Strange Problem with DeWalt Planer - Streaks in the wood

[Shannon Grizzell]

Hi all,

Over the last few years I haven't done much woodworking at all. So recently I decided a need to build a desk. I have a DeWalt DW735 planer that I've had for years and have had good luck with. I pull out the old 735, put a set of brand new blades in and start to plane some cherry. Immediately I get multiple "streaks" in the wood, running the entire length of the board. I think "Great, the blades are already nicked." I check the blades, clean everything, make sure there are no stray chips and try a couple more boards. Same thing. I flip the blades, clean everything again. Try again. Same thing... streaks.

When I tried to clean up the streaks with a sander or scraper, I notice they are not ridges as one would expect from nicked blades, but are depressions in the wood.

I run a board half way through and shut the planer off, then raised the cutter to see if I could see where the streaks are coming from. As it turns out, the streaks correspond exactly to the position of the screws that hold the blades in place. It appears the screws are rubbing the wood and making depressions in the wood. I thought perhaps I might have a defective blade that was too thick cause the screws to sit too high, but a check with digital calipers showed all three blades were thinner than the set I replaced.

Has anyone else encounter such an odd issue? If so, did you find a solution? My only ideas at this point are to try to shave a tiny bit of metal off the screw heads, but I am reluctant to do that since as I don't want to unbalance the cutter head.

Any thoughts are appreciated!

Regards,
Shannon

[Mike Henderson]

Try to slide the blades forward as much as you can - so that the cutting part of the blade sticks out as far as possible. Then see if you still get the grooves.

It's obvious that the blades are not "wide" enough - the cutting edge is too far back. Compare the distance from one of the alignment holes in the blade to the cutting edge between your old blade and your new blade.

You did say those were new blades, didn't you? And not resharpened blades?

Mike

[Shannon Grizzell]

Hi Mike.

Thanks for the suggestion. I compared the new and old blades and the new ones are a good millimeter "narrower" than the old ones.

These are brand new DeWalt brand replacement blades, not resharpened. They'll be going back to the store where I bought them. They must have over-machined the bottom surface of the blade during manufacturing.

-sg

[Davis Young]

One millimeter might not seem a lot but there isn't much clearance between the screw heads and the wood surface. As covered by others in a recent thread, I stripped the hex recess in some of the screws when changing out the knives in my 735. So I thought I would be clever in changing out all the screws from the button head (domed) to socket head (cylinder) so if it happened again, I could at least grab them with a vise grip if the hex recess stripped. Well when I ran a test board, I got the same scoring results. The change in geometry probably only added a millimeter or so to the profile but it was enough.

[John T Barker]

I'm trying to understand the geometry you are dealing with. If your new blades are thinner this should result in the holding screws sinking deeper to hold them. Deeper should bring the screw heads closer to the rotational axis, not further away which would result in contact with the wood. Am I missing something?

[Larry Frank]

I just put Infinity blades on my 735 and very happy with them.

[Shannon Grizzell]

John,

The new blades were thinner by about 4 to 5/100 of a millimeter - not much, it would seem. But when placed against the old blades, back to back, the new one were about a millimeter narrower. This means that the circumference of the cut is also closer to the rotational axis by about 0.5 mm. Apparently this is enough to bring the screws into contact with the wood.

I've not had a chance to replace the blades yet, but when I do, I'll let everyone know how it goes.

Larry, I might just have to try the Infinity blades next time. I've seen a few mentions of them now.

Thanks!

-sg