Lapping a Plane Iron

[Dave MacDonald]

Hi,

I'm fairly new to this. I have a solid bench and am slowly building up my supply of hand tools. I recently made a Krenov-style plane and bought a new iron for it (HSS, wedged but without a chip breaker), but I'm having a hard time lapping the blade.

My sharpening equipment includes some Norton waterstones (220, 1000, 4000), a honing guide, and a 1-inch belt sander that I use once in a while to sharpen my kitchen knives.

The problem is that the face has a shape that's exactly the reverse of what I want. There's a high spot, roughly half-moon shaped and half the width of the blade that comes to about 1/16 of the edge in the center. The edge itself and the corners are low. I've spent probably a couple of hours on the stones (1000 to start with, then I lost patience and moved to the 220) with not much progress; the profile seems to be staying the same. I flattened the stones before I started and have done so a couple of times since.

I realized later that the high spot is probably acting as a fulcrum so that at least one low area is probably always in contact with the stone as well. If this is the case I'm having a hard time seeing how I can get the face flat near the edge.

I'd really appreciate some advice!

Thanks,
Dave

[Jim Nardi]

Good quality paper glued to a flat surface is better. Waterstones don't flatten HSS all that quickly. Start with a 320/400 grit to get it flat.

[Stephen Reid]

Dave even though you said you flatened the stones,are you sure there flat?High in the center and low edges sounds like a hollow stone to me.How are you flattening the stones?Get a piece of plate glass and some coarse sandpaper to flatten with.Make some pencil marks all across the stone then lap it should show if its flat.If that all checks out maybe you have a really warped iron,any chance to exchange it?Worst case I have seen irons hollow ground like a japanese blade with a dremel type grider.Crude but it saved a lot of work to get the high spot off.Hope this helps.Steve

Not from BC by any chance are you?

[James Scheffler]

Good quality paper glued to a flat surface is better. Waterstones don't flatten HSS all that quickly. Start with a 320/400 grit to get it flat.

I'll up the ante (well, actually lower it ;)). I would drop down to 100 grit wet/dry (I use the stuff from Klingspor). Standard dry sandpaper also works ok but the wet/dry lubricated with water seems to last longer. Be prepared to go through a couple of sheets if the high spot is sizable.

Jim

[Jim Kountz]

I cheat and use my Worksharp!!

[jerry nazard]

Check out p. 67 of The Handplane Book by Garrett Hack. Free download on FWW site if you are a member.*

*Mods: I hope it is OK to reference this, please kill my post if I have screwed up. :o

[Jeff Willard]

Worst case I have seen irons hollow ground like a japanese blade with a dremel type grider.


I did this on the sole of a #3 Footprint plane. Not very attractive, but it works.

[Mike Henderson]

I've even done the same thing on a regular grinder. I'll carefully grind the high spot down, maybe even creating a low spot (as long as it's not close to the edge). That way, I can flatten the back. If I wear the edge down to where I'm getting into the hollow, I'll have to flatten the back some more, but that usually takes a very long time.

Mike

[Johnny Kleso]

220 grit Sand Paper on a flat surface is the best way and when your new its hard to know your stones are really flat..

You can also try flattening your stones on some sand paper..

Try picking up some 1/4"plus glass as a true flat surface till you buy a small surface plate from Enco .. Sign up for their news letter and use the free shipping code to get it delivered if you dont live near a store..

I would not hollow grind the iron if any thing use the ruler trick to get it flat..

Once its dead flat its always cake after that if you hollow grind it some day your back to flattening again..

[John Coloccia]

Personally, if someone sent me a new blade that was so far out of whack, I'd ask for a replacement blade. When you get a blade, you expect to have to flatten the back and sharpen/hone the bevel, but you also expect it to be reasonably flat such that you can rub it on a stone and flatten it. You don't expect the back of the blade to wobble. I've never gotten a new blade like that, anyway.

That said, I've personally used very coarse sandpaper (like 80 grit) to straighten stuff like this out. For whatever reason, the coarser grit seems to make it much easier for me to get the wobble out. It introduces a new problem of making it easy to sand a taper into the iron, though. LOL. It's tough to win sometimes.

Truly the BEST solution, though, would be to find someone in the area that will work the problem with you. Then you would have a fixed iron PLUS you will see how someone who really knows what they're doing approaches fixing it, sharpening, honing etc. If you could find someone like that, this could be a fantastic learning experience. There were many times I wished I knew someone like that. I spent a lot of time, $$$ and frustration figuring stuff out on my own.

[Jim Koepke]

Dave,

Welcome to the Creek. Your profile does not list your location, there may be a helpful Creeker near you.

You do not say how you flatten your stones. There have been many complaints of diamond flattening stones not being flat and causing more problems than they solve.

The other question, is there a possibility of an exchange for the blade. I have worked some pretty bad blades, but not if it was bought new.

If the blade is wobbling in the plane, the ruler trick is not the answer.

Without powered equipment and a way to hold this blade, it is going to be easier to change the side the bevel is on than to remove such a defect.

jim

[Johnny Kleso]

Jim,

Why will the Rule Trick not work for sharpening his blade?

If the blade is warped and you tighten your lever cap that will seat the blade just fine........

It only needs to be sharp as I am thinking he is not talking about a warped blade since its NEW and he just needs to put more elbow grease into the new blade........

Whats your logic for the rule trick not getting the blade shape?

[Jim Koepke]

Jim,

Why will the Rule Trick not work for sharpening his blade?

If the blade is warped and you tighten your lever cap that will seat the blade just fine........

It only needs to be sharp as I am thinking he is not talking about a warped blade since its NEW and he just needs to put more elbow grease into the new blade........

Whats your logic for the rule trick not getting the blade shape?

This part of his original post:



The problem is that the face has a shape that's exactly the reverse of what I want. There's a high spot, roughly half-moon shaped and half the width of the blade that comes to about 1/16 of the edge in the center. The edge itself and the corners are low.


And this:



I realized later that the high spot is probably acting as a fulcrum


His problem seems to be not so much getting this blade sharp. If that was the only concern, the ruler trick would take care of the problem. My take is that this may also be a seating problem with the blade in the plane. Though, that was not mentioned in the OP. One of the respondents mentioned wobble and that may have made me think there is a problem not mentioned.

So, I guess we should ask Dave for some more information.

Is this defect on the bevel side of the blade or the back side?

Is this plane bevel up or bevel down?

Is the high spot on the blade causing a problem with seating or use of the plane?

If so, please relate as much information and observation as possible so we can help solve the problem.

jim

[Dave MacDonald]

Thanks everybody for your insight. Here's an update:


You do not say how you flatten your stones.I was using 90x grit on plate glass. I found that it dished the glass pretty quickly, so now I'm trying 120x drywall screen on a new, flat sheet of glass. Turns out one side of the stone was pretty dished, which probably explains what I was seeing. I did manage to get that side flat before moving on. I'm using a 220x Norton waterstone. I also have a 1000x and a 4000x. More on this in a second.


His problem seems to be not so much getting this blade sharp. If that was the only concern, the ruler trick would take care of the problem. My take is that this may also be a seating problem with the blade in the plane.I've really just been thinking about getting the blade sharp. I've been resisting the ruler trick mainly out of pride -- I can cut tight-fitting dovetails by hand; why can't I flatten a piece of steel?

I ended up buying a new iron -- it's a small iron meant for an Asian plane and not very expensive. I checked it with a straightedge before I touched it to the stone. Interestingly, it was fairly flat across the width but has a camber over its length, convex on the face and concave on the back. The old one seems to have this too. I can't think of why the iron would be ground this way. Only thing I can think of is that, since it's meant to be wedged without a chip breaker, maybe the wedging force flattens it against the bed. It may have been an issue because, with the first iron, I had the whole iron on the stone, so it would have been rocking. With the new one, I'm lapping only 1" or so behind the edge, which does seem to be relatively straight.

Nevertheless, though the grinding marks are gone or fading from much of that 1", there's a band of about 1/32" directly behind the edge that hasn't yet touched the stone, as far as I can tell from the scratch pattern.

Since checking the stones more carefully, though, I'm also finding it difficult to get them dead flat. I've moved on to drywall screen on plate glass so that I can keep the glass flat. I can easily get it to the point where the pencil marks are all off, which was my previous standard for flatness. But when I check it with a straightedge, it's not looking great, and in fact is beginning to look slightly crowned. I've been taking a couple of hundred strokes with fairly light pressure, then re-flattening. With the first iron, I was using fairly heavy pressure.

This seems far more complicated than it should be... I think maybe I'll throw it all out the window. That would feel good.

[Jim Koepke]

This seems far more complicated than it should be... I think maybe I'll throw it all out the window. That would feel good.

It should not be this complicated. I do not usually mention this, but I have not flattened my stones in some time. On one of them I can even feel the waves. I usually only work the last 1/4 to 1/2 inch of the back. Often, if a polished area appears edge to edge and it is only 1/32 inch wide, that is enough for a plane blade. I do hone the backs of my blade each time they are taken to the stones. Almost all of my blades have their initial flattening/sharpening on an Mk. II Power Sharpening System.

Yes, I like to make things ultra sharp, but there is also a point where the blade is going to do all that is asked of it, so there is no need to "whip" it any more. There are just too many projects needing to get done and too many blades in my shop to try and hone them all to perfection.

ymmv

My suggestion is to work the edge to as sharp as you can and try the blade in the plane to see how it goes.

jim

[Leigh Betsch]

Rip a piece of 100 grit sand paper about 1/2" narrower than the blade width. Glue it to a glass plate. Also glue on a wood strip to guide the plane blade. Use this set up to sand just the center of the blade to remove the high spot. I then use the same method to sand a relief in the blade so when I put the blade back on the stone it will only make contact for about a 1/2" at the cutting edge and 1/4" at the back edge. This way it it much easier to avoid rocking the blade and creating a high spot.
I also find when I use a waterstone with a slurry I tend to remove more metal along the corners and create a high spot in the center of the blade. I think this happens because I don't have the correct technique an get more slurry under the corners. I've switched to diamond an ceramic stones and no longer have the problem.

[Dave MacDonald]

Thanks everybody for your insight. In the end, I got the stones flat, used the ruler trick, and started making shavings. Jim, your advice to get on with the project was good advice! I got down to it and finished my Christmas gifts just in time! On the other hand, I'm glad to have gone through a little bit of sharpening purgatory, as I'm starting to feel like I know what I'm doing.

Thanks again,
Dave

[Jim Koepke]

On the other hand, I'm glad to have gone through a little bit of sharpening purgatory, as I'm starting to feel like I know what I'm doing.

If one never travels the rough roads in life, the smooth roads will not be appreciated for what they really are.

jim

[Josh Bowman]

Thanks everybody for your insight. Here's an update:
I've really just been thinking about getting the blade sharp. I've been resisting the ruler trick mainly out of pride -- I can cut tight-fitting dovetails by hand; why can't I flatten a piece of steel?

This seems far more complicated than it should be... I think maybe I'll throw it all out the window. That would feel good.

Dave read some of my thread in the Neanderthal, "What have I bought myself into"
My non flat blades were Hock's.
1st find a clear grassey area. Throw the blades.
2nd go find them and clean the grass and dirt off.
3rd use the ruler trick

I to couldn't bring myself to use the trick on expensive Hock blades. But as Mr. Hock told me and others here, steel is a funny animal. It's complicated to make hard and flat. Now I'm an "in the closet" ruler user. I only could go part way. I used a thin piece of flashing, which allowed less back bevel. As the nice folks finally convinced me, the trick will flatten more area than you use in a long while and I want to be a wood worker NOT a steel worker.
Hope it helps. Oh....as more than one pointed out, you should be able to skip a lot of the grits. Once I got flat on my course DMT, I went to my King 800 then to 4000 then a MDF block with dimond paste. I think you could skip the MDF block....it just makes it pretty.....I'm sure on a microscope, it helps, but results are what it's about. These folks had me flat enough, sharp enough and able to cut 1/1000 cherry shavens with only light pressure pushing the plane!
Josh

[Gil Knowles]

Hi
I have been reading this thread with interest.
Pardon my ignorance but what is this ruler trick people are talking about?

Many thanks

[Josh Bowman]

I am not the expert to answer this, but since I mentioned it. Here are some pictures from Woodworing Magizine.
Briefly instead of flattening the entire back of an iron, you use a ruler flat on the edge of your stone and rub the iron back bevel on the stone while the up hill of the iron is riding on the ruler. It's kind of hard to keep the ruler from sliding with you, that is what the second picture is of Swartz, trying to show how the ruler can be traped on the stone with to rare earth magnets.
It took me from being absolutely a wits end trying to level a large hump, to having about 3/8" of the back of iron done in about 5-10 minutes.
Anyone got wisdom, I've given in to it and am open for better methods to use the ruler trick.
Josh

[jerry nazard]

I am also a convert to the ruler trick. I use the "trick" after the back of the blade is reasonably (just about) flat. Here is a good video:

http://www.youtube.com/user/LieNielsen#p/u/21/yzeAsX-09o4

[Josh Bowman]

I am also a convert to the ruler trick. I use the "trick" after the back of the blade is reasonably (just about) flat. Here is a good video:

http://www.youtube.com/user/LieNielsen#p/u/21/yzeAsX-09o4

This is a great site! I got a Stanley 112 for Christmas and there was videos on how to set it up and use it. Plus lots of good stuff on sharpening.