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The following procedure is intended for assisting in grinding the face and gullet of finger joint cutters in one operation- using a radiused grinding wheel. Note: Proper gullet radius and depth are critical to the optimal functioning of the finger joint cutters.Proper gullet radius distributes the cutting load over a wider area and lessens the chance for cutter breakage. Proper gullet depth assures that the joint is cut with the bevel of the cutter and not the index surface of the cutter.


Grinding the cutter face and maintenance of the gullet radius and depth can be accomplished in one step with the correct radius grinding wheel and an AceCo hook gage. The process can also be accomplished in two separate operations using two separate grinding wheels. There are different hook gauges for the various cutters that AceCo offers. It is necessary to have the correct type of grinding wheel for the process. Contact the technical staff at AceCo for specifics.

1)     Verify that the diameter of the head and arbor are the same size.

2)     Wipe the arbor clean and examine for burrs, scarring or damage.

3)     Wipe the inside bore of the head clean and examine for burrs, scarring or damage.

4)     Do not attempt to mount the head on the arbor if either the head or arbor has damage.

5)     Both the arbor and head are precision tools that operate under high pressure. This pressure can embed dirt or burrs into the mated surfaces, thereby locking the two units together making removal difficult. Damage to one will most certainly damage the other.

6)     Correct any damaged areas before proceeding. Do not use a hone inside the Ace-Loc sleeve to remove burrs. If the sleeve is damaged, contact AceCo’s technical staff before proceeding.

7)     Verify that the number of notches on the indexing plate can be divided evenly by the number of bolts in the head to be ground. Change the indexing plate if necessary. Inspect the indexing plate and lock to ensure that they are tight and in good condition.

8)     Loosen the relief valve to release pressure in the head.

9)     Carefully install the head on the arbor, making sure the cutters are facing the proper side of the grinding wheel.

10)   Before pressurizing the head, verify that the cutter stacks will clear both ends of the grinding wheel. Adjust the limit switches or reposition head on the arbor if necessary.

11)   Select a cutter stack to be ground and position next to the grinding wheel. Always begin grinding with stack/bolt # 1. This will aid in solving grinding related issues that may arise.

12)   Rotate the head until the faces of the cutters to be ground are in a vertical position; a small combination square works well for this. The cutters should be parallel to the grinding wheel.

13)   Close the relief port and pressurize the head to the recommended pressure engraved on the end of the Ace-Loc hydraulic sleeve.

14)   Wipe all excess grease from around the inlet valve and relief valve using a cotton swab.

15)   Re-check the knife stack faces, they should still be vertical. Adjust if necessary.

16)   Color all knife stack faces with a felt tipped marker to aid in identifying grind pattern.

17)   Set grinding wheel height and depth to within .030” of the cutter faces and gullets.

18)   Make a few test passes to ensure that the cutter stack clears the wheel at both ends of travel. Adjust cutter head or grinding wheel if necessary.

19)   Turn on wheel and coolant. Position coolant nozzles to the point of cutter/grinder contact.

20)   Start table motion and slowly adjust the wheel inward toward the cutters.

21)   Adjust the grinding wheel inward only when the cutters are positioned on the leading edge of the wheel. Adjusting the wheel on the trailing side could cause excessive grinding pressure when the cutters return to the leading edge, thereby overheating and possibly damaging the cutter tips.

22)   Adjust wheel very slowly toward the cutters until light contact is made.

23)   Advance the wheel inward .0005” every few passes, until a good grind pattern is visible. Grinding with light passes will minimize the size of burrs created on the sides and tips of the cutters.

24)   The grind pattern should be uniform across entire face of cutter stack- side to side, top to bottom. Continue grinding until square, sharp corners have been achieved. Check under magnification using a 10X – 20X loop.

25)   Once grind pattern is uniform, stop machine and check the cutter stack with an AceCo hook gage. Inspect at both ends of the stack. Verify that the gauge being used is correct for the joint length of the cutters being ground.


26)   Check for correct angle and proper gullet depth according to the radius profile and engraved line on the hook gage. It is helpful to have either a light source or a reflective item behind the cutter stack being inspected.

27)   Proper hook angle and gullet depth is attainable without grinding into the cutter head.

28)   If a hook angle adjustment is necessary, rotate the cutter tips toward or away from the wheel a very slight amount. This will require a height and infeed adjustment to the grinding wheel before proceeding.

29)   If angle and depth are acceptable and all cutter faces are uniformly cleaned up, start the grinding process; advancing the wheel inward .0005” each pass until .002” of material has been removed.

30)   Re-check hook angle and inspect cutter tips under magnification to ensure that the corners are square and sharp. It is time to grind the remaining cutter stacks.

31)   Mark this position on the infeed wheel and grind remaining stacks to this depth.

32)   Color the cutter stacks with a felt tipped marker.

33)   Back the grinder infeed out until there is no contact between the cutters and wheel.

34)   Start the grinder without coolant and very slowly advance the infeed until very light contact is made between the wheel and cutter stack.

35)   Allow the grinder to make one pass. stop and examine the cutter stack for marker left on the corners of the end cutters. Any remaining marker indicates a low area that must be ground out before proceeding.

36)   Start the grinder and coolant, then advance the wheel in slightly and allow to dwell until all marker is removed.

37)   Check both ends of cutter stack with a hook gage as per step 26.

38)   Repeat steps 33 – 35 until all marker is removed with one pass.

39)   Repeat steps 19 – 30 on all remaining cutter stacks.

40)   After all stacks have been ground, make one final pass, allowing the grinding wheel to make several dwell passes across the knives. The infeed should not be changed from the marked position.

41)   Return the head/arbor to the original starting position (cutter stack/bolt # 1). This will correctly position the arbor for the next head to be ground.

42)   Before de-pressurizing the head, examine the areas around the sleeve, inlet and relief valves for grease seepage. Do not install the head on a machine spindle until the grease leaks have been identified, inspected and eliminated.

43)   When finished, depressurize and remove head. Blow off all moisture and grinding residue with compressed air. Spray head with light coat of WD-40.