Leading Manufacturer of Small Precision Mechanical Components

Stock Drive Products and Sterling Instrument manufacture long and short-run, high quality precision parts and assemblies. Mechanical components produced and distributed at SDP/SI are timing belts, pulleys, sprockets, couplings, universal joints, fasteners, gearmotors, sintered bearings, precision ball bearings, precision gears – ground spur gears, helical gears, miter gears, bevel gears, internal gears, rack and pinion and precision gearheads.  For over fifty years SDP/SI has been supplying precision mechanical parts to a wide variety of aerospace, medical and commercial industries.

SDP/SI’s experienced work force of engineers, manufacturing personnel and sales staff assist customers in choosing the most appropriate option for their application. From a cost effective stock item, modified component or a custom mechanical component,SDP/SI is recognized in the industry as the only source for small mechanical components.

Both companies are ISO 9001 Registered, with Sterling Instrument also being AS9100C Registered. Additionally, they provide a complete offering of technical articles, downloadable CAD models, extensive precision machining capabilities, online eStore and numerous engineering tools. Customers do not just purchase commercial or precision mechanical components; they purchase the flexibility and knowledge to fulfill their applications’ requirements as efficiently as possible – Setting ideas into motion.

>> New SI • ISO 7 Clean Room
Sterling Instrument announces their latest commitment to their customers.

>> Manufacturing Facilities
SDP/SI offers a variety of Design & Manufacturing services including: Gear Cutting, Turning, Milling, and Molding.


New Series of 1 mm Pitch Timing Belt Pulleys from SDP for Miniature Applications.
>> Read More

Recent investment in new CNC multi-axis and CNC swiss style turning machines has enabled us to produce a greater range of products. New to SDP/SI are Screw Machine Products. Find out how we can help you with your next screw machine part order.


Center Distance Designer is an easy tool used to determine the center distance or belt length of a belt drive system. Instead of doing the calculations and looking through tables of information, this tool does it for you in a few simple steps.


Selecting the right coupling for your application is not always an easy task. Many different application considerations and coupling styles have to be evaluated before the right coupling can be selected. We have compiled some useful information to make the selection process easier.