How to CNC machine table legs in wood
CarveTech machines sculptured table legsUSA-based woodworker CarveTech specializes in complex 3D artistic wood carving for kitchen cabinets and other types of furniture. Both rotary carvings and flat stock carvings are possible, allowing even the most wild designs (Queen Anne legs, claw foot table legs, sculptured table legs, etc).
Various table legs made by Carvetech.
A specialism of CarveTech is the production of table legs that are machined from four (or more) sides. This is done using an indexer (rotation axis) on the CNC machine, and allows various designs. For instance round legs with a relief, sculptured square legs, 'Queen Anne' type legs with and without claw.
The pictures above show some examples.
The leg is designed in 3D, using a CAD program called Moi3D. This picture is an Moi screenshot.
The design of each leg is done in 3D, using a CAD program called Moment of inspiration, see moi3d.com. CarveTech are very enthusiastic about the ease of use that Moi offers, allowing them to create these complex designs much quicker than with the CAD software they used before.
The toolpaths shown above are Offset toolpaths, where the cutter follows the outer contours of the geometry.
It will be clear that for CarveTech the rotation axis support is a very important feature of DeskProto.
The alternative would have been to wrap a 2D design round a cylinder (as offered by other lowcost CAM programs), however CarveTech found that this approach comes with some serious disadvantages:
- Wraps seams are never perfect.
- Many 3D designs are impossible.
- Wrapping will cause staircase effects on steep walls.
DeskProto will create toolpaths round a real 3D model (both indexed and continuous rotation are possible), which allows far more complicated geometries to be machined.
The leg is machined from four sides, this photo shows the machine while finishing the fourth side.
The large machine shown above was originally made by CNC Conversion Kit, and was later customized by CarveTech to satisfy their needs. As you can see it is a great design for machining table legs, with it's long rotary axis, while large flat parts can be machined as well without having to remove the rotary axis.
Video on YouTube about the new Offset strategy in DeskProto V6.1, showing this leg being carved.
When machining series of a product, like in this case a series of four legs, keeping the machining time low is more important than when machining just one product. CarveTech keeps machining times low by playing with different strategies, ambient skipping, freeform segments, and other options that DeskProto offers.
Detail picture: the lowest part of the leg
The legs have been machined in hard maple wood. The beaded corners play games with the light, which makes the result a clear eye catcher. The result can be made even more pleasing by applying some wood-oil or varnish, as that will make the grain of the wood more visible.
Three maple legs standing upright.
For indexed machining it is VERY important to set the machine's workpiece zero point with the tip of the cutter EXACTLY on the rotation axis. Any small deviation here will be visible in the results.
Eight low table pedestal legs(10" x 10' x 22"), in Red Oak wood.
A few more pictures showing great results made by CarveTech, machined in wood using DeskProto.
Two custom carved corbels (consoles), in cherry wood.