This latest version of my push drill uses a collet chuck (rather than a 3-jaw chuck) for increased gripping force. The set of collets provided will handle diameters from 0.25" (6.35mm) down to 0.044" (1.1mm), as well as standard ¼" hex drive and 4mm hex drive shanks. It also incorporates the one-way clutch from my previous push drill that eliminates the back-turning of the bit when you raise the slider nut back up.

Printing
Print all parts in PLA in the orientations shown. No supports are needed. Use 0.2mm layers for all parts except for the slider nut and the collets, which should be printed with 0.15mm layers. The main shaft of the drill prints on end, you should include a good sized brim for stability while printing.

When printing the collets, make sure to use a very low speed for the perimeter lines – about 20mm/sec. – to insure that the small cross-sections print cleanly.

Assembly
First place the slider nut into the clutch housing, teeth-side first. Then press the cap on the other side. Slide this assembly, cap-end first onto the twisty shaft. Push the nub into the end of the shaft until it clicks in place. When pushing the slider down (towards the chuck), it shout drive the drill clockwise. When you slide the nut back up, it should rotate freely inside the clutch housing.

The collets simply fit into the conical cavity in the chuck and are held in place with the collet chuck ring.

Applying a light film of lubricant on all mating surfaces, will may everything work more smoothly. You should now be ready to insert your bit into one of the collets, tighten it down and start drilling.