Help! Chipped Planer blades first pass after changing

[Benjimin Young]

A little background, not my first rodeo with myplanner or blade changing.

I have owned my Dewalt DW735 planer for a log time and amvery happy with it. I have changed the blades and serviced the planer severaltimes over the years with no problems. So what went wrong this time?

Background... the blades were old and needed replacement andthe planned was is need of a cleaning. I had planed some short 16" long 11/2" mahogany 12" wide and was surprised the planner with potentiallydulled blades could handle it, but just barely, with very shallow cuts but theblades did the job. I later planed down some painted finger jointed pine doorjambs. To explain, the wood came from a new exterior replacement door jamb butI only need the door and not the jamb. So I though I wood salvage the jambs forsome wine boxes. I have done this type of salvage many time before. Note, Ialso use a good metal detector from Lee Valley (lesson learned a long timeback).

Anyway, on to the problem. After multiple passes on the threepieces of painted finger jointed pine the planer kicked off (reset switch) somethingthat has never happened before. I decided to service the planer, did a completecleaning and flipped the blades over to their unused side, all went as wellusual. I then tested with the 3 foot piece (same pine finger joint, 5"wide) which it seemed to handle with no problem but it came out with 5 majorridges, the kind you get when you chip a blade.

I opened up the planner again and the brand new side of theblades had 5 chips on all three. I immediately checked the wood with the metaldetector and also did a very careful visual inspection. I even tested the metaldetector by introducing a nail, it was working fine. There is nothing I canfind in the finger jointed pine that should have chipped the blade, especial in5 spots. so I then checked the planner blade installation and everything looknormal. One last comment, I think the blades were Powertec not Dewalt butremember I had already been using the other side of the blades previously withno issues.

I will throw away the attempted salvaged pine wood just incase but I don't want to waste another set of blades without knowing what wentwrong. Hence I am reaching out to this group for thoughts.

Can blades be good hardened steel on one side but be badsteel on other the side?
Is it possible I overheated the blades when the planerstalled; but there was no discoloration from over heating
Is it possible that painted finger jointed pine can havesomething non-metallic in the manufacture process that would leave 5 chips inthe planner blades on the first light 3 ft pass
Did I do something wrong in the blade change process; again Ihave done this many time in the past.
Other thought?

A big mystery to me.

[Thomas McCurnin]

The blade change process on that planer is simple and idiot proof. I don’t resharpen those blades and just use new ones and change out to new ones for important stock. They’re cheap.

That leaves either the depth of cut or the stock as culprits.

I would re-try with new blades on pine, planing off no more than a 16th. Then tell me what happens.

[Dan Friedrichs]

That is weird...

Dumb question, but are you sure the blades are flipped the right-side-up?

[Jim Becker]

Planing painted material can be iffy...you never know what's embedded in it, such as dirt, sand, etc., and there are so many things that can damage the sharp knives on the planer. Keep a more worn set for stripping off paint if you must work with material like that, and change out for clean, sharp ones to further process the wood to dimension.

[Andrew Hughes]

I have experienced the same thing with reclaimed wood.
Even the smallest patch of old paint is hard on knives.
Thats the payment to work with good old wood.

Good Luck

[David Stone (CT)]

I've planed painted wood a few times. It tends to do a number on the knives, as the others above have said. When I do that now, I use a handheld belt sander to get rid of the bulk of the paint first.

[Brian Tymchak]

I learned the lesson about planing painted wood when I jointed some double primed pine window trim as a first test run when I got my jointer. Three nicks and the first inch of the jointer blades instantly dulled.

[Leo Graywacz]

Two issues. 1. paint. 2. finger jointed wood.

Paint can be tough on cutters. Enamels are very hard, leaded paints even tougher.

The glue in the finger joint is very abrasive.

[Mel Fulks]

Those knives are thin and the feed is really slow. I think the edges run hot.

[Zac wingert]

Planing paint will cause almost instant problems. I know because I tried it. Dulled the knives almost to being like a butter knife in a couple passes. Sounded like the planer was gonna explode. It’s the paint, can’t do it. Simple as that.

[Greg Funk]

Planing paint will cause almost instant problems. I know because I tried it. Dulled the knives almost to being like a butter knife in a couple passes. Sounded like the planer was gonna explode. It’s the paint, can’t do it. Simple as that.

20 yrs ago when we built our house we were putting up pre painted rough cedar 1” thick. To fit around some widow trim I needed to take the cedar down to about 3/4”. I got through one or two boards before destroying a set of blades. Switched to carbide and it was fine. I might have resharpened the blades after finishing, I don’t recall, but I did end up planing off a lot of paint with the carbide.

[roger wiegand]

Knots? Knots in old pine can be incredibly hard.

[Dan Hahr]

My money’s one either a staple or piece of grit embedded in the wood.

Dan

[Mel Fulks]

Sure,it had to hit some grit. Whenever we had to run something that might have grit we used fastest speed for first
pass and removed as much wood as the machine wood do. That's pretty standard . You don't have that option with that
machine. In commercial shops its common to pay a little more for wood from a place that handles the stuff right.
I'm sure many here have seen rocks stuck in wood and didn't see all of the grit.

[Benjimin Young]

Solved! I installed a new set of blades and all is back to normal. I did not try testing on the same pine wood which is now cut into shorts in the wood burning bin. expensive firewood!

Thanks for all the input, it appears many of you were bang on, the problem was paint related. The back of the door jambs had the usual "relief cuts" which had been pre-milled into the wood and then the wood was factory primed. I am guessing those "relief" groves had more paint than the rest of the wood because the chips in the blades lineup with the relief cuts.
Hopefully someone on this forum can learn from my mistake and avoid it themselves;no more painted wood in my planner.

But the wood gods has taken pity on me as my friend just gave me some more mahogany shorts and a few walnut shorts. LOL.