Chip-out from a year-old moulder
A month ago, we started getting chip marks on the faces of the wood (top and outside heads). The inside and bottom come out perfect. We have tried everything we could think of, adjusting the suction draw, changing the knives and heads, using high-speed steel instead of carbide knives, we've even put makeshift baffles in the collector hoods.
We have three other moulders, and have no such problems with them. Suction from the blower is more than adequate. I would appreciate any suggestions.
These are only a few of the possible problems. Since you state that other machines are not giving you the same problem, I would lean toward a machine alignment problem. If the fences were not aligned correctly the wood would be allowed to move. This can cause a variety of finish problems. The hold-downs and hold-overs can also allow the wood to move, causing problems.
I have had a few problems with chipping caused by the extension of the knife out of the head. If the extension is not enough, the chip can be forced to curl faster and pull the wood.
Another area that should be looked into is the belts that you are using. Worn or damaged belts can cause the spindle to vibrate. This vibration will show up on the wood as chatter, tear out and chipping.
You might also look at the wear on the table and fences. Worn parts can cause loss of control, creating problems in the finish.
Dave Rankin, forum moderator
From the original questioner:
We had limited success with your suggestion, enough that we could start running again.
I just had a thought: On the top and side heads, we have a section of flexible pipe, corrugated, about 6-feet long. Could the corrugations cause enough interference in the air flow to cause the chip marks?
The type of pipe that you are using can reduce the amount of suction that your system will have at the end of the pipe. This can allow the dust to be trapped between the shoe or rollers and the wood surface.
I have experienced the same problem. If you are not having a problem on the fence side or the bottom, it sounds like material is not being removed equally from each cutter.
I have also had to adjust the feed rate to meet the demand for stock removal. Some tooling changes I made were to the hook angle (to 5 degrees) and to a head with a larger gullet.
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