For practical use or shop decoration
15"-16" saw blades, can be
purchased or use
bandsaw blade cut-off
Example pictures: Birdseye Maple and Claro Walnut
Single model .crv files with tabs
2-sided 3D carving
Download also contains .stl and .dwg files
and full-size images
Windlass toggle locks with button into
stretcher part. Hemp twine as bowstring.
Cheeks (uprights) are made from 2 doweled halves
No mortising or drilling required, all parts can be cut on CNC
Front and rear handle are also glued from 2 halves and capture the brass pins
Sanded and buffed on the lathe (could be done in a drill press as well.
FEA for 1000N (225 lbs) string load
Max stress ~25N/mm^2 (3600 psi)
Sufficient safety factor 4-5
16.25" Strip of 15tpi bandsaw blade
Ends 1/2" annealed red hot to soften the hardened steel
Drilled with 1.2mm bit
Small finish nails hammered in with interference fit.
Clipped to fit the brass pins
Some tips and instructions:
The bottom side roughing toolpath for the cheeks is done with a ¼” endmill bit for speed reasons, everything else is done with 1/8” endmill and 1/8" ballnose bits. To save the bit change one can of course go to 1/8” (much slower) but then the allowance should also be reduced to save the unnecessary cutting time.
Both .crv files reference z-zero from the material surface for all top side toolpaths and from the spoilboard for all bottom side toolpaths. The toolpath for the spoilboard dowel holes (flip alignment) is also referenced to the spoilboard as z-zero
The dowels for flip alignment as well as for the cheek gluing are all 5mm bamboo rods (a.k.a. marshmallow sticks). This can be increased to regular ¼” dowels but it will take some essential material away.
The handle pins are 3" x 5/16" (M8 x 80mm) partially threaded and decapitated brass bolts (easy to slot with a hacksaw) with the threads glued into the handle. But regular partially threaded 5/16 steel bolts (hex or carriage) would work just as well.
If the blade is only 15" long (can be purchased from Highlandwoodworking.com), the pin length extending from the handles should be 1/2" longer
How to use it properly:
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