Introduction: Fabricating a Pocket Billiards (Pool) Mechanical Bridge
Solving Life's small problems with home digital fabrication.
A favorite past time of my beautiful wife is to play billiards. But along with being short of stature she also has short arms for the across table shots. Many places either do not have a “bridge” or have one that is not available when needed. My solution was to produce a mechanical bridge that would attach to one of the extra on-site pool cues. This mechanical bridge attachment had to be small and lightweight so she could carry it in her purse. When a bridge is needed she takes a extra pool cue and attaches it to the end for those hard to reach angles.
The great thing about home digital fabrication is you can very quickly make simple objects to solve problems.
Step 1: CAD Layout of Bridge
First begin by sketching the shape of the bridge. Any functional shape will work but for this first one I stayed with a traditional design.
The width should be about 4.5 inches and height about 2.4-2.5 inches. After the shape is produced in the CAD sketch extrude to 0.25 inchs. After Extruding to the thickness of 0.25 inches fillet all edges by 0.125 inches. This will give a nice rounded edge and less clean-up after printing.
Step 2: Extruding
Extrude the 0.625 inch circular area to 1/2 inch depth that the pool cue receiving hole will go through.
Next extrude the0.375 circular area for the clamping screw. This is a compound angle that will be at a 45 degree in the xy plane and 20 degree in the Z-Y plane. This will allow easy access to the clamping screw.
Place a hole in the larger circular extrusion (pool cue) of 0.51 inches. This will fit most cues.
Place a hole in the smaller circular extrusion for the clamping screw of 0.125 inches
Step 3: Printing
Print the bridge with 20-40% infill. This will give it a light weight and adequate strength.
Step 4: Clamping Screw Assembly
While the printing is going on with all its melodic stepper tones, assemble the clamping screw.
The 8-32 nylon machine screw and and acorn nut can be purchased at the local hardware store.
Cut a section of the screw thread approximately 0.625 inches long (you will not need the screw head).
You can use a sharp pair of flush cutting diagonal cutters to do the job.
Place a small amount of glue in the acorn nut to fix the nut to the screw thread.
This will form the small thumb screw to clamp the bridge to the pool cue.
Step 5: Trim Finished Print
After the print is complete use a file to trim and smooth the edges of the bridge. Some sandpaper may be required on the edge that touches the table felt.
All this cleanup should be done by hand as power sanders and die grinders (Dremel tool) will melt the plastic as you try to sand. This will leave little balls of plastic on the "downstream" side of the sander.
Always be careful with the knives. It can be a real drag trying to explain to the ER physician how 3d printing resulted in you cutting your hand!
Step 6: Threading the Clamping Hole
With a 8-32 Tap, thread the hole for the clamping screw.
Take it slow
Going too fast will cause the plastic to gum up the tap and end up with poor threads.
Once the threads are completed insert the assembled 8-32 clamping screw in the hole.
The Nylon screw will not damage the pool cue.
NOW go have some fun!
Or stay home and Make something else........