Device for measuring a machine tool pull-in or clamping force

A force measuring device for measuring a force that a machine tool exerts on a tool holder, comprising:

• a) a piston body defining a bore, said bore slidably receiving a piston;
• b) a pressure chamber communicating with at least a portion of said piston and containing a fluid;
• c) a pressure gauge communicating with said pressure chamber, such that movement in said piston in at least one direction exerts compressive force on said fluid contained in said pressure chamber, said forces exerted on said fluid being communicated to said pressure gauge;
• and
• d) a retention member coupled to said piston and engageable by a machine tool, such that forces exerted on said retention member are transmitted to said piston.

A method for measuring a retention force exerted by a machine tool on a tool holder, comprising:

• a) providing a piston body defining a bore that slidably receives a piston;
• b) providing a pressure chamber communicating with said piston;
• c) allowing said machine tool to apply a retention force to said piston which is communicated to said pressure chamber;
• d) communicating said pressure in said fluid chamber to a pressure gauge;
• and
• e) inhibiting said piston from rotating relative to said piston body.