I’m very new to wood working, I’m working on a wooden knife sheath and I’m unsure what the best way to go about carving out the inside of this wood would be? is there a tool that would do it with precision?
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This looks like the perfect job for the Shaper, and Shaper trace. Perhaps @tomthm and @TravisGood could weigh in.
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Oh yes, you nailed it. The Shaper products would do almost all of it very nicely. Let’s break it down as James suggested.
Shaper Trace: First you trace the knife on paper. This outline then gets converted into vectors using the Shaper Trace app and the Shaper Trace frame. Check out the videos on this product page.
Shaper Origin: The vectors get transferred to this handheld CNC for cutting. This would require you taking the class from Tommy but it’s a worthwhile as the tool can be really handy to use. You can get a feel for the tool cutting pockets here.
Lastly, to finish off the job you’ll need to use a chisel. The two sharp points of your knife can’t be cut to such a fine point using an end mill as any bit had a radius. It’s simple to do but it’s an essential step if you want a perfect fit.
If this sounds interesting then look for Tommy’s next class.
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From what I know of the Shaper Origin, that’s the most purpose-built tool for the job.
That said, I’ve done very similar things before by creating the desired shape in plywood (cut by hand or laser) and then using it as a pattern on a router with a pattern bit to remove what you don’t need. It would have to be a very short bit or a fairly thick pattern material, but it’s doable. Alternatively, possibly easier, is to use a router bit with a bushing, like in this video.
And if you don’t feel like trying either, I think a very cool touch would be cutting out a very thin piece of contrasting wood and sandwiching that between the two sides of the sheath. That way you create a very thin space where the blade is going to sit, rather than trying to hog out a shallow space. Basically like a welt you’d see in a leather sheath. Here’s an example from this video before glue-up:
The last idea might not be a bad one since you already have the body pieces cut to size. Clamping them down to use with a router will be tricky (I personally don’t know how to use the Shaper Origin and can’t tell how it would deal with smaller pieces of stock).
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@TravisGood great description. Does Asmbly have a Shaper Trace somewhere in the space? Sounds like a handy item I’m sure I can find a use for in the future.
Now that I think about it, I’m not sure. I had one at Asmbly but it’s now in California. Dave used to have one we could use but he’s no longer a member. @tomthm would know best. If we don’t have one then at $99 it’s a relative no-brainer. Perhaps Tommy or @jamesfreeman has the budget for such an ad-on.
I have a Shaper Trace anyone is welcome to use. As it produces SNG files that can be used for a variety of tools, Asmbly could really use one. I’m on it.
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I really like the last idea but I don’t want to cut the plank in half anymore. What’s the point of the router pattern could I not just do the inside by eye it doesn’t need to be perfect?
Routers aren’t safe tools to use freehand, so you cannot do it by eye. You need a pattern, a fence, a bushing, etc. to guide the router to use it safely.
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You’re right that it wouldn’t have to be perfect at all, but like Ethan said: using a router without a pattern/bushing combo is… dicey, to say the least. It might be OK on a large flat piece, but it looks like your planks are maybe 3-4" wide? Even with a pattern, holding the piece down and providing good support on the sides would be a challenge.
Just to clarify the “middle section” idea: I’m not suggesting you resaw the plank you already have, but to add a third one instead (maybe from a different, contrasting wood species if you want to accent it). Admittedly, it does involve milling more wood to a thickness of maybe 1/8" or so, and then cutting out the blade shape by hand (or bandsaw if you’re good on it). And, of course, you’d need to like the aesthetic itself. If you really wanted to make the sheath look seamless it’s not the right solution.
So yeah, it’s a matter of safety and ease. By no means do I want to discourage you from taking a class like the Origin – I’m looking forward to taking it myself. It’s just that the sandwich approach is something you can knock out in under an hour starting with a blank board.
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I’m going to go against type here and ask… how much precision do you really need, given that you won’t see 90%+ of the surface area? Are you looking for a friction fit on the sides of the blade? If you want to go the router+template way, workholding may be difficult. You might be able to 3D print something with a template and some extra clamping spaces. But I would actually recommend something else for this: a chisel and mallet.
Here’s one of my favorite youtube metal-forgers (not a woodworker!) making a sandwich-style handle: https://www.youtube.com/watch?v=2kygsSfN3EQ
The approach is pretty simple: trace, carve shallowly, test fit, repeat. It can be time consuming but meditative! The bonus is you really don’t need much workholding: 2 bench dogs on the end vise of the artisan workbench would be all. Just take your time, test frequently, and sneak up on exactly the fit you want. You can even switch to sandpaper once you’re close to dial in the fit you want.
And if you slip up and gouge the surface inside the sheath… there’s no impact on your finished project! You get to learn and hide your mistakes at the same time. 
I could also see this being done to a more consistent quality with a ‘router plane’ - but that is a tool I have limited familiarity with, and I haven’t seen one around the shop.
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Adding to the Shaper Trace convo:
I own a Shaper Trace, it’s great but the Trace is tied to a Shaper account. I don’t think you can download the app and take a photo on someone else’s Trace / a shared makerspace Trace.
Hopefully I’m wrong about that, but that’s been my experience using mine.
to do something similar recently, i traced an object on graph paper and scanned it using the scanner of the multi function printer in the textiles room. i have no idea how to scan in windows, but that scanner shows up in linux and works if you are on the wifi.
there are also many open source tools and plugins to turn the trace in a scanned image into vectors without purchasing a shaper trace.
You were correct about Shaper Trace. It’s tied to an account but anyone can now setup a Shaper account for free. Once you have that you can also use Shaper Studio which is now free (though the website doesn’t yet reflect this). With this account you can sign into the Trace app.
The Trace tool is much easier to anybody to use nowadays.
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