Abstract: A method of making a high load tool having a hard body of plastic material with compression plates on opposites sides to compress and strengthen the body. The method includes the steps of inserting passage forming pipes into a container and retaining the passage forming pipes in predetermined locations. Epoxy resin is poured into the container to cover the passage forming pipes and then the epoxy resin is cured. Elongated rods are inserted into the passage forming pipes and a pair of load spreader plates are placed at opposite ends of the elongated rods. Threaded bolts are advanced on at least one end of the elongated rods to move the spreader means towards one another and to compressively load the body.

Abstract: Epoxy tooling which inherently expands and contracts with temperature changes for making parts of metal or plastic has elongated rods extending through guide tubes within the tooling and compression washers or plates on opposite sides thereof. These compression devices for strengthening the tool can be selectively adjusted toward and away from one another using nuts threaded on the rods for varying the compression load on the tooling in accordance with varying tool operating loads, working temperatures and amounts of expansion or contraction. Epoxy tools for molding plastics are heated and expanded to a working temperature and then compressively loaded in selected areas prior to molding operations to prevent tool stress cracking or epoxy tools for metal stamping are compressively loaded and supported in selected areas of high tensile stress and operated at room temperatures for high load metal stamping without fracture.

Abstract: Very large tools can be cast-to-size by making a pattern of the article to be formed by the tool, laying the pattern up in a pattern box, applying a release coat and coating the pattern and box with a tough, curable tool surface layer. A small amount of epoxy filled with a thermally conductive particulate filler is cast into the pattern box before the surface layer fully cures. Relatively large chunks of thermally conductive material are added to the box which are covered with additional cast epoxy. The cure of the epoxy is controlled to effect complete cure at room temperature within a few days but never to exceed a peak cure temperature above about 70.degree. C.