Diamond Edge No. 7 not working correctly?

[Tynyyn]

I've got a DE No. 7c plane that I love.  Every single time I use it the plane works superbly.  Just a wonderful tool in my hands and make me feel like a gifted woodworker.  The other day I was hand milling some 5/4 red oak which is about 7" x  32".  I started with a Stanley No. 40 to get the cup and bend out of the oak.  That is a great tool, also.  My problem started right after I surfaced one side flat.  I tilted the No. 7 onto its corner to see if the cup and bend was gone and I noticed that both ends of the board were still high, I could see light coming from beneath the middle of the No. 7.  I got out my Stanley No. 3 and began planning the ends to make the board semi flat.

Now comes the problem.  When I start using the No. 7 it will not take a cut.  I lower the blade and it still will not cut.  It felt like it was going over a piece of glass.  I got pissed and took out my Bedrock No. 605 to see if any shavings would come off and low and behold, the 605 began cutting like there was no tomorrow.  Back to the No. 7 and still no shavings.  Back to the No. 3 and I get shavings.  No. 605 gets good shavings and back again to the No. 7, still no shavings.

I raised, lowered, raised and lowered the blade on the No. 7 and I could not get any shavings, only whisps of curls.  Not even a thimble full. 

Could one of you plane gurus try to explain what I was doing wrong?  When I put the board up on it edge to mill it square the No. 7 behaved like a champ.  Yet while on that expanse of flatness I could not get it to cut.

[Strokes77]

Any plane that usually works, but doesn't perform as expected on a given piece... stop, and sharpen.

I would say 95% of the time that is the issue.

[bandit571]

More than likely, the # 7, being a LOT longer than the other planes used, is hitting the high spots on the ends, and nothing in the middle.   Get the ends of the board down to match the middle...and then try that 22" long plane....the 9" #3 and a 14" # 605 would hit in the lower middle areas, because they fit in there.

[Skip J.]

More than likely, the # 7, being a LOT longer than the other planes used, is hitting the high spots on the ends, and nothing in the middle.   Get the ends of the board down to match the middle...and then try that 22" long plane....the 9" #3 and a 14" # 605 would hit in the lower middle areas, because they fit in there.

This.... 32" is almost too short to use a #7 on effectively to flatten.... get flat - checked with a straight edge - with a smaller plane first, then maybe a few lite cuts with a 7 before a smooth plane, but maybe not...

[Jim Waldron]

Any plane that usually works, but doesn't perform as expected on a given piece... stop, and sharpen.

I would say 95% of the time that is the issue.

+1

The #7 is probably riding on the wear; sharpen properly and the wear disappears and the blade cuts nicely once again. (A proper sharpening always continues far enough to remove the wear; if one stops too soon, the apparent sharpness is an illusion. Until the wear is gone, there is no relief behind the edge and the blade "skids" across the surface without cutting. That's why the primary bevel isn't 45 degrees to match the bed angle.)