Hey all,
I received a private message asking if there is no simple answer to this issue. Because when I answer privately, then only one person benefits, but not all, so I try to avoid that, so my answer is here:
You are right, there is no simple answer. The answer would be simple if you start from zero and build your own machine, then you simple choose a stepper that has the brake integrated and the driver that has a pin for the brake and the problem is solved. But if you have an Elite/Masso with the Masso closed-loop stepper motors with integrated stepper drivers, I would assume you would want the same motor/driver, but with brake, if possible. But they are not available with brake. So the solution for Elite/Masso would be:
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Either you choose a different stepper motor, but one with brake integrated, and use the Masso Documentation to make it run with the Masso G3 Touch Controller. Besides the stepper, you need a driver, or a stepper with integrated driver. To make wiring simple, you would choose a driver which supports the brake already with a pin that is for the brake control. You will also need to power supply the brake.
The Masso G3 supports a lot of different steppers/drivers, so this is clearly possible, see here for examples. I assume Onefinity will give you no support for that, but the Masso community/forum probably will.
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or you retrofit a separate brake. Since your Elite motor to my knowledge has no shaft that protrudes at its end, you will have to put the brake in front of the stepper, between the stepper and the ball screw, with an additional coupler. If you searched the forum, you know that Tom @TMToronto found one and could possibly tell you more (link). I have no experience with retrofitting a brake to a stepper.
But if it’s the problem that arose when switching to a heavy spindle, that comes down with gravity when on Masso startup you initially hit estop, what I would do first is replace the ball screw with a less steeper one. I wrote that already above: With the switch to the Z-20 assembly that is found on Elite Series and also available as upgrade on Original Series, the Z ball screw pitch was changed. It changed from 4 mm per revolution to 10 mm per revolution. This means that after the electromagnetic holding force is gone when the stepper has got its power cut, the remaining purely magnetic holding force has a lower transmission ratio than with the older, less steeper ball screw, and can now carry much less spindle weight on its own. Plus the friction is lower.
With the old 4 mm / rev ball screw on Z-16 assembly, nearly noone complained about the spindle moving with gravity by itself, when the stepper was powered off. And the spindles were probably the same 2.2 kW water-cooled ER-20 spindles with about 5-6 kg weight. So you see, the problem is not the missing brake, but came up with the much steeper ball screw. And what you will get with replacing ball screw is more detail on Z.
Ball screws are available at CNC components suppliers or directly at the manufacturers (e.g. HIWIN and MISUMI are popular brands).
Disclaimer: I have not tested a Z-20 with another ball screw, I don’t even own a Z-20. I just own a Z-16 with its 16 mm diameter hollow shafts and its 4 mm / rev ball screw, like hundreds of forum members do 
A characteristic feature of the ball screw is its pitch. It is the straight-line distance (“travel”) of the screw nut per revolution of the screw, measured in millimeters. It corresponds to the distance between adjacent thread flanks (for single-start threads). This slope is not equal to the slope of that ramp which results from rolling the running groove to an inclined plane. That ramp slope is the quotient of the two cathets of the slope triangle (stroke distance per circumference) and is usually given as a dimensionless number in percent. The convention of specifying spindle pitches in millimeters and thus relating them to a revolution or the rotational speed instead of the circumference facilitates most calculations for dimensioning a machine axis, since speeds and torques are usually transmitted from the drive motor onward. The pitch, together with the speed in the product, conveniently gives the feed. However, the geometry of the ramp rolled up to the screw plays a significant role in the design of the ball screws.
– Source: Ball screw – Wikipedia (DE)
