Riten Industries Inc. Anatomy of a Tailstock Rebuild-Repair

Established in 1969, Riten Industries, Inc. is the largest domestic manufacturer of live centers, dead centers, and face drivers in the work holding industry.

A growing part of its re-engineering platform, Riten is at the forefront of leveraging solutions to eliminate machine downtime due to tailstock failure. The fact is that a lot of machinery becomes obsolete before its time, and the original OEM may not exist anymore to provide timely replacements. If a machine becomes obsolete, Riten has developed a dedicated tailstock ‘rebuild-repair’ program that includes a bearing assembly inventory platform that allows manufacturers to strategically schedule downtime.

Riten Tailstock Rebuild–Repair Process

Some tailstock projects are quoted by Riten based on existing lathe assembly drawings. A budgetary proposal is provided for a repair based on these drawings, with the understanding that it is subject to change based on the condition of the tool as received. From there, Riten executes its established tailstock repair process.

Step 1:

Upon receipt, the tool is photographed and a project folder is assigned containing detailed inspection forms tailored to the scope of the project. Riten’s Repair Department then disassembles the tool—documenting the process with notes and photographs specific to each step. Once the tool is fully disassembled, a bill of material is created detailing all the essential components.

Step 2:

Based on the findings, Riten designed and manufactured a new quill with an upgraded four-piece bearing design. This new design was an upgrade with more capacity than the existing bearing design. They also designed and manufactured a replaceable point spindle instead of the existing solid spindle, since the customer noted that the spindle points of their existing lathes were easily damaged. This new design was highly efficient and performed much better than the old design.

A year later, however, Deister came back with a desire to achieve additional bearing life. Riten then initiated a review of the application on-site and discovered that part of the process involved an eccentric load that they were not aware of. Eccentric loads are very hard on both the bearing assembly and the spindle of the lathe.

The review revealed that Deister was turning shafts that weighed between 1,500 and 3,000 pounds. Once these are turned complete, a new center hole was cut that is offset (not on-center) and turn a new bearing journal, resulting in an unbalanced shaft. In effect, a heavy, eccentric shaft spinning at high RPM can literally walk the machine across the floor, which is extremely hard on the equipment and its effective lifespan. However, this shaft design is key to the performance of equipment Deister is known for.

Again, after reviewing the application on-site, Riten suggested key changes to both the process and the selection of dead centers. In addition to premature wear on the bearing assemblies, they were breaking dead centers which is a vital safety concern. In many cases, the center hole sizes were inadequate, therefore, charts were provided that specified minimum center hole sizes based on the weight of the part.

Additionally, the bearing assembly in the new unit was upgraded to a matched set of six angular contact bearings. The existing four-bearing assembly was replaced with a six-bearing assembly in the same custom quill. When designing the quill, room was left in the assembly for additional bearings—if they proved necessary.

Riten orders and inventories a spare bearing assembly with every customer repair. This is essential for limiting production downtime for a repair—reducing downtime to 2 to 3 weeks vs. 3 to 5 months for the repair.