Geometric Chuck

UPDATES! See below.

This chuck was not designed for and should not be used on a high-speed lathe! Most conventional wood lathes do not turn slowly enough to use this chuck. Do not attempt to turn this chuck faster than 5 rpm!

There is a PDF Build Guide in the files section. Please read all the instructions before attempting to build the chuck.

The geometric chuck is used as an accessory to an ornamental or rose engine lathe. It can create circular patterns by offsetting the workpiece from the lathe center, while at the same time turning the workpiece at a different rate than that of the lathe. This chuck is designed to turn at a fixed ratio of 5:1. It also has the capability to change direction, which will change the orientation of the loops it creates and therefore the design. Although the gear ratio on this chuck is set, hundreds of different patterns and designs can still be created. 

Features:

• Single stage.
• 5:1 gear ratio.
• 1 x 8 teeth per inch spindle.
• Directional change feature.
• 120 position main gear.
• Eccentric pivot. 

Print details:

• Material: PETG (PLA may also work but I have not tested it thoroughly.)
• Layer height: 0.15mm
• Supports: Yes, on many of the parts.
• Infill: 20% in most cases. 100% for smaller parts and gears, and around holes and bearing openings.
• Perimeters: Should be increased to at least 3 for additional strength. 

All parts shone were printed on a Prusa i3 MK3S+.

A parts list is provided in the PDF Build Guide found in the files section. Read the entire guide and understand the design before starting the build. Many of the bolts required will need to be cut to length. You also may want to test and tune your printer to make sure it prints correctly. Tolerances are very close on some parts, gears must mesh correctly, and bearings must fit snuggly without slipping.

Remember to work safe. 

• This design has many pinch points. Be aware of moving parts while machines are running.
• Do not overreach or use excessive force to perform any machine operation.
• Never wear loose clothing, watch, rings, or gloves when operating a lathe.
• Tie back long hair or anything which could be caught in moving parts.
• Keep small childen away from machinery, and away from small loose parts which could be a choking hazard. 
• Always wear eye and face protection when operating a lathe.

UPDATE 2/22/23:  I have included files for an updated eccentric plate. The new plate includes space for two spindle bearings as opposed to the single bearing on the original plate. Two bearings improve the stiffness of the spindle and improve the results when cutting wood. The new plate will make the chuck slightly larger horizontally, but I haven't found that to outweigh the benefit of the extra sturdiness of the spindle. I highly recomend using the updated parts.

A few smaller parts will also be required to be changed with the new plate, including a new longer spindle. The updated new parts will be in a separate folder and marked as 3-3. The older version parts (eccentric plate and spindle) will still be included as they still work fine. I have not included a build guide with the new parts, but it should be easy to understand if you see how the original is built.   

UPDATE: 6/29/23

• Added metric spindle and base plate. (M30-3.5) Items are labeled “metric”.