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Sharpening Curved Blades

Sharpening StropsWhen it comes to moulding plane irons and carving chisels my philosophy is to not sharpen. I prefer only to hone. In both instances my cutting edges don’t encounter a lot of abuse so I’m not having to grind out a nick in the edge or re-shape a bevel angle. My moulding planes only get used after the bulk of the wood has been removed by the rabbet plane and a tough day for my carving chisels is being tapped lightly by a lightweight mallet through a forgiving wood like Mahogany, Walnut, or Basswood. So these tools usually only see the strop. I have a Butz bench strop that handles just about everything and recently got one of those Flexcut Slip Strop for my carving chisels. Really this block is mostly for my V tools since I strop the gouges on the Butz strop. Constant vigilance is the watchword here (and a Mad Eye Moody catch phrase). You never want your tools to get so dull that a strop won’t do the job. However after a while stropping can round over a cutting edge. This effect is usually called “dubbing” and it is caused by the somewhat flexible nature of the leather. AS you press and iron into the leather it moulds around the edge and over time the iron takes on the rounded shape. So at some point, you need a coarser solution to reshape the cutting edge.

DMT Diamond WaveFor me this coarser method usually means my water stones. I use my grinder only to remove a lot of metal, though lately I have been pulling out the Tormek for some of my really difficult shaped carving gouges like backbents and veiners. The problem with even ceramic water stones like my Shaptons is that the usually narrow blade will quickly take your stone out of flat. This is why you see so many carvers who are big fans of oil stones which will resist dishing a lot more than a much more friable water stone. For me though I have used oil stones a significant amount at the Steppingstone Museum, I don’t want them in my own shop. I have committed to water as a lubricant and adding in a system that will require oil would just make for a bigger mess. I try to keep sharpening as simple as possible and confined to a small dedicated space. So a few years ago I jumped on a new product made by DMT. The Diamond Wave is a cool product that combines and constantly changing concave and convex surface with the durability of diamond. It is a 2 sided stone with fine and extra fine grits on each side. With it I am able to match any gouge sweep or moulding iron profile, and remove more steel to clean up a dubbed edge. I can then flip the steel over and remove the burr or add a back bevel in some cases with my carving gouges. It is lubricated with water and has proven to be the perfect solution for my shop. Once I have cleaned up my edge I can then go back to the strop to bring the edge to its final sharpness.

It really is an ingenious tool that I have come to rely on. Though I admit it gets taken for granted because as I said at the outset of this article, I usually just need to strop my tools. I’m only writing about it now as the time came for a whole bunch of my carving gouges to retouch the edges and the Diamond Wave made my life so much easier. There are a lot of solutions out there for carving gouges and moulding irons but for something simple and inexpensive, the Diamond Wave can’t be beat. Give it a shot.

Your Turn

How do you sharpen your curved edges? Please share your thoughts and experience in the comments section below.

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Brander Roullett

I was just thinking about this area of my shop last night. Timely post.

Currently I have Oilstones, and a homemade strop. However, I have no solution for the insides of my carving chisels, especially the really difficult V tool. I’ve ordered a couple hard Arkansas slip stones for shaping but they haven’t arrived yet.

I recently acquired some thin leather, and I’m going to create some stropping blocks with blocks of wood shaped to the insides of my gouges with leather glued on them. This is some I learned from Chris Pye on his http://www.woodcarvingworkshops.tv/ site.

A tip I discovered recently to make my strop work better is adding a little baby oil to the green stuff on my strop. It “emulsifies” the green stuff and helps it stick to the leather without reducing it’s honing power. You can use mineral oil, I just had some baby oil left over from our first kid and it works great!

The strop is a really amazing addition to the sharpening set, and I use it before I start carving anything. A couple quick swipes, and you very rarely have to touch a stone unless you’ve beaten the crap out of it.

Badger

Tim Ogden

Shannon,

a quick correction. The wave’s don’t have diamonds on both sides (at least not those currently sold). You have to pick fine or extra fine when you buy.

Tim

    Shannon

    Really? I can’t imagine why they would change that. I’m going to take a closer look at mine but it is clearly marked Fine/Extra Fine. I really only use the extra fine anyway but I wonder if mine is truly double sided now.

MIke Szymanski

Just a quick thought. I am a caricature carver starting to get more into actual woodworking, and through my experience with stropping profiled carving tools one good way to dress the inside profile, is to use loose unsewn cloth buffing wheels, charged with stropping compound. This will easily conform to the profile of the tool, this works especially well with V-tools, just making sure that the wheel is spinning away from the cutting edge, and that the cutting edge is more or less parallel to the wheels surface so as not to round over. These are often mounted to second hand shoe polishers, or a drill chuck mandrill, and can be obtained quite cheaply. Hope this helps.

    Shannon

    Agreed Mike. I picked up that tip from Chuck Bender when I took a carving class with him. He has a buffing wheel on his bench grinder and it made quick work of the stropping process. I have tried the same thing with my small 4″ buffing wheel with great success.

Larry Jackson

How do I sharpen my curved blades? For hollows and rounds, I strop them right on the workpiece itself. For the final two “burnishing” passes of whatever cove or ovolo I’m sticking, I set my iron for as fine a cut as possible, apply a light coat of green chromium oxide honing compound to the wood, and then lightly shave away wisps of green shavings, until I am perfectly bottomed out, and left with bare, polished wood. Works like a charm, every time. I get a beautiful finish to the profile, and as a bonus, the resulting edge is stropped and ready to go the next time I need the plane . For carving tools, I use each of my H&R’s to cut coves and ovolos into the faces and onto the edges of variously thicknessed scraps of hardwood strips , once again apply my little green friend, and frequently strop on whichever hardwood strop best fits the sweep of the gouge, every time I feel the gouge beginning to fight the grain of my carving. A very hard wood like maple doesn’t deflect under pressure as much as a leather strop does, and I’ve found it easier to maintain a consistent freehand angle, and continuous rocking stroke within the channels of the strop, to avoid rounding over or neglecting the wings of the gouge. I have however been known to drop a gouge or iron onto my concrete shop floor from time to time, so thanks, Shannon, for the heads-up on the “Diamond Wave”.

Dave

You mentioned sharpening hollows and rounds on your tormek. I started making hollows and rounds and am quite literally stuck on grinding a profile on the blades. I tried every Tormek jig I have and I cant seem to find the right one to grind the blade for the hollow blade. I considered using a bench grinder with a 1/2 or 1/4 inch thick wheel to get the inside radius, but cant seem to find any on the internet that has a rounded profile. Im assuming the flat profile wheels may not do the job.

I would really love to shape the initial profiles on my Tormek if I can, but frankly Ill take anything that works at this point.

I would appreciate any comment you may have on making the initial grind on the moulding planes.

Thanks again, I have been following you for a while and really enjoyed watching your journey.

Dave

    Shannon

    I use the 1/2 and 1/4″ thick wheels available through Tools for Working Wood and I shape the wheel into a curve. I don’t know of any curved wheels either but it is a simple matter to shape the stone with a diamond dressing tool.