I was turning a bowl with my 1/2" superflute bowl gouge. Since it was getting dull & I didn't feel like sharpening, I pulled out a 1/4" deep fluted gouge that I almost never use. I was amazed at how much easier it was to use!
Of course, my first thought was that since the super flute gouge was dull it obviously wasn't cutting very well. So I sharpened it up & still the deep flute was easier to use.
Both gouges are ground identically (65 degree or so nose, wings ground back at about 45 degrees, both sharpened with a homemade wolverine-like jig).
So what's the deal with super flute vs. deep flute bowl gouges? Is it just a preference? Am I using or grinding the super flute gouge incorrectly? Is the difference in size between the gouges a contributing factor (I tried to take similar sized shavings with both)?
>Chris, the deep flute allows you to place the cutting point of the tool below its centerline; not the centerline of the wood but the centerline of the tip of the tool itself. This, if used properly, can virtually eliminate catches. The shallow flutes cause the cutting point of the tip to be too high, making it necessary to cut with the cutting edge above the centerline of the tool. Anytime the cutting edge is above the centerline of the tool the tool will rotate or twist INTO the wood instead of rotating OUT of the wood. There are other factors involved here but I don't know how to describe them without a chalkboard. This is a simple, yet very complex tool. Small changes to the shape can have drastic effects on the handling of the tool. Most people who try to sharpen without a jig learn this very quickly. You are doing ok, then you go to the grinder, and you come back with a totally different tool. Again, small changes alter the way the tool bites. My suggestion would be to have you take the gouge to someone who is proficient with one and let them tune it up.
>Chris, deepflute and superflute are one and the same. Superflute is a name given by Henry Taylor. I use a 1/4 inch gouge a lot for certain cuts, and yes it works very well. However, I sharpen my 1/2 inch gouges with a 60 deg. nose and my 1/4 inch gouge with a 45 deg. nose. Makes it a more versatile tool for me.
>OK, maybe I've got the names wrong. When I said "deep flute" I meant the more U-shaped flute. When I said "super flute" I meant the more V-shaped flute.
The smaller tool will tend to cut "easier" because it is taking a smaller amount of wood. I frequently use my smaller gouge for light, final cuts to get very clean surfaces. They also have smaller bevels which means that the heel of the bevel is less prone to drag on the wood.
As for flute shapes, there are gouges that range from very "round" like a super flute to very "V" like the Glaser. There are many different preferences by many turners, but here are my observations. For the record, I use a Sorby (U- shaped) and a Glaser (V-shaped) as my two most-used bowl gouges. Both have 1/2" bars. I'll disregard types of steel and handles for this discussion.
#1 - The "V" flutes tend to pack full of chips much more readily than the "U" flutes. I frequently have to stop to clean out the "V" flutes especially on a pull cut/scrape.
#2 - The "V" flutes have a tighter radius at the tip which means that very small handle rotations will change the cut a lot as compared to the "U" flutes. Handle rotatations on "U" flutes cause more gradual changes.
#2a - This tip shape difference also means that, right where cut is occurring, you are theoretically engaging more cutting edge with the "U" flute at any one time than the "V" flute because the whole radius is larger with the "U". As an analogy, consider a large radius scraper inside a bowl vs a small radius scraper. The larger radius will engage more wood at one time than the smaller radius.
#3 - "V" flutes are excellent if you grind the wings STRAIGHT back; not slightly convex. For anyone that has used a shear scraper on the outside of a vessel/bowl, when scraping the surface of a convex object, a straight edge work much better than a convex edge. Convex edges tend to leave ripples/spirals. "U" flutes are very difficult to grind this way and are more typically ground with a convex wing.
#4 - "U" shaped flutes present a more uniform bevel to the wood throughout the rotation of the handle. If you think of the "U" gouge as a round tube with the top ground off, the wall thickness is uniform throughout the gouge. This means that the bevels are more uniform is length around the whole cutting edge. This makes the "U" shaped tools a bit easier to sharpen. As you pass the "U" flute around the grinding wheel, the amount of metal to be removed is more or less constant for any angle. On a "V" flute, the bevel is shortest right under the tip. this means that you have to speed up the tool movement on the grinding wheel as you pass across the tip or you will end up over sharpening it. Since the wings are thicker, the relative amount of time that the tool must linger on the wheel is longer.
This last point is one of "touch". Just like many turners have the tendency to over sharpen their rouging gouges in the middle such that the wings end up protruding foreward, I have seen many more Glaser gouges with the noses over sharpened because of this issue.
