MZI Precision offers professional rebuilding of spindles, servo motors, and gearboxes. Those three belong in one sentence because on a real machine they fail together, get misdiagnosed for each other, and are best evaluated by one shop that sees all three.
When the spindle is not the problem
A machine that loses position, throws feedback alarms, or runs rough does not necessarily have a bad spindle. Sometimes the servo motor driving an axis is at fault. Sometimes an encoder or proximity switch is reporting garbage. And sometimes the gearbox next to the spindle is the source. In one investigation MZI documented, a vertical milling spindle kept burning up its bearings days after a correct rebuild because the oil-filled gearbox driving it had no proper seal, and gearbox oil was washing the grease out of the spindle bearings. Another rebuild would have failed the same way; the fix was an engineered top-end cover that stopped the oil, plus upgraded bearings. The full story is in the failure analysis guide.
That is why diagnosis comes first. Call with the symptoms and we will help determine which component is failing before anything gets pulled from the machine.
Which component is failing? A quick triage
Before anything gets pulled from the machine, the symptoms narrow the suspects:
- Lost position or orientation, tool changer misbehaving, nothing audible. The cause could be the servo, the encoder, a proximity switch, or a mechanical fault that presents as electrical. In one documented MZI case, every sensor tested fine and the cause was a coupling that could not hold position.
- Bearings that keep burning up after correct rebuilds. Look at what sits next to the spindle. In another documented case, an unsealed gearbox was washing the grease out of the spindle bearings with oil.
- Noise, roughness, or a change in sound at the spindle. The spindle bearings themselves are the usual cause; the failure symptoms guide covers what to listen for.
- Feedback alarms with a healthy-sounding spindle. Encoder and proximity switch testing settles it without guesswork.
The triage exists to give us the symptoms over the phone, so the right component comes out of the machine the first time.
What the electrical checks cover
Every spindle that goes through MZI’s inspection room gets three electrical tests alongside the mechanical measurements:
- Motor winding testing. The windings of an integral spindle motor are tested as part of inspection, and motor rewinding is an MZI service when they fail.
- Encoder testing. Position and speed feedback devices are verified rather than assumed.
- Proximity switch testing. Orientation and position sensors are tested against their settings, gap, and pickup. In one documented case the proximity switch tested fine, which forced the search toward a mechanical root cause everyone else had missed.
Gearbox rebuilds
Industrial gearbox repair and rebuilds carry the same logic as spindle work: wear is progressive, failures show up as noise and heat, and a rebuild restores the unit rather than gambling on a replacement. Because MZI rebuilds the spindles these gearboxes drive, a gearbox that comes in gets evaluated in context, including the sealing between gearbox and spindle that caused the failure described above.
Servo motor rebuilds
Servo motors from the same machines come through the same shop: disassembly, inspection, winding and feedback testing, and rebuild. If a servo fault is suspected alongside a spindle problem, send them together; one evaluation covers both, and the quote separates them line by line.
Electric motor repair
MZI also repairs electric motors more broadly; the capability is described on the electric motor repair page. The shop’s focus remains CNC spindle repair and spindle rebuilds, with motor work offered alongside.
Start with a phone call
Edward Zitney
President
(714) 475-4016
He has spent more than 44 years in spindle rebuilding and remanufacturing. He learned the trade over more than two decades at Precision Balancing & Analyzing, the shop long regarded in the industry as the standard for spindle work, later oversaw SKF Machine Tool Services, held service leadership roles at Setco, and wrote a published column on spindle remanufacturing for Fabricating & Metalworking.
Marco Guerrero
Partner
(949) 374-0060
He came up on the shop side of this industry. He started with his hands, welding and fabricating for the racing industry, then spent fifteen years as general manager growing a machining job shop, the same kind of shop that sends MZI spindles today. He has sold CNC machines too, so he knows what new equipment costs and when a rebuild is the smarter call. Today he and Ed are partners in MZI Precision, and his standard is simple: every customer feels informed and supported from the first call to the day the spindle ships back.
Call (714) 379-6505 and describe what changed. With a little information about your spindle we can diagnose the problem and determine your best action.
What to expect on the call:
- You talk directly with a spindle expert.
- Some problems can be diagnosed over the phone, and a few do not require removing the spindle at all.
- If your spindle should come in: disassembly, inspection, failure analysis, and a line-item quote, at no charge until your purchase order approves the rebuild.