Ball Screws
Common Ball Screw Problems

Symptom:
Screw is slightly out of tolerance. Runs a little rough. May be slightly bent.
Solution:
Straighten screw. New balls. New tubes. Make new custom nylon wipers. Re-pack and adjust preload.
Symptom:
All symptoms of the above, PLUS the screw is extremely out of tolerance.
Solution:
All of the repair procedures for the above, plus you will need a screw and nut regrind, from minor (dust grind) to major regrind.
Symptom:
All symptoms of the above, PLUS damaged journal ends.
Solution:
All repairs done above, plus a chrome and grind on the journals.
Symptom:
Symptoms present are a combination of all of the above, PLUS the nut is beyond economical repair (B.E.R.).
Solution:
Procedures and repairs performed in all of the above, plus fabrication of a new nut may be needed.
Symptom:
Entire screw is beyond economical repair generally because a regrind would penetrate into the case hardening.
Solution:
You need to have an entire new ballscrew assembly manufactured. It may be possible to quick fix your old ballscrew to keep your machine operating while a new ballscrew is being manufactured. However, a quick-fix is neither a St. Lawrence - Troy warranted repair, nor is it a permanent repair.

St. Lawrence - Troy, L.L.C. is qualified to repair Ballscrews and
feedback devices from all Manufacturers,both Domestic and Foreign.
Engineering & design of new screws!

Evaluation Prior To Repair

Spindles


Common Spindle Problems

The Wrong Spindle for the Job. Too often, a grinding or boring spindle is used in an application for which it was never intended by the original manufacturer. Frequently, we can make design modifications in your spindle to achieve that "little extra" performance - but only within the inherent capacity of the spindle itself - and only if you let us know that you are using the unit in such a manner. We also carry a large stock of used spindles. A quick check with us might provide you with the right spindle, at a fraction of the original cost.

RPM Most spindles have a rated maximum operating speed stamped on the Spindle Body or Housing Plate. It is essential that we know, when rebuilding your spindle, if you are deviating from that RPM, so that we may provide the proper bearing preloads optimum to your application. Running a spindle too fast or too slow will almost always result in poor performance.

Outside Influences. The spindle is usually the first component of the boring or grinding machine to be blamed when things go wrong. Very often the cause of the trouble is elsewhere.

  1. Drive Motors and Idlers - Bad bearings or out-of-balance will transfer through the spindle into the work and will eventually damage the spindle.
  2. Quills, Wheel Adaptors and Boring Bars - All tool holding or wheel holding attachments to the spindle must mate perfectly to the pilot surfaces of the spindle face. Bad taper; rusted, bent or out-of-round holding devices can result in excessive vibration and/or misalignment of the tool or wheel to the work piece.
  3. Excessive Belt Tension - This is one of the biggest causes of spindle failure for belt driven spindles! the belt should be just tight enough to avoid slippage. Excessive tightening only creates shaft deflection and cocks the rear bearings out of alignment, causing poor performance, heat and early failure. Improper belt alignment also causes friction and vibration problems. Check with our Sales Engineering staff about the use of Poly-V Belts for your application.
  4. Contamination - Cleanliness is the rule when we assemble and test your rebuilt spindle. Precison bearings are expensive! We all know that production conditions are not laboratory conditions, however certain common sense precautions can prevent early spindle failures caused by contamination. When coolant is used, direct the flow away from the Spindle Nose as much as possible. Grinding dust and other metal fines suspended in coolant create havoc when introduced into the Bearing Compliment of a spindle.