that is glued, and then clamp the two pieces together being sure not to get plastic wrap caught in the joint.

as you can see here, somewhere under all of those clamps is a cherry top being glued together



I will let this sit overnight before unclamping, scraping off the excess glue, and then gluing the next set. for this prototype bass there are three sets total. I already have the Ash body core completed, so once this top is cured all that remains is the bottom set.

after all three sets are fully cured, I will run each thru the thicknessing sander to ensure that each panel is uniformly flat and for the final thickness. when this is done it's time to glue all of the panels to form the body core blank.

someplace between all those clamps is a lefty bass body sandwich curing during its glue-up. I glued all of the parts together in a single operation so that I would have even moisture expansion on both sides simultaneously. if I would have only glued one side at a time, there is potential for uneven movement (which could cause warping when the wood expires the moisture later during the build progress)




this will cure for several days to several weeks depending on how long it takes for the moisture content to restabilize. if I used an epoxy based glue instead of water based glue, this problem would not occur - but those glues are significantly more difficult to deal with

all the best,

R

the next step is to transfer the centerline and body pattern onto the body blank in preparation for routing the neck pocket.

As you can see in this image, I have the body outline traced onto the body blank. To do this I reference the glue joint of the top and lay the body template onto the blank. Once it's traced I locate the theoretical scale location - in this case it's a 34" scale instrument, so I locate the 34" reference location per my detailed design plans. Once this is located I can also locate the end of the neck pocket, and with this located I then trace out the pocket outline from a routing template.



If this bass were to get thru-body string ferrules, I would also square-up the butt end so I could reference it when drilling the ferrule hole ... but I think that thru-body stringing is purely marketing hype (I surely cannot hear any difference), and I do my best not to have these installed on a build.

The next part in this step is to visit a drill press and utilize a 7/8"D Forstner bit to rough out most of the neck pocket wood (the first 1/2" of depth) - this saves a lot of routing time (and router bits!) and leaves me to only need to route the final 1/8" in depth and 1/16" of the side wall with a router.



and a close-up of the roughed neck pocket




Once this is done I attach the routing template with double sided tape and route the neck pocket to a finished depth of 5/8"



the finished neck pocket looks like this (with a check of the depth utilizing a dial caliper)



I can now cut out the body shape at a bandsaw, leaving about 1/16" of excess material to trim off utilizing a body shape template and a pattern bit in my router.



more to come next time I get back out to the shop ...

all the best,

R

the next step is to cut out the body shape to its final detailed contour utilizing a full thickness body pattern and a HUGE 3/4"D x 2-1/2" long twist bit with pattern bearing. the makeshift base plate for my router really comes in handy for this step, as it gives me significant additional leverage and balance for the router ensuring I'll have a nice perpendicular cut. this set-up also allows me to route "climb cuts" out on the skinny horns - a technique that helps me to reduce the potential for tear outs. the full thickness template is temporarily attached with double sided carpet tape (3M make an excellent product that is about 1/32" thick - perfect!)



here's a close-up of the neck pocket area so you can get an idea of just how clean of a cut I can get with this set-up. with a sharp router bit, there is very little clean-up sanding needed on the perimeter curves




and since I can never resist when at this stage, I gave my neck template a test fit to see how the body was going to look with a neck attached ... not too bad, eh?




all the best,

R

I got the body front and back edges rounded over with a 1/2"R bit. American Cherry is quite sensitive to heat build-up from power tools, and you can see a couple rashes on the rounded edge. these will easily sand out when I start detail sanding the body ... but that time hasn't come just yet

also on the completion list this evening was roughing out the control cavity. using the same workflow as was used for the neck pocket, I roughed the control cavity to a depth of 1-7/16" using a 7/8"D Forstner bit and a drill press



I'll finish the control cavity with a router by using a plunge bit that has a pattern bearing mounted on its shaft and a template of the cavity. before I do this, though, I will lay-out the control knob locations and drill the pot shaft holes ... this will leave me a perfectly smooth cavity bottom when I come back and finish it up with the router.

all the best,

R

I got a little free-time to spend in the shop this morning, and progressed the body further ... and I got to play with a new tool!

once I had the tummy cut contour defined I set out to rough out the cut using an angle grinder (new tool!) loaded with a chain-saw like bit. in what used to take me about 30 minutes to rough out with a rasp, I spent about 5 minutes with the grinder.



once this was roughed out I used a spokeshave to fine tune the carving and give it the final shape



after this it I used a furniture scraper and sandpaper to give the tummy cut its final clean-up and edge rounding. I also sanded some of the edge round over rash marks off




I also broke out the drill press again to make the countersinks for the neck mounting ferrules. each of these requires two drilling operations - one to drill a 9/16"D x 3/16" deep countersink, and the second to drill a 3/16"D thru hole that the neck screw will pass thru. when drilling the countersinks it's important to remember that a loose fit on the sides is good - there's going to be a spray finish that will want to collect into the holes, and a loose fit makes for less headache when installing the neck later on. here you can see three of the ferrules sitting in their holes, and one ferrule on top of the body for reference (and the remaining hole empty) for reference.



as you can see in this image, the arm contour is also carved into the top face




once I have concensus on the control knob locations I'll drill the pot shaft holes and clean up the control cavity. my day-job is going to keep me away from completing this step of the project for the coming week, but when I return to it I'll wrap this step up and switch into sanding mode

all the best,

R

I'll detail the steps and offer up a few sanding techniques when I get to this step of working on the body.

I'll also be starting construction on the neck once I have the body finish sanded. I like to make sure everything fits snugly before going forward with finishing the body

all the best,

R

the next step is to test fit the neck and key hardware

here's how ...

all the best,

R

the next step is to apply the spray finish

here's how ...

all the best,

R

the final step is to buff and polish the completed body

here's how ...

all the best,

R

progressed Step 7 on the afternoon of March 29th 2008

R