On 3/27/2014 4:20 PM, dpb wrote: ...
Oh, and perhaps one of the most likely -- knives (or at least one knife) dull enough to burnish instead of cut cleanly. A little paint thinner on a rag will uncover this real quick--the burnished spot won't suck it up like the cleanly cut sections will...
"woodchucker" wrote
Check the cutter head bearings for up and down play, and that all the bolts holding the bearings to the frame are present and tight. It sounds like it is vibrating, or oscillating up and down, either that or the hold down rollers are not putting enough pressure on the wood.
Is there a metal plate that reverses the direction of the chips immediately before the outfeed roller? Any kind of sturdy steel that is adjusted so it barely clears the finished height of the wood after it leaves the cutter head and before the wood gets to the feed roller? If there is, it should be adjusted only a few thousandths above the surface of the wood. I use a piece of copy paper to put between it and the wood, then lower it so the paper can not be pulled out, or just barely pulled out. That must be done every time blades are re-installed, or you can get some bad results. It sounds like the particular piece of wood this happened to had just the right weight, length and flexibility to reach harmonic resonance of each individual blade hitting the surface, which then amplifies as it continues and flexes the wood enough to float the feed rollers up off of the bed. If there was rigid steel holding the wood down, it would not allow it to be vibrated up off of the bed.
Harmonic resonance is a weird thing. FM, to most people. I would venture a guess that this is involved in your problem in some way. If you have a strobe, try it while it is running with the guards off. It might show something.
"woodchucker" wrote in
Could still have to do with weight, flexibility (or lack of it) and harmonic resonance between the blade strikes, the resonance of the wood and the resonance of the springs. Change any one of the factors, and the resonance goes away.
You may be on to something there with the board deflection... or lack there of.
Dewalt made an error in using coarse threads on the table adjustment. The screws are at the hinge point and 1/4 turn goes from lower than the platen, to ridiculous height above the platen. Add to that when you set the lock nut, it wants to move the setting, any slight movement (backlash in the wrench to screw) is a large adjustment.
Had it been fine threads I probably could zero in much easier. I still have some snipe on entry, so I am working the infeed table trying to sneak up on no snipe. but the waves are gone.
Thanks John, I would not have thought my adjustments were out since they have been working for quite some time w/o issue. I had added more pressure because it removed the snipe on both ends.
When I hit the lottery, maybe I can get a nice big hunk of iron with a
20" table and helical head.Thanks everyone. I'll post info tomorrow when I finally remove the snipe. (if I remove the snipe).
You are welcome...
I was pretty sure that was the problem as I've had some similar experiences over the years... not all with planers. One of the most memorable was when I worked in the Gunsmith Shop at Colonial Williamsburg. We were reaming out a hand-forged barrel using a hand turned reaming machine. It seemed like there was a hard spot in the barrel as with each pass with a new and larger bit we had a problem in the same spot.
While watching what was happening I realized that the real problem was the reaming bar was camming over the edge of the hole at the end of the barrel when it reached a certain point. The bottom line was the barrel center was not in line with the reaming machine center. That may seem like an obvious mistake until you see what a hand forged gun barrel looks like at each step of the way... center is an estimation for quite a while! ;~)
Glad it worked out!
John
woodchucker wrote in news:3NednQqfCvnV86nOnZ2dnUVZ snipped-for-privacy@ptd.net:
Maybe you should switch back to the vac for a pass and see if it clears up. On sanders, too much suction can cause the tool to stick to the work. I wonder if something similar is happening here. (Just a guess.)
Puckdropper
----------------------------------------------------- I had this problem with a DeWalt, DW-733 at least 10 years ago.
Tech service was aware of the problem and walked me thru the fix.
It involved removing some parts, but forgot what they were.
Lew
I know the feeling.. I can't remember what I cut up some parts for.. Hmmm... maybe a call.. the teflon helped, but now you have me curious.
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