Tear-Out Problems with Cherry

Tips on tuning up machinery to minimize tear-out when making end-matched wood strip flooring. May 16, 2008

I make solid wood flooring out of cherry and oak timber. I am experiencing significant tearout on the groove side of my end matching. I'm not very experienced with making flooring, which is why I'm not sure if the tearout is caused by my moulder or the timber. Needless to say, chunks missing from the edge of the board don't make the best looking flooring.

The moulder is a IIDA Woodsman M-122. The wood is 3/4" cherry. For the last batch we ran, the cutter was brand new. We are hogging approximately 1.5 mm off the back side, and 1 mm on the face side.

Forum Responses
(Solid Wood Machining Forum)
From Dave Rankin, forum technical advisor:
You state the end match is tearing out. Are you running this on a tenoner or on an end-matcher? Either way, check to make sure that the backup blocks are in place and are correctly shaped.

If you are talking about the groove cut on the side of the board (lineal footage), then you may have one of several problems.

1. Make sure that the wood is run end to end and that no gap is seen between the boards. If you do see a gap this may mean that the feed rollers are different diameters.

2. Make sure that the cutters are sharp. Dull tools will increase the tearout potential.

3. Make sure that you are holding the wood to the table and against the fence. Use extra holddown and holdover rollers as needed. Wood that is not controlled can experience many finish problems including tearout.

4. Make sure that the table rollers are not too high. They should not be more than .006" (.15mm) above the table.

5. Feed the wood into the machine properly. The orientation of the bow is important. The ends of the wood should touch the infeed table. This means the bow is up in the middle. Also the sides of the wood should be straight line ripped (or close) to provide good control of the wood.

6. Moisture content should be 6-8% and the wood should be properly conditioned to allow for proper milling.

From contributor P:
One thing I may add... What degree hook angle on the cutterhead are you using? I would suggest 12 degree. You will get less lineal footage on your runs, but it will help with the tearout issue.

From contributor J:
Run a straight edge from your fence to the groove cutter. Make sure it just rubs the straight edge. If it hits heavy, this will cause chip out like you described. And as stated above, if cherry is over-dried or dried improperly, it tends to be brittle. A little more info on your setup would help too.

From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
I would add to Dave's list: Tear-out is greater when you take a large cut (deep and fast; or a lot of wood removal per knife). So, cut more slowly. Of course, too slowly generates heat and rapid dulling.

From contributor K:
On a small scale I wipe the cherry down with a damp rag before planing. That will eliminate tear out. Maybe that's not feasible on a large scale.