Open Source Folding Ping Pong Table

This article will guide you through the creation of a fully functional folding ping pong table made entirely from CNC cut wood panels;

It's an advanced project and many basic CNC milling and woodworking techniques will not be detailed here as we feel that you already know them.

The project is intended to be cut on a full format CNC machine such as the Mekanika FAB model, as many of the parts are too large for desktop models.

Although it is possible to cut these parts on smaller models using the tilling technique, many adjustments to the file would be required and this guide does not cover this technique (yet).

The tutorial is also available as a video:

Download the files used in the project:

• 3D Files (.f3d & .obj)
• G-Code files

2x 18mm plywood panels 
1220 x 2440mm minimum
For the table structure. It can be any other type of panel, but we recommend plywood.

 
1x 18mm plywood panels 
1530 x 3050mm (or 2x 1530x1530mm)
For the table top. It can be any other type of panel, but we recommend plywood.

Hardware

• 12x M10x 100mm screws
  (or M12 if you're not using steel tubing)
• 12x M10 locking nuts
• 24x M10 large washers
• 4x Ø12x72mm steel tubes (Ø10mm hole)
• 8x Ø12x54mm steel pipe (Ø10mm hole)
• 1x piano hinge (L1200 x  H34mm max.)
• 4x swivel wheels (100mm high)
• Optional: 90° metal brackets

The file has been prepared for an 8mm Upcut 3 flutes roughing bit from the Boss Ultimate kit from Fraiser.

It allows very fast cuts and rough finishes are not a big deal here as all parts will need to be hand sanded and finished anyway.

If you want a better finish, you can either use a compression bit or start with a downcut for the first pass and then use an upcut for better chip evacuation (but you will have to change the G-code).

Any 8mm bit can be used for the provided G-codes, but feeds and speeds may need to be adjusted. We strongly recommend that you open the Fusion360 file and adjust each operation parameter to suit your end mill and machine capabilities. You could also customize it for 6 or 10mm end mills for example...

Before assembly, do all the necessary finishing on the parts: 

• Clean the edges of tabs and add chamfers or fillets to make them nicer and safer. 
• Sanding everything to at least 120 grit is also a good idea since there are moving parts (sanded surfaces make joints smoother by reducing friction). 
• You can then apply your favorite color/lacquer/finish to all parts.

• Front feet are each made of 3 parts. The inner and outer parts are different (one with a full hollow area, one with partial pocket area) and the middle part has a direction. I recommend doing a blank mounting of all of the feet before fixing. Make sure the alignment of the parts are perfect and glue/screw them together.

• Place the logo crossbar connecting the front feet. Make sure the feet are in the same direction they are not symmetrical (there is an angle at the bottom).
  It will fit in the pockets in the feet (may need a bit of hammering depending on your panel tolerances). You can then use screws to secure the crossbar to the feet.

• The inner feet/articulations are simpler (no direction). Align and glue/screw together 2 pieces for each of the 4 joints. The little round piece is a spacer that doesn't really need to be attached to the rest (the joint will hold it).

• Assemble the base of the table, do not hesitate to put a good amount of glue/screws as it can be solicited quite a lot in use. Add the 4 swivel wheels to each corner of the base.

• Assemble the 2 top structures made of 2 long arms connected by 2 crossbars.
  The crossbar with the pins on top goes to the inside (the larger side of the arms).
  Bolt the crossbars firmly to the arms.

• You can then begin the full assembly of the structure:

• All joints are fixed this way:
  screw / washer / steel tube / washer / locknut
  It should not be tightened too much to allow rotation, but enough to prevent wobbling..
• Use the 72mm tubes where the screw goes through 4 panels (bottom joints) and the 54mm where it goes through 3 panels (top joints).
  You may need to have your tubes/screws cut to different sizes than these theoretical sizes, depending on your panel thickness, finish, etc.
  It is possible to not use steel tubes, but the joints will be harder to move and probably less durable.

• We'll now attach the piano hinge to the table tops.
  Locate the two table tops on top of each other. Make sure that the 2 horizontal pockets on both panels are on the same side (so that the playing sides are facing each other.)
  
  We recommend putting a temporary 4mm spacer between the two panels to allow some space for the hinge.
  Once prepared, align the two panels perfectly, fix them temporarily with clamps and screw the piano hinge to the edges that are closest to the 2 horizontal pockets.

• You'll need some friendly hands for the next step: you'll need to place the heavy table tops on the structure:
• Add some glue on all the top edges of the structures and proceed to put the panels on it with some friend's help.
  My technique to handle this tricky step was to put it folded on one side of the structure and then unfold the second part (as seen on the animation).
  Be careful as the tabletop is the key holding everything together, so until it's fixed, the structure can be wobbly and moving (that's why 3 or 4  helps a lot).
  
  If you have a large workshop, it might be easier to do this step before the previous one. It really depends on your technique, tools available and personal preference...
• Then you can screw the table top: depending on your tools you can:
  - Put long screws into the crossbars from the bottom (to avoid screws on the surface).
  - Use a pocket jig on the crossbars to fix screws in diagonally to the table top (be careful that it doesn't go through the surface).
  - Use metal brackets to fix the table top to the arms and crossbars.
• Tighten them firmly, as each folding of the table will put a lot of tension on these fixings.

• And it's done!
  You can get a quick-fix net from any sporting goods store and some rackets and balls.
  
  Wait until the glue is dry before folding it.
  It should fold easily. You can also add some wax on the moving parts to help with the friction if it is too high.
  
  Enjoy your games, feel free to send us pictures of your creation and/or improvements on this open source project!