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Sentry Logo and Furnace


Percival B. Crocker takes control of a struggling furnace manufacturer,  Eaton Electric Furnace Company, which had manufactured specialized steel heat treating furnaces. He organizes Eaton into The Sentry Company and begins manufacturing small tool room heat treating furnaces and quench systems in Taunton, MA.

furnace image


Percival discovers that carbon deposits in furnaces contribute to protecting high speed steel during heat treating at very high temperatures. He designs a carbon box specifically to use with his furnaces, branding it “The Diamond Block.” The Diamond Block is still being used today.       

map of foxboro location


To accommodate growth, Sentry moves to a larger facility in Foxboro, MA.



Bristol Crocker, son of Sentry’s founder, along with Walter Makins from General Heat Treat, discover that thin stainless steel sheets can be used to protect tool steel from oxidizing at hardening temperatures. After research, the best stainless steel for these purposes is selected, and the process is patented.

VakPak65 Containers


Bristol further discovers that stainless steel foil can be cut to desired sizes and welded on three sides to form an easy-to-use, air-tight container for the heat treatment of tool steels. This new product is formally named Sen/Pak Heat Treat Containers and is highlighted at the 1966 International Manufacturing Technology Show in Chicago.

VakPak65 Logo


Our flagship product gets a new name. Originally known as “Sen/Pak,” our heat-treating containers and wraps are rebranded as VakPak65™ and are now available in more standard sizes – and custom sizes – than ever before.

Older Sentry Furnace


After 99 years, Sentry ends the manufacture of heat treat furnaces. The Sentry name retires as the longest-running family-owned furnace manufacturer in the world.

VakCo Logo


Under the direction of Thomas Crocker, the third generation of family ownership, Sentry Company officially changes its name to VakCo, to reflect its exclusive new focus on heat-treating containers and wraps.

Map Location of new building


VakCo expands its manufacturing operations and moves headquarters to 65 Leonard Street, still in our historic home of Foxboro, Massachusetts.

New Website


VakCo launches a new website with features and tools to facilitate our easiest, most efficient customer interactions ever.