Vector Drives and Parabolic flutes -Seriously!

[Thom Sturgill]

I'm very unsure about a parabolic flute myself. It seems like it should be the best thing since bottled beer, on paper. Are end users going to be able to sharpen well enough to take advantage of the flute profile? If the edge is misground or missharpened it has the potential to be far worse than any conventional profile I believe.

Hu

Actually I think the opposite is true. If you grind a V shaped fluted gouge so that the edge is straight when viewed from the side it is almost unusable as it is very difficult to control how much edge is exposed to the cut. A Parabolic fluted gouge would still be fine.

[hu lowery]

Actually I think the opposite is true. If you grind a V shaped fluted gouge so that the edge is straight when viewed from the side it is almost unusable as it is very difficult to control how much edge is exposed to the cut. A Parabolic fluted gouge would still be fine.

Thom,

Time will tell. You seem to be working with a very fixed set of assumptions, I'm working with a range of possibilities. I have worked with a parabolic profile before. I was amazed at how sensitive it was to the slightest changes. It finally came down to getting it close and then staying with testing for weeks until locking down a design. Since this wasn't a cutting tool the parabolic profile stayed the same for the life of the product. A good thing because there was one machine in the world set up to cut that exact profile.

Hu

[Thom Sturgill]

Thom,

Time will tell. You seem to be working with a very fixed set of assumptions, I'm working with a range of possibilities. I have worked with a parabolic profile before. I was amazed at how sensitive it was to the slightest changes. It finally came down to getting it close and then staying with testing for weeks until locking down a design. Since this wasn't a cutting tool the parabolic profile stayed the same for the life of the product. A good thing because there was one machine in the world set up to cut that exact profile.

Hu

I understand that the cutter to make the flute is harder to make and resharpen for a true parabolic. Many 'parabolic' flutes are actually elliptical which is easier to do mechanically. Over the range of the curve used for the flute almost impossible to tell the difference.

I started with parabolic flute gouges and then bought several Thompson's V gouges. While I loved the edge and how long it wore, I had trouble getting a profile that worked well. My original 'training' had been on elliptical fluted tools and the instructions said to grind the sweep straight so that is what I was doing with the V. It needs to be ground in a gentle curve and it is easy to mess up the nose. Watching other club members struggle with sharpening I searched out videos on fixing problems (Dave at D-Way has an excellent one) and realized what we were doing wrong. I no longer have problems getting a working grind, but I still think that an elliptical gouge is easier, less prone to profile errors.

[Hilel Salomon]

I'm not a good enough turner to get into flute shape efficiency. I just know that I like Thompson and Hamlet superflute gouges and have a slew of them. I do, however, know what courteous discourse should be and can readily discern discourtesy. Surely, there is a more polite way of stating something than stating " From what I was told/heard, I don't think Thompson knows what a parabolic flute is. If Thompson says: "that with a slightly curved wing, his V is the same thing..", then I know he doesn't know."
To discredit someone on the basis of "I was told/heard" is already tenuous at best. Hate mail is unwelcome in a forum that provides people with information, and one which includes incredibly helpful and kind turners, and I hope that no one directs this at anyone. One way to avoid this is to treat subject matters without engaging in personalization. I, for one, am tired of the kind of discourse one sees at the political debates and would hope that such things don't find their way into our forum.

[Joe Kaufman]

Agree with your comments.

[Doug Ladendorf]

+1

I got to see a couple of Glenn Lucas' demos at Totally Turning and he is a terrific turner. My daughter and I met him as well and had a nice chat. He is effective at sales as well and we bought one of his DVDs on platter turning. I thought it was funny that he tried to steer us to his sharpening DVD which focused on sharpening his tools his way. I don't have his tools nor have a particular sharpening issue. I see lots of people turning beautiful work without one particular grind on one particular flute. Lots of ways to skin a cat.

Doug

[hu lowery]

I understand that the cutter to make the flute is harder to make and resharpen for a true parabolic. Many 'parabolic' flutes are actually elliptical which is easier to do mechanically. Over the range of the curve used for the flute almost impossible to tell the difference.

I started with parabolic flute gouges and then bought several Thompson's V gouges. While I loved the edge and how long it wore, I had trouble getting a profile that worked well. My original 'training' had been on elliptical fluted tools and the instructions said to grind the sweep straight so that is what I was doing with the V. It needs to be ground in a gentle curve and it is easy to mess up the nose. Watching other club members struggle with sharpening I searched out videos on fixing problems (Dave at D-Way has an excellent one) and realized what we were doing wrong. I no longer have problems getting a working grind, but I still think that an elliptical gouge is easier, less prone to profile errors.

The gouges I am using now are "V" gouges by name however the modified V is much closer to an elipse. Still needs that slight curve to the top of the cutting edge and no question that it is hard to cut on an aggressive wheel. Not really hard if you pay attention but a couple of quick touch up sharpenings and the edge can either be too flat or a hump created as more of the curve has a tendency to move towards the nose with my grinding. I went to a 350 grit CBN wheel for the bowl gouges and I find it about perfect. Not hard to do minor reshaping but not nearly as touchy causing accidental reshaping. I'd like to try a 600 grit wheel but I doubt I wear out the 350 grit wheel in my lifetime.

Being able to grind straight and let the flute provide the curve as you describe with the elliptical flute would be nice. Right now I have a handful of bowl gouges from different suppliers. The thought is that I will decide which flute I like best and migrate over to that one configuration. I might, one more of those roundtuit things!

Hu

[allen thunem]

Hilel
Your comments are very eloquent and spot on.
This is no place for "mudslinging"

I'm not a good enough turner to get into flute shape efficiency. I just know that I like Thompson and Hamlet superflute gouges and have a slew of them. I do, however, know what courteous discourse should be and can readily discern discourtesy. Surely, there is a more polite way of stating something than stating " From what I was told/heard, I don't think Thompson knows what a parabolic flute is. If Thompson says: "that with a slightly curved wing, his V is the same thing..", then I know he doesn't know."
To discredit someone on the basis of "I was told/heard" is already tenuous at best. Hate mail is unwelcome in a forum that provides people with information, and one which includes incredibly helpful and kind turners, and I hope that no one directs this at anyone. One way to avoid this is to treat subject matters without engaging in personalization. I, for one, am tired of the kind of discourse one sees at the political debates and would hope that such things don't find their way into our forum.

[Reed Gray]

Thom and Hu, I think some of it depends on how you use and hold your gouges. My grinds vary a bit from one sharpening to the next since I don't use jigs, though when I did use a gouge jig I still got some variation. I hold my tools more level, rolled over to almost 90 degrees, and do most of the cutting with the nose while the wing is actually scraping. I do still, on occasion, drop the handle, and use more of the wing. I am thinking that maybe because my grinds vary, I may have developed more of a roll and move the tool till it cuts method, rather than hold the tool in the same way every time to get the cut. Straight wing or slightly convex or even slightly concave don't seem to make much difference to me.

robo hippy

[Pat Scott]

...is a more polite way of stating something than stating " From what I was told/heard, I don't think Thompson knows what a parabolic flute is. If Thompson says: "that with a slightly curved wing, his V is the same thing..", then I know he doesn't know."

"I was told/heard" was my way of not naming sources. You'd be surprised at who the sources are, but I won't mention names because someone would surely take offense. PM me if you want more info. I was shocked when I was told that Lyle's gouge is not parabolic even though it's marketed as such. There was no mudslinging, only sharing information. Sorry if you don't agree.

Does anyone on this forum own one of Lyle's "parabolic" gouges? Can you post a picture of the flute profile? Lyle's website only has a side picture.

I've been taught how to sharpen V-gouges and parabolic flute gouges, and I know a little more now on when/why to use one over the other. A lot of people on this forum are Thompson fans. I own maybe 6 of his gouges and scrapers, so he gets my money the same as you. My intent is to share what I learned and maybe open someones eyes and educate them. Sorry if I'm not politically correct enough. But you can't argue that it's impossible to create a parabolic gouge from a V-gouge, even if the V-gouge wing is sharpened with a curve to it. If someone says they are the same thing, wouldn't that make you question it? Think of it as sharpening a chisel or plane blade and putting a radius on the cutting edge - the blade still has a flat back. A parabolic gouge would have a curved back, and the way you sharpen and use them is different because the cutting edge and cutting action is different.

[Reed Gray]

Well, I don't know how to picture and post, and don't have a camera to do it with either. I think the differences between parabolic and elliptical can be more according to personal differences rather than actual mechanical differences, or they are so small that they make no perceivable differences to 99% of the people that use them. I would expect that both can have hugely varying arcs and/or lines and still fit the definition. I would have to take a class with Glenn to find out if any of it really makes sense.

robo hippy

[Bill Blasic]

I hosted Glenn Lucas this past month and he did three days of hands on in my shop. I did not do any of the hands on but did listen in a few times. What Glenn told me was that with the V you cannot sharpen it and not get a little dip towards the nose as this is where he cuts with his parabolic flute, he showed me a few of the tools and yes there was a dip. I did a hands on with Jimmy Clewes a while back and I took one of his gouges and had him sharpen it. I just took a not so good photo and will try to post it but there is no dip. You can finds Jimmy's reasons as to how the design works probably on his website. Above I posted that Doug Thompson knows what a parabolic shape is, he is going to make a parabolic fluted gouge in the future. Will be expensive for tooling but he is looking into it.Clewes.JPG

[Thom Sturgill]

If I understand correctly, Lyle was a big parabolic fan and did sell a parabolic fluted gouge. Then he started selling Thompsons gouges which, as you said, have straight sided V flutes. I think Lyle just hasn't updated his site. I've heard Doug say that parabolic flutes are too expensive to produce, he would have to charge more for them.

I have had issues with ridges in the flutes of his tools, probably because the bits were not replaced soon enough. While I can not fault the steel, the heat treatment, or the cost, I do prefer a different flute shape and polished flutes, which leads me to D-Way for fluted tools in the future. Carter and Son also uses a V flute for economic reasons according to someone who sells them.

[Reed Gray]

Bill, I am guessing that by 'dip' you mean that the wing has a slight arc to it rather than being straight. Almost all of my gouges have that arc as it is more difficult to get a perfectly straight line down the wing than it is to get the arc, which seems to happen all by itself. Even had it on my Glaser V, which is a way to steep V for me.

robo hippy

[hu lowery]

Bill, I am guessing that by 'dip' you mean that the wing has a slight arc to it rather than being straight. Almost all of my gouges have that arc as it is more difficult to get a perfectly straight line down the wing than it is to get the arc, which seems to happen all by itself. Even had it on my Glaser V, which is a way to steep V for me.

robo hippy

Reed,

When I try to force a grind that doesn't suit the flute I actually get a pretty narrow and ugly dip right behind the nose on my Crown bowl gouge that was flat across the nose when new, now swept back. I don't remember the exact details why I got it, maybe from getting carried away sweeping the wings back or trying to get the nose too narrow. Might have been the opposite, trying to widen the nose. Regardless, that little dip makes for an ugly handling gouge!

A general comment to the thread, I have Lyle's DVD's and had downloaded a bunch of his youtube stuff prior to that. I'm pretty sure I remember him saying somewhere that the combination of his grind and the flute makes his gouge a parabolic one. This is what can cause confusion, with a little effort I could cut a parabolic edge on a skew! I suppose I could call it a parabolic skew then if I really wanted to.

Unless we are willing to go to a lot of effort we are pretty much stuck with the flute profile we buy. The flute profile limits the grinds we can cut somewhat but we still have a good bit of latitude. No sense feuding over what really amounts to splitting hairs and some people's marketing. Had I been the one coining the term I would have never called the taper I put on billiard cue shafts a parabolic taper. It's a compound curve, actually a pair of them and since "parabolic taper" is what this style was called long before I started using it I went with standard terminology. If somebody told me technically speaking my taper wasn't a parabolic taper I could make a good argument either way but I'd prefer to call that taper compound curves.

I hate to see us arguing over "potatoe" or "patata" and I think that is all we are doing, led by some people's marketing.

Hu