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Bench plane cuts at corners of blade but not middle.

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Forum topic by gauntlet21 posted 02-04-2019 06:42 PM 792 views 0 times favorited 7 replies Add to Favorites Watch
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gauntlet21

69 posts in 606 days


02-04-2019 06:42 PM

Topic tags/keywords: hand plane troubleshooting bench plane

I’ve been hand planing for about 9 months now and occasionally when I have a relatively flat face on a board and the entire width of the bench plane is capable of cutting, the plane will continuously cut at both corners but not in the middle regardless of where I am on the board.

My setups are, new Lie-Nielsen #4 and #6 with original blades. The blades a recently sharpened and believe it or not, I have attempted Rob Cosman’s and Matt Estlea’s techniques to put a camber on the blades. I have the cap iron quite tight and the chip breaker is very close to the blade’s edge (1/32nd or so).

I have a couple theories but wanted to ask someone with more experience. Perhaps the cap iron is too tight and is causing the blade to “cup” ever so slightly in the middle?

I’d appreciate any other ideas.

Thanks


7 replies so far

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WayneC

14358 posts in 4493 days


#1 posted 02-04-2019 08:34 PM

Have you run a machinist’s square across the blade to ensure it is square and straight? Is your sharpening stone flat?

-- We must guard our enthusiasm as we would our life - James Krenov

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Smitty_Cabinetshop

16134 posts in 3014 days


#2 posted 02-04-2019 08:40 PM



I have attempted Rob Cosman s and Matt Estlea s techniques to put a camber on the blades.

Thanks

- gauntlet21

Check it with a straight edge, as Wayne suggests. It’s either cambered or it’s not, and it’s a key piece of the puzzle

-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive --

View Robert's profile

Robert

3405 posts in 1876 days


#3 posted 02-04-2019 08:42 PM

Sounds like plane tracks, which is caused by 1) sharp corners on the iron and/or 2) planing depth too low.

Given the frog support close to the mouth + the thickness of a LN iron cap iron pressure won’t cause bowing.

I would back off on the planing depth I’ll bet that’s what you’ve got.

-- Everything is a prototype thats why its one of a kind!!

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Sylvain

827 posts in 2895 days


#4 posted 02-05-2019 03:40 PM

If there is no “relief angle”, the blade will skate on the wood.
What is the iron bevel angle at the very tip of the blade (in the middle if not the same across the width)?
interesting reading (read also answers to comments).

-- Sylvain, Brussels, Belgium, Europe - The more I learn, the more there is to learn

View gauntlet21's profile

gauntlet21

69 posts in 606 days


#5 posted 02-15-2019 10:26 PM

I did check to see if my blade had a camber and it did not. Also, one error I believe I have made was in following the modified sharpening techniques of Rob Cosman when I took off my training wheels (Veritas MkII Honing Guide) and started sharpening freehand. Rob only uses 2 stones when resharpening his blades which already have a defined back, primary, and secondary bevel. I happen to have multiple sharpening stones and tend to touch my blades up using more than just two. In the sequence, I guess I found that as I move to a finer stone, I increase the secondary bevel ever so slightly. And as I resharpen, that secondary bevel gets larger and larger and larger. I’ve measured my secondary bevel to be about 35 degrees when I intended it to be closer to 25-28. My blade has just been skipping along the top of the workpiece. I’m in the process of flattening that secondary bevel back down to 25 degrees and will update once I’ve completed the resharpening. I’m also going to be sure that I get an actual (observable) camber on that blade. I’ve yet to buy a bench grinder so I’ll make good use of my 320 grit sharpening stone. Thanks for the feedback.

Dan

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Johnny7

468 posts in 1486 days


#6 posted 02-15-2019 10:53 PM


If there is no “relief angle”, the blade will skate on the wood.
What is the iron bevel angle at the very tip of the blade (in the middle if not the same across the width)?
interesting reading (read also answers to comments).

- Sylvain

Sylvain,

Great job of diagnosing the OP’s issue!
Apparently, that’s exactly what was wrong.

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Sylvain

827 posts in 2895 days


#7 posted 02-17-2019 10:49 AM

Johnny7,
I hope it will solve the problem.
The hint is that if you start at the edge, the protruding iron will of course engage the board but not if you start in the middle.
Then one increase the depth which will only cause taking bigger chunk at the edge but with no improvement in the middle. Then one push hard downward, with the described results.
I have been there.

-- Sylvain, Brussels, Belgium, Europe - The more I learn, the more there is to learn

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