As the CNC guru where I work, the thing that challenges me most often is: How are we going to secure that piece of wood to the bed of our CNC?

 

All our CNCs either came with a t-track bed, or have been modified by me to have t-track slots for clamps or jigs that can hold work in place.  Most store-bought clamps hold work DOWN, but it is often more important to keep work from moving sideways.  For that I've designed clamps I can cut out using the CNC which hold work by the top AND the side. 

 

On occasion I get project boards that will have something cut on the entire top surface.  Any clamp I might use would be in the way of the spinning cutter.   One solution (not my favorite) is to break the job into two or more tool paths.  Each should leave room on the top for enough clamps to hold the work down. When the first is done the clamps are moved for the second tool path to cut where they used to be.   A solution I've been using more of lately is to have the students hot-glue their project board to a slightly larger (1" extra around the perimeter minimum) scrap board.  The glue holds the project board to scrap.  The scrap then is where clamps are applied to hold all down and in position. 

 

I also am challenged to affix large and/or unusually shaped things to the CNC bed for some CNC work. The bed of our Probotix CNCs can be removed entirely to expose a t-slotted extrusion frame.  Using drop-in nuts I've been able to mount an array of different jigs/brackets/fixtures to that frame which then let me clamp onto the unusual part. This adjustable angle clamping jig (and a larger version I use where I work) clamps to the front rail of the CNC frame and has let me cut most unusual things.  That jig can be clamped at any angle between 90 (vertical) and 0 horizontal) and work can then be clamped at any angle on the face of that jig.

 

I had to cut a mortise array 4 times on the bottom of an assembled student cabinet project as a solution for mounting her tapered legs to the cabinet.  To hang her cabinet under the CNC I made bridging supports that spanned from side to side, bolting into the frame on each side.  Photo below.  LINK to the blogpost about it.  

 

Each semester brings new challenges.  The reason I chose CNCs made by Probotix is the potential their open frame design brings.  I mount their CNCs on a simple frame with no top surface.  This leave the volume beneath them open to the floor for whatever challenge may yet come. 

 

4D

 

  

Good info. Thanks for sharing.

BTW, all the joinery on that cabinet was also done on the CNC.   Half blind dovetails on the bottom corners.  Tapered french dovetails between sides and the top. Tapered french dovetails between shelf and sides, and small dividers between shelf and top.   The circular pin (tenon) array holding the legs to the bottom is an original solution designed initially just for this project.  The student didn't want any hardware showing.  Bottom shelf is only .5" thick. Pins are .4" long, cut in the end grain of the legs.  The tapered legs were also cut on the rotary axis of our CNC.  Clamped at an angle under the router to cut the pins out.

 

4D