Now that the cutters have been installed on the head and the top plate has been lowered in the correct position (See article: Installation of Cutters on a Finger Joint Head), it’s time to post the cutter stacks and tighten the nuts to the specified torque value. Before you begin, however, the setup stand must be bolted to a stable workbench.
- All nuts and washers should be installed with anti-seize compound. Nuts should be no more than finger tight at this point. Wipe away excess anti-seize from top plate, nuts, and washers. Do not allow anti-seize to get between the cutters or cutters and bottom of the top plate surface.
- Rotate all the cutter stacks back toward the center mast of the head before placing the head on the multi-post setup stand. The rolled back knife stacks will allow maximum clearance between the cutters and the alignment posts when lowering the head into position- preventing damage to the knives.
- Verify that the alignment dowel is placed in the center position. There are three locating holes drilled into the bottom plate of the setup stand. The center hole is for aligning/posting up the cutters. The left and right pin locations are for torquing: the left hole is for torquing clockwise rotating heads and the right hole for torquing counter-clockwise rotating heads.
- Slowly lower the head onto the mast of the setup stand. DO NOT DROP the HEAD. Verify that the alignment dowel is safely inserted into the machined recess of the bolt head. Always install “bolt # 1” down on the alignment dowel each time the cutters are aligned or re-posted. This will aid in identifying any alignment or grinding issues that may arise in the future.
- Lightly position the cutters against the alignment post from the top of the stack downward. If the cutters are difficult to move, it may be necessary to loosen the nuts on the adjacent bolts. It is also helpful to use a pull-up tool to rotate the cutters against the alignment post. Do not use excessive force when positioning the cutters against the alignment post, as a distortion of the post may result.
- Examine to verify that all cutters in each stack are against the alignment post.
- As each cutter stack is aligned against the post, lightly tighten each nut with a wrench. Grip the head of the wrench to avoid overtightening. Take care: knife stacks can move away from the alignment post on counterclockwise rotating heads with right-hand threaded bolts. Left hand bolts will eliminate this as the cutters are rolled toward the alignment post when tightened.
- When all cutter stacks have been positioned against the alignment post and the nuts lightly tightened, check all knives on all stacks with a .002” (.050mm) thick piece of shim stock. The shim should be cut to a point approximately 0.040” (1mm) in width so each individual cutter may be checked. If the .002” (.050mm) shim can be inserted between the cutter and post, that knife is not posted correctly and must be pulled against the alignment post before proceeding. Loosen the nut, repost the cutter and recheck the stack. This check will reduce the grinding time required to equalize all cutters.
- When all cutter stacks have been checked, rotate the head back away from the alignment post to the pin location for torqueing. Again: the center hole is for aligning the cutters. The left and right pin locations are for torqueing: the left hole for right hand threads/clockwise rotating heads and the right hole for left and right hand threaded bolts/counter clockwise rotating heads.
Do not torque bolts with cutters against the alignment post.
- Torque all nuts to 25 ft/lb (35 Nm) in a crisscross pattern. See the diagram below.
- Rotate the head to the alignment pin location again and recheck with .002” (0.50mm) shim as outlined in step 8. Reposition any rolled back cutters against the alignment post. You will have to back the nut off to reposition the cutters. If the cutters are difficult to move, it will be necessary to loosen the nuts on the adjacent bolts.
- When all cutter stacks have been checked and corrected, reposition head on the correct torqueing pin and proceed with torqueing in a crisscross pattern in 50 ft/lb (70 Nm) increments.
- For 3/4” bolts, a maximum of 250 ft/lb (340Nm) is recommended. For 9/16” bolts, a maximum of 140 ft/lb (190Nm) is recommended. Over tightening can result in bolt and or head damage. Under tightening can cause cutter and head damage. Torque values may be different for different cutter stack height variations. Call AceCo for assitance if torque value is in question.
- When all bolts have been torqued to the proper value, repeat the torqueing sequence one final time.
***Always have your torque wrench calibrated at least once every year.
***Never use a torque wrench to break loose a tightened nut.
***Always use a breaker bar to loosen the nuts.