Matching Cavity Covers

[brian d]

Hi all,

When you do rear cavity covers matching the back of the body wood, how do you get the grain to match up?

I can see that if you cap the back, you can cut out the cover before sticking on the cap to the body, but what tool do you use and how do you get a fine enough cut line without cutting in from the edge of the piece?

Thanks in advance,

Brian.

[Mattia]

Hi all,

When you do rear cavity covers matching the back of the body wood, how do you get the grain to match up?

I can see that if you cap the back, you can cut out the cover before sticking on the cap to the body, but what tool do you use and how do you get a fine enough cut line without cutting in from the edge of the piece?

Thanks in advance,

Brian.

←

A very fine kerfed blade? Scroll saw or similar? Alternately, slice a bookmatch off the back of your blank (1/8" or so), and you'll have an almost perfect match with a very tight fit. What I've done and will do again on bodies without caps on the back (because frankly, I don't much like capping backs. Mahogany, ash, limba, beautiful in their own right, and deserve a good showing off) is scribe around the pickup cover, use a dremel with a very fine bit to route through, clean up a little, and bind the cover to 'fill' the gap. Works nice, even works on carved backs (although it's a tad fiddly).

[stiggz]

well this isnt an 'exact' match, but have a look anyway, its very close though.

pic 1

i basically found a patch of wood further down the peice i used for the wings, cut a peice about 1/4 inch thick off that, and just rotated it till it looked alright, then cut out the cover and stained it.

luke

Edited September 6, 2005 by where's the beef???

[erikbojerik]

Scroll saw works great on back caps, or on hollowbodies where the back plate is thin enough. Make a small slice in the wood with an exacto knife or razor blade, then insert the scroll saw blade, fit the blade to the saw, and saw away.

I have found it to be a bit of an art when it comes to sawing straight lines. The temptation is to go slow to keep the piece straight and keep the blade from wandering, but too slow and you get all kinds of little undulations. Too fast and the blade will wander on you.

[frank falbo]

For a solid body you could always start with 9/4 stock and resaw 1/4" back from it. After resurfacing you'd have grains that were less than 1/4" away from your actual back surface. So you could then cut all your plates from the exact corresponding location on that piece. If you were doing a thinner guitar, then you could still start with 8/4 stock and saw it down too. Otherwise get some wood that's a "good match" and anyone who's "normal" isn't going to care about a slight mismatch.

[Marzocchi705]

i did that the same way beef said, works well but for the next natural cover i will resaw a slice of the back, this guitar is too thick at just shy of 2"...

[Devon Headen]

What I've done and will do again on bodies without caps on the back (because frankly, I don't much like capping backs. Mahogany, ash, limba, beautiful in their own right, and deserve a good showing off) is scribe around the pickup cover, use a dremel with a very fine bit to route through, clean up a little, and bind the cover to 'fill' the gap. Works nice, even works on carved backs (although it's a tad fiddly).

←

I don't quite get what you're saying. Can you try describing it a different way? Thanks

[jay5]

Im a bit miffed about mattia's method as well. The only way I can imagine it is with a semihollow body.

[Mattia]

Yeah, my method really only applies to previously hollowed out (ie, seperate top) bodies. I pretty much only build that way, so I tend to assume that as a given. Oops. The resawing method's the way to go otherwise, or if it's something like mahogany, simply a piece from further up the board can provide a good match.

My method, step by step:

1) Take guitar

2) Flip guitar onto its front, exposing the back

3) Mark out electronics cavity shape

4) Scribe around the line with a nice, sharp, new #11 blade do give the dremel something to follow.

5) Get dremel in a router base (like, your inlay setup) with the smallest diameter bit/end mill you can find.

6) Route along the line you just marked very carefully, taking many small steps. If the back is flat, I'd say make a template and use that

7) Once the cover's loose, clean up the edges, and add binding to the cover (or several layers of veneer, whatever works for you) so it fits nice and snug.

Done.

[Devon Headen]

Ok, that's what I thought after your first post. I don't get what the cover is screwed onto, though. If you cut a section of the back out, there's just gonna be a gaping hole underneath, right?

[Mattia]

Yeah, but gluing a few cleats for support is easily done.

[Devon Headen]

Touche.

OK, I'm through. I just like saying 'touche' .

[brian d]

Thanks to all for your help. Since I'm planning on having a cap at the back, I'll try Mattia's advice.

Excuse my ignorance, but what is a scrollsaw? From what I can tell, it works like a bandsaw with a small height. What is the advantage of a scroll saw over a bandsaw for a job like this?

Thanks,

Brian.

[Marzocchi705]

Scroll saw is much smaller.

[Devon Headen]

They are two totally different machines. A band saw has a circular blade that travels in a continuous downstroke. A scroll say has a short, straight blade that attatches above and below the table. The path of travel on the scroll saw is up/down, but it only cuts on the downstroke. The advantage of a scroll saw in this situation is that you can pierce the plate out of the back. There's no way to make that cut on a bandsaw without cutting in from the side of the plank.

[brian d]

Let me see if I understand you, Devon....

you make a straight slit with a (for example) exacto knife that pierces the piece that will be the back, somewhere along the cavity cover line.

then you put the scrollsaw blade through that slit before it is mounted on the blade. then you mount the blade on the saw.

start up the scroll saw and cut out the cavity cover.

Stick the back cap on the back of the guitar, and route the cavity.

Now you have a cavity cover that matches perfectly apart from a gap the thickness of the scrollsaw cut.

Is that about it?

Do you route the cavity a touch smaller than the cover to have somewhere to screw the cover to?

Thanks,

Brian.

[Devon Headen]

Sounds about right. Look at pictures of control cavity routs to get the idea of how it should be shaped to have wood to screw in to. The rout isn't usually the same shape as the cover.