prime_mover
Aluminum
- Joined
- Jul 3, 2017
Recently the spindle in my 2013 Mini-Mill went out. I got 8 years of use out of it, maybe a few thousand hours of spindle run time. I don't know exactly how many hours because the mobo battery died and the hours reset. It still shows total hours in parameters but not spindle hours, I think. The first sign of trouble was when the sound signature suddenly changed from normal to something more akin to a table saw being fed some plywood. It would bounce back and forth between normal sounding and the table saw sound before eventually always sounding like the saw. Over a couple of months it sounded worse and worse until eventually sounding like a plastic bucket filled with rocks, and finally one day the surface finishes on my parts degraded, and so I decided it was time for the rebuild. I had the spindle rebuilt by a reputable spindle rebuilding company for $5k. It's been up and running again for two weeks now, maybe 30-40 hours spindle runtime, and has started making the table saw sound again.
I am hogging aluminum with a stubby 3/4" 3 flute end mill, but it's only pocketing and profiling at less than 1x axial depth, and usually 10-20% radial, and .004 to .007" IPT, depending on how much radial engagement there is. Always 6k RPM. The end mill is being held in a Schunk hydraulic holder with 2.5" gage length. The spindle load is always well below 100%, usually 40-60%. As the cutter wears the sound of the cut gets louder and there is a fair bit of vibration going through the machine, then I swap the cutter for a fresh one. The other roughing I have done is slotting aluminum with a 3/8" end mill. ~.270" depth of cut, .005" ipt, 6k rpm, sk16 holder with 2" gage length. It's a moderately loud cut and the spindle load is at about 60-70%.
I would not think that those cuts in aluminum would cause spindle bearing damage, especially after 30 something hours of run time. The rebuild has a 1 year warranty, so presumably I am covered if it is on its way out again. I've still got 1500 parts left to make to complete the current job, so hopefully it makes it at least that far....
I am hogging aluminum with a stubby 3/4" 3 flute end mill, but it's only pocketing and profiling at less than 1x axial depth, and usually 10-20% radial, and .004 to .007" IPT, depending on how much radial engagement there is. Always 6k RPM. The end mill is being held in a Schunk hydraulic holder with 2.5" gage length. The spindle load is always well below 100%, usually 40-60%. As the cutter wears the sound of the cut gets louder and there is a fair bit of vibration going through the machine, then I swap the cutter for a fresh one. The other roughing I have done is slotting aluminum with a 3/8" end mill. ~.270" depth of cut, .005" ipt, 6k rpm, sk16 holder with 2" gage length. It's a moderately loud cut and the spindle load is at about 60-70%.
I would not think that those cuts in aluminum would cause spindle bearing damage, especially after 30 something hours of run time. The rebuild has a 1 year warranty, so presumably I am covered if it is on its way out again. I've still got 1500 parts left to make to complete the current job, so hopefully it makes it at least that far....
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