I really don't like slotted screw or bolt heads. It's difficult to keep a driver centred in the slot, especially when driving with power. The only 1/4-20 wing bolts I could find locally are slotted and working with them is a bit of a PITA, so I decided to try my hand at converting them with heat to a suitable new drive type. I decided on #3 Robertson. Here's my process.
- a drill press (doesn't need to be plugged in)
- a platform to hold the bolt
- clamps to fasten the platform to the drill press table
- a #3 Robertson driver bit chucked in the drill press
- a blowtorch and igniter
- A small hammer to tap the drill press table and / or platform into alignment
- A slotted screwdriver to insert the bolt into the platform
- A #3 Robertson screwdriver to remove the completed bolt from the platform
- A hobby knife to trim off the slag from the melting process
1. Create a mounting platform of some type. I had already tapped a small piece of ply for a strength test so I mounted that to a larger piece the size of my drill press table.
2. Insert a bolt in the platform.
3. Place the platform on the drill press table
4. Set the depth stop of the bit carefully - it should go into the bolt about 2/3 of the depth of the head. Too shallow and the driver may cam out of the bolt - too deep and the head is weakened. When the depth is correct, make an alignment mark on the column of the drill press.
5. Align the bolt to the bit as closely as possible. I eyeballed it and that was close enough in all cases. Note the position of the bit, indexed 45º to the slot.
6. Clamp the platform to the drill press table.
7. Check the alignment again. Use a small hammer to tap the platform or the drill press table into place.
8. When the alignment is correct, fire up the blowtorch.