Fixing (and avoiding) concave edge on swept-back spindle gouge

[Jamie Straw]

I'm finding that my spindle gouge grinding (fingernail grind -- "swept-back" might not be the right term) tends to make the side edges barely straight, and sometimes concave, which I know is *not* a good idea. Is there a common mistake that leads to this? What's the direct route to fixing it once it happens? [Data: I use the Wolverine set-up.] I muddled around for some time and was able to get an acceptable (and very sharp) grind on 3 gouges, but I'd like to get that slightly convex shape on those edges.

 

[hockenbery]

I'm finding that my spindle gouge grinding (fingernail grind -- "swept-back" might not be the right term) tends to make the side edges barely straight, and sometimes concave, which I know is *not* a good idea. Is there a common mistake that leads to this? What's the direct route to fixing it once it happens? [Data: I use the Wolverine set-up.] I muddled around for some time and was able to get an acceptable (and very sharp) grind on 3 gouges, but I'd like to get that slightly convex shape on those edges.

As you know the gouge should have a continuous convex curve on the cutting edge.

Jigs work best with the tool continually moving So that the contact point in the wheel the wheel moves along the cutting edge curve.
If you change directions don't pause in one spot. If the gouge is held in one spot at dip will be ground in the cutting edge.
If you hesitate when changing directions or linger at the edge of the wing you will get a dip.

Correction is to grind everywhere but the dip. Easier said than done...

Have fun work safely,

Al

 

[john lucas]

this video should answer your problem, I think it I understand what your asking. https://www.youtube.com/watch?v=M9G16ylEZHQ

 

[Hu Lowery]

Start at the back of the wing

The jig does nothing to control that part of the wing shape, it is up to the person grinding. I start at the back of the wing and make one pass towards the nose, never reversing directions. If the wing doesn't suit me I make another pass from the back of the wing to the nose. The nose takes a very light touch to grind, a slow wheel, or both. One trick for the nose, even the wings if you are cutting off more metal than you like, is to flip the grinder off before grinding. Even my eight inch variable speed grinder has plenty of inertia to let me grind one side and the nose after the grinder is off. Probably could sharpen the entire gouge and mine is a little lightweight grinder.

Until you are very comfortable with your grinding a black sharpie or markalot is your friend. Blacken the entire bevel and make a very light pass and see how you are sharpening. If you have already sharpened using the settings you are using now, a feather touch should take all of the black marking off. If you tend to not sharpen perfectly, checking the black left after one very light pass will tell the story.

It is usually easier to get a full ninety degree swing if you are standing a little to one side of the wheel than dead in front of it. Move to the opposite side of the side of the gouge you are sharpening and sharpen almost to the nose. Reverse your position and sharpen the other side of the gouge going past center and across the nose. A common mistake is starting at the nose or going across the nose from both sides. Also if you try to sharpen to the middle of the nose from each side it is very difficult to blend things perfectly. You usually end up with a point or overground nose. Since the wings have to be ground to match, overgrinding a nose eats a lot of steel in a hurry. if you get a point or the nose isn't perfectly blended a few quick strokes with a diamond hone may be preferable to more grinding.

Take a practice swing or two with the gouge before turning the grinder on. It insures that you can move freely through the arc you want to grind and builds a little muscle memory. May seem odd but spending a few minutes at the grinder now and then going through the motions with the grinder off, carefully watching the edge of your gouge can be a big help learning to grind.

If you are grinding to a new profile or get badly out of shape there is nothing wrong with turning the flute of the gouge directly into the stone and shaping to the slightly convex shape you want. Very easy to lose the shape again sharpening though so don't do this except when making a large change.

All I know about sharpening and a little more! Lyle Jamieson has an excellent video on youtube. Doug Thompson had an excellent video too, about an hour long. I can't find it now and it may have been pulled down and only offered for sale now.

Hu

 

[Bill Boehme]

I like Hu's explanation. I'll add that my solution to the wings getting a little too flat is to grind back the nose and then fairing the nose into the wings. Be judicious in grinding the wings as it is very easy to overdo it. Remind yourself when grinding that the jig only controls the angle that the tool is presented to the stone and controlling the shape is still up to you. Use a feather light touch and do as Hu said about using a black Sharpie.

Regarding the Doug Thompson sharpening video, it was on the website of the Southwest Missouri Woodturners when he did the demo for their February 2014 meeting. The page is still HERE, but as you can see, the link to the video is broken. I sent an email to their webmaster a couple months ago, but there was no response.

There is also THIS PAGE on their website that has several broken links to the video.

 

[Jamie Straw]

Thanks all...

Thanks, everyone, for the detailed info. Proud to say I more or less fell into the right approach, getting more comfortable at the grinder, but the details above help me focus. The video was very helpful. My hands aren't steady enough to free-hand with most gouges, though doing OK with the skews.

 

[Bill Boehme]

... My hands aren't steady enough to free-hand with most gouges, though doing OK with the skews.

Sharpening whether freehand or using a jig is generally smoother if you primarily use your body to move the tool.

 

[hockenbery]

My hands aren't steady enough to free-hand with most gouges, though doing OK with the skews.

Sharpening without a jig is often called free hand, that is bad name since "freehanders" always use some support just as in turning.
Support may be a side of the grinder, a body part, or a platform (you probably use this with your skews) or some other support for the hands or the tool.

I learned a simple way to sharpen spindle gouges with a 30 degree bevel by holding the bevel on the wheel with one hand and turning the end of the handle,with the fingers in the other hand which is held against my body or on the top of my thigh depending on the handle length. The gouge is pushed up the wheel by turning the body rotated by the fingers to keep the edge on the wheel.

To the untrained eye it might appear unsupported but it is a solid and totally repeatable.

Al

 

[john lucas]

About 6 minutes into this video I show the technique Al is talking about. It can be done without using the V arm by simply resting the tool on a good tool rest at the start of the cut and then pushing it up the stone as you rotate the tool. https://www.youtube.com/watch?v=BOEL7Q3CpZc

 

[Jamie Straw]

Sharpening whether freehand or using a jig is generally smoother if you primarily use your body to move the tool.

As with turning, yes? I'm getting there!

 

[Jamie Straw]

Sharpening without a jig is often called free hand, that is bad name since "freehanders" always use some support just as in turning. Support may be a side of the grinder, a body part, or a platform (you probably use this with your skews) or some other support for the hands or the tool.

I learned a simple way to sharpen spindle gouges with a 30 degree bevel by holding the bevel on the wheel with one hand and turning the end of the handle,with the fingers in the other hand which is held against my body or on the top of my thigh depending on the handle length. The gouge is pushed up the wheel by turning the body rotated by the fingers to keep the edge on the wheel.

To the untrained eye it might appear unsupported but it is a solid and totally repeatable.

Al

I may need to lower the height of my grinder to get that approach to work, but in general I probably need to develop better support. The skew is easy because I can use more hand and less finger-tip control, let alone the rolling motion. These hands have many miles and a couple of surgeries in their history -- fine motor performance ain't what it used to be. Thanks for giving details on your technique, it helps!

 

[Jamie Straw]

Videos appreciated!

About 6 minutes into this video I show the technique Al is talking about. It can be done without using the V arm by simply resting the tool on a good tool rest at the start of the cut and then pushing it up the stone as you rotate the tool. https://www.youtube.com/watch?v=BOEL7Q3CpZc

Thanks, John, I've watched that one a couple of times, and will probably watch it 10 more. Today was very frustrating -- was trying to get a Bonnie Klein type profile on the 3/8" spindle gouge (after watching the AAW DVD), got it profiled, but when I ground it I simply could not get that nice curve on the edge. Straight edge, yes (improvement over concave), but no curve. I profiled it again, took another stab at it, and got closer. Took it to the lathe for a couple of minutes, and at least it seemed to be cutting with the correct part of the edge.

Both of the videos you've linked in this thread have been very helpful, just need to sort out all the variables I guess, and practice, practice, practice. I understand much more about the Wolverine jig and the geometry of how it works. One thing Bonnie mentioned in her segment of the DVD was that when she freehands, at the point she goes up the wheel, she also goes to the other side (i.e., if grinding the left wing, she heads to the right side of the wheel). I tried that today (with the Wolverine hanging on) and that seemed to help.

I know you probably don't need them, but have you ever used the Raptor angle-setting do-dahs? I have a set from way back, and tested one today -- it was a good 5 degrees off when I set the platform with the 35-degree claw. Not helpful.

 

[Douglas Ladendorf]

You ask great questions Jamie, and get equally great answers! I have picked up a couple things here as well. Tuning in so I don't miss any more nuggets that may turn up.

 

[robo hippy]

I guess the main advice I can give here is that the grinds do not have to be perfect. Close works as long as it is sharp, then the next time you go to the grinder, change it a bit. If your flute edge is straight and you want a curve, spend a bit more time on the nose.

I have never tried the Raptor jigs. One friend says 'they look really nice hanging on the wall' as they were not even close for him. 5 degrees off is not much of a problem, and you can 'adjust' to it.

For running up the wheel on your wings, a number of people do that. I found it easier to just swing and roll the gouge on the platform. I have tried the other method, and it does work, but I would need to relearn a few things.

robo hippy

 

[Jamie Straw]

More on the way, I hope they're good

You ask great questions Jamie, and get equally great answers! I have picked up a couple things here as well. Tuning in so I don't miss any more nuggets that may turn up.

Thanks, Douglas, glad they help others too. I'll be back this weekend with several queries. I've been cutting up green wood for future use, getting ideas (always dangerous) but have tons of questions. Having found my Turning Green Wood book (by Michael O'Donnell) will help tremendously.

 

[Jamie Straw]

Going with the flow...

I guess the main advice I can give here is that the grinds do not have to be perfect. Close works as long as it is sharp, then the next time you go to the grinder, change it a bit. If your flute edge is straight and you want a curve, spend a bit more time on the nose.

I have never tried the Raptor jigs. One friend says 'they look really nice hanging on the wall' as they were not even close for him. 5 degrees off is not much of a problem, and you can 'adjust' to it.

For running up the wheel on your wings, a number of people do that. I found it easier to just swing and roll the gouge on the platform. I have tried the other method, and it does work, but I would need to relearn a few things.

robo hippy

Yep, after reading a dozen or so threads about sharpening, I'm reassured by the fact that things can vary some and it's a learning process. I've been distracted from working on sharpening by sorting out wood and cutting it up for future use, but the grinder will get a workout this weekend -- I've yet to get the spindle gouges close enough to be truly functional. The Raptors look totally cool hanging on the wall, but have been a bit disappointing. I'm inclined to stick with the roll-technique rather than going up the wheel. Really tempted to try sharpening on either a belt sander or big disk. Sees to have fewer pitfalls than the grinding wheel, but will tough it out. BTW, I have a cousin who lives in Bend, so next time I schedule a visit, I'll check and see if you'll be around. A stop in Eugene is doable!

 

[robo hippy]

I guess I can add that 'free hand' sharpening has 2 different methods. One is using the platform to set angles, and the tool remains flat on the platform. The other involves using a finger on a rest or platform, and it acts like a tool rest, and you pivot, roll, and sweep from your finger. In both cases, you use the same cutting skills that you use when cutting wood with your tools.

Look forward to meeting you some time.

robo hippy

 

[john lucas]

Jamie I used to sharpen on a disc sander. It has some real advantages. The closer you get to the center the less surface feet or surface speed you have so it removes less metal. It also deosn't heat the tool up as much when your closer to the middle. When learning to sharpen if you stay closer to the middle since it doesn't remove metal so fast you can move the tool slower and watch the edge and not ruin a grind so quickly. Of course the outer edges will remove metal very fast and really heat the tool. I used to sharpen all my carbon steel tools on the disc sander because it was rare to overheat one if you stayed close to the middle. The HSS tools won't be hurt by overheating so you can sharpen them further out.

 

[Jamie Straw]

Jamie I used to sharpen on a disc sander. It has some real advantages. The closer you get to the center the less surface feet or surface speed you have so it removes less metal. It also deosn't heat the tool up as much when your closer to the middle. When learning to sharpen if you stay closer to the middle since it doesn't remove metal so fast you can move the tool slower and watch the edge and not ruin a grind so quickly. Of course the outer edges will remove metal very fast and really heat the tool. I used to sharpen all my carbon steel tools on the disc sander because it was rare to overheat one if you stayed close to the middle. The HSS tools won't be hurt by overheating so you can sharpen them further out.

Yep, I remembered the "center-of-the-disc" thing when I was getting ready to re-profile the spindle gouges. Works pretty well! Finally, today, I got a great profile and grind on the smallest spindle gouge -- it's been SUCH a challenge! Reading DeHeer's Demystifying Sharpening was a big help, combined with your videos and Bonnie Klein's demo and going reallllllly slow. Yipeee!