Thread: 'What flute profile does this gouge have?

Hi Neil

Thanks for taking the time to provide such a detailed reply to my Q's. Much appreciated. Provides much needed info.

I am just a weekend woodturner with admittedly around 50 yrs experience. That doesn't mean that I can't appreciate high quality Tools and Machinery. Also as a scientist I also can't help myself from wanting to understand and asking WHY & HOW when presented with new info.

My original Turning tools were Sorby forged tools bought in the 60's & 70's. I was then fortunate to obtain one of the earliest Superfutes ( Now only a stub) and was introduced to HSS. More recently I have acquired a new Superflute, two Hamlet ASP & HSS, and two Thomson V10 V flutes. As you can see my experience is limited hence the Q's. With these new gouges I have been experimenting with Fingernail Grinds. ( my original training was with Traditional straight across grinds)

I have both a GPW copy of the Oneway Varigrind and an Unijig. More recently I bought a Hannes grinding jig but haven't yet used it.

As you well know there a three seperate adjustments you can make on the first two jigs. In combination with flute shape and how much you grind the various areas of the wings you can achieve a myriad of different grinds- some radical and some more subtle.

When you think about it, when you grind wings on a bowl gouge you not only set the nose angle ( say 60 deg) but you can also vary the included angle of the wing side grind from very acute to less acute. This included angle is also influenced by the Flute shape. Because of the wing and curved flute shape the wing cutting angle is actually difficult to measure but the difference is easy to see as you move to the extremes.

As I understand it David indicates that his Ellsworth grind produces a constant 60deg angle from the nose around onto the wings and this is what gives his gouge and grind its particular characteristics that he prefers. However I don't have a genuine Ellsworth gouge to compare. Also as I understand David's grind, the higher you make the wings ( which makes the included angle more acute) the more aggressive is the grind, particularly for dry wood.

Recently in my inquisitive way I have been experimenting with the various settings on the Varigrind and can confirm that you can easily change the acuteness of the wings compared to the nose. What effect this has on the performance of the gouge is my next task.

Cheers
Ron

Ron, thanks for your above post on gouges, grinds and jigs.

These are topics that could each have a thread of their own. I'm in two minds whether we should expand the discussion here in this thread on those topics that are, IMO, inextricably related to flute profiles or spin them off to a separate thread or threads.

Perhaps for the benefit of those searching by topic in the future we should start a new thread under the topic Gouges, grinds and jigs. Would you like to kick that off? If you think appropriate, you could include a link back to this thread on flute profiles where applicable.

Originally Posted by NeilS

....the steel at the bottom of the flute on this VM (5/8" bowl gouge) is about 6.5mm.

In comparison with other gouges with a similar flute profile, this is on the thicker side with the Henry Taylor having 5.5mm and the Woodcut 7mm.

I should also measure the Ellsworth signature gouge that has a very open parabolic/catenary flute to see how that compares with the others.

I went back and measured the thickness of the steel at the bottom of the Ellsworth and it is similar to that of the Henry Taylor at 5.25mm.

As I mention earlier, I find that this thickness has an effect on how the bevel rubs through the 'transition area' inside a bowl. The thinner this area of steel, the shorter the bevel will be in the tip area and, for the way I turn, the better it will rub and arc through the transition area. The longer bevel may not be an issue for other turners and their technique or can be modified. A secondary bevel on the heel, as used by some turners and on the Henry Taylor M42 Stay Sharp gouge as it comes, can overcome this if it is an issue for you.

Originally Posted by NeilS

As I mention earlier, I find that this thickness has an effect on how the bevel rubs through the 'transition area' inside a bowl. The thinner this area of steel, the shorter the bevel will be in the tip area and, for the way I turn, the better it will rub and arc through the transition area. The longer bevel may not be an issue for other turners and their technique or can be modified

While I like the shorter bevels, I find that it depends on the size of the bowl and the radius of the inner curve as to how long a bevel feels comfortable.

I also prefer the wings swept back about 60 degrees but, depending on the flute profile, this needs to change to keep the side profile of the cutting edge from becoming too extreme one way or t'other. (ie. bird-beak or cadillac fins.) Due to this I've become a fan of the D. Thompsons, due to both the steel content and the flute profile easily grinding to the shape I prefer.

Anyways, the point of this is that as a result I have quite a few Thompson's of different sizes, giving me a selection of my profile with different tip bevel lengths to suit whatever curve I'm working on.

I dislike switching between gouges with slightly different grinds for finishing cuts as I find that one can easily make a mistake when, eg. sheer- or back-cutting with a wing on one, then switching gouges and misjudging the required angle on the new one. Way too many unrecoverable catches lay down that path for me!

Yesterday I ground out the 'tracks' from the bottom of the VM gouge flute. I started and spent most of the effort with #80 grit and did a bit of a cleanup with finer grits after the #80 had removed the tracks.

Flute scoring.jpg Flute scoring - 1hr.jpg Flute scoring - 2hrs.jpg

The first photo is of the deep milling tracks before the #80. The second photo was after 1 hour with the #80. Third photo is of smooth flute at 2 hours.

Those tracks were the worst I have worked on and deeper than any of the P&Ns I have cleaned up.

If you have a diamond hone with a profile that matches the flute that will speedup the process, just don't be tempted to run a rotary diamond burr across the flute as that will create its own problems.

I only worked on the first 25mm at the end of the flute. Two hours is quite an investment of time. This needs to be taken into account when considering the relative cost of gouges. The value of your time vs $s will be different equation for each turner.

Why grind out the tracks? If left, those tracks would have considerably weakened the edge and reduced its sharpness at the most critical area of the tip, as well as increasing the frequency of having to go back to resharpen.

Originally Posted by Skew ChiDAMN!!

While I like the shorter bevels, I find that it depends on the size of the bowl and the radius of the inner curve as to how long a bevel feels comfortable.

I also prefer the wings swept back about 60 degrees but, depending on the flute profile, this needs to change to keep the side profile of the cutting edge from becoming too extreme one way or t'other. (ie. bird-beak or cadillac fins.) Due to this I've become a fan of the D. Thompsons, due to both the steel content and the flute profile easily grinding to the shape I prefer.

Anyways, the point of this is that as a result I have quite a few Thompson's of different sizes, giving me a selection of my profile with different tip bevel lengths to suit whatever curve I'm working on.

I dislike switching between gouges with slightly different grinds for finishing cuts as I find that one can easily make a mistake when, eg. sheer- or back-cutting with a wing on one, then switching gouges and misjudging the required angle on the new one. Way too many unrecoverable catches lay down that path for me!

All good points, Andy.

Now that the flute tip of this gouge has been ground smooth, the one remaining thing to do is test out the durability of the edge. This is something that has to be done over time as it is not until a gouge has been resharpened many times that you can know that you are working with the steel that represents the heat treatment for of the majority of the blade. The metal on the very tip of a new gouge can be tempered differently (softer or harder) to the remainder of the gouge and it is not until that has been ground away that you know what you have from there on.

I will report back when I get down the blade a bit.

Originally Posted by NeilS

Those tracks were the worst I have worked on and deeper than any of the P&Ns I have cleaned up.

I thought they looked bad!

I only worked on the first 25mm at the end of the flute. Two hours is quite an investment of time. This needs to be taken into account when considering the relative cost of gouges. The value of your time vs $s will be different equation for each turner.

Why grind out the tracks? If left, those tracks would have considerably weakened the edge and reduced its sharpness at the most critical area of the tip, as well as increasing the frequency of having to go back to resharpen.

Considering that the cutting edge is the junction of the bevel and flute, as long as the flute has any ridges or grooves you will not get a good edge; it'll be either saw- or snaggle-toothed.

One should consider time spent on polishing a new tools flute to be just as important an aspect of preparing a new tool as one considers choosing a handle or the initial sharpening profile. Sometimes one is lucky with a tool and it's only a minor polish. Other times, well... you have a prime example. Luck of the draw and all that.

Personally I like to polish as much of the flute as I estimate being 'usable' so I only have to do it once per tool lifetime... otherwise the lazies kick in and I tend to 'put up with' a bad cutting edge - once I grind back that far - for far too long before I get around to repolishing.

ie. It's worth spending the time.

Originally Posted by NeilS

I will report back when I get down the blade a bit.

Rather than waiting to grind the tip back over time I decided to just grind

10mm off

the tip of the Vicmarc bowl gouge and re-profile it (I will report on that separately). My report on the durability of the edge after doing that can be found here in a thread where I have reported previously on the durability of some other bowl gouges.

OK, in summary, this is what I thought of the Vicmarc bowl gouge:

Pros:

• Now that P&N is going/has gone, this gouge is competitively priced among the unhandled options (shop around).
• It has a good wide parabolic (catenary) flute profile if you like this style, as many of us do.
• The powdered metal vanadium 10% steel held up well in a demanding edge durability test, even on our toughest Australian hardwoods.
• It is good to have another Australian made tool, although the steel is probably made off shore (?).

Cons:

• The finish on the flute profile was less than ordinary (see photos in posts above). Gouges from Thompson & P&N have needed to be further polished, with the P&Ns being hard work at times to get them up to full performance, but the finish on this gouge was the worst I have experienced, taking close to 2 hours of hand grinding to get 1" of the flute into a satisfactory condition. Power grinding would have reduced the time required, however, that comes with risks. Price and finish are a trade off, but the surface finish on the flute is not just a matter of cosmetics; a finish on the the flute that is at least as fine as your re-grinding wheel is critical to the performance of the gouge.
• The bevel grind profile, as supplied, on the gouge was in my opinion an unsatisfactory starting point for many turners. Yes, it should only be a starting point and would not be an issue for experienced turners who are confident about the grinds they use, but my concern is for the novice turners who often struggle to get a satisfactory grind on their bowl gouges in the beginning stages of their turning. IMO, the grind on the gouge as supplied was unhelpful for these users, which I will expand on more detail in my next post that I hope to get to later today or tomorrow morning.

The finish on the flute profile was less than ordinary (see photos in posts above). Gouges from Thompson & P&N have needed to be further polished, with the P&Ns being hard work at times to get them up to full performance, but the finish on this gouge was the worst I have experienced, taking close to 2 hours of hand grinding to get 1" of the flute into a satisfactory condition. Power grinding would have reduced the time required, however, that comes with risks. Price and finish are a trade off, but the surface finish on the flute is not just a matter of cosmetics; a finish on the the flute that is at least as fine as your re-grinding wheel is critical to the performance of the gouge.

As Vicmarc has a reputation for making high quality equipment, I wonder if this one slipped passed their quality assurance people. All the gouges I have, Crown, Thompson, Sorby, even Chinese made Bodger by Penn State Industries are better finished than your VM. All mine appear to have a ground flute and only need a little honing with some rolled up 320 or 400 grit on the inside to be nice and slick.

Have you sent them a photo as delivered and asked if that is their usual quality?

The VM bowl gouge shown here is much smoother than yours: Vicmarc 1/2 Inch Bowl Gouge put the cursor over the photo for detail.

Back to my gripe about the bevel grind as supplied on the Vicmarc.

I look for two things on the initial grind that comes on a gouge, regardless of the nose angle or its flute profile:

1. The tip of the gouge as viewed from above looking down on the flute matches (ie it is a mirror image of) the the flute profile as viewed from the end.
2. The edge running up from the tip to the wings form a convex curve when viewed from the side (in elevation).

If a novice turner gets a bowl gouge that comes with a grind like this they have an excellent chance of quickly learning how to master the gouge and to resharpen it so it performs at its optimum. What they do later to modify the grind when they have become experienced turners will then be based on a sound point of departure to which they can return as a reference point. Experienced turners can look after themselves. It's the novices that are my concern.

Here is the above and end view of the grind on the Vicmarc bowl gouge (the two views juxtaposed) as it came.

VM - supplied grind top-side view.jpg

That is looking more like an chook egg than a mirror image.

The side view shows a straight (maybe even slightly concave) edge profile. Here it is.

VM supplied grind - sm.jpg

That is not a grind profile that we should be putting into the hands of a novices. I'm not alone in thinking this. I will expand on this in a separate thread.

I reground the gouge edge to the following convex profile and it started to behave much better.

VM after grind mod - sm.jpg

And, here is the end and above view of the reground profile with the two views juxtaposed. Not perfect, but very close to a mirror image.

VM flute top & end view inverted.JPG

That is a better starting point for a gouge with that flute profile. I would be far more confident in putting it into the hands of a novice turner and know the grind won't be working against them from the start.

I will adapt it a bit from there for my own use to my preferred grind (with more swept back wings), but the tip and most of the grind will remain like this in keeping with its parabolic/catenary flute profile.

As mentioned, I will start another thread with support for my views on this. And, if you have alternative views we can explore those there.

That is not a grind profile that we should be putting into the hands of a novices. I'm not alone in thinking this. I will expand on this in a separate thread.

I reground the gouge edge to the following convex profile and it started to behave much better.






The above is most interesting, which I never have considered. The straight or concave grind would cut on the tip or the back and probably be unstable on the inside of the bowl. The convex grind would fit the inside better and cut in the middle of the grind.

I need to have a look at my bowl gouges. I have been using a wolverine jig and just stick the gouge in it to the mark on my lathe bed, give a swipe on the grinder and keep cutting.

I don't know why this is underlined, I can't make it stop.