How do you make a Grain-Matched Control Cover?

[Gilmourisgod]

I'm about to start my second build, I'd like to attempt to make a continuous grain matched rear control cavity cover, where the cover itself is cut directly out of the back wood. Something like this:
Homebrew


I have this Stewmac control cavity template set:
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I can picture running a fine dremel around the inside perimeter of the template to cut a fine cavity-shaped slot in the back wood, and then maybe cutting it out with a coping saw, but I figure you Crafty Bast*rds have an ingenious technique for doing this. If so, please school me!

 

[Jisch]

I've done matching covers on my last two basses, there are three ways that I can think of:
1) find a piece of wood that closely matches (or is a bookmatch of) the body wood. If you have a solid body with no top and don't want the cover to go over the edge of the bass this is your only option

2) If you are ok with the cover extending over the edge of the instrument, then you can cut a slot into the body from the side, cut the inside edges out from the back and slide out the piece of wood that will be used as the cover. I guess I'd use a fret saw or something with a similar, thin kerf.

3) if you have an instrument with a top and a jigsaw (or maybe coping saw), then you can route out the control cavity from the front, then drill a small hole somewhere along where you will cut. Feed the blade through the hole and cut out the cover. In this case you will have to glue in some kind of supports for the cover (I've been using magnets). You can see it in post 12 and 13 in this build: Four string fretted bolt on

I hope that helps and curious to see if anyone else has thought of a better way.

 

[Rôckhewer]

Alex, you have seen a few of my builds, right?

All these I did by very carefully following a fine line with a fine scroll saw blade . By drilling tiny hole & feeding blade through.. & then tighten it in the saw.
The line doesn't have to be exactly perfect. Just really close.
You can have a heavy 1/16" gap all around... and when you shoot the finish on...just make sure to get some around the edge of the cover.
You will actually have to sand it to fit back in.
Ok, that doesn't apply with a natural finish.
That one I did I was just extra careful.
If you don't have access to a scroll saw... a coping saw might work... but it is very hard to saw that true of a line, by hand.
That is how I did this one that I had to wrap with a strip to "fix" it.:

I'm not too proud of that one.

BUT....if you use a jewlers saw!!...super fine blade! you will have such a small kerf, that when you sand out any wobble....it should be just about perfect.

There is another way I know of that is completely different.
That is when you aquire the wood for the back... make sure there is enough thickness to resaw an extra panel out of it for the side your cover is on.
Then you can hack out the hole any ol' way...and uss the extra piece for the cover. It might not be perfectly matchable...but it will be really close.

 

[Gilmourisgod]

Thanks for suggestions! I don't have an electric coping saw, but the jeweler's saw might work. I was picturing you guys using some kind of sleeved pattern bit or fancy overhead router, maybe I'm overthinking it. If I ran a dremel around the inside of the plastic template, it would probably melt. I may try an experiment using the plastic template to make a wood template in the shape of the cover, and running a dremel around the OUTSIDE of that wood template to cut a 1/16" slot that would "liberate" the island of wood that become the cover. Per usual, some practice on scrap mandatory.

 

[Jisch]

I don't have a lot of dremel bits, but the ones I do have wouldn't do a very good job of cutting like that. I can't imagine getting a 1/16" bit cut through wood sideways like that and have it be a clean cut. You could use a bigger bit and wrap a piece of wood around it like RH did up there. With a bit, it would be a consistent seam.

 

[Rôckhewer]

Actually...the dremel thing might just work.
I have a tiny 3 flute carbide bit that cuts smaller than 1/16" kerf. I use it for inlay.

And when I cut pickup routes, I use a template that is MDF with the edge saturated with CA glue.
The shaft of a 1/4" bit rides right against it,
....no bearing, no problem! I have used it like 5 times with no deformation.
That might be something I might just try for my next e-cavity cover...

 

[I-Am-The-Slime]

Here's my amateur take on a "fancy overhead router" I wrapped the cover with veneer to regain the wood lost in the rout

I was working on the control cavity cover for the double-cut this evening.

I drew out the shape based on the cavity already cut in the core (see above). The position of the walnut top (well, bottom, actually) in relation to the core during glue-up will be set with screws in the "nubs". The battery for the preamp will be partly tucked away.

I was inspired by this video to use my drill press as a router


I used a finishing nail with its head cut off and the tip cut at ~45 degrees as a bit

Made a template from a piece of scrap and went at it (max speed) with passes about as deep as the point at the tip

And the result (I plan to add maple veneer binding to the cover)

 

[Gilmourisgod]

The CA saturation might work, I was wondering how to keep the dremel from eroding or burning the template. I have a spiral downcut 1/8" bit I used on my inlays, probably too big. Stewmac sells dremel bits for cutting binding ledges that have no bearings, so its not completely cockeyed.

 

[Jisch]

I'll have to check that out, it would be better than using the jigsaw from an accuracy standpoint.

I just looked at the bits at Stewmac and this is what I would worry about:
"Use the larger bits for removing wood in the middle of your inlay work, and save the fine bits for the fine details. The fine detail bits are fragile, for routing intricate details only."

Would they be up to the task?

 

[Gilmourisgod]

Distinctly possible they'd break, think of it as a study in physics. Science! I've had a teeny one break on me, so light that even moving at the speed of sound, it did no damage to me or the wood. Mass x Velocity = Blah Blah Blah. Worth a try at any rate. The one I broke had the tiny little grinder ball on the tip, which just vanished, a 1/16" straight shaft spiral upcut should survive, I'll let you know!

 

[Jisch]

I would be more concerned about the bass than my personal safety, although eye protection would be a very good idea during the experiment. If it broke half way through the cut I think it would be difficult to recover elegantly.

 

[fhm555]

Maybe this would work better than a headless nail?

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[Gilmourisgod]

Maybe this would work better than a headless nail?

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Or better yet, this one:
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You'd have to make the template slightly undersized to account for the 1/4" shaft, but you could chuck that in a regular router and have Boatload's o' Power (another good band name, BTW). I don't know which would burn the template more, probably the 1/4" shaft, but for a one-off control cavity, maybe who cares.

 

[Rôckhewer]

This is where I get bits .
Typically used for CNC where you can precisely control the speed and feed rates to minimize bit breakage. But they can be used with a Dremel router base too if you are careful.
They are 1/8" shank & go as tiny as 1/64" kerf for a 3 flute bit.
Granted the depth of cut ability for a bit that small isn't going to be very substantial... but you also don't need to go that small for a e-cavity cover kerf.
Their 1/16" bit has a 0.3" depth of cut which is plenty... and is only $12
You could go smaller.... not cut all the way through...and easily finish the cut with a jewlers saw following the precise kerf you made with the bit.
Piece of cake!
Carbide 3-flute End-mills for Hardwood and Composite Cutting

 

[Gilmourisgod]

Thanks Rock, that's what I was picturing, a shallow cut just to get a nice outline, then deepening by other means. The next build will have a figured walnut cap, so I can cut through the whole depth of the body for the cavity, then cover over with the cap.