Multi-part dovetail repair broach assembly and methods of use

A broach assembly for establishing contact surfaces in a dovetail slot of a turbine wheel with surfaces of a bucket dovetail receivable in the slot, comprising:

• a sub-assembly including a plurality of cutters each having an opening therethrough and cutting surfaces about margins of the cutters and a plurality of spacers each having an opening therethrough and interposed between said cutters;
• a lead and a lag carried by said sub-assembly adjacent opposite ends thereof for respectively leading the sub-assembly into the slot and facilitating withdrawal of the sub-assembly from the slot;
• each of said lead, lag, cutters and spacers having a dovetail shape generally corresponding to the shape of the dovetail slot, said spacers and said cutters having apices;
• said spacers and said cutters having progressively tapered surfaces forming a continuously tapered surface along said apices thereof and in a direction from said lead toward said lag for engaging a surface in the slot enabling generally oppositely facing cutting surfaces of said cutters to progressively cut the contact surfaces of the slot as the assembly passes through the slot lead end first.

A method of progressively cutting surfaces in a slot of a first part to establish contact with mating surfaces of a second part receivable in the slot comprising the steps of:

• providing a sub-assembly of alternating cutters and spacers each having a marginal configuration generally conforming to the configuration of the slot with said spacer margins being inset from the cutter margins;
• forming a continuously tapered surface along surfaces of the spacers and cutters on a side of the sub-assembly facing generally opposite to cutting surfaces formed on the cutters;
• and
• passing the sub-assembly through the slot with the tapered surface engaging a surface in the slot and in a direction enabling the cutting surfaces of the cutters to progressively cut the surfaces of the slot to form contact surfaces for engaging the mating surfaces of the second part upon reception of the second part in the cut slot of the first part.