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A downhole tool (10) for mounting on a drill string comprises: a mandrel (16); a body (18) axially movably mounted on the mandrel; and radially extendable members, such as stabiliser blades or cutters (30), mounted in the body and being operatively associated with the mandrel such that relative axia

A downhole tool (10) for mounting on a drill string comprises: a mandrel (16); a body (18) axially movably mounted on the mandrel; and radially extendable members, such as stabiliser blades or cutters (30), mounted in the body and being operatively associated with the mandrel such that relative axial movement of the mandrel and body induces radial movement of the members. Application of axial tension to the tool produces axial movement of the body relative to the mandrel, tending to retract the members from an extended configuration. The mandrel may be arranged to draw the members inwardly to permit positive retraction of the members from an extended configuration. Further, the body may define a channel (32) and the mandrel and the members include an arrangement (38, 39, 40, 42) for maintaining a desired orientation of the members relative to the body channel.

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A downhole tool (10) for mounting on a drill string comprises: a mandrel (16); a body (18) axially movably mounted on the mandrel; and radially extendable members, such as stabiliser blades or cutters (30), mounted in the body and being operatively associated with the mandrel such that relative axia

A downhole tool (10) for mounting on a drill string comprises: a mandrel (16); a body (18) axially movably mounted on the mandrel; and radially extendable members, such as stabiliser blades or cutters (30), mounted in the body and being operatively associated with the mandrel such that relative axial movement of the mandrel and body induces radial movement of the members. Application of axial tension to the tool produces axial movement of the body relative to the mandrel, tending to retract the members from an extended configuration. The mandrel may be arranged to draw the members inwardly to permit positive retraction of the members from an extended configuration. Further, the body may define a channel (32) and the mandrel and the members include an arrangement (38, 39, 40, 42) for maintaining a desired orientation of the members relative to the body channel. od as in claim 8, further comprising the step of wrapping said mold in a porous silica after coating said mold with a final coat. 11. A method as in claim 8, wherein said outer diameter is between 15 and 20 inches. 12. A method as in claim 8, wherein said height is between 6 and 9 inches. 13. A method as in claim 8, wherein said base wall portion is between 0.20 and 0.30 inches thick. 14. A method as in claim 8, further comprising twelve gates between twelve atomisers. 15. A method as in claim 8, wherein said thinwall portion is less than 0.035 inches thick and free of gating. 16. A method as in claim 8, wherein said step of cleaning said mold further comprises the steps of: placing said mold in a Boilverclave; and placing said mold in a Dewax kiln. 17. A method as in claim 8, wherein said step of pouring said molten metal is at a temperature between 1560° and 1570° C. 18. A method as in claim 8, wherein said step of heating said mold in said furnace is at a temperature between 1045° C. and 1055° C. 19. A method for casting a metal combustion case, comprising the steps of: injecting investment casting wax into a metal wax injection die to form a wax assembly; washing said wax assembly; drying said wax assembly; dipping said wax assembly in a primary coat; allowing said primary coat to dry; dipping said wax assembly in at least one backup coat; allowing said backup coat to dry, resulting in a mold with a mold cavity having an outer diameter between 12 and 22 inches, a height between 5 and 10 inches, a thinwall portion with a thickness less than 0.035 inches and free of gating, a base wall portion with a thickness less than 0.30 inches and with twelve gates and twelve atomisers, wherein said twelve gates are between said twelve atomisers; placing said mold in a Boilverclave; and placing said mold in a Dewax kiln; coating said mold with a final coat; wrapping said mold in Kerlane; positioning said mold in a preheated furnace so that the furnace substantially surrounds the mold and so that a longitudinal axis of the long thin portion of the mold cavity is in an upright orientation; heating said mold in said furnace to a temperature between 1045° C. and 1055° C.; drawing a vacuum in said furnace; heating a nickel based alloy metal until it forms a molten metal; pouring said molten metal at a temperature between 1560° C. and 1570° C. into the mold cavity; breaking said vacuum; withdrawing said mold, wherein said molten metal has been poured; and solidifying said molten metal in said mold cavity so as to cause said molten metal to solidify to form a metal article with an equiaxed grain structure. 20. A method for casting a metal combustion case for use within a gas turbine engine, comprising the steps of: injecting investment casting wax into a metal wax injection die to form a wax assembly; washing said wax assembly; drying said wax assembly; dipping said wax assembly in a primary coat; allowing said primary coat to dry; dipping said wax assembly in at least one backup coat; allowing said backup coat to dry, resulting in a mold with a mold cavity having a height, a thinwall portion less than 0.05 inches thick and free of gating and a base wall portion with a thickness less than 10 times the thickness of the thinwall portion and having at least one gate; placing said mold in a Boilverclave; and placing said mold in a Dewax kiln; coating said mold with a final coat; wrapping said mold in Kerlane; positioning said mold in a preheated furnace so that the furnace substantially surrounds the mold and so that a longitudinal axis of the long thin portion of the mold cavity is in an upright orientation; heating said mold in said furnace to a temperature between 1045° C. and 1055° C.; drawing a vacuum in said furnace; heating a nickel based alloy metal until it forms a molten metal; pouring said molten metal at a temperature between 1560° C. and 1570° C. into the mold cavity; breakin