Recurve bow (1) – Hand grip

Since I seem to like making ‘weapons’ (see here and here), why not add a bow to the list? I’ll do this one in 2 parts; First the hand grip (riser) and later on the 2 limbs, which I admit I’ll need to do some research on.

I did not create the design myself, all credit for that goes out to the original designer over at GrabCAD.

Now, because I didn’t want to ruin a big block of expensive wood, I decided to do a test carve first with a piece of free salvaged lumber. I had no idea which kind of wood it was, because it had been painted pink. But it had the perfect thickness and width, so all I needed to do was cut off the required length. Turns out it is some kind of laminated ply, but as a beam instead of the usual plywood sheet. Not that it matters, in fact I usually like the layered look on organic shapes.

Cutting time! First a roughing pass to hog out most of the material, then a profile cut most of the way through, but not completely. Finally a finishing pass.  Then turn the stock around, align with dowels, rinse and repeat.

Roughing & profiling:

Parallel finishing:

All done!

I cut out the part with a hacksaw and did some sanding and cleanup here and there. This was scrap wood after all…

Overall, I like how it turned out. I’m not sure if I’ll even make another version with better wood. In any case, it feels really comfortable and doesn’t weigh all that much. And I’m sure it is plenty strong.

Just as a test I timed all the different operations to see whether the RhinoCAM estimates were somewhat on point. Most freeware apps I used before were way off, and usually in the negative way. But RhinoCAM seems to be pretty close, with real-life even being slightly faster. That’s good to know! As a reference, I also checked the estimates of Basic CNC Viewer, a simple gcode viewer app that I often use to visually check my toolpaths before committing to the CNC.

RhinoCAM
estimate
Basic CNC Viewer
estimate
Real-life
cutting time
Recto
Roughing 43 mins 41 mins 39 mins
Profiling 24 mins 22 mins 23 mins
Finishing 55 mins 55 mins 53 mins
Verso
Roughing 16 mins 15 mins 15 mins
Profiling 13 mins 12 mins 9 mins
Finishing 42 mins 42 mins 38 mins
TOTAL 193 mins 187 mins 177 mins

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