Axing the Knife: CJS Millworks

CJS Millworks of Stamford CT was gaining a reputation for being the shop to turn to for difficult custom millwork pieces: smooth, such as pieces with radii along curved edges; intricate pocketed table tops; lattice work with 3D perspectives, etc. Some of these pieces, however, required very time consuming knife cutting with a shaper and this approach was not cost-effective with the low volumes that were frequently requested. The company wanted to find a way to use its CNC Router to eliminate knife cutting for all but high volume work.

Mastercam Router was chosen because its automated Swept 2D toolpath was ideally suited for projecting full profiles along a radius using a small standard cutting tool. Programmer Steve Scenna, Jr. said, “This blew the whole thing wide open. First, we didn’t have to buy a $200 or $300 knife every time we wanted to cut a profile. More important, instead of spending days making templates, we were spending just hours writing programs for our CNC Router.”

For example, an architect asked CJS Millworks to create a rectangular table with a very intricate deep cut pattern in a tabletop made from handpicked reclaimed white oak. The design, which was given to CJS as a photograph, called for cutting an extensive pattern of very deep pockets in a 2” deep tabletop. The pattern was drawn in AutoCAD and imported into Mastercam. Ramping was used to make the pocket cuts less aggressive in order to avoid the potential for chipping. Swept 2D was used to create the movements for cutting all of the radius edges with a fluting bit.

Scenna estimated that creating this tabletop prior to implementing Mastercam would have taken several days. With the CAM software it took several hours to program the CNC Router and about an hour to cut the tabletop. To see the tabletop actually being made check out “Screen To Machine” on YouTube at

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