Questions for Misters Schlumpf and Keeton

[Dan Forman]

I've been doing a lot of research on bowl gouge grinds recently, enough to realize that both geometry and personal preference come into play. In the "Favorite grind and why (http://www.sawmillcreek.org/showthread.php?141238-Your-favorite-bowl-gouge-GRIND-and-why)" thread.

There is a picture of the grind favored by Steve and John, which is described as a 42* bevel angle and 1 3/4 to 1 7/8" wings. This puzzled me, because these measurements just didn't sound like they matched the images in the post.

When I did my best to re-create that angle on paper, from the picture, I came up with about 50*, which I think reflects a different way of measuring. I usually measure relative to the flute, I think Steve's method measures relative to a line perpendicular with the flute. The slight difference (2*) in the two measurements from different perspectives could be easily accounted for by my imperfect drawing method. So I think that I have resolved this first question.

As to the length of the wings, I again rely on a crude, comparative method, measuring (on the screen picture) the diameter of the tool, (in real life 5/8"), in relation to the length of the wings, which comes to just a tad over twice the diameter of the tool, or in real life somewhere around 1 1/4" by my calculation. I decided to try this re-creation because when I marked 1 3/4" on my gouge (same one as Steve's), the wings looked like they would be impossibly long.

So question #1 is: If you measure the wings, from the farthest forward point of the tool, how long are they now? From my reading I also gleaned that grinds can easily change over time, either by accident or choice, so what was measured once may not be consistent over time.

Question #2 : How do you set the varigrind to attain your grind? Factors would include "stickout" (tool projection from the varigrind holder), angle of the varigrind leg, with the third factor being distance from pocket to grinding wheel, which would be easy to figure given the other two settings. I'm guessing that you would need around 2 1/2" of stickout to get a wing that long. I have been running into the holder just getting a 3/4" wing using the Oneway recommended 1 3/4" stickout.

Question #3: Does this grind still work on bowls deeper than the average salad bowl? My 5/8" Thompson is now ground to about 63* relative to the flute, which helps to negotiate the lower portions of the bowl, whereas my Dway sharpened to about 43* doesn't like to go deep at all.

Question #4: Has there been any evolution of this grind since the above linked post from 05/30/10?


I want to give this grind a try, but don't want to waste any more of that precious Thompson steel than necessary by experimentation, so any clarification you gentlemen can give would be appreciated.

I'm also trying to learn to use a traditional grind gouge for lower parts of bowls, which is a whole other ballgame.

Thanks,

Dan

[John Keeton]

Dan, I fixed the hotlink for you. We are going to a church program shortly, but when I return I will take some pics of my gouges, with angles and settings in order to respond to the questions.

[Steve Schlumpf]

Dan,

I have a simple 2x4 cutoff that I use as a depth gauge. The depth for the Doug Thompson 5/8" V gouge is set at 2 1/8". I have a 1/2" dowel that I use to maintain constant distance from the v-arm to the grinder platform. It is 7 1/8" long.

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Since picking up the CBN wheel from Dave Schneider, I have modified my grind somewhat. It is also important for you to note that I turn mostly hollow forms and am not all that concerned about how well the nose travels across the transition portion of a bowl. I do have good luck with the gouge as is when turning a bowl but I raise the nose of the gouge above centerline when moving through the transition area and that maintains contact and a clean cut... at least for me.

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Measurement of the actual angle is guesswork at best but here is how I came up with the original angle. Again, I have changed the nose profile on my gouge, so all the numbers most likely have changed. As I interpret this, the nose is now at 61.75*.

Hope this helps!

[Dan Forman]

Thanks Steve, that pretty much confirms what I was thinking. I know that you and John haven't been doing many bowls lately, but I think this grind would still do well with bowls, enough to give it a shot. I have a lot of bowl roughouts to finish up, then will be doing more hollow forms myself. I lost my settings, so my grinds have been very inconsistent of late, this latest set of pics looks pretty close to what I used to have, with the exception that your wings are about twice as long as mine. I'll see how close I can get to yours, and how it works out for me.

Dan

[Dan Forman]

John, will be interesting to see if/how your settings have changed in relation to Steve's over the past year and a half. Thanks.

Dan

[John Keeton]

Dan, my Thompson 1/2" V and my D-Way are both ground to this angle - about 43*.

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I have a 2" deep hole drilled in one of the 2x4's of my bench beneath my grinder setup that I use to set my Vari-grind jig - the pic below is a little deceptive because of the angle - it actually is 2" to the tip of the gouge. And, this pic also shows the setting for the jig, which I never change for any of my tools. I change only the arm setting of the Wolverine to achieve different grinds.

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This is the arm setting for both of my 1/2" gouges - 6"

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And, these are pics of the D-Way on top and the Thompson below.
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They have a primary bevel grind that is probably 38-40* that removes most of the metal, and I also grind off the heel. I only repeat those grinds as needed - probably every 4 or 5 times on the heel - less often on the primary bevel. I also attempt to make the nose profile approximate the flute shape of the gouge. In other words, the D-Way gouge is much more round in the flute, so the nose profile (viewed from the top) appears the same as the profile of the flute when viewed from the tip of the gouge.

The wings of the Thompson are about 1-1/16" and the D-Way just barely under an inch. Keep in mind that Steve is showing his 5/8" gouge. I should have measured my 5/8" V, but it is ground the same - the wings are longer simply because of the size of the tool. I also have another 1/2" Thompson that is ground closer to 56 - 58* that I bought to use on bowl interiors - have yet to do one since buying it. I may play with that angle once I do a bowl or two with it. The wings are not swept back as far on that gouge.

Hope this helps!

[Scott Hackler]

Hmmmm, you guys have really swept back those wings..... I am constantly experimenting and altering my grinds, but one constant is that I too grinds off the heals. If I had an angle measure tool I would check mine.

[Dan Forman]

John, Thanks for the pics and descriptions. I can see how those angles work well with hollow forms, but I think if and when you finally get around to doing a humble bowl ;), you will probably find the steeper angled gouge more helpful in the bottom third or so of the bowl, unless it is pretty shallow.

My 5/8 Thompson now looks pretty close to Steve's, with wings of 1 1/4", and bevel of 55*, which I may end up changing back to 60* if I need be. I figured as long as I'm experimenting, it's easier to change to steeper than it is to go shallower. I had a little excitement when I realized I hadn't locked down the leg tight enough, and it started shifting around in the early stages of grinding, but no harm done. Glad I have the CBN wheels, didn't take long at all, and no heat to speak of.

Going to try the new grind out tonight if I survive my first attempt at coring with the Mcnaughten center saver. I watched Robo Hippy's video a few times, think I'm ready for the adventure.

[Steve Schlumpf]

Dan - you will find that the wings come in quite handy for rapidly removing a ton of wood! That .. and you can make some amazingly thin slices when doing sheer cuts! Have fun and beware of the wings... they will slice you in a heartbeat - so don't use your fingers to wipe any debris out of the flute!! DAMHIKT!!

[robert baccus]

dan, if i may chirp in here, a 1/2"U fluted bowl gouge ground to a 70 deg.(almost flat) bevel will cut curls off the bottom of a bowl. takes all the difficulty out of the transition area and bottom turning. cuts smooth enough for a finish cut. good luck--------------old forester

[Dan Forman]

Steve --- I have already noticed one thing about the new grind, the wings now impinge upon the area that I used to hold with my left hand, so have to be very careful about that.
I somehow managed to survive the coring, only got one extra bowl out of a 14 inch blank, but was being very conservative due to it being my first try, and not wanting to lose the big bowl. More on that later too.

Dan

[Dan Forman]

dan, if i may chirp in here, a 1/2"U fluted bowl gouge ground to a 70 deg.(almost flat) bevel will cut curls off the bottom of a bowl. takes all the difficulty out of the transition area and bottom turning. cuts smooth enough for a finish cut. good luck--------------old forester

Robert --- I have a Sorby traditional half inch U gouge, which I was having a hard time with, but I think the angle was too steep, like about 80* or so. I knocked that back tonight to what I thought was about 70*, but turned out to be more like 60*, and it worked well. The DWay is a U as well, the Thompson is a V. They are both 5/8", but I have a Dway 1/2" too that I haven't really used yet. Were you referring to a traditional grind, or one of the fingernail varieties?

Dan

[David DeCristoforo]

So here's a (stupid?) quesrion. How do you "ride the bevel" if you grind most of it away?

[John Keeton]

David, I guess I have just become accustomed to a very small working bevel. I do the same on my detail gouges - a much smaller working bevel. I can tell this - I don't get any heel marks/bruising!!:D

[Bob Bergstrom]

I,m finding more and more professional turners using more pointed and relieved bevels all the time. Once you understand control in cutting there is only a small portion of the gouge that is necessary to have in contact with the wood to make a clean cut. 1/8" bevel usually is all that is needed if the tool is sharp and will require less pressure to keep it cutting. I also believe that a relatively small width on the nose. Again it allows for a very small but very clean cut across the fibers of wood. Cindy Drozda's tools are examples of this on a smaller scale. Johannes Michelsen's bowl gouges are provide minimumal contact on the wood when cutting his thin hats.

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[Rick Markham]

"Dang, you fellers ain't got no heels... must be the secret to them fancy turnins!" :D

I stopped grinding my heel off, maybe I will grind if off again... though I don't get any heel marks or bruising anymore either :p

[robert baccus]

Sorry about that. i intended to say a perfectly flat on the end grind. the bevel is very short--obout 70 deg but the end of the gouge is 90 deg. to the shaft. sounds spooky but is pure pleasure to use. this grind was used in the UK but just never made across the pond. it and sanding sealer seem to be the best kept secret in woodturning.-----------------old forester

[robert baccus]

I told you it sounds funny but you can ride an almost flat bevel very nicely. raise the handle a bit and out comes curls. been turning for 25 years and using this grind(on a cheap dedicated bowl gouge) for 20 of it. my turning friends seem to like it after trying mine. difficult to get a catch at all. i also grind 2 roughing gouges the same. they do not roughout a spindle as quickly but almost refuse to catch on a bowl ect. great to hog off green wood especially. good luch------------old forester

[robert baccus]

I've cut a lot of shavings with a short double bevel. have you cut any with a 70 deg. bevel? they both work, one is a dedicated tool that does a finish cut on bowl bottoms. good luck----------old forester

[Dan Forman]

Robert --- Is this the sort of grind you were referring to? This is the one I called a traditional grind, though I did move the wings back just a few degrees to avoid any unpleasant surprises. The bevel on this is 60*, not as steep as I thought as I was grinding it, but it works pretty well in transition area and bottom of the bowl. It was steeper, but I couldn't get it to engage the wood very well. This is a Sorby u shaped flute.

If this isn't it, can you show a picture of yours for clarification?

Dan

[Dan Forman]

Here are the other two gouges that I adjusted yesterday. Of the two, I got along best with the shorter winged DWay gouge.

Dan

[robert baccus]

hey, you'r real close yeah. a little steeper and flat with no rounding on the bevel. i lay mine on the table of a 1" belt sander, raise the handle a bit and just rotate. easy to repeat, a gives a flat bevel. i know it takes courage to do this to a perfectely proper gouge. sometimes it's hard to think or act outside the box. LOL--------------old forester

[Dan Forman]

Robert, so the face is flat vertically except for the bevel, but there is a little relief for the wings, right?

Dan

[robert baccus]

Roger hat Dan. the wings do not get in the way as you lead with the bottom of tht"U". let me know how it works out please. LOL-------old forester

[robert baccus]

Sorry--that would be --roger that. been hanging christmas lights all night!

[Dan Forman]

My brain hurts trying to visualize this gouge of yours! :confused: Is it something like this, but just a single 70* bevel? If not, I think I really really need a picture.

Dan

[Dennis Ford]

My brain hurts trying to visualize this gouge of yours! :confused: Is it something like this, but just a single 70* bevel? If not, I think I really really need a picture.

Dan
I will jump in for Mr Baccus here. The grind he is talking about is like your picture with a single 70 deg bevel. Some of this has already been posted but these are pros/cons of this grind as I see it:
+ Very unlikely to get a catch
+ Allows bevel contact on bottom of deep bowls
+ The high angle stays sharp longer (especially on hard or abrasive woods)
+ Easy to grind with or without a jig
+ Less likely to tear some highly figured woods
- Removes less wood per rotation
- Will not reach into most details

[Dan Forman]

As long as there is a bevel of an 1/8" or so, it really doesn't matter whether the rest is flat or convex does it? The bevel should should prevent an overly aggressive self feed, and the degree to which the wings are swept back will determine the size of the bite, correct? If this is true, then all I should need to do is gradually increase the size of the bevel in the course of ordinary sharpening.

How is the tool oriented through the course of the pass, and where on the tool does take the shaving (front, center, or back of the nose)? Is it used just in the lower two thirds, or can you start on the edge?

Dan

[Dennis Ford]

I hope I am not stepping on toes here, Robert uses this style grind more than I do. If he answers also, great.
Either single bevel or double bevel will work, you only need enough bevel to be able to feel when it is rubbing (how much this is will vary from person to person).
Any part of the edge can be used to take a shaving (depends on direction of cut and where on the piece you are cutting).
Starting a cut with the wing (regardless of grind) is an advanced skill.

One thing that I should have mentioned earlier is that it is dangerous to attempt a 70 deg (or higher angle) grind with a jig that only supports the tool in one place; Oneway, Ellsworth etc style jig. The tool can be forced down into the wheel, possibly causing the wheel to fracture.

[Ron Bontz]

Man. I think I need a tutorial after all this showing the first grind followed by the 2nd. Interesting.

[robert baccus]

Thanks for expansion on this. my head is fuzzy and i have been trying to be rational after midnite. on the wings i leave mine 90deg but i'm sure this is optional. due to this i cut only with the bottom of the flute to avoid surprises.-----dangerously overmedicated old forester

[robert baccus]

Dan, i sent an e-mail reply to your e-mail and it never made it to SC., sorry about that. basically i related that i measured my gouge and found it 77deg. on a forestry tour in school days we toured several hwd veneer mills in la. we were amazed to see the peeler knives were set at almost right angles to the rotating wood and were almost square in construction. they ran a pressure just ahead of the knife(8' knife) and produced miles of 1/36" high grade veneer. this started my experimenting with almost square bevels and as dennis noted they cut almost without grabs on bowl bottoms. hope this answers your questions. would appreciate any feedback. i appreciate the comments by Mr. Ford. ---------old forester

[Dan Forman]

Thanks Robert. It may be a couple of days before I get to turn again, but I'll play with the bevel angles when I do, and report back. I got some of the CorrosionX too, and the Fluid Film just arrived today, so an update on the rust situation will be in the works as well.

Dan