Some may remember my attempts at getting this machine CNC ready. Well, that got shoved on the wish list. So for now I am setting the little mill up permanently for horizontal use as circumstances changed in the workshop and I got a vertical mill. One issue with the SU1 for horizontal work is the powered spindle that can be swapped between vertical and horizontal. It's speed range is 200-2500rpm, thats not really very useful. Too slow for small cutters vertically and too fast for horizontal cutters, you can slow the spindle down further but it starts to get a bit unstable and cog below 150rpm.
I figured I would print some new pulleys and see how it goes. My assumption was the belt included would be a T5 or XL style belt, sadly it isn't and doesn't seem to be any sort of standard. Rather than waste more time and prints I converted it to T5 belting. No big deal as I know the spindle and motor are 130mm between centres so easy to calculate the required belt and get one ordered.
I could have bought the small pulley off the shelf, but heck, if you do 3D printing....
I set too designing new pulleys, 18 and 72 tooth. Whilst the 18 is cheap to buy, a 72 is not, another bonus of printing your own pulley is you're not stuck with standard sizes. I printed both pulleys. Picture below compares the original set with the new. The printer did a good job of accurately printing these, I used the 0.3mm nozzle so they are a longer time printing but with good detail. I cocked up a bit printing the large pulley, as that print took 11hrs, if I had made it a spoked pulley it would have printed faster, but even an 11hr print is quicker than waiting for a replacement from a 3rd party.
Both pulleys installed easily and aligned using a straight edge. I recently got a UNI-T Mini Tachometer from Banggood for very little money. Useful bit of kit and it can also be used as a counter, handy for winding coils. It verified the new speed range from around 60-1388rpm, an ideal speed range for the cutters I intend to use. A couple of arbours have been machined for other cutter sets, but I got a reasonable set of Mod 0.5 cutters from Banggood that have 16mm bores, same as the SU1 horizontal spindle.
The machine hasn't really been used for much other than brass and plastics, the pulleys seem to be holding up so far and a little bit of oil on the belt is no bad thing.
