This is a printable jig to make really precise top and bottom plywood frame parts for the Rostock delta robot 3D printer.
This jig is designed to work with plywood pieces of 350x300 mm. You may be able to drill both (top and bottom) at the same time.
12 mm (or maybe 9 mm) thick plywood is recommended to make the frame as strong as necessary. 6 mm thin plywood may be okay if your plywood is very good, and you are planning to make a back/side frame anyway, or if you are building a mini Rostock.
Print the jig in PLA or ABS, it should fit on a 8x8 inch Prusa heated bed.
Align the drill jig with the longer edge of the plywood so that the middle hole is on the center line. Drill a 4mm hole in the middle and attach the jig with a M4 screw and nut.
Maybe use a small clamp to hold the jig in place. Drill two holes through the jig near the edge. Optionally put a M4 screw in the first hole before drilling the second one.
Repeat step 3 twice at 120 degree angles. If you draw a straight line through the middle hole, parallel to the first edge, then you can align the sides of the jig to this line.
With M4 screws in the new holes, mark the outside edge of the drill jig onto the plywood with a sharp pencil. Then remove the drill jig and cut away the 2 front corners of the plywood where the motor brackets will be attached. Use a precision circular table saw for best results, but a handheld jigsaw works okay too.
- Attach a motor bracket to each pair of holes, then drill through its other two holes into the plywood. For the two front brackets it's okay to use only one of the inner holes because the other one overlaps with the heated bed.
Alternative: If you have a strong laser, make a DXF or EPS file of this design and laser cut from 6mm plywood. If 6mm plywood is not strong enough, maybe use two layers for the bottom frame. Upload your file to Thingiverse so that others can use it too.