Portable Drill Guide

I sometimes need a tool to assist me in accurately drilling vertical holes in a piece of work that I cannot drill with the drill press. This tool will allow you to use your portable drill and drill holes straight down, however it is not intended as a drill press.

Printing

Preparation

• Base - This items is the part that will be in contact with the work being drilled
• Mount - The portable drill is inserted into this. It is not designed to necessarily hold the drill, but rather to give it a fairly sturdy connection so that it isn't too squirrely while you use the drill.
• I printed all the parts in PLA, no supports and 40% infill for a bit more strength.

Additional Resources

• 4x 9.5mm x 250mm metal rods. I have a piece of aluminum tubing laying around and used that. Its not the strongest but it works
• Optional - 4x 10mm long compression springs

Assembly

• Once your rods are cut to length, clean each end of burrs and consider beveling slightly.
• Insert a rod into each socket in the base. If the rods are not tight enough consider drilling a hole through the each socket and rod and inserting a self-tapping screw to hold it in place. I needed to do this as the rods tended to pull out of the sockets when raising the drill from the work after drilling.
• If you're using the compression springs, place one over each rod. This will assist in returning the drill up from the work and keep it from dropping down unintentionally. 
• Once all rods are in place insert each rod into a corresponding socket in the Mount.

The base can be clamped to the work if needed and can accommodate a fairly long drill bit.

Improvements

• Close the sockets in the base so that the rods can't extend onto the work if not restrained
• Create a wider foot for the base so that its a bit more stable