Jointer make ripples

[Scott Corbett]

I have a 6" Jet jointer that is now making ripples across the width of the edge. The ripples are about 0.002 between peak and valley. About every 1/16. Note that they are across the edge, not running the length of the board. Taking off about 1/32. Feedrate and type of wood do not seem to affect the results.
Replaced the knives, tightened everything, aligned outfeed and knives to within .001, replaced belt twice with link belt, cursed it, waxed tables, cursed it, rechecked alignment, gave up. Cannot feel any up and down movement in the cutterhead.

Anyone have a clue (about this problem)?

[Steve Jenkins]

Ripples parallel to the cutterhead have to be made by the knives. Most often it is too fast a feed rate or 1 knife higher than the rest. It could be a bad bearing causing the head to go up and down as it spins. I know you said feed rate doesn't affect it but try feeding your stock much slower. faster should spread the ripples out and slower make them closer together. Steve

[Ted Shrader]

Scott -

You hit most of the prime causes. Initial reaction is one knife is a lttle bit too high. But you checked that. Does it do the same thing across the whole width of the knife? ie move the fence over a little bit at a time and check it. That might indicate one (or the other) of the cutterhead bearings.

Must be some other kind of vibration...... Did you check the motor mount bolts? If the motor is moving around, it could shake the whole cabinet and transmit to the cutterhead.

Good luck,
Ted

[Scott Corbett]

I now have a few more things to consider from your input both here and on two other forums (not sure if it is considered polite to mention the names).

I forgot to mention in the original post that I don't think that my technique has changed significantly and the machine did not produce these ripples the first couple of years. But I did let it sit idle for a few months (a sad story not related to woodworking).

[Dave Moran]

I the machine did not produce these ripples the first couple of years. But I did let it sit idle for a few months (a sad story not related to woodworking).

Scott, that might be the clue, if the belt was tight, it could have compressed where it was sitting in the pullys giving a vibration each time one of the compressed areas crosses the pulley. Try warming your shop and let it run a while to see if it will relax or replace the belt.

Just a thought

[Scott Corbett]

I was not clear. The belt has been replaced twice since that idle time. I used link belts in both cases. I suppose it might be possible that a ball bearing in the cutterhead was flattened by the long idle period. Seems unlikely though.

[Joseph N. Myers]

Scott,

Have you tried cutting something wider, say 5" and see if the same thing happens? Also, try cutting a little deeper, say 1/16 and see what happens.

If everything still the same, check the most unlikely thing you can think of ---that's usually my problem. I personally would check to see if the blades are facing the right direction (I seem to remember doing it the wrong way a couple of times in the past).

Regards, and good luck, Joe