[project5k]

escott, your right, but in mycase, where i spend 90% of my time running 1/8" and smaller endmills, i dont think im in any danger of rigidity issues.

I am aware that my increasing the rpm in this manner will reduce the available torque at the EM, but do you really think its gonna be an issue on a 1/32" endmill, or even a 1/8"?
I dont.

and on thoes rare occasions when i do use an EM larger than that, i still have low range in the gearbox to go to when i need more torque. Yes i know that it'll be less, but still, doubtfull i'll go there.

its just like a transformer. you can up the voltage, but have less available amperage, and vice versa.

[imserv]

OK....here are the assumptions I am making:


3) The maximum RPM for an X3 is 2000 RPM

Always challenge your assumptions. 2000 rpm max is very poor performance in Aluminum, plastic, or wood. It may be OK in soft steel with large cutters, but with small cutters it is way too slow.

Mount a 30,000 rpm spindle on the side of your spindle casting and see how your calculations come out. Even a 10,000 rpm spindle will multiply your max ipm by 5 times.

Fred Smith - IMService
http://www.imsrv.com

[escott76]

its just like a transformer. you can up the voltage, but have less available amperage, and vice versa.

My point is that it isn't always a linear relationship. Technically neither is a transformer, but a motors curve generally looks a little funkier.
Small EM are crappy for a variety of reasons, and machine rigidity will play a role in how fast you can ultimately go regardless of spindle speed. Don't forget that you are still moving something around, and that thing has weight and therefore inertia. If the mechanics overshoot a couple tenths on a half inch endmill nothing happens. That same overcut on a tiny one can kill it.
Again, these things are a total system, and you can't look at parts of it like they are in a vacuum. It's not to say that making your spindle faster isn't a good idea, just try to keep the big picture in mind

[project5k]

absolutely agree. the one thing that i will say is that if you have enough lash in your movement system that you can overshoot by a couple tenths of an inch, perhaps spindle speed shouldnt be the first concern.

[Geof]

absolutely agree. the one thing that i will say is that if you have enough lash in your movement system that you can overshoot by a couple tenths of an inch, perhaps spindle speed shouldnt be the first concern.

Probably the meaning in escott76's 'tenths' is tenth of a thousand, in other words 0.0001".

In machinist 'lingo' tenths are .0001" and 1/10 of an inch is a hundred thou.

[SCzEngrgGroup]

escott, your right, but in mycase, where i spend 90% of my time running 1/8" and smaller endmills, i dont think im in any danger of rigidity issues.

I am aware that my increasing the rpm in this manner will reduce the available torque at the EM, but do you really think its gonna be an issue on a 1/32" endmill, or even a 1/8"?
I dont.

and on thoes rare occasions when i do use an EM larger than that, i still have low range in the gearbox to go to when i need more torque. Yes i know that it'll be less, but still, doubtfull i'll go there.

its just like a transformer. you can up the voltage, but have less available amperage, and vice versa.

"i dont think im in any danger of rigidity issues." - Don't be so sure.... One of the things that can kill tiny endmills is vibration, which is related to rigidity. Small vibrations that can be absorbed by a large endmill can quickly fatigue and break a small one. At 1/32", even a few tenths can do it. Spindle runout is another critical factor, for the same reason.

Regards,
Ray L.