Strong Driver Kit (Bi-Directional Clutch)

parts required  2x 3/16" washer (Ø14mm and 1.2mm height)

                            1x M3 14mm socket head screw (leftover from the Prusa MK3S kit).  Slightly longer or shorter is okay.

                            1x spring from unused pen

optional              1x M3 washer

I was inspire by FreddyZ and LoboCNC's amazing mini ratchet screwdrivers.  I had a ratchet driver in the past, but it broke when I needed it.  So I created a driver with a more reliable clutch mechanism.  It's simple to use.  Just push the driver to engage the clutch and you can drive the socket in the clockwise or anti-clockwise direction; remove the pressure and the socket can spin freely.

The driver have a reinforced 4mm hex sockets and storage for seven 4mm driver bits.  That's a 8-in-1 tool!  You can even use the exposed washer as a slotted screwdriver.

It would be stronger, if I used a 4mm axle in the driver, but I only have M3 screws.  In the unlikely event where the mechanism failed, you can just use the socket head by itself to drive the bit.

If you want something even stronger, without any moving parts.  I have a 1/4" bit driver (with storage for 6 bits) and a combined 4mm and 1/4" bit driver (with storage for up to 14 bits).

Printing Notes

Printed in ABS with 0.2 layer height.

I printed the cap with the same material but a different color that the body; and found that the cap did not fit.  I had scale up the cap by 2 percent for a perfect fit.  Different color of the same material seems to print differently.

Brim is recommended when printing the body and cap, as it only a small amount of contact the print bed.

If the driver bit is too loose and falls out, you can scale down the model in x and y direction;  or try magnetize the reinforcing washers.

Assembly Notes

Insert the socket head screw from inside the body.  The head should be inside the body and the threads exposed outside the body.

If you have a M3 washer, place it over the screw thread.  The washer is to help the socket head to spin more freely.

Cut the spring to 12mm long and place it over the screw thread.

Finally, screw the thread into the socket head, until it is flush with the base of the bit recess.  If your screw is longer, you'll have a larger gap between the clutch, or the screw intrude into the bit recess.  If your screw is shorter, it might not hold the socket head as well.

Finally insert the washers into the socket head.

pocket size driver kit with bi-directional clutch