Method of making a master die for use in an abrasion process

Claim 1

A method of making an oversize negative master die member from a positive model member, which negative die member is oversize in horizontal dimensions with respect to the positive model and may be used in automated electrode forming apparatus that applies circular translation to the master die member or to a workpiece member or both to thereby abrade a positive electrode member from the workpiece member within the master die member, said method comprising the steps of: affixing an oversize stylus to a tracing member of a machining and tracing apparatus, said oversize stylus being oversize in diameter compared to the machining or cutting member thereof, placing the model member in said machining apparatus and tracing said model with said oversize stylus while simultaneously cutting and machining the workpiece member to an oversize machined member which is oversize with respect to the model in a horizontal direction only and is of the same depth as the model, utilizing the oversize machined member to prepare the said negative oversize master die member and applying circular translation of an amplitude equal to the oversize in stylus diameter utilizing automated electrode forming apparatus in conjunction with said master die so formed, to thereby form electrodes of the identical size as said model.

Claim 2

A method of making an oversize negative master die member from a positive model member, which negative die member is oversize in horizontal dimensions with respect to the positive model and may be used in automated electrode forming apparatus that applies circular translation to the master die member or to a workpiece member or both to thereby abrade a positive electrode member from the workpiece member within the master die member, said method comprising the steps of: affixing an oversize stylus to a tracing member of a machining and tracing apparatus, said oversize stylus being oversize in diameter compared to the machining or cutting member thereof, placing the model member in said machining apparatus and tracing said model with said oversize stylus while simultaneously cutting and machining the workpiece member to an oversize machined member which is oversize with respect to the model in a horizontal direction only and is of the same depth as the model, utilizing the oversize machined member to prepare the said negative oversize master die member and applying circular translation of an amplitude equal to the oversize in stylus diameter utilizing automated electrode forming apparatus in conjunction with said master die so formed, to thereby form electrodes of the identical size as said model.

Claim 3

The method of claim one wherein the oversize machined workpiece member is composed of an electrically conductive composition and the negative master die member is a metal die prepared by electrical discharge machining using the oversize machined member as the electrode.

Claim 4

The method of claim two wherein the machined member is formed from graphite.

Claim 5

The method of claim one wherein the oversize machined member is placed in a plastic-abrasive composition, the composition is allowed to cure and the negative master die member is formed in the plastic-abrasive composition.

Claim 6

The method of claim one wherein the workpiece member is a nonconductive material such as plastic or wood.

Claim 7

The method of claim one wherein the workpiece member is an electrically conductive composition selected from the group consisting of graphite, copper, silver and similar materials.