I am an amateur level woodworker, looking to cut a curved recess into a piece of wood, which I will then be using as a "back" to display a drinks bottle, in a similar style to the picture below, but with the back curve of the bottle nestling into the recess shape in the wood. The curved recess therefore needs to be the same approx size and curve as the length of the bottle back. Any tips or suggestions much appreciated.
The curved recess therefore needs to be the same approx size and curve as the length of the bottle back.
If you're just making one, get some gouges and just carve the recess. Lay out the outline, maybe use a drill press to drill holes to the desired depths on a grid, and then get to work.
If you're making many, either buy a small CNC router to do the work, or buy or build a router duplicator so that once you've made one, you can quickly make as many copies as you want.
If you're making a small-ish number, maybe visit your local maker space or find a friend who has a suitable CNC.
If I was making 1 or 2, I'd take my angle grinder with a flapper disk (sand paper flaps) and just grind it out. Would probably start with a practice piece, takes a little getting used to the first time. But a 4 1/2" angle grinder should make a decently close arc for a wine bottle.
As Graphus pointed out, while this is probably the fastest way to get what you are looking for, some safety precautions should be considered and accounted for.
This throws a lot of sawdust into the air so you will want a well ventilated area and a dust mask, maybe some safety googles as well.
This is a high speed torque handheld machine. you want to make sure the piece you are working on is clamped down well so it won't move. The piece can be spun and shot across a work shop in the blink of an eye.
Once again it is a high speed torque machine that you hold and control with your hands. start with a test piece and get used to it. make sure you have the reversible handle attached and use it as well, it makes a big difference in being able to control where the grinder travels.
What you're trying to do is "cut a cove" in the wood. There are a multitude of techniques for this, but the most available is likely to involve a table saw. If you don't have a table saw, you could use a router. Either one of these power tools will likely have a multitude of videos available on YouTube showing how it can be done.
Cove cutting on a table saw requires moving the wood at an angle relative to the blade. Instead of the axis of motion being parallel to the axis of cutting, it will be at an angle usually between 15 and 40 degrees (could be more, could be less, depending on the "curve" you want). This will require a temporary fence set at an angle, and a great deal of fiddling to get all the positioning stuff exactly right.
Here is a video demonstrating cutting a cove with a table saw: https://youtu.be/vVlvwJelz9s
And here is a page that will help you print a chart of settings for cove cutting: https://woodgears.ca/cove/calculate.html (There is a link from that page to a how-to article on the same site for more details.)
Cove cutting on a table saw is very sensitive to the tooth bevel, if any. If you are using a dedicated ATB saw blade, you might want to change it out for a different bevel. A FTG blade, or ATBR/"Combo" blade, you will probably be okay. If you are just using the blade that came with the saw, it's likely a combo blade.
The take-away from that is that you should run some test cuts, and you should finish at least one of your test pieces, to ensure that you know how deep to cut and how much depth to leave alone so you can sand away any tooth marks.
There are three ways to cut a cove with a router. The first is to make the entire cut with a dedicated bit. These bits are usually pretty small - the overall width is probable limited to a bit over an inch, max. (Here's a 1" bit, notice the head/shank ratio.) These are okay for "fluting" but probably not what you want for gentle coves.
The second way is with an edging cove bit. This bit comes with a guide bearing at the end of the bit and is intended to ride along a smooth edge, cutting a cove shape along the edge. (Here's an example. ) Because these bits can be quite wide, you will generally find them with a thicker shank and you will have to slow down the router speed when using them. (If you have a "one speed" router, you might be able to find an external speed control for a plug-in unit, or you might have to buy or borrow a different router. This is no joke: using a wide router bit at too high a speed can result in a really angry piece of sharpened steel flying at your face. Don't do it!) My suggestion with this setup would be to split your wood in two, use the cove bit on matching sides, and then glue the pieces back together. Be aware that for best results with these bits, you'll definitely want a router table setup.
Finally, a third way would be to build some sort of sled or jig to let you "swing" the entire router body like a pendulum. You would then use a simple square bit to do the cutting, and move the entire thing along the wood a little at a time. This would let you do the cutting on any kind of router (almost - unusual body shapes might make it hard to build an appropriate jig, or to balance it) with just a cheap, common bit.
