Ellipse Chuck

UPDATES: See below…

The ellipse chuck is designed to be used on an ornamental or rose engine lathe to make an ellipse shape or design. It works by allowing the workpiece to slide back and forth while turning. The width of the ellipse can be controlled by changing the position of the slide. The size of the ellipse can be controlled by changing the position of the cutter or pen. The baseplate is attached to the front of the lathe, while the turntable and spindle slide are attached to the lathe spindle. When this chuck is combined with a rosette pattern on a rose engine lathe, the ellipse shape can reflect the rosette pattern as well as the ellipse pattern.

Print details:

• Material: PETG (PLA may also work but I have not tested it thoroughly.)
• Layer height: 0.20mm
• Supports: Yes, but only a few. 
• Infill: 20% in most cases. 100% for smaller parts, 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+.

Parts list:

• 8-M6x40 socket head cap screws
• 8-M6 square nuts
• 12-M3 threaded inserts
• 2-M6x40 cap screws or 110mm of M6 threaded rod
• 6mm washers 
• 2- 8mm x 203mm steel rod 
• 4-lock collars
• 4-8mm id x 15mm od x 24mm long linear bearings
• 4-M6x55 flathead bolts
• 4-M6 lock nuts
• 8-M6x12 threaded inserts
• 6-M6x20 bolt
• 1-80x100x10 radial bearing
• MDF or melamine if used for baseplate

Updates:

• 07/03/23 Added metric parts. Metric (30-3.5) spindle and turntable were added.

Dimensions for alternative base plate made of MDF or melamine board. 1 piece.

Support material:

Remove all supports completely before starting the build. A hobby knife, flat and round files (3mm round), needle nose pliers, and sandpaper are all helpful.

Build video:

Considerations for fitting the chuck to your lathe:

The baseplate must mount to the front of your lathe. This can be accomplished with 4 bolts through the baseplate. The turntable is threaded 1 inch x 8 tpi, and is attached to your lathe spindle. There should be about a 2mm gap between the baseplate and the turntable when mounted. 

I have 26mm from the front of my lathe (where the base plate is mounted) to the rear of the threaded portion of the spindle (where the turntable seats onto the spindle). If your lathe is different that this, you may need to modify the baseplate or turntable to fit properly. If your distance is greater than this, you might be able to add a spacer between the baseplate and the front of your lathe in order to mount the baseplate. If it's less, then you may be able to cut a small bit off the end of the turntable, or use an adapter on the spindle to increase the distance. If it is too much less, the ellipse chuck may not work on your lathe.

This tool was not designed to hold a heavy metal chuck, I would recommend using threaded wood glue blocks to attach the workpiece. This tool 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 safely. Do not attempt to turn this at speeds faster than 5 rpm. 

Remember to work safe. 

• 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 children 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.
• 3D printed tools are made of plastic, be mindful of the limitations of the material.