Looking for some help contouring and rounding off a body blank

5redlights

Hi 

I've got a bass body from booboo guitars that I need to do some wood work on, and was looking for some tips. It's a slab body, and I'm looking to put in a belly cut, arm contour (maybe) and round of the edges, as they're square at the moment. 

Equipment wise, I've got a sheet sander and a dremel. Looks like I'd need to buy a saw rasp for the belly cut, which is fine. Using this equipment, is it just a case of taking it slow, or are there any particular tips anyone could help with? 

Thanks 

TTony

I use simple rasps for belly cuts ...


https://www.axminster.co.uk/microplane-handled-rasps-package-deal-717368

Followed by lots of sandpaper.  And then some more sandpaper.  You'll make a real mess of the body to begin with, but trying to make finer cuts as you get closer to the final shape, and then lots of sandpaper should ensure you end up with a nice smooth belly cut.  You can also you the cabinet makers scrapers for the finer cutts



I've also got a square version of those microplanes, which I use when I want straight cuts - as you might want for an arm contour.   I find them really efficient/effective, though other rasps are available!


For body roundovers, the a router + roundover bit.  The bits come in different sizes, so you can apply anything from a barely noticeable to a definite roundover - or even a combined roundover & ledge like this;



I'd not try doing that without a router.  Just be extra careful when you get to the horns - there's not so much body there to support the router, so you need to concentrate on keeping it flat and against the body & edge.

WezV

Any kind or rasp will get you there, but the shinto saw rasps are quick.

They are not the best for the gut cut as it's a concave carve with a flat tool, but you can do them that way at a push, better to use a half round rasp for the deepest section of the cut.


Another method is to draw the outline of the contour on back and side, and saw slots between the two lines.   You can then chisel away the excess.  Will see if I can find a vid in a mo 

Many ways to skin a cat

randella

The arm contour isn't a compound curve - it falls away in one direction only.  The start of the contour, on top of the body, is a straight line.  Look at a Strat closely, you'll see what I mean.  The curve doesn't follow the outline of the body, it only falls from the top of the body to the edge.

Two things help with this - a flat piece of scrap wood (bit of ply or MDF is fine) as wide as the countour, onto which you can stick sandpaper and use as a big, flat sanding block after you've got close with your rasp.  The other thing is a straight-edge.  You should be straight - along the width of the contour - from the top of the body all the way down the curve.

As you're sanding, scribble all over the area with pencil so you can see any low spots, feel with your fingertips, remark with pencil, rinse, repeat.

It's very satisfying when it's done - take your time, make sure you know what you're gunning for, mark it out accordingly, keep checking.

Danielsguitars

I think I did nearly all my contouring with a Shinto rasp last time followed by different blocks and grits of paper 

I did use a Japanese half round rasp for the cutaway contour I did

Roland

My approach is similar to everyone else’s. First draw the edges of the chamfers in pencil. Not only does this show you how far you want to cut, it also helps you see what angle the slope should be. As @randella says, it’s not a simple curve. 

I use a curved rasp to remove the bulk of the wood. Pictured is a handmade one which I picked up at a woodworking show. It has the advantage of irregular teeth, so does cut grooves the way a machine made rasp does. As you can see, it leaves a rough surface which you need to sand out.

For the forearm chamfer, and the two ends of the belly chamfer, I use a spoke shave. You can see at the top of the picture that it leaves a smoother finish. Unfortunately I can’t use the spokeshave on the concave curves because it tends to dig in. 

There’s a tendency when sanding to round the edges, but not touch the middle of the chamfer. To combat this I use the rasp right down to the line on the concave curves. For the convex curves I make flat sanding blocks by sticking sandpaper to wood blocks with double sided tape. For sanding the concave curves I stick it to round dowels.

HilditchGuitars

I did my first gut cut with a half round rasp, took some effort on the Sapele body. The Shinto saw rasps are a very good way to remove bulk quick, and you can get somewhere near the curve by rotating it as you cut. I like the saw and chisel suggestion above actually, I bet that's a pretty quick method.

You can round the edges with all the above mentioned hand tools too, more labour intensive but if you have immediate access to them why not? A router is undoubtedly the quickest and most consistent method, but they can be big investments.

I use a plane to start my forearm chamfer, then finish off with rasps etc.
A good way to help remove some of the deep gouges left by the rasps is to use a file, you can even be quite detailed in shaping with them. Then you can use 80 grit to sand to shape before moving through the grits. Valid point on sanding blocks too.

guitargeek62

For rib contours I preferred using an angle grinder and flap sanding disc. You just have to be a little careful as it’s very easy to over-do it and go too far! Once the bulk was off I’d tidy it up with scrapers and sanding, simples I used the same approach to take most of the material away from forearm contours too, but then finished those with a wide flat sanding block to ensure the contour was as it should be