Measuring Hook Angle on Moulder Heads
Here's a primer on how to measure the hook angle on a moulder head. September 28, 2006
Question
I need to know how to determine the degree of hook on moulder heads. I have no paperwork on the heads that are in stock at my current employer, and I am trying to have knife stock profiled, and the profiler needs the degree of hook. Can you use a protractor, tape measurer, etc.?
Forum Responses
(Solid Wood Machining Forum)
From contributor A:
Draw a line through the center of your heads from the tip of knife slot. Then use a protractor (or whatever you have) to measure hook angle off that line.
From contributor B:
The hook angle can be adjusted a little bit by the grind of the knife or by extending the knife further out of the head. The hook angle on most square heads is around 38-40 degrees. If you are using a square head please be aware that they must be maintained very well or the knives can loosen.
From contributor E:
I use a protractor to measure hook angle. Using a copy machine, I make a print of the side of the head. A straight line through the center of the head to the knife projection would be about 5/16" out of the head - then adjust the protractor to determine the corrugated pocket angle.
From contributor C:
I have a Profimat 22N, and I run mostly flooring with it. When running hickory and to a lesser extent white oak, I have problems with the length of the slivers coming off the right side head being so long that they constantly cross and plug the dust collection port, both at the machine and in the tube. I am running face down, tongue on the right head, using Byrd dedicated flooring cutters. The hook angle on these cutters is 15 degrees. Would a 10 degree angle help make shorter chips?
From contributor E:
I do not think that changing the hook to 10 degree will eliminate this problem. Are the tools you are using universal insert heads or dedicated heads? Also, how much material plus the profile are you removing? If your material is oversized by more than 1/4", then you may want to reduce the oversized amount to no more than 1/4". Another option is to use shear tooling that will break up the cut. What is the moisture content of the lumber?
From contributor C:
I oversize blanks by a 1/4, and try to take an 1/8 each side. Lumber is at 7-8 % Heads are dedicated flooring cutters.
From contributor D:
Check to make sure your rebate cutter is set properly - just a thought.
From contributor F:
To contributor C: Your problem is probably the head design itself. Are you running rough lumber? The problem with dedicated insert heads is that no one ever makes the knives tall enough. The height of the knife will probably only handle like 7/8" thick material. If you feed in a piece that is 1 inch thick, then the right side cutter will not remove all of the excess material above the knife. This unremoved portion of stock then gets sheared off on the fence after the right head and gets plugged up in your pipe. I would guess the strings you are seeing are like 6-10 inches long. I’ve seen it a thousand times. If this is the case, you need a taller cutter/knife.
From contributor D:
When that starts happening again drop you table down so you’re taking more off your first bottom head. That should clear things up.
From contributor E:
I agree - the tool may not be tall enough. If this is the case, you can lower the infeed table as advised. You might also speak with the tooling manufacturer to see why the tool was made short. Some companies will provide the proper tool if this if the problem.
