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Step 5Make The Lock Turning Clamp
In this section we make the all important part that connects the motor to the lock.
(This is a reasonably clunky way to do this, but it's simple and cheap. If you think of a better way, please mention it in comments.)
What we're making is a clamp that attaches to the D-shaft of our motor and fits easily over the lock latch so that it can turn the lock. It attaches securely to the motor, but there is some give in it so that it can slip if it finds its self between a rock and a hard place. (Which we prefer to wrenching the project to pieces.)
Drilling the holes:
First take the piece of metal that's 4 1/2" long and 1 1/4" tall. and cut it in half so you get two 2 1/4" pieces.
Tape them together, mark each side so you know which side is "out", and mark one of the long edges as "up". This will all help you keep everything lined up as you go.
Measure and mark the center line from top to bottom. 1/2" each side of this center line and 1/4" from the top mark holes for drilling.
Drill 1/8" holes at these marks. Marking the points with a punch, or giving it a whack with a hammer and nail will make your drilling more accurate.
The edge with the holes is the side that attaches to the motor.
Bending the metal
Measure the width of your lock latch (the narrow way) and divide by 2. This distance is how much zig we're going to bend into each piece of metal. Mark this zig distance along each strip. Bend one piece so it zigs to the left, the other so it zigs to the right. Make sure that the screw holes at the top of the pieces stay lined up and the bends don't keep the pieces from meeting at the top.
Finishing and sizing
For this part you'll need your motor, the two 1/8" screws and a couple matching nuts.
Put the screws through the holes in the top of the plates so it makes an upside down "Y" (sort of) and place the motor shaft in the top between the screws. Screw nuts on each side and tighten until it's firmly (but not really firmly) attached. The small amount of give between the metal and the shaft will let the motor spin if it meets too much resistance. (Rather than breaking something important.)
Check the other end for fit over the lock. It should fit a little loosely over the lock latch. Not so firmly that it's clamped tight, but not so loose that it can turn without turning the lock. Adjust the bend of the flanges if you need to.
After you've got the adjustments right, tighten another nut onto the end of the screws and tighten them up against the first ones. This will help lock them in place.
(This is a reasonably clunky way to do this, but it's simple and cheap. If you think of a better way, please mention it in comments.)
What we're making is a clamp that attaches to the D-shaft of our motor and fits easily over the lock latch so that it can turn the lock. It attaches securely to the motor, but there is some give in it so that it can slip if it finds its self between a rock and a hard place. (Which we prefer to wrenching the project to pieces.)
Drilling the holes:
First take the piece of metal that's 4 1/2" long and 1 1/4" tall. and cut it in half so you get two 2 1/4" pieces.
Tape them together, mark each side so you know which side is "out", and mark one of the long edges as "up". This will all help you keep everything lined up as you go.
Measure and mark the center line from top to bottom. 1/2" each side of this center line and 1/4" from the top mark holes for drilling.
Drill 1/8" holes at these marks. Marking the points with a punch, or giving it a whack with a hammer and nail will make your drilling more accurate.
The edge with the holes is the side that attaches to the motor.
Bending the metal
Measure the width of your lock latch (the narrow way) and divide by 2. This distance is how much zig we're going to bend into each piece of metal. Mark this zig distance along each strip. Bend one piece so it zigs to the left, the other so it zigs to the right. Make sure that the screw holes at the top of the pieces stay lined up and the bends don't keep the pieces from meeting at the top.
Finishing and sizing
For this part you'll need your motor, the two 1/8" screws and a couple matching nuts.
Put the screws through the holes in the top of the plates so it makes an upside down "Y" (sort of) and place the motor shaft in the top between the screws. Screw nuts on each side and tighten until it's firmly (but not really firmly) attached. The small amount of give between the metal and the shaft will let the motor spin if it meets too much resistance. (Rather than breaking something important.)
Check the other end for fit over the lock. It should fit a little loosely over the lock latch. Not so firmly that it's clamped tight, but not so loose that it can turn without turning the lock. Adjust the bend of the flanges if you need to.
After you've got the adjustments right, tighten another nut onto the end of the screws and tighten them up against the first ones. This will help lock them in place.
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For the motor shaft/deadbolt interface, one thing that caught my attention as a possibility is aluminum C-channel. It would work by the same principle of the sheetmetal approach you used, slipping over the deadbolt. The attachment of the aluminum to the shaft might end up being difficult, though, which could negate the benefit of not having to bend sheetmetal.
Another option might be to fix a piece of aluminum c channel to the deadbolt with some extra off one side, making it something like the equivalent of a servo horn, and using a servo to control it.
If anyone else has a brilliant idea for this particular step of the project, I'd love to hear it.
The 3M command strips should work. If they don't, 3M's extra strength double sided foam tape definitely will, though more permanently . (Back in my dorm days we stuck a chair to the ceiling with it...)