Okuma M660V- 15k Cat40 vs 12k Cat 50?

Okuma recently introduced a 60" X travel machine in their Genos lineup, with an optional 12k rpm 50 taper spindle.

12k on the 50 taper would get you near the top end of SFM on all but the smallest tools in anything other than aluminum.

What're your opinions on a Cat 50 12k rpm big plus spindle vs the cat 40 15k big plus spindle?

Edit: Lets just assume its used for general job shop work. Mix of steels, titaniums, and aluminums.
Spindle option is about $10k extra, so not a huge deal over the life of the machine.

It all depends on the work you do.

Agreed with MtnDew.

It makes a HUGE difference if you are zipping around with a 3/8" endmill with HEM, or using a 2" extended flute porcupine cutter @ 70% stepover.

Of course, nobody runs exclusively one of those two scenarios. Hence the questions....

Things to consider...

50 taper will most likely have slower accel/decel.
50 taper will likely have slower toolchange.
50 taper should be more rigid. Not always true, but within the same brand I'd expect it to be.

What do the HP and torque curves look like and how do they align with your projected work?

Assuming that it is still the same basic casting, rails, etc... as the 460/560, I think you'll be way happier with the 40 taper. While they are quite robust, it's not the type of machine where I'd commit to taking slow heavy cuts all the time.

I've been very pleased with the performance of the 40 taper big plus in hard metals. I daresay the rigidity of that interface might exceed the power and rigidity of the machine tool. The only compelling reason I see to consider 50 taper is if it has more low end torque available. The 15k spindle is a little anemic at low speeds, but I have yet to find it to be a liability. It's just pushed me to use more HSM style toolpaths for heavy material removal in hard metals, which is where the machine shines anyways.