Planer cutting deeper in middle of cut

[Jared Cuneo]

After some parallel adjustments, my planer is now cutting even across the cut, however its cuting deeper in the middle of the boards by about .01 to .015 not huge, but if I plane both sides of a couple boards and hold them toghether, I can see that both boards are concave and see daylight through them.

for diagnostic purposes, I have set the tables exactly flush and level, and no real change....this seems impossible to me. If the in/outfeeds are exactly level, there is no influence on how deep the cutterhead cuts except for the distance between the platen and the blades right? This is a Delta lunchbox. I can lift the cutterhead by hand a slight amount when at rest, but this should not matter once the board is fully supported right? I just don't see how it would cut deeper in the middle of the cut.....

Thanks for any help...

JC

[Jim Becker]

Are you checking the thickness of the board itself of just relying on holding two boards together? Unless you know those boards were perfectly flat before you thicknessed them, you can't depend upon that particular test. Even if they were perfectly flat, uneven moisture release could also cause them to bow enough to show daylight between them. Check the thickness with a caliper to verify the issue. And be sure that your rollers are not set too high if they are adjustable. (Posting the specific model of the Delta planer might also be helpful to folks)

[Jared Cuneo]

Thanks Jim. Its a Delta TP305, non adjustable rollers. As for the boards, yes, I jointed them flat first, I used some maple and walnut just to make sure it wasnt wood related or something....both species show exact same result.....If I flip it after planing one side, I make hourglass shaped boards :(

Oh, and I am using a caliper to measure the variance, its .01 to .015 difference (ends exactly the same, middle -.01+)

JC

[Jeff Fondaw]

Jared - I was making some cutting boards a few days ago and noticed that my Delta planer was dishing the middle of the board deeper than the edges. Later I changed the blades and found that each blade had collected sawdust underneath the middle of the blade which caused it to bow ever so slightly. These blades had been on for quite some time so I don't know how long it took the get in this condition. Hope this helps.

[Jared Cuneo]

Thanks for the reply Jeff, but this condition is not along the width of the board, rather this is along the length of the board...strange....

JC

[Josiah Bartlett]

How well are you supporting the ends of the boards, and how long are they? It sounds like you are bending the boards down at the ends while planing. It could also be that both of your outfeed tables are equally too high or low and they are forcing the board to deflect as the rollers bear down on the board. You want the most support by the bed right under the knives.

[Jared Cuneo]

It's almost like my platen is curved from infeed to outfeed by .01. tables are exactly flush for these tests (I normally have them flush on the inner edges and slightly elevated at the ends).

JC

[Chuck Wintle]

It's almost like my platen is curved from infeed to outfeed by .01. tables are exactly flush for these tests (I normally have them flush on the inner edges and slightly elevated at the ends).

JC

maybe its related to how deep of a cut you are taking on each pass? :)

[Cliff Rohrabacher]

What means did you employ to check the jointing flatness?

[Lee Schierer]

I don't know your planer, but if the cutter is overhead and there are rollers on the table under the board, the rollers may be set too high above teh table surface so the pressure from the feed roller and cutter head is bowing the board as it goes through the planer.

[Jason Beam]

Forgive me for asking what's been already asked, but I'm not sure I read the answer correctly.

What exactly are you measuring with the calipers?

If the planer is the problem, you would be getting thinner (forget the gap between two boards). If the jointing is the problem, the board will be the same thickness, but "bowed" a bit.

I can't see any reason that more wood would get removed between the ends of the board unless the board itself is pushing up into the rollers more in the middle. That's got to be a non-straight reference surface, or some odd flexing phenomena happening halfway through the cut.

Again, sorry for repeating ... but i wanna know for sure that you're measuring thickness, not straightness. A planer doesn't do straight, only thick. :)

[Jared Cuneo]

Correct Jason, thats exactly what is happening....thinner in the middle. viewed edge on, the boards looks like hourglasses.

Using a steel straightedge to determine straightness, as well as the top of my saw. No rollers on the bed, just flat sheet metal. The boards are (thickness as measured with calipers) getting thinner in the middle...IE:

.75 on ends, .74 or .735 in the middle.

JC

[Jason Beam]

No wonder you're asking for help, then!! I have NO idea why it'd do that ... weird.

[Jared Cuneo]

I'm desperate here, The only thing I can think of is that my platen is crowned somehow and I just have never noticed this before. I'm somewhat new to WW and as I get better my tolerance for loose tolerances goes down :)

I've sent an email to Delta for help, but unanswered so far.....

JC

[Gary Keedwell]

How long have you had your planer? Have you put a straightedge on the blades, themselves. Do you hace a good 12" steel ruler?
Gary

[Jared Cuneo]

Here is an update, I pulled the cover off the platen (its sheet steel covering a series of milled sections of the body) and cleaned it real good with mineral spirits. It was pretty clean but it was my last resort. Then I reinstalled, cleaned the top of the platen and waxed all of the surfaces. I'm down to about half of the original error now. If I only surface the unjointed side, I can get it within .004-.006, which is acceptable for this low end planer I suppose. I'm not thrilled but can live with this until such time as I can get a good 15" some day.

I tell you, if I could buy all of my tools all over again, it would be a mid-grade contractor saw and the best 8" jointer and heavy 15" planer I could afford. I'd rather have perfect 4 square starting stock and slightly wonky saws than vice versa.

3 days of shop time lost, but lesson learned....

Oh, and yes Gary, I have a Starett 12" combo, the blades are fine.....and just to reiterate for any future parties the crown was not across the width, but rather the length of the bed.....bizarre since even this should not affect the distance between teh head and platen....

JC

[Pat Germain]

Pardon me for being a biscuit, Jared, but I'm still confused about where your boards are thinner. Are they coming out like (exaggeration) wooden gutters? Or, are they coming out where the end you feed and the end that comes out are thicker than the rest?

If your boards are coming out like wooden gutters, is it possible there's some kind of debris stuck beneath the center of one of the knives? Have you replaced the knives recently? I've heard of people having such a problem.