Following on from my post about mass production, here is a bit of a post about a crazy challenge I set myself.
For the LEEDR data acquisition(DAQ) units and for my DIY solar PV kit I needed to cut a number of pieces of wire and cable to an exact length. For example: the DAQ unit required 8 pieces of wire for every connector and there were 25 unit to make, hence 200 pieces of cable to cut and strip. While cutting this cable I thought about making it automatic and I set myself a challenge to build an automatic cable cutting machine from parts within my workshop.
I never got it completed in time for the DAQ deadline (hence I had to cut all those pieces by hand), but now have it working in a very basic form and hopefully it will be useful in the future. I also learnt a lot, including stepper motor control and H bridge motor control.
Here is one version of the cable cutter. I have since added a better cable feed mechanism. It is based upon a stepper motor drive from a broken printer, an arduino and an old drill which is used to power the screw thread drive for the cable cutter.
Here is a video of it in action:
The cable is fed from a spool and goes over an old computer mouse. This is an optical sensor to check how much cable has been spooled out.
In the first version, the optical sensor from the mouse was not used, but I will implement it later.
The cable is fed using a stepper motor from a printer. This is powered using a stepper motor controller IC. A sprung rubber roller holds applys enough pressure to grip the cable. This then feeds through the metal tube (this has been replaced with a plastic funnel to funnel the cable into the correct position).
A top view of the stepper motor and roller.
This is the arduino controller, the stepper motor control IC and the MOSFET H bridge for controlling the drill motor.
At present the arduino code is told how many pieces of wire to cut and how long they should be. There are start and stop buttons and also manual feed buttons to get the wire into the correct position.
This is the old drill which drives a 4mm threaded rod which converts the rotational motion into linear motion to drive the cutter handles up and down. Limit switches give inputs to the arduino for fully up and fully down.
The screw thead and the limit switch.
Close up of the cutter blades.
I quite like setting myself little challenges – its a great way of getting something up and running quickly and its a great way of learning the priacticalities. Next additions are an automatic wire stripping tool and an LCD interface to control the number of pieces of wire and their length.