Questions About Gouges

[Angie Orfanedes]

I am a beginner at wood turning, and I am trying to understand the varieties of gouges and their uses. So I would appreciate drawing on the knowledge of you experienced Creekers...so some questions:

1. Roughing gouge - okay, I know I am supposed to call this a spindle roughing gouge, because you must never, never use it to rough out a bowl.
a. Is this strictly because of the straight grind...and the wings may catch?
b. Can I use it to rough out the outside of a bowl - where the wings are unlikely to catch?
c. Why don't people put a fingernail grind on a roughing gouge and use it as a universal tool - is it strictly because you loose cutting edges on the tool?

2. Spindle gouge
a. Is this different than a bowl gouge strictly by virtue of the depth of the flutes?
b. I am guessing I really could use that on a bowl -again presuming the tool is not ground straight across?

3. Bowl gouge
a. I am presuming the fingernail grind is to provide additional clearance as you cut concave areas of the bowl?
b. Why are deep fluted bowl gouges good? Is it because they are stiffer and can hang out over the tool rest more before chattering?
c. What determines the size of the bowl gouge I should use (3/8, 1/2, 5/8...etc)? Is it related to the bowl size?

4. Gouge material: I see choices of HSS, cryogenically heat treated material, powdered metal technology, and other exotic descriptions of the tool steel used. I presume all I should care about is that the business end of the tool (a) can be resharpened many times, (a) that it can hold an edge for a reasonable number of cuts, and (c) that it is strong enough to withstand the cutting forces without vibrating like a tuning fork or bending like a noodle. Is this correct? Is all the talk about exotic materials or treatments just so much marketing hype?

I hope you don't mind all my questions - and I really would appreciate your help. I find that I learn better (and can remember) if I understand the reasoning behind the tool choices. Thanks.

[George Guadiane]

So that you know, mine are cursory answers, you have asked a major book's worth of good questions.

I am a beginner at wood turning, and I am trying to understand the varieties of gouges and their uses. So I would appreciate drawing on the knowledge of you experienced Creekers...so some questions:

1. Roughing gouge - okay, I know I am supposed to call this a spindle roughing gouge, because you must never, never use it to rough out a bowl.
a. Is this strictly because of the straight grind...and the wings may catch?
b. Can I use it to rough out the outside of a bowl - where the wings are unlikely to catch?
c. Why don't people put a fingernail grind on a roughing gouge and use it as a universal tool - is it strictly because you loose cutting edges on the tool?
The spindle roughing gouge is designed for outside work, end grain running up and down the length of the lathe... Having broken one before I understood this and why (in a moment), I can tell you it's exciting:
The shank of most spindle roughing gouges will not be strong enough to handle the difference in stress applied in side grain orientation, the first "catch" is usually the last. Doug Thompson makes a 1 1/4 inch SRG(I think) Roughing gouge that SHOULD stand up to about anything you can throw at it, I have one and love it.
The grind is not good for inside roughing IMO, for the reasons you state.
I have not heard of anyone using a fingernail grind on a roughing gouge, but if they do, your suggestion seems likely.



2. Spindle gouge
a. Is this different than a bowl gouge strictly by virtue of the depth of the flutes?
b. I am guessing I really could use that on a bowl -again presuming the tool is not ground straight across?Depth of flutes, shapes of flutes, type of grind, angle of grind - spindle/detail gouges vary widely with users, in my experience.



3. Bowl gouge
a. I am presuming the fingernail grind is to provide additional clearance as you cut concave areas of the bowl?
b. Why are deep fluted bowl gouges good? Is it because they are stiffer and can hang out over the tool rest more before chattering?
c. What determines the size of the bowl gouge I should use (3/8, 1/2, 5/8...etc)? Is it related to the bowl size?a. Yes, and to provide more cutting surface, options for angle of approach
b. Got me, I like them for many things, I'm not the mechanic/machinist for this.
c. Bigger tools show less vibration in use, for me, big, as often as possible. Smaller for detail and fine work



4. Gouge material: I see choices of HSS, cryogenically heat treated material, powdered metal technology, and other exotic descriptions of the tool steel used. I presume all I should care about is that the business end of the tool (a) can be resharpened many times, (a) that it can hold an edge for a reasonable number of cuts, and (c) that it is strong enough to withstand the cutting forces without vibrating like a tuning fork or bending like a noodle. Is this correct? Is all the talk about exotic materials or treatments just so much marketing hype?You need to go to Doug Thompson's site and read everything, till you understand it, it has been a valued resource for MANY of us, but NO, not just hype, in use, and I have a great number of his tools (and I will be replacing others with his as quickly as I can find the dough) I find them to be TOP quality that stays sharper longer.
Doug (and others) has done a lot of investigation, trial and error experimentation to find the best tool stock and the best treatments available to make the best tools I have used (so far, but if he finds "better stuff," I'm sure he'll use it).



I hope you don't mind all my questions - and I really would appreciate your help. I find that I learn better (and can remember) if I understand the reasoning behind the tool choices. Thanks.

By the way, I get nothing from this seeming advertisement, when I find something I like, I talk about it.
G

[David Walser]

You ask:


1. Roughing gouge - okay, I know I am supposed to call this a spindle
a. Is this strictly because of the straight grind...and the wings may catch? No. The spindle roughing gouge (SRG) is forged from flat sheet steel stock. This leaves a thin and comparatively weak tang that is not strong enough to withstand the stresses created by reaching the tool far over the tool rest. (When turning a bowl, you'll almost always need to reach over the tool rest a good distance.) In contrast, a bowl gouge is milled from solid bar stock, leaving a solid shaft for attaching the gouge to the tool handle. This solid bar is far stronger than the comparatively weaker tang of the SRG. The wings make the SRG more likely to catch, but it's the weak tang that can make a catch a disaster.
b. Can I use it to rough out the outside of a bowl - where the wings are unlikely to catch? It can be done, but it's NOT recommended. If you do get a catch, the weak tang of the SRG is apt to bend if not break.
c. Why don't people put a fingernail grind on a roughing gouge and use it as a universal tool - is it strictly because you loose cutting edges on the tool? Some put a fingernail grind on their SRG. I have one with such a grind and I like it for certain things (like turning a large bead or a large cove). However, for most things, I prefer the traditional shape of the SRG. The square wings allow you to cut right up to a pommel. Also, despite it's name, a SRG can leave a very smooth surface that rivals that of a skew.
2. Spindle gouge
a. Is this different than a bowl gouge strictly by virtue of the depth of the flutes? Yes. The typical bowl gouge has a deeper flute, allowing it to take a deeper cut.
b. I am guessing I really could use that on a bowl -again presuming the tool is not ground straight across? Yes. Both bowl gouge's and spindle gouge's are milled from solid round bar stock and are strong enough to reach over the tool rest in bowl turning. Just be sure your spindle gouge is "large enough" for what you want to do. A 3/8" spindle gouge will flex more than a 1/2" gouge (bowl or spindle). Flex leads to chatter, making it difficult to get a smooth cut. The solution? Move the tool rest closer, if possible.
3. Bowl gouge
a. I am presuming the fingernail grind is to provide additional clearance as you cut concave areas of the bowl? No, not really. The more swept back wings of a fingernail grind on a spindle gouge allow a "sharper point" allowing access to areas that cannot be reached with a traditional grind, such as turning a bead. That's generally not an issue with bowl turning. Instead, a bowl gouge's swept back wings allow more flexibility in using the tool -- cutting back farther on the wing instead of just at the tip of the tool or using the wing as a scraping tool. In addition, the swept back wings create a larger cutting edge, allowing more wood to be removed with each cut.
b. Why are deep fluted bowl gouges good? Is it because they are stiffer and can hang out over the tool rest more before chattering? No, the deep flute allows more material to be removed with each cut. It also allows the wings to be used as cutting edges. The deep flute, if anything, increases chatter (compared to a shallow fluted gouge made from the same bar stock.)
c. What determines the size of the bowl gouge I should use (3/8, 1/2, 5/8...etc)? Is it related to the bowl size? Use the size that allows you to reach your bowl without chatter and that allows you to remove material efficiently. Usually, that means a smaller bowl can be turned effectively with a smaller gouge. As a general rule, if the larger gouge can reach into the area you want to cut (it's not blocked by the face plate or the bowl blank), larger is better.
4. Gouge material: I see choices of HSS, cryogenically heat treated material, powdered metal technology, and other exotic descriptions of the tool steel used. I presume all I should care about is that the business end of the tool (a) can be resharpened many times, (a) that it can hold an edge for a reasonable number of cuts, and (c) that it is strong enough to withstand the cutting forces without vibrating like a tuning fork or bending like a noodle. Is this correct? Is all the talk about exotic materials or treatments just so much marketing hype? It's not just hype. The more exotic steels will hold an edge longer than plain Jane HSS. How much longer might be hype. When starting out, it's not WRONG to get HSS gouges. You have to learn how to sharpen, which grind profile you prefer, etc. For most of us, that's easier to do with a less expensive HSS gouge.

HTH!

[Dennis Ford]

The issue with strength of shank / tang of a roughing gouge has been covered already. Other than that, the questions you asked and the detail you asked them in, suggest that you know a lot more than you realize. Gouges can be used for purposes other than advertised (with caution if you are trying something new). Exotic metals allow you to go longer between sharpenings. Most of us buy tools partly because we need them and partly because we like to buy tools.

[Angie Orfanedes]

Thanks for all the replies, that info really helps.

[Keith Albertson]

George and Dave,

Thank you so much for your taking the time to answer Angie's questions with so much detail. As a newbie, I have been baffled by the selection of gouges hanging from Woodcraft's walls. Your discussion of the different gouges makes the differences in these gouges very understandable now.

In the short time I've been visiting this forum I've been continually amazed at how much time and energy its members are willing to spend to help a fellow turner.

Keith Albertson

[Doug Thompson]

You have some great answers and I'll add a few things.

When a SRG is used on the outside of a bowl the wings are ground back a bit to prevent a catch, I've seen them ground from 30 to 45 degrees.

Bowl gouges have a deep flute and cutting angles that drive the cutting forces into the tool rest.

Flute shape has everything to do with how the tool is sharpened to keep your cutting angles correct. Look straight down the flute and see the profile... now look straight down at your grind they should look the same. Hummm A V shape bowl gouge will be ground with a small nose radius and straight wings. A mistake I have seen is when a U shape bowl gouge is ground like a V shape flute, the nose angle is correct but the wings loose the sharp angle needed for a clean cut. Spindle gouges are the same sharpened with a large radius like the flute. Detail gouges have the same flute shape as the spindle gouge but because the flute depth is shallower the flute width is also narrower, a narrow flute leaves extra stock on either side which needs to ground away so we create a fingernail grind on a detail gouge.

[Rasmus Petersen]

I know this is an old thread, but i ran accross it when searching for some other information, and found my self wondering, Doug, when you describe the angel of the V shape opposed to U shape and the angel ?? picture please.. sounds like exactly the problems i have been having with my gouges..

[Doug Thompson]

The nose angle doesn't change between the 2 shapes, 60 degrees is a good starting point. The wings of a bowl gouge which is set by the leg angle of the Vari-grind is very important... if the wings are to thin like a knife edge they will not hold up, to thick and it won't cut the wood. The shape of the grind put on the bowl gouge can affect how the tool cuts or doesn't... not so much with the V shape flute but the U shape flute really can be made useless with the wrong grind. The rule of thumb is look down the flute and look straight down at the grind the shape should be close to the same... this keeps the cutting angles close to where they should be. A mistake I see is a U shape flute ground to a point like a V shape gouge should be, the cutting angles are lost OR it's about the same as using a detail gouge for a bowl gouge. Sorry I don't have pictures... does this answer the question or should I try again.

[Rasmus Petersen]

thanks doug :)

[Gordon Seto]

Sorry I don't have pictures...
Doug,
You have such picture under your nose.
Look familiar?
http://www.thompsonlathetools.com/images/five-gouges.jpg
It is on the front page
http://www.thompsonlathetools.com/
The first from the left is the V and the one next to it is the U bowl gouges. The difference is obvious. The top view of the V has a pointier fingernail shape.

[Rasmus Petersen]

and i can see that i have issues with the wings getting much to blunt on my gouges. (i think) i havent had time to pick up my bowlgouges in months, been turning small stuff, jewlery, ornaments, pens, tops, mushrooms like a madman i hope to get time to tear some bowls out when christmas is over..