Adjustment screwdriver for 1/4 inch shaft

thingiverse

Many antique radios, TV's etc. include adjustment potentiometers that are controlled by a 1/4" diameter shaft with a slot down the center. Sometimes, it is not desirable or not convenient to grasp the shaft with your hand, and at other times the adjustment may be affected if the shaft is in contact with skin or with a metal screwdriver. Of course, these shafts can be adjusted using a metal or plastic screwdriver. However, the flat blade of the screwdriver easily slips out of the slot in the shaft. This screwdriver includes a surrounding tube that extends beyond the screwdriver blade. In use, the extended tube is first placed over the shaft, and then the screwdriver is rotated until the blade falls into the slot. During adjustment, the screwdriver blade is prevented from sliding laterally out of the slot. Versions of this approach do exist for adjustment of smaller tunable coils. However, the outer tube does not extend beyond the blade, which makes them hard to insert into the slot in the first place. I have included files for both of these types of adjustment. If you are curious, this was motivated by a 1948 Motorola VK-101 TV that I am restoring. Several adjustment pots are located along the side of the chassis, and are accessible through holes in the side of the cabinet. This screwdriver will be the perfect tool to access those pots once the TV is reinstalled in the cabinet. In addition, many tunable coils have small slotted adjustments that extend above the chassis. The smaller tool uploaded here is perfect for tuning those. Update: Turns out that the larger blade screwdriver is about an inch too short for use with the Motorola VK-101. So I'm printing one an inch longer. If you need the longer length, let me know and I'll post it. Also, the smaller blade version proved to be too weak to make adjustments, at least for my purposes.