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ZMB psyks

Cavity Cover Madness? Woodworking Question

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IM000973.jpg

I was reading the thread about magnets instead of screws or whatever and I looked at this photo. It's obvious that the cavity cover was made from the same piece of wood as was covering the cavity before there was a cavity... if that makes sense.

But how the hell? is there something I'm missing. Sorry but this seems impossible to me or maybe it's really obvious and I'm just blind.

cheers

ZMB psyks

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IM000973.jpg

I was reading the thread about magnets instead of screws or whatever and I looked at this photo. It's obvious that the cavity cover was made from the same piece of wood as was covering the cavity before there was a cavity... if that makes sense.

But how the hell? is there something I'm missing. Sorry but this seems impossible to me or maybe it's really obvious and I'm just blind.

cheers

ZMB psyks

It took me a moment too. That a laminated top. The builder cut out the cavity all the way through the body, then applied the top.

The builder must have added some mounts after the hole was cut for the cover to rest on.

It's very very nice work.

-John

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Yep...the body is face-down. Most likely the builder routed out the cavity but not all the way through, just leaving enough thickness for the cover.

Notice the gouge in the back? That's just enough room to insert the blade for a scroll saw to cut out the cover. Then most likely he installed supports inside the cavity to hold up the cover and hold in the magnets.

I wonder how he's going to fix the gouge....

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or he thicknessed the body using a router jig so he could leave the cavity cover section higher, saw it off - relevel the body and have a piece to cut the cover... the way setch showed us

He has a great match on that piece... the method i suggest wont get a good match on a flatsawn body but that looked pretty well quarter sawn to me so could be the way he did it

hopefully he will come by and let us know!!

I think he did it this way because the other picture shows he hasnt had to add any more supports inside

IM000733.jpg

i will PM him to make sure he sees this thread

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oh, and i think the gouge is on purpose - otherwise he would never get that cover off!!! I have done similar things on some of mine before - a bit smaller though

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all those theories sound good. I hadn't noticed the thin top... on the... bottom. I thought it was one piece. Meh, I have eyes don't I ??? *checks eyes*

I wonder how he actually did this though, should be interesting to know.

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oh yeah, that would work wezV, thanks

So he just cut thin slices from the back of the body, up to the right thickness obviously, then just routed them out... genious!

Edited by ZMB psyks

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This is simpler than it looks. The cover is cut from the same piece as the body so that the grain is near perfect. It is easier on quartersawn straight grained woods to do this and you can see the results in these pictures. It looks like it is the same piece but it is just the next consecutive slice of wood from the body. The route is done from the back (like normal) and the depth is set to the same depth as the cavity cover. The gouge is to get your finger in there to pop the cover off when you need to get inside.

~David

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wez's idea is right. that is jasons guitar and he explained it to someone one time that had that exact question. he thicknessed the back with a router, except for the part that would be the cavity. i remember he took it down 3/8" i believe. the he took a japanese saw and cut it off.

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The way it was done was how everyone described it. There are easier ways, however at the time I didn't have resaw equipment, so I basically needed to route down the thickness on the body as killemall said about 3/8" I think and just left a raised section that I cut with a japanese handsaw, they are flexible which enables you to get a fairly flat cut against the body. I would suggest leaving an area as big as you can cut, so you can properly align the grain. I'll post a couple pics of the process, I didn't really have much equipment at the time, so I kinda just made due, worked out though.

stinky zebrawood chips

Done routing

Handsaw the cover

Starting to clean up body and cover

Pretty close on the grain match!

Designing cavity and cover templates

Laminating cover for extra stability

Routed and test fitted

IM000639.jpg

Honestly, the only reason I put all those pictures is because I took hundreds of photos while working, so I might as well use them somewhere. As I said, I didn't have many tools or money at the time, so it is what it is and there are better ways to go about it I'm sure. I just posted pics to show how I did it, I would definitely look to the advice above from some of the other posters as there is more experience there. This project is getting close to being finished, slow process for me, but its enjoyable. The notch was done to remove the cover, thankfully I remembered to do this before gluing on the top, wheew. I saw a few guitars with small notches and honestly, from a short distance it looked like some kind of dent or knot, so I kinda made it more of a noticeble feature as I prefered this look, should look better when finished. With a somewhat thick wood cover you need some notch otherwise there's no getting it off, especially when its snug and overdone with magnets, didn't need that many. Thank you Wez for the heads up, probably would never have seen this thread. J

Edited by jmrentis

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one way i was thinking about doing mine was to do this. get my body to its rough shape, flat sand the back. make sure the front is pretty level (if your doing a carvetop, do this before you carve the top :D)

then get a bandsaw, and resaw a maybe 1/8" peice off the back of the guitar. (works well for through necks :D) then get rid of the bandsaw marks on the new back of the guitar, and you are free to cut out your cover B)

its an idea though

DAM i just read what was adressed in that link

near the same idea :-p

i guess i dont have all the good ones!

Edited by Kenny

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Hey jmrentis, that was an ingenious way to do it, considering your resources!

Edit: I just typed out the same thing Kenny said right above me! :DB) And that was yesterday. Man, I need to make sure I read everything before I reply, anyhow, if you feel like reading it anyway... here's my method. :D I'll be trying this on my next instrument.

You can take a body blank with plenty of extra thickness to a mill shop and have them resaw a slice off the top that is the thickness you want your cavity cover to be (I'd probably have them go a little thicker, then clean up the cut with a surface planer or sander if I'm in the mill shop anyhow). Then you simply route your cavity and cut out the cover from the matching grain on the thin slice you had made. This will eliminate the need for lamination, but requires that you have enough excess wood and resources to do the resaw. Quartersawn Black Limba is an ideal wood for this as the grain is so pronounced and stays somewhat even through the thickness of the board. This also means that since you'll have a full size 1/8 inch or so slice of your body wood, you'll have plenty left over for headstock overlays, inlays, etc, rather than routing it away. :D

With my resources, I prefer a mill shop to the home band saw for 2 reasons:

1) If you've already glued the body blank, it may not fit into the bandsaw you have. You could fix this by just cutting a slice off of half of the body blank before you glue it up, then planing both to be even again before you glue up. It's all about planning ahead! Something I'm not always good at... B)

2) because the resaw blades at the shop are wider and produce a cleaner cut, you'll have less waste. This is only important if you have a marginal amount of extra wood to work with.

Edited by Bassisgreat

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Here's another example to supplement Jason's pics.

Cutting the covers:

12_preparing_covers2.jpg

Final result:

65_back_closeup.jpg

Like Wez pointed out, this is easier on a well quartered body, but if you cut the blanks oversize you can get pretty good results on rift or flatsawn bodies too.

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