OK, I admit it, I thought I couldn’t go wrong buying a $10 dollar cordless screwdriver. Yeah, nice idea – but not so much. My backup plan, in case the screwdriver really stunk, was to adapt the parts into a robot drive motor. As a robot wheel drive this screwdriver might not be a bad buy.
As a power screwdriver this model kinda stinks. It’s rated at 4.8 Volts / 180 RPM and comes with a 6V / 300mA charger. The motor / gearbox does not generate a lot of torque. However, the worst aspect of the screwdriver is the charger. Both the charger and the screwdriver get very warm after a day on charge. Not good. In other words, you can’t just leave the screwdriver on charge for days on end. What a waste of energy!
Given the screwdriver stunk as a screwdriver, it only seemed right and OK to rip apart the brand new screwdriver to see if option B was going to work. Below are some findings from the teardown:
- Of course, the batteries are cheap-o Ni-Cd 600 mAh.
- The gearbox, which is a nice planetary two-stage, needs to be mounted in the case to stay together. Without the case screws, there is nothing holding the motor and gearbox together.
- To use the motor / gearbox in a robot much of the original housing around the motor and gearbox would need to remain. The housing would be needed to hold the motor and gearbox together.
- While the front of the screwdriver looks made of metal, it is not. The gearbox is all plastic except for the sun gear on the motor.
- Testing the motor on my power supply I found the motor does not even start to try to turn until 1 amp of current is flowing! Not the most efficient motor / gearbox combo. After a little break in, I found the minimum motor speed / current was 1/2 Volt and 1/2 Amp. So, just to free-wheel, the motor / gearbox consume a 1/4 Watt of energy. Not great.
So, bottom line, not the best choice for either option A or option B. In hindsight, I should have known that a $10 cordless screwdriver was going to stink!