When someone requests "DIAMOND" knurl or wants to roll a "DIAMOND PATTERN" on a part, there are several questions that need to be answered. It is very easy to confuse what is required on the part and on the knurling die itself. First we need to know whether a MALE (raised pyramid) or FEMALE (depressed pyramid) pattern is required on the part to be rolled. If the print just says "Diamond Knurl", we assume it to mean "MALE DIAMOND" Knurl on the part. Then we need to know what type holder will be used.
Rolling a "MALE" Pattern from the Cross-slide
- Use a set of RH and LH Diagonal knurls if a 2-die holder is available. The rolls can be fed axially at .005/.030" per revolution if necessary. Most of the knurling pressure will be absorbed in the holder if it can completely straddle the part, thereby greatly reducing part deflection and wear on the main spindle and cross-slide.
- If only a single wheel ("BUMP") holder is available, a "FEMALE DIAMOND" knurling tool must be used. This method is fine as long as the knurled section is relatively narrow, close to the collet and large enough in diameter so as not to deflect/bend too much.
Rolling a "MALE" Pattern from the Turret
- If a Brown & Sharpe (or other brand) two die holder with swivel knurl blocks is available, us a set of (2) straight knurls set a 30° angle to the axis of the part. Feed axially onto the work piece at approximately .010/.030" per revolution. Bevels are not required on the knurls.
- If the knurl blocks do not swivel, or you need to knurl close to a shoulder, use a set of RH and LH Diagonal knurls (convex axial feed knurls are recommended, chamfered wheels as a second choice).
Rolling a "FEMALE" Pattern
- A female pattern on the work piece can only be produced using a "MALE" diamond tool. This is normally accomplished by using a single wheel "BUMP" knurl tool from the cross-slide. Although it is possible to use two knurls in a straddle type holder, it is not normally done because of tracking problems and the necessity to custom match the tooth location across the width of the knurl dies.
Under normal circumstances a single "MALE" or "FEMALE" knurling die cannot be fed along the axis of a part. If this is a necessity, the holder must be tipped slightly and the knurl fed axially so that it advances very close to one axial pitch of the tooth spacing for each revolution.