3mm Machining
REC offers three types of 3mm machining. 
The first and least expensive process we offer is performed on an in-house custom machine which operates like a slitting saw. Attached to a special jig and fixture, the rotor is slowly manoeuvered on "air over hydraulic" tracks passed a small diameter cutting blade with a selected number of sharp carbide bits. This method provides no adjustment to select a desired clearance. The cutting blades are exactly 3 mm wide leaving a rotor with a seal clearance of approximately .0025 in. Although adequate and again, inexpensive, the finish is not a high enough quality to accept ceramic apex seals. This method is also not capable of cutting 93 up rotors or any other rotors with the induction hardened slots.
Cost $35.00 per slot
The second and still economical type of 3mm machining is performed using a special "end mill" attached to a milling machine. Unlike the slitting saw, the end mill bit does not complete the cut all in one pass. Using a 2mm wide end mill, we cut up one side of the slot and then back down the other. This process translates to conventional milling on the first pass and climb milling on the second pass creating a non-uniform finish. It is recommended to hand dress the slot with a stone or fining Emery paper to a finish of your liking. Specific rotor to seal clearances are available with this procedure. We can offer tolerances accurate from 2/10 to 3/10 thousandths of an inch.
Cost $55.00 per slot
The final but most expensive method of 3mm machining is done using a process referred to as EDM. This process uses a very thin wire that electro statically erodes away the material from within the slot. This provides one of the most impressive and accurate finishes and clearance tolerances. EDM is optimal for any high-performance or racing application. Providing tolerances accurate to one ten thousandths of an inch, the slots will now accept any material of apex seal desired including ceramics and carbon.
Cost $75.00 per slot