Length of Cut The catalog gives the recommended minimum and maximum lengths of cut for all stock "Minute Man"® Broaches. Two or more workpieces may be stacked to establish the minimum length of cut. When using keyway broaches, make sure that the cut does not exceed the standard length of the appropriate bushing. When broaching any hole, be sure that at least two teeth are engaged at all times.

Set-up
Maintain a rigid set-up at all times. The workpiece must be solidly fixed or nested perfectly square with the baseplate and ram face. Check to make sure that all square and parallel surfaces on the face of the ram and the baseplate remain true.

Alignment
Proper alignment of the broach, workpiece, and ram is the most important factor in all broaching operations. Misalignment can cause drifting, deflection, and even breakage. Alignment Tips--If a keyway broach drifts, we offer the following suggestions:

1. Reverse workpiece or turn broach so teeth face toward the back of the press.
2. Let the bushing protrude above the workpiece to give more support to the back of the broach
      thereby helping to keep it aligned. If a collared bushing is used, place it upside down under
      the workpiece.
3. Make sure the broach is centered under the ram at the beginning of the cut. If the
      broach moves out of alignment after starting to cut, back off the pressure on the ram and
      align the broach itself. Repeat during successive cuts to ensure perfectly straight cuts.

Materials
duMONT Broaches can be used in various materials as follows:

Iron and Steel
Use the standard broach as supplied. Never attempt to broach any material harder than Rockwell Rc35.

Brass and Free Machining Bronze
Remove rake and stone a slight land on the crest of the teeth to prevent drifting.

duMONT Special Broaches are always engineered to provide the correct tooth form, pitch, and rake angle for the material specified.

Lubrication
Broach lubrication is a vital factor in achieving longer broach life and a cleaner finish. Always lubricate the back of the keyway broaches, regardless of the material to be cut, in order to reduce friction. Various materials require different lubricants as follows:

Steel
For mild steel a good quality cutting oil or water soluble coolant brushed on the teeth is recommended. For tough steels, such as nickel alloys, we recommend a good grade of sulfer base cutting oil.

Brass and Bronze
Brass is usually broached dry, but bronzes are worked better with an oil or soluble oil.

Cast Iron
Cast iron is almost always broached dry, but be sure to oil the back of the broach.

Aluminum
Straight kerosene may be used, but special lubricants are available. Contact your cutting oil dealer.

Troubleshooting
Most broaching failures (poor finish, drifting, deflection, breakage, chatter marks, or edge wear) can be attributed to deficiencies in alignment, lubrication, broach sharpness, tooth configuration or design, material hardness, and incorrect broaching speed or pressure, as detailed in this section.

If you have specific questions or problems not covered on these pages,
contact your "Minute Man"® distributor: Maryland Metrics.