Thursday, June 16, 2016

New motor on the mill

I have been limping by with a 2 hp electric motor on my 600 mm stone mill.  Normally these stones are installed in mills with 15 hp motors.  Since I am using a 9.6:1 gear reduction, I can't really capture 15 hp, but I do need more than 2 hp.  I have been running the 2 hp at 15-16 amps, and full load amps on the 2 hp is 13 amps.  I have been biting my nails and hoping not to burn out this little motor.

Anyway, my dream motor has always been a 5 hp, but single phase motors in this hp range are actually kind of rare.  3 phase is much more common once you get past 2 hp.  So craigslist is full of 3 phase 5 hp motors for ~ $100, but never a single phase.  Until last week, when a brand new, in the box, single phase 7.5 hp showed up on craigslist, for $150.  Score!

It's an absolute beauty, and a TEFC enclosure to boot.  I had to spend a day learning about couplings, though, since the new motor has a larger shaft.  The newer type jaw couplings are inexpensive and more tolerant of the grid coupling that I had been using.  The one I installed runs very quiet and smooth.

I did the first run on Thursday and found I was running around 19 amps.  According to the power curve specs, this should be around 4 hp.  Which is perfect, since the gearbox has a max hp of 4.65.  I did not mill enough to get a good measure of speed, but I think it was milling over 200 lbs/hr.  This is a good rate, being about as fast as I can feed the hopper and bag the flour.

It's hay season in this part of the county so I cut the rest of the red clover on Thursday.  I can't believe people ever did acreage of hay by hand.  The clover is very hard work, and a lot of it was knocked down which made it go three times as slow.  I plan to rake it up and store it in the barn for the herd.

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