Spindle repair, set back true to the machine
Cavco rebuilds machine tool spindles and sets them back true to the machine. Runout, heat, noise and a finish that has gone off are the bearings more often than not, sometimes the journals or the taper, and sometimes not the spindle at all but the ways and the table it runs over. We measure first, rebuild the spindle with new bearings and seals, regrind what has worn, and align it to the machine, so the numbers on the part come back, not just the numbers on the bench.
What a spindle problem looks like on the part
The spindle gets the blame because it is the part that turns. The marks it leaves are the same marks worn ways and a tired head leave, so the first job is telling them apart, with an indicator, before anything is ordered.
- Measured with an indicator on the taper or a test bar. Bearings first, then a journal that has worn or a taper that has picked up.
- A spindle that runs hot at speed is a bearing with the wrong preload, the wrong grade, or lubrication that is not reaching it. Left alone it takes the journal with it.
- A rumble or a whine that follows the spindle rather than the axis. Bearings, or an imbalance that a rebuild corrects on the way back in.
- Chatter marks or a finish that changed on the same tooling. Often bearings, and about as often the ways and the head that carry the spindle, which is why we measure the machine and not only the spindle.
- A tool or a chuck that no longer seats, or seats and runs out. The taper is reground true to the bearing journals so the tool runs on the spindle's axis, not near it.
- On a knee mill, a quill that rocks in its bore puts every symptom above on the part. The quill and its bore are brought back to a running fit before the spindle inside it is judged.
A spindle on a bench is true to itself. The machine is what it has to be true to
A cartridge shop rebuilds a spindle to run true on the bench, and for a motorised cartridge that is exactly the right place for it. What the bench cannot tell you is whether the spindle runs true to the table it will cut over, square to the ways it will travel on, and on centre with the tailstock it will turn between. That is the geometry around the spindle, and it is where a rebuilt spindle goes back to making the same bad part. We rebuild the spindle and put the machine right around it in the same job, and you get the measurements from both.
Where the ways under the head are gone, the spindle is the smaller job, and it meets rebuilding, way grinding and alignment. We say which before the work starts.
Spindle repair by machine
Bearings are bearings. What carries them, and what they have to run true to, is different on every machine.
- Spindle repair on surface grinders, Okamoto, Brown and Sharpe and Mattison among them, is the wheelhead spindle and its bearings, and on the larger machines the workhead too. A wheelhead spindle that has lost its preload shows as a finish that will not clean up, and the rebuild goes back aligned to the table travel so the wheel runs parallel to the work.
- Spindle repair on Bridgeport mills is more often the quill than the spindle inside it. The quill and its bore are fitted back to a running clearance, the spindle bearings replaced, and the head trammed to the table when it goes back.
- Spindle repair on Hardinge lathes is part of the rebuild, because the collet spindle is what the machine's accuracy sits on. Bearings, preload, and the spindle set true to the bed so the machine turns parallel again.
- Spindle repair on horizontal boring mills is the quill spindle and its bearings, often rebuilt in place on a machine too large to move, and always aligned to the ways and the table afterwards, because a boring mill spindle that is true to itself and not to the table still bores crooked.
- Spindle repair on vertical turret lathes is the table spindle and its bearings under a table that carries tons, and the table is relevelled and the rail realigned when the bearings go back.
- Spindle repair on Kellenberger and Studer cylindrical grinders is the wheelhead and workhead spindles, rebuilt and aligned to each other and to the table. On CNC lathes and machining centres the plain and rolling bearing spindles are ours. A motorised cartridge goes to a cartridge shop, and we do the removal, the refit and the geometry.
Wheelheads and workheads on their own are covered on the grinder repair page. Telling a spindle fault from chatter, taper and the rest is diagnostics. A spindle that failed with a drive or a control fault belongs with CNC machine repair.
Questions we get
- A part that comes out oval, tapered or with a poor finish gets blamed on the spindle, and about half the time the spindle is fine. Worn ways under the head, a table that has lost its level, a quill with play in it, all put the same marks on the part. We put an indicator on the spindle nose and the machine before anything comes apart, so the answer is a number, and the number says which.
- The spindle comes out and comes apart. Bearings are replaced with the right grade for the speed and the load, seals go in new, journals and tapers that have worn or picked up are reground true, and the assembly goes back with the preload set and the runout measured at the nose. Then it goes back into the machine and is aligned to the ways and the table, which is the part a spindle on a bench cannot have.
- Ourselves, for the spindles machine tools were built with, plain and rolling bearing spindles, quills, grinder wheelheads and workheads. The motorised high-speed cartridge in a modern machining centre is a different animal, and that goes to a cartridge shop. We pull it, put the rebuilt one back, and prove the machine's geometry around it, which is the half of that job a cartridge shop does not do.
- A measurement visit is the cheapest part of a spindle problem, and it is the one that stops a shop paying for a spindle rebuild it did not need. Tell us the machine and what the part is doing and we will give you a budgetary range from jobs like it, then a quote once we have measured.
- The diagnosis, always. The alignment, always. The rebuild itself depends on the spindle. A quill or a grinder head comes to the shop, and a big boring mill spindle is often rebuilt in place. Either way the machine is measured at the end and you get the figures.
- Surface grinders, Okamoto, Brown and Sharpe and Mattison among them, and their wheelheads and workheads. Bridgeport and other knee mill quills and heads. Hardinge toolroom lathes, where the spindle is part of every rebuild. Horizontal boring mills, vertical turret lathes, Kellenberger and Studer cylindrical grinders, and CNC lathes and machining centres. If yours is not on the list, ask.
Reviewed September 2026 by Cavco Machine Tool Rebuilding, LLC.
Tell us which machine and what the part is doing
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