Dewalt 735 crowning the wood

My 735 planer put a continuous crown on some 35" long pieces I put through it.

The pieces were on a sloped sled, to taper them. The sled is flat and the wood was secured so it couldn't move around during the milling. It's been a few years since I last used this sled. Back then I got flat sides from the planing.

I bought the planer new in 2011, and it has seen moderate use. The blades are about 6 months old.

Could this be due to wear on the rollers? If so are they easy to replace? Or is there another reason for the crowning?

I have not run test pieces through the planer since this happened - it was last night. I'll do that today. I haven't noticed this issue before.

This photo is of about 2/3 of a board with a straight edge that shows the crowning.

Attachment 372385

Mark is the wood jointed or prepared with a flat bottom before you feed it though. Lately there's been some talk about not needing a jointer to mill wood square flat and true.

I doubt that it is due to wear on the rollers. I have owned my 735 for about 10 years and I notice nothing different about the rollers. Unless you have planed a huge amount of wood since 2011, I think I'd look elsewhere.

I also doubt that it is due to wear on the knives, but that is more likely than roller wear. You could try a new set of knives to see if you get the same results.

As Andrew Hughes already asked was the wood jointed flat on one face before planing the taper? If not, the crown could be due the fact the wood wasn't flat on down side when planed.

If the wood had some stress in it and you took more off one side it could have bent because the remaining stress isn't even anymore.

Sounds like a jig problem. It may be flexing or compressing. Cheers

My guess is that the wood was supported at the two ends and the pressure of the rollers bent it as it went thru the thicknesser. You need to support the wood over all of its length.

Andrew and Randy - the wood was flat on the sled side. The top of the sled was flat. But Wayne nailed it, the underside of the jig is concave, by a little over 1/8" at it's deepest. It's in the dumpster now.

The incredible thing to me is that the four pieces of lumber on the sled are from 2 1/8" thick on one end down to 1 1/2" on the other end, and they are 3" wide each, so that was 12" of the 13" planer bed capacity taken up. I was taking very light passes, a quarter crank of the handle, and still the little planer distorted the wood.
Edit - in actuality the sled is longer than the bed of the planer (no infeed or outfeed tables), so this is what causes the crowning, not the planer distorting wood that thick.

I'm glad you got it figured out. Looking at the bright side of things at least you know how to plane a crown in a board with a taper. That's something right.:)

A small gap is apparent in the picture between the material and the jig. Was this the gap you identified on the underside of the jig?

David - no, the gap on the very bottom of the jig, that runs on the planer bed, is about 18"+ at it's widest.

The gap you see in the picture is tiny, the picture is magnified, but it's another good reason the jig is now in the dumpster.