How to round plane iron corners?

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Forum topic by groland posted 01-01-2011 08:50 PM 4109 views 3 times favorited 8 replies Add to Favorites Watch
View groland's profile


149 posts in 2832 days

01-01-2011 08:50 PM

I have a new Lie Nielsen low angle block plane. While it is very sharp and cuts well, it leaves “edges” on the cuts that are unsightly. I understand that a blade can be cambered with a slight curve to eliminate this or that the corners can be rounded slightly which will leave most of the cut flat, but prevent the edges.

My main concerning this time is smoothing and flattening a table top, so I’m interested in:

1. Whether it is better to camber or round the blade edges? (I’m kind of leaning towards the latter, but I have no “real” basis for preferring this.)

2. What is the best way to do this? I have oilstones, adhesive-backed abrasive paper in a number of grite and a 6” grinder with a fine white stone wheel. What ought I to use?

If you know of a good video on this, might you point me towards it?

Happy New Year to all!


8 replies so far

View richgreer's profile


4541 posts in 2495 days

#1 posted 01-02-2011 12:45 AM

While I don’t know this for a fact, I suspect that you may be taking too big of a bite with each pass. For a smoothing plane the objective is to take a sliver of wood so fine that you can read through it. If you take a smaller bite the edges will be much less noticeable – but they will probably still be there.

My opinion is that it is probably better to round the edges on a smoothing plane and camber the blade on a jack plane. I say it this way because I don’t know which you have.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View paratrooper34's profile


865 posts in 2372 days

#2 posted 01-02-2011 01:18 AM

Groland, there is a good video of Chris Schwarz showing how he files the corners of his plane blades. Here is the link:

Also, you might want to look into getting a bigger plane to smooth and flatten a tabletop. If the tabletop is big, you will want a big plane, #7 or #8 to get the whole thing flat and a #4 to smooth it out. A block plane is only going to frustrate you if you attempt to do those tasks with it.

Personally, I do not nip the corners on my block plane. I leave the blade straight all the way across because I never use it to smooth anything. I use a #3 or #4 to smooth. For anything small or irregular, I use a card scraper. So no need for a block plane to smooth.

-- Mike

View Marc5's profile


304 posts in 2762 days

#3 posted 01-02-2011 02:24 AM

It sounds to me that you are describing a LN #5 Block (bevel up) Plane. If so, I nipped the corners of my LN 164 which is a bevel up smoother and found that it was all needed and should be similar no matter the size of the bevel up plane. Take small bite while planing and you should be OK. I use my #4 bevel up smoother honed to 42 degrees which performs like a #4 with a high angle frog and it is used on almost all of my projects.

Stones or Scary Sharp is your choice, you will find plenty of people in both camps. Both are good methods and it really depends on which method you are most comfortable with. I prefer water stones myself as it seems to be faster doing a 2 step process (1000 grit to 8000) then going through several grades of paper to achieve the same results. Good luck.

You can find Lie Nielsen videos on planes on youtube.

-- Marc

View lwllms's profile


555 posts in 2702 days

#4 posted 01-02-2011 04:41 AM


While doing your final honing, just pick up each side of the iron about 5ยบ. About three passes should be ample. Do this on your fine oil stone, don’t do it on a water stone unless you want to see how easy it is to dig a trench in a water stone. There are easier ways to ruin a file than what Chris does. I’m gonna have to talk to him about that but he’s sold on water stones, their limitations and all the unnecessary work that goes into maintaining them. The next time Chris comes here, I’ll drag is arse back to our stones and show him how oil stones can perform it they’re maintained.

View gko's profile


83 posts in 2665 days

#5 posted 01-02-2011 01:05 PM

On a bevel up plane work on the corners of the back or flat side of the blade. The first time I flatten the back of any blade I go through a coarse diamond stone (extra coarse on really bad blades) until the whole edge is covered. I use a stroke parallel to the edge I learned in Japan. Then I work on the bevel on the coarse stone. Next I go to a 1000 water stone. I start on the bevel and go back and forth between the back and the bevel 2 or 3 times lightening the pressure each time to slowly reduce the burr. I then end it with about 3 stroke (5 the first time I sharpen the blade) on each corner of the back. I have a natural water stone that is about 2 – 3K and also end with 3 strokes on each corner. Finally, I do the same thing on an 8000 water stone until no burr remains.

On a bevel down blade you work on the corners of the bevel to prevent the corners from digging in. Make sure your stones are absolutely flat. Flattening stones will begin to round over and leave a dip in your stone. You should have an even trail of metal when sharpening and not two streaks on the outside edges. I use as coarse a wet and dry sandpaper I can get on a granite block under running water.

I use the coarse stone only the first time I work on a plane blade unless I get a chip. Then I usually only work on the bevel to grind out a chip. If I’m just touching up the blade I just spend 2 or 3 minutes on the 8000. Of course on duller blades you should go down to the coarser stones.

On the back of Japanese blades instead of the diamond stone I use 80 grit carborundum powder with water on a flat steel plate which grinds down to about a 1000 grit stone then I head for the natural and 8000. I get a totally flat mirror image without a bending of the image near the edge.

Geesh, I didn’t realize I’ve been writing so much. Sorry about the length.

-- Wood Menehune, Honolulu

View fussy's profile


980 posts in 2471 days

#6 posted 01-02-2011 11:32 PM


Don’t screw up a nice block plane by rounding or cambering (same thing) the corners. A block plane is small to take on a small job and needs to be straighjt. For a big job, get a BIG plane. At least a #5 smoother depending on the size of your table.


-- Steve in KY. 44 years so far with my lovely bride. Think I'll keep her.

View Steve Rathke's profile

Steve Rathke

27 posts in 3133 days

#7 posted 01-04-2011 05:04 AM

Are you using bevel up plane smoother or jack or a little block 90 1/2 style? I would recommend the jack or smoother in the bevel up for surface prep. Lie Nielsen sells additional blades so try it out if you can afford a 2nd blade. Sharpening a camber is easy on a water stone, sandpaper, or anywhere you use a roller support – simply apply more pressure on either side alternately for a few strokes. David Charlesworth books and dvd on sharpening are a good resource. Also Taunton’s complete illustrated guide on sharpening by Thomas Lie Nielsen is good.

View jusfine's profile


2405 posts in 2346 days

#8 posted 01-04-2011 05:38 AM

Go to Utube, type in Rob Cosman and see his method for sharpening, he teaches this exact thing on video and also sells a DVD for sharpening. I have ordered it, but have not received it yet.

-- Randy "You are judged as much by the questions you ask as the answers you give..."

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