Step 24: Follow up / Improvements
The pulleys on the Y axis have come loose more often that I liked. The problem wasn't the time require to re-tighten them but that they would have to be checked before each use to make sure they were secure. I had cut out a propeller end cone to find out it was circular because I hadn't noticed the pulleys had come loose. To solve this problem I attached 1/4" shaft collars to the pulleys using 10 minute epoxy as shown in Photo #1. All of the HDPE parts were cut using this setup without the pulleys loosening. When running at less than 30 inches per minute the movement of the machine is slightly jittery as the discrete steps of the stepper motors is magnified. In the future I will be replacing the 40 tooth pulleys with 20-30 tooth versions to increase the resolution of the machine and make it;s movement smoother. I imagine these will come with the same size set screws as before so I will take the time to bore out the threads and re-tap them to accept 8-32 set screws as are on the shaft collars.
I had expected the aluminum rails to show signs of wear from the contact with the V-groove bearings as this was experienced on my first machine. The rails have worn a little bit as shown in Photo #2 but shouldn't require replacing any time soon. I will make a concious effort to use different parts of the machine when cutting smaller items so that the wear isn't concentrated in a particular area. If this becomes a problem I might consider making my own V-groove bearings from HDPE and fitting them around a skate bearing. The HDPE against aluminum should have very low friction and good wear characteristics.
The part I was the most concerned about was the elastic band driving the spindle. This had taken a bit of damage during the construction process and I didn't know how quickly it would wear if it was slipping over the pulleys. Photo #3 shows the elastic band in good conditions with minor wear that as taken off the lettering. The pulleys in Photo #4 show a bit more wear but is mostly cosmetic.
The home-made spindle has performed well and as been quiet enough to use in an apartment but I would like a bit more power and the ability to use higher quality 1/4" shank router bits. I will be looking out for garage sales to pick up a 1/3 HP induction motor (similar to the one in this) and trim router to make a beefier hight powered version of the current spindle.