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View Full Version : Sharpening advice. #6 x 40mm gouge.



Gene Davis
04-22-2015, 1:22 PM
I ignored this fine old piece bought 35 years ago from Frog tool. Used it as-is for some log joint work, then threw it in the tool box and occasionally used it to remove glue squeeze out. Glue left on it obviously caused pitting on the inside.

Pics show what I mean.

I want to know how best to clean this up so it can be well-sharpened. As shown in the pics, what you see is the result of me taking a piece of soft wood, shaping it with a block plane to try to match the concave grind of the sweep, and then sanding with 120 grit paper.

It is going to take me a week of hand work with the sandpaper to get through the pitting.

What is a better approach?

I've a 1x30 benchtop sander-grinder, and a 3450 rpm bench grinder, and a collection of waterstones from 600 to 8000 grit, but no shaped stones for working on carving tools.

Jim Koepke
04-22-2015, 1:51 PM
Pits are difficult to get rid of if you are not willing to grind past them.

To get a better match with a block of wood it can be carved down with the blade you are working to redeem.

Sometimes changing from an out cannel to an in cannel grind will also lessen the effects of pitting. During the transition you can have both grinds.

jtk

ian maybury
04-22-2015, 2:05 PM
I've started looking at sharpening carving tools lately Gene, basically because i have a number of in cannel and out cannel gouges and am also thinking of getting into doing more carving.

The Chris Pye book (Volume 1 of his series) is very good on the specifics of sharpening the various sorts of carving tools with pages on gouges like yours: http://www.chrispye-woodcarving.com/home/books#a1

Part of my reason for getting a bit more serious about the topic is that i wanted to gear up so that i could sharpen most oddly shaped varieties of chisels and carving tools. The risk if you buy just the first option that covers a specific job is that you may end up doing the same on multiple occasions as other tools pop up.

It's all detailed in the book, but there's typically a bevel on both sides of the edge with a carving gouge. (a much smaller one on the inside) The cutting edge is first straightened by lightly touching it at right angles to a sanding belt or similar (you will need to cut back enough to get past any oddly shaped bevel(s), corners and pitting), the bevels are then worked to gradually bring the resulting flat face to a cutting edge of the required profile using a stone or other shaped abrasive. Care is needed to correctly form and retain the corners, and the line/corner where the bevel ends is faired in a little to prevent it digging into the wood when you lever off it.

The squaring of the edge and the initial forming of the main bevel can be done by hand on an (ideally low speed) flat surface grinder - e.g. the top surface of a Work Sharp disc, or possibly with your sander with great care to avoid overheating it. Even so it's pretty quick to remove metal so getting rid of your pits shouldn't be too hard.

The shapes are then refined using shaped abrasive - which you say you don't have. Options seem to be diamond or waterstone cones, or shaped slip stones, or 3M scary sharp poly backed self adhesive sharpening flim over a turned/otherwise shaped wooden dowel or whatever. The issue with waterstones is that they wear quickly, while diamond cones will need care to only use the right (small) part of the surface. Another option (which i'm using) is 3M or other poly backed self adhesive (scary sharp) sharpening film stuck on hardwood shapes - dowels of various diameters and so on.

Chris Pye does Arkansas fine, and carborundum med and coarse slip oil stone sets in various radii which are fairly widely available - i've bought enough to try out as well as the film. Tools for Working Wood in Brooklyn are a source - they have the Pye books and stones, also the 3M sharpening film.

I figure that the film gives great flexibility to form whatever backing shape is required in wood. (some it seems use only this and stropping) The slip stones only wear slowly, but i'm not sure about using oil. I've already had good results sharpening in cannel gouges using abrasive film over wooden dowels turned to the required size - typical at least a bit (and ideally quite a lot) smaller than the radius of the gouge.

The shaped edge is then finished on a shaped strop - usually folded over leather - with the ability it gives to rapidly touch up an edge very important….

Warren Mickley
04-22-2015, 2:45 PM
For the rough work we use a coarse India slip stone, $10. They are 3/16 along one edge, 1/2 along the other edge, 1 3/4 wide, and 4 1/2 long. You don't want smaller slip stones; they will cramp your hand. You don't want conical stones; you want a consistent radius that is considerably smaller than the inside radius of your tool, in this case 1/2 inch. Stop if you get tired so you don't get sloppy.

You will want a finer stone also like a fine India, $10, or an Arkansas, maybe $22.

Mike Holbrook
04-22-2015, 4:15 PM
Spyderco makes elliptical, triangular and round rods from ceramic that are relatively fine and hard, more a finishing stone. Lee Valley sells a selection of wood "slips" that: diamond grit, buffing compound, diamond lapping film, 3M Micro Abrasive sheets, sticky sandpaper...can be stuck to. I often just use wood dowels wrapped or coated in an abrasive. EZE-Lap makes round and elliptical sharpening rods coated in the same abrasive as their diamond plates.

ian maybury
04-22-2015, 4:37 PM
+1 on the conical stuff. Never tried it, but it seems impossible to do anything but to create a convex bevel using a cone. The slip stones can add up in cost as i discovered...

Maybe it's just me, but i find it far easier to maintain an accurate bevel angle when moving the tool over a clamped slip or bench stone. Lots seem to sharpen using slips held in the hand, and it's necessary some of the time to see the area being worked on - but i seem to find it a lot harder to maintain an accurate bevel angle that way. Maybe there's trick?

Frederick Skelly
04-22-2015, 7:59 PM
Ive been struggling to figure out how to get a really sharp edge on round bladed tools (H&Rs, gouges). Thanks for the tips and overall "primer" guys!

Ian, Im ordering that book right NOW, before I buy another single thing!

Best to all,
Fred

Mike Henderson
04-22-2015, 10:49 PM
When sharpening carving tools, you generally want the tool square across the edge. Note that your corners are rounded. Trying to tell someone how to sharpen carving tools in text (like this forum) is tough.

But before you do a whole lot of work on that tool, let me first say that a 40mm gouge is not something you'd use very much in carving - unless you're doing some really big carvings. For normal size work you'd use much smaller gouges. I think the widest I have is about 35mm and I only use that for shaping the ball on a ball and claw foot.

But the way you sharpen any gouge that has a damaged edge - and carving tools mostly get damaged by falling off the bench - is to first grind it square across. Then, when you look down on the end of the gouge, you'll see the flat. Slowly and carefully, using power sharpening methods, you gradually grind the bevel, stopping often to look down on the edge to see where the flat is getting thinner and where it's still wide. This allows you to adjust your grinding. You grind until the flat goes away.

Then to a stone and side-to-side motion (if you don't have a power honing wheel). Work up through the grits until you finish with maybe 8000 grit.

You have an additional challenge of the pitting so you're going to have to remove some metal from the inside of the gouge. Sandpaper on a shaped piece of wood will do that for you. Do that before grinding the bevel. Or sacrifice some of the gouge and grind the end back past the pitting. If you do that, follow the instructions above to sharpen it.

It's much easier to demonstrate this than to describe it. Here's (http://www.mikes-woodwork.com/SharpeningDisk.htm)how to make a sharpening disk for gouges, if you have a lathe.

Mike

Chuck Hart
04-22-2015, 11:47 PM
Ive been struggling to figure out how to get a really sharp edge on round bladed tools (H&Rs, gouges). Thanks for the tips and overall "primer" guys!

Ian, Im ordering that book right NOW, before I buy another single thing!

Best to all,
Fred

Fred you can get a used or new book from ABE Books for $7+ up to $30 depending on your likes.

http://www.abebooks.com/?cm_mmc=ggl-_-US_AbeBooks_Brand-_-Top+Brand-_-abe%20books&gclid=CJiTh4nCi8UCFdKFfgod6S8ARA

Chuck

Mike Holbrook
04-23-2015, 6:12 AM
If one needs to grind to remove enough metal there are a couple good options. The cheapest is to use the abrasive cylinders made to work on a drill press or hand drill. Dremel makes a good selection of abrasive stones and cylindrical paper backed attachments. Some turners and carvers who have lathes just charge a round rod on their lathe with diamond or one of the sharpening compounds.

Some of the newer CBN grinding wheels have rounded edges. At least one wheel I know of, available through Woodturning Wonders, has a rounded edge that extends well past the edge which can be helpful. These wheels get a great deal of use from guys who turn and need to be constantly sharpening turning tools. If the amount of work requiring this degree of grinding isn't that great the hand drill or Dremel tool are good options, allowing the user to clamp the piece being worked and then get down into it with the drill mounted abrasive.

Drew Langsner's classic book "The Chairmaker's Workshop" offers some tips on sharpening the curved rounded blades used in chairmaking, including large gouges. Peter Galbert's new book "Chairmaker's Notebook" offers advise on sharpening just about any tool used in chair making. Galbert devised a special sharpening devise, the Drawsharp, especially for sharpening drawknives. Galbert's devise is now made commercially by Benchmade I believe. There are many YouTube videos out there on the subject. Curtis Buchanan has a good one showing how he sharpens a Barr Tools heavy gouge, similar to the OP's tool using conventional grinders and wheels. Curtis uses his gouge for taking off the maple chair leg pieces that protrude through Windsor chair seats:
https://www.youtube.com/watch?v=OVZl6WVUCio

Curtis has other YouTube videos on sharpening Adzes.....

Gene Davis
04-23-2015, 9:51 AM
Thanks to all for the advice. I'll be working on the inside (concave) surface of this with sandpaper and slips until I can minimize the pitting.

The bevel side will be done with the belt sander, 400g, and then polished up with compound on a felt wheel running at 3450 rpm.

My planned use is to approximate the adzed texture on a copy of a piece shown in Denver's museum. All in pine. Pic attached.

I also attached a pic of a scrap piece of poplar I chopped with the gouge as-is and before this new attempt at sharpening. I think that with the pitting I have in the top, even if I am unable to grind through it all, the effect on the cutting edge won't mess up my chopped surfaces.

Karl Andersson
04-23-2015, 10:56 AM
Gene,
I'll second Ian's suggestion to use Chris Pye's advice and put a small inside bevel on it as well as your main outside bevel. This would lower the angle of incidence (attack) of the chisel and, in my experience doing relief carving, allows an easier/ cleaner cutting shallow scoop, which is what you're trying to do anyways. This would get you carving faster as well, since a small bevel is easier to grind than smoothing the large surface area of that inside hollow.
Karl

Tom McMahon
04-23-2015, 12:54 PM
Gene,
I'll second Ian's suggestion to use Chris Pye's advice and put a small inside bevel on it as well as your main outside bevel. This would lower the angle of incidence (attack) of the chisel and, in my experience doing relief carving, allows an easier/ cleaner cutting shallow scoop, which is what you're trying to do anyways. This would get you carving faster as well, since a small bevel is easier to grind than smoothing the large surface area of that inside hollow.
Karl
I will third

Gene Davis
04-23-2015, 2:49 PM
And the way to shape that top concave bevel is with a slipstone?

Warren Mickley
04-23-2015, 5:42 PM
Some carvers put a small bevel on the inside of the flute (on the order of 10 degrees) and then lengthen the outside bevel so that it is in the 20 degrees range. Others have a bevel closer to 30 degrees on the outside and no bevel on the inside. For either method you really ought to have a slip stone.

As mentioned, making a small bevel on the inside is somewhat easier to get started with, although you do have to lengthen the outside bevel. The single bevel (outside) is somewhat easier to maintain because that bevel is smaller and the flute area can be more precisely maintained because the slip rubs flat on the inner surface.

There are some subtle geometry differences which are difficult to describe. But I have noted that carvers who use double bevel are more likely to use bent gouges in addition to straight gouges, and carvers who use single bevel are more likely to use back bent gouges than bent gouges, just because of the subtle differences of attack.

Howard Pollack
04-24-2015, 11:06 AM
I recently posted almost the exact same question on the carving forum (below) here is a video of Chris Pye restoring such a gouge that someone posted https://www.youtube.com/watch?v=JoEJX-Hsp88 It is clear and helpful.
Howard