Having problems with getting my plane blade back flat

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Forum topic by Vodo posted 03-25-2013 05:07 PM 1519 views 0 times favorited 14 replies Add to Favorites Watch
View Vodo's profile


18 posts in 1967 days

03-25-2013 05:07 PM

Topic tags/keywords: sharpening plane

I’m a new woodworker. I bought a cheapo starter-plane at Harbor Freight (yes, I know – that’s another thread.) and I’m trying to get the back of the plane blade flat. I have 2 “pits” or “hallows” toward the front on the sides. I’ve been working this for about 40 minutes on a DMT Diamond bench stone and it doesn’t seem to have made much progress.

Someone suggested using the “ruler trick”. Would that help?


2 Norton waterstones, DMT bench stone and veritas MK II

After about 5 minutes. Black mark is sharpie

After about 40 minutes.

-- AKA vodo. I belong in a blue state.

14 replies so far

View Richard's profile


1916 posts in 2656 days

#1 posted 03-25-2013 05:20 PM

I think that if you can get the first inch or so from the cutting edge flat you will be fine. Getting the entire back flat will most likely not happen with a cheap plane blade.

View chrisstef's profile


17308 posts in 2972 days

#2 posted 03-25-2013 05:26 PM

+1 to Richard. You dont need the entire back flattened just the first inch or so. If the stones are taking too long you can always invert a belt sander clamped into a vice to save some wear and tear on the arms and fingertips, just dont over heat it too much. Ive started at 80 grit for some of my more hammered irons.

-- Its not a crack, its a casting imperfection.

View Vodo's profile


18 posts in 1967 days

#3 posted 03-25-2013 05:33 PM

The 1st inch or so is my problem…. the dips are toward the front, unfortunately.

-- AKA vodo. I belong in a blue state.

View popmandude's profile


109 posts in 2986 days

#4 posted 03-25-2013 05:40 PM

That’s a job for multiple grits of sand-paper on a flat surface.

Good luck

View yrob's profile


340 posts in 3618 days

#5 posted 03-25-2013 05:45 PM

The first time you do that can take a long time, especially on less expensive planes for which the quality control is not good.

Rejoice in the fact that once its done, you no longer have to deal with it. Meanwhile, be aggressive and use a very coarse diamond stone or sandpaper. You can get rid of the scratches with higher grits once you get it flat.

If your blade is so warped that you can not manage to flatten it, perhaps you should replace the blade.

-- Yves

View Mosquito's profile


9278 posts in 2258 days

#6 posted 03-25-2013 05:53 PM

From the edge up to where the hole begins is all that you should to do (you won’t be able to use the iron once it gets back that fary anyway). I see that the issues are right at the edge, but only flattening an inch or less will make it easier, since you’ll be removing less material.

The ruler trick would make it quicker, but I’m not much of a fan of the ruler trick myself, for no real reason other than personal preference.

No matter what you end up doing, I think that iron will take a little while regardless

-- Mos - Twin Cities, MN - -

View Richard's profile


1916 posts in 2656 days

#7 posted 03-25-2013 05:53 PM

What Randy said , flat surface with sand paper ,coarse grit wet/dry paper and just work the last couple of inch’s till it gets flat then go to your stones and DMT. Trying to use the stones for this is just going to wear them down to the point that they need to flattened. It does take a while so just keep going and it will get there.

View BinghamtonEd's profile


2297 posts in 2335 days

#8 posted 03-25-2013 05:54 PM

I too own that HF plane (and hey, its a good plane for the whole $7 it costs). I don’t think my plane was as out-of-flat as yours, but I use the scary sharp method and started at 80 grit. The 80 grit seemed to cut it down relatively quickly. I bet if you took it back and explained the problem, they’d replace it without issue, however who knows if you’ll find the next one to be better or worse.

-- - The mightiest oak in the forest is just a little nut that held its ground.

View Jorge G.'s profile

Jorge G.

1537 posts in 2441 days

#9 posted 03-25-2013 05:56 PM

I am not a fan of Charlsworth’s (sp?) ruler trick, but in cases like this where you are using a cheap blade it is the best solution and will save you a lot of aggravation. When you are flattening the back use a thin metal ruler to support and “tilt” the blade, this way you only polish a small are on the back. This is equivalent as putting a very shallow back bevel on the blade.

-- To surrender a dream leaves life as it is — and not as it could be.

View BTimmons's profile


2303 posts in 2451 days

#10 posted 03-25-2013 05:59 PM

I agree with the others, you only need to flatten the part close to the edge. Even on my good planes I only flatten the portion of the iron that’s a half inch away from the edge. Once you focus your efforts on a smaller portion of the iron, you’ll find that flattening goes much quicker.

-- Brian Timmons -

View bandit571's profile


19729 posts in 2649 days

#11 posted 03-25-2013 06:19 PM

If you mean this plane?

I held it flat on a beltsander until the back was flat. 100-120 grit belt, and a bit worn at that.

I hold the belt sander upside down in the vise, and lock it in the “On” switch. Fingertips tell when it is getting too warm. Dunk it in something to cool it down, and go again.

Used this trick to work on most of the smaller irons I’ve had….

-- A Planer? I'M the planer, this is what I use

View bondogaposis's profile


4683 posts in 2317 days

#12 posted 03-25-2013 07:28 PM

What grit diamond stone? It looks like you need something coarser.

-- Bondo Gaposis

View Tim's profile


3781 posts in 1927 days

#13 posted 03-26-2013 01:45 AM

You’re holding most or all of blade on the stones. As mentioned, you only need to hold an inch or less, and the rest hangs off. Just make sure to maintain even pressure.

Here's a Woodtreks video that explains it in a lot of detail.

But for a $7 plane with a guarantee, like others said, I’d return it and get a new one that hopefully started out flatter from the mill. Higher return rates is one of the signals they have that their quality isn’t acceptable.

View Don W's profile

Don W

18685 posts in 2533 days

#14 posted 03-26-2013 04:44 PM

if that iron was mine I’d hit it on a belt sand first (before spending 40 minutes) then spend a few on the DMT. So you’ve got 3 choices.

1. if you got a sander. use it.
2. ruler trick. I’m not a fan either, but if you don’t have a belt sander, it will save a lot of time.
3. Only flatten about 1/4” up. Use your courses DMT and a block of wood same width as the iron but longer so you can put some force into it.

-- - Collecting is an investment in the past, and the future.

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