This one is for Larry and anyone brave enough to disagree….in watching Larry Williams’ video on sharpening moulding plane irons, he heats the iron with a torch and then quenches it…why is this necessary? What happens if you just flatten the back and then sharpen the profile without the heat treatment? I only watched the video once, maybe I just missed the reason when I was distracted by a kitten or a grandchild (or maybe I just have trouble paying attention).
Neil
Replies
I can't comment on Lary's video but, in general, you never want to touch the profile except to remove any burrs that might form from sharpening the flat back. Otherwise, you may change the profile. You can ruin tool steel by heating and quenching if you don't know what you are doing.
In the video I sharpened other molding planes as one would normally do, without annealing the iron. In the case you mention, I sharpened a small cove/ovolo profile with delicate features and a small quirk. Through multiple sharpenings in the past this plane's iron no longer matched the profile of the plane. Re-profiling that iron would be a daunting, tedious and time consuming job with slips. With files it's very easy and that's what I was trying to show. To re-profile with files you must anneal the iron and after the profile is done it has to be re-hardened.
I strongly disagree with the old idea that you never work the bevel of a molding plane iron when sharpening. You're basically working with compound angles here which are created by the difference between the bevel angle and the bed angle. If you work only the face of the iron you will change the profile slightly every time you sharpen. If one really wants molding planes to function like they can, one needs to be prepared to maintain the profile. It's all a very easy process and that's mostly what the video is about.
I have also read never to mess with the bevel side, but have found that you have to from time to time, especially on older planes. Next time you are buying from Toolsforworkingwood or Lee Valley, add a few pieces of their 3m microabrasive sheets - you can cut them up and wrap them around dowels or other shapes of wood to match the profile you want to sharpen.
Barry, I'm not really sure
Barry,
I'm not really sure where the idea that you shouldn't work on the bevel of a molding plane started. One thing I'd be willing to bet a devalued dollar on is that those who promote this have never sharpend a molding plane iron and ended up with a properly working molding plane.
The idea of not working the bevel can also come from the experience of messing some up. Of course there are many molding knives, most won't be significantly altered by a few back sharpenings ,unless those are aggressive sharpenings. If it's a profile one uses frequently, some restoration may be needed in time. Delving into the world of annealing and rehardening tool steel just to restore a profile seems a bit over the top for your average user, especially a beginner. We don't even go that route when grinding custom shaper knives on a blank. Can't say I've run into molding plane knives that can't be worked with stones or paper. I see many boxes of old Stanley 45 blades where all but a couple have ever been used, unfortunately those have often had the bevel worked and not very well. When answering a question for someone who is obviously not experienced, I would opt for a more simple, practical suggestion. When that individual comes back, complaining about the loss of a profile from numerous sharpenings or difficulties with certain species or types of cuts, that may be a different answer but in the case of an inexperienced user, I'd say, leave the bevel alone.
Molding plane irons and machine molding knives are very different animals. I'm not talking about pseudo molding planes like the Stanley combination planes but real ones--the wooden bodied molding planes. The profile MUST match the profile of the plane.
Annealing and hardening water or oil hardening tool steel in molding plane irons is very simple. The price of admission is a good torch. One needs a furnace to do anything much bigger but molding plane irons are easy with a good torch. I'm sure I stressed the need for a good torch in the video. There's nothing to be afraid of here.
Hardening new molding plane irons is easy. I can show someone how to do it in five minutes and, if they'll follow three simple rules, they can heat treat small tools more accurately than I can in the computer controlled furnace we use for bigger plane irons. The three rules are:
1. Use a good torch that gives a large working area, about a 2" diameter circle.
2. Keep the steel and the work environment clean.
3. Adequately pre-heat the steel.
The original poster asked how to sharpen a molding plane iron. Are you saying you anneal, harden and temper your molding plane irons each time they need sharpening? How do you do that? Put a finely sharpened edge on your annealed steel blade and it's still sharp and ready to use after you harden and temper it? You don't have to grind, stone or use some other method to get the edge sharp, how do you do that? Are you saying you can't sharpen an iron that is already shaped, sharpened and used with a few strokes on the flat back, gently remove any burr on the beveled edge with fine stones,maybe a leather strop or micro sandpaper, because the profile won't be perfect and therefore won't work?
I didn't say I anneal and reharden each time I sharpen. In fact, you shouldn't do that. Each time the steel is rehardened the grain structure becomes more coarse. Sharpen and maintain the irons so this isn't necessary.
However, when tuning up an old complex molding plane for the first time annealing so one can work with files is often the most practical approach. Unlike slips, sand paper or other abrasives; files are available with safe edges or faces. Working with appropriately sized files the safe faces and edges allow reshaping small features without fouling adjoining surfaces. If one does much of this they'll quickly realize that most of the work comes from correcting fouled surfaces from previous sharpening attempts that rendered the tool useless. The method I showed in the video allows re-establishing the location of the cutting edge and quickly working to that while reshaping the bevels for both appropriate clearance angles and creating lands on which one can effectively use slips. Files are considerably more aggressive and offer control that's just not possible in abrasives like slips. To use files in restoring function to many old complex molding planes you have to anneal the iron.
You are giving all sorts of information about shaping or reshaping a new or existing iron, how does this answer the OPs question? If his iron is in good shape but just needs the edge honed up a bit, how do you do it? My answer is sharpen a little on the flat back, clean up any wire edge on the bevel, as necessary, and don't do anything aggresive that might change the profile. Do you have a diiferent answer?
If I may jump into the fray.......The op asked this:
" in watching Larry Williams' video on sharpening moulding plane irons, he heats the iron with a torch and then quenches it...why is this necessary?"
In answering the OP's question, Larry is saying that you only need to anneal the existing iron if and only if the iron does not match the profile of the moulding plane, due to improper sharpening or wear. I believe it was pretty clear that Larry also states not to do this unless it is necessary to change the profile of the iron to match the plane.
It is much easier to change the profile of an existing iron to match the moulding plane if it isn't hardened, because then you can use files instead of slips, etc......and the only way to deal with that is to anneal the iron, re-shape it, and re-harden it.
At least, that's what I read.
Jeff
Jeff, I'm aware of annealing as well as hardening and tempering but I'm no expert. I got the impression the OP was asking how to sharpen a molding plane blade, not reshape or make a new one. I posted my response. Larry followed with this response,
"I'm not really sure where the idea that you shouldn't work on the bevel of a molding plane started. One thing I'd be willing to bet a devalued dollar on is that those who promote this have never sharpend a molding plane iron and ended up with a properly working molding plane."
My question to him wasn't about shaping a molding iron, it was about honing an existing iron that didn't need reshaping. So far he still hasn't given an answer. I'd like to know if there is a different method for honing a molding plane iron. I know enough about going through the heat treating process to know that you don't end up with a sharp edge, it still has to be sharpened after tempering. If there is some practical way to get that edge that is different from what I stated, so I can end "up with a properly working molding plane." , let's hear it.
No matter what tool you sharpen, the cutting edge is made up of the meeting of two surfaces at an angle. The dulling adhesive wear you have to remove during sharpening is on both surfaces. That wear is very shallow but relatively long when measured back from the cutting edge. Yes, if you remove enough steel from one surface, you can remove the wear from the second surface. Because of the length of that wear you have to remove a lot of steel from one surface to eliminate the wear from the other--a lot more steel than if you maintain both surfaces. In a profiled blade like a molding plane iron the more steel you remove from the flat face, the more you change the profile. Maintaining both surfaces that make up the edge reduces the amount of change each sharpening. Refining the profile by honing the bevel with slips is a constant and should be done each time one sharpens. It's just not that difficult and failing to maintain both surfaces most often results in only doing half the job when honing. That's why I'm no fan of honing guides, the difficult surface to maintain on something like a bench plane iron or a chisel is the flat face and honing guides tend to cause people to focus only on the bevel which results in a half complete sharpening job.
the necessity of annealing
So Larry, I understand that using files may be called for when the iron profile is really out of whack and you don't want to spend two hours with slips and such, but what happens if you use the files to restore the desired profile then sharpen with the slips WITHOUT using the annealing process? I ask this question because I respect your opinion as it is based on years of experience, but I always like to know why (I always hated it when as a kid grownups replied "because I said so, that's why)- guess I haven't outgrown that.
Neil, an annealling novice
Files won't effectively cut or bite into hardend steel. While files are generally harder than a plane iron, it takes a lot of force to get them to bite into a hardened woodworking tool--so much force that all real control is lost and the file will wear out almost instantly. If you want to use files you have to anneal the steel.
the bulb came on
Okay, now I think I understand...obviously I slept through metallurgy 101.....thanks Larry.
Neil, still a novice but making progress
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