I think you use servo motor for Spindle.
Constantly moving, does not hurt to Servo motor?

I think you use servo motor for Spindle.
Constantly moving, does not hurt to Servo motor?

I'm sure your right.
I had this stepper/gearbox from a previous project and just decided to use it for a proto-type. Originaly I was going to have a real indexed axis, thus the stepper. In the end I just decided to use it for a spindle.
I actualy have a real spindle with a 3 jaw chuck and a matching tailstock that's off an old Sherline that would work much better. Speed control and on/off all right there on the front panel of it. But what fun is that ?

I think you use servo motor for Spindle.
Constantly moving, does not hurt to Servo motor?

Servo motors do have a duty cycle and are expected to have 'rest' time and therefor have no provision for cooling. Running constantly might cause heat build up in the motor. The motor is rated 6,000 RPM and I have had no problems thus far running continuously at about 4,000 (a guess) with the mill on 'low range' if you will. On high range, at 7,000 RPM, both the spindle and the motor get hot after a while. On my previous X2 mill I ran 7,500 RPM for long periods and had an aluminum finned block on the side of the head to draw off the head. The spindle motor of the X2 has active cooling and it got hot, but not overly so. 

In my application I do not plan to run the spindle at high speeds for more than 10 minutes or so at a time, so it is not a priority to investigate that. If I do need to run at the MAX 8,500 design speed for extended periods, I would need to add cooling to both the motor and spindle lower bearing. The lower bearing is currently pressed into a 1" thick block of aluminum which dissipates the bearing heat quite well enough for what I am currently doing.

Active cooling would be relatively easy to add.

thx for information

AC servos have a continuous rating and an intermittent rating.
AC Servos (or DC Brushless, same thing   ) have their windings in the casing  of the motor which means they are very efficient at dissipating the heat.
Hood

i have two yaskawa AC servo motor. and i want use them Instead Spindle
With This description should not be a problem

AC servos have a continuous rating and an intermittent rating.
AC Servos (or DC Brushless, same thing  ) have their windings in the casing  of the motor which means they are very efficient at dissipating the heat.

Good point, Hood. I should have mentioned that the motor that was asked about is a DC brush motor. It has continuous 7.6A and max 38A. This motor is Keling and they provide only minimal information on their motors. Higher end DC brush motors provide more information about how long the motor can be at max amps or how hot is is allowed to get without damage. I have a DC brushless motor to play with but it is far too small for the spindle. Perhaps I should consider and AC servo motor for the spindle.

I do know that the stepper gets hotter just holding perfectly still than it does spinning. Sort of makes sense, but not intuitively.

Update on 4th AXIS (rotating, but not indexed).

Everything is working as hoped for!  Not sure why the resetswapedaxis() was not working originaly, or why the spindle speeds were not displaying correctly, but the next time I tried it everything worked fine. I suspect I had changed things so much it just needed to be restared to get back in sync.

I'll post up a video when I get it working on the machine.
Thanks to everyone for the help.

Development has continued during the last several months and I finally have a few picture of the latest iteration of the 4th axis. It is quite a different animal at this point. I do not have time to do a 'build thread' and I will have very limited time to answer questions, but I will try.

The 4th axis is bigger, has a 6" 6 jaw chuck and an entirely new pneumatic lock system. The previous pocket bike mechanical caliper actuated by a linear air cylinder works OK, but had reached it's max potential and I needed more holding power. The solution finally was to design and build a new integrated pneumatic caliper from scratch. Subequently I went with a new rotor, this time from a highway legal vehicle and as large as I could possibly cram into the enlarged frame. I then went on to design an articulated version of the caliper which not locks up the spindle so tight you cannot turn it by hand even with a 12" long lever.

The single and two stage reduction now use the same belt. You just need to move it.

So, the 4th axis development is now completed and I am moving on to work on the 5C tailstock and then the trunnion table. These new items are what most people are interested in. I have included a photo of the first tailstock mock up for proof of concept. It works great. Instead of an aluminum 'nonsense' test piece, what is shown here is an actual finished 4thaxis part. It is an  integral one piece shaft extension with the pulley teeth cut right on the same piece of steel.  This pulley is for a 750 watt Mitsubishi industrial AC servo motor that is going on one of the 4th axis. I am currently using a 400 watt Mitsubishi AC servo motor on my new prototype. Pictures in next post.