• January Turning Challenge: Thin-Stemmed Something! (click here for details)
  • Conversations are now Direct Messages (click here for details)
  • Congratulations to Gabriel Hoff for "Spalted Beech Round Bottom Box" being selected as Turning of the Week for January 6, 2024 (click here for details)
  • Welcome new registering member. Your username must be your real First and Last name (for example: John Doe). "Screen names" and "handles" are not allowed and your registration will be deleted if you don't use your real name. Also, do not use all caps nor all lower case.

Finishing inside of a bowl

Choose the best answer.....

The inside and outside of a bowl can be best finished with a

A. Freshly sharpened bowl gouge
B. Freshly sharpened round scraper; also in shear mode
C. Hunter tool/ round carbide insert tool in shear mode
D. All of the above.

Rob Wallace
 
Alex Ku said:
Michael,
what is a continental?
Click to expand...

Tool like the old smith made, with the same thickness all across, ground with a constant angle bevel. Almost catchless, since there's no place for it to roll, and no heel bruises from different thickness of material. My original on the left, and there isn't much more metal below the picture, with his Lee Valley replacement on the right. http://i35.photobucket.com/albums/d160/GoodOnesGone/Bevels.jpg

As you can see from the video, it's used at angles close to parallel to the bed, making it easy to control and easy on the back of the upright turner, rather than at steeper angles where the bed or banjo might interfere, and people complain about stooping and peering. http://i35.photobucket.com/albums/d160/GoodOnesGone/Gouge-Curves.jpg

I like the extended sweet spot with no danger of over-rotating and catching the nose of the tool. If you've got one, give it a whirl. If you don't pick one up and leave it fairly blunt, rather than with a nose to cove spindle work.

Your Hunter is a tighter curve tool on the same principle at 90 degrees to the handle, as with hook/ring tools. All points equivalent.
 
My preference is for a really sharp bowl gouge. I have one ground in the Stewart Batty grind of 40 degrees which is the same angle I use on my spindle gouges. This works for most bowls but is to shallow an angle for really steep sided bowls. for those I prefer the Hunter tool. I'll start the cut with the Stewart batty grind and then when it gets too steep to rub the bevel I'll switch to the Hunter tool. I think the edge holds at least as good as he says if not better. I have not changed my Hunter #4 cutter yet and it's my most frequently used of the Hunter series.
For beginners who aren't comfortable with the bowl gouge I suggest the thickest round nose scraper you can find. Thick tools chatter less and are easier to control than the 1/4" thick variety. Mine is almost 1/2" thick and 1 1/2" wide.
 
challenge yourself

I have been turning for a little over a year now. I started with the round nose scraper and it worked well for me. However, I was challenged to learn to use a bowl gouge. I started with a 40 degree angle bowl gouge with long wings and I got many catches. I then found that a bowl gouge with a shallow angle was much easier to use, fewer catches and a better finish cut. I tried different tools, but like the shallow grind bowl gouge best. I also like to use the round cutter lightly for a finish cut. I am glad that I challenged myself and continue to do so. Although I listen to all advice and try many things, I use what works best for me.
 
There are a number of ways to do it and as your skills progress, your use of the 80 grit gouge will diminish. There does come a point on each bowl when that is as good as you can do for this one, and it is time to move on.

I have always found the inside of a bowl more difficult to get a good cutting job on than the outside. Being concave in shape is part of it, and it effects how the tools cut and act. Also, your vision is restricted.

A good sharp bowl gouge is important for a clean cut. Also, your right hand (or the one on the handle) does all the work, and the hand on the tool rest does almost nothing. The more you wrestle/ death grip with the tool rest hand, the more trouble you will have getting a smooth and clean cut.

For a gouge, I prefer the swept back/Ellsworth/Irish grind with about a 45 degree bevel. I also grind about half of the lower part of the bevel off. I do this by rolling the bottom of the gouge and nose on the rough grinding stone. By removing the sharp angled edge, you get your bevel closer to the cutting edge for better control. This really helps get rid of the concentric rings that form on the inside of the bowl. This doesn't happen as much on the outside of the bowl because of the convex shape allows your bevel to be closer to the cutting edge, and you aren't rubbing on that sharp bottom edge. I hold my gouge level, and roll it away from the cut, to about 2 oclock. Some lower the handle to get a better shear angle, but that never felt comfortable to me.

I haven't tried the continental gouge like Michael uses. There are 2 main differences between it and a spindle roughing gouge. A spindle gouge has a deeper flute, and is ground more square across the front while a continental gouge is shallower, and the front profile is more of a ) shape. It is not a good idea to use a spingle roughing gouge on a bowl, especially on the inside. With the square profile, the corners of the gouge are very likely to dig in, and you get big catch and can also break your gouge.

I use scrapers a lot on bowls, both for roughing and for finish cuts. The thing to remember here is that a scraping cut, where the scraper is flat on the tool rest is better suited for roughing cuts. A scraping cut does tend to 'pull' on the fibers and you will get more tear out. For a finish cut with a scraper, you need to have it at a 45 degree angle (up on its edge) to the wood rotation. This is a very light pressure touch up only cut, and you will have to make several passes to clean up even small ripples, hills and valleys. With a shear cut on the outside of a bowl, I pull from the base of the bowl to the rim. Note, this cut can be done with both the scraper or a gouge. On the inside, I pull from the center to the rim. I know this is backwards, but the cuts you take are so light that you get no tear out. Using a scraper flat on the tool rest on the inside of a bowl, especially if you are near the rim is asking for an explosion. When most of the inside of the bowl has been removed, the walls and especially the rim is very flexable. Think of a soap bubble here. Left to itself, it will stay round, but any small draft will start the outside of it to rippling. It will start to oscilate/vibrate with only slight pressure. A scraping cut will make it vibrate more, you will hear all sorts of howling noises. If it doesn't vibrate to the point of explosion, when you turn off the lathe, you will see regular divots around the rim of your bowl. When the vibration is severe enough, it can oscilate to the point where you get a big catch and your bowl explodes. This is more of a problem on bigger bowls than on smaller ones. If you are doing a big bowl, take it down in stages. Remove most of the bulk for an inch or two, then clean it up with a shear cut. Take it down another inch or so, then again clean it up. Do this all the way to the bottom. You can do a finish cut on the outside of a bowl from base to the rim in one pass because there is the mass of the inside of the bowl to keep everything stable and vibration free. You can seldom do this on the inside of a bowl because it moves as you remove wood, and the walls become flexable.

For the best cutting edge on a scraper, I prefer a straight off the grinder burr. First, I hone off the old burr on a flat diamond stone, then grind a fresh edge. I use a finer grinding wheel for this, and apply some 'push' into the wheel rather than just kissing it. I have tried a burnished burr, and didn't find it to have any benefits.

I do prefer the swept back grind on a scraper, mostly what is refered some times as an inside scraper which is swept back to the left. This is a some what specialized tool. A round nose works, and is a more versatile tool if you are trying to true up the outside of a bowl (which you can't do with an inside scraper) that has been reversed and is ready for hollowing out the inside. For me, I have the outside done before I reverse, and don't mess with it. Having it perfectly round/even on the outside with no run out is only important if you are turning very thin, in the 1/8 inch or less range. If you have 1/16 of run out, that is plus or minus 1/32 of an inch. Not enough to notice without measuring. Whether using a recess or a tenon, I use a finish cut on the surfaces of it, a very light scrape that only removes dust particles. I can easily get run out of less than 1/16 inch.

robo hippy
 
I use a half inch bowl gouge ground straight across, at about 50 degree bevel.
 
😀
robo hippy said:
There are a number of ways to do it and as your skills progress, your use of the 80 grit gouge will diminish. There does come a point on each bowl when that is as good as you can do for this one, and it is time to move on.

I have always found the inside of a bowl more difficult to get a good cutting job on than the outside. Being concave in shape is part of it, and it effects how the tools cut and act. Also, your vision is restricted.

A good sharp bowl gouge is important for a clean cut. Also, your right hand (or the one on the handle) does all the work, and the hand on the tool rest does almost nothing. The more you wrestle/ death grip with the tool rest hand, the more trouble you will have getting a smooth and clean cut.

For a gouge, I prefer the swept back/Ellsworth/Irish grind with about a 45 degree bevel. I also grind about half of the lower part of the bevel off. I do this by rolling the bottom of the gouge and nose on the rough grinding stone. By removing the sharp angled edge, you get your bevel closer to the cutting edge for better control. This really helps get rid of the concentric rings that form on the inside of the bowl. This doesn't happen as much on the outside of the bowl because of the convex shape allows your bevel to be closer to the cutting edge, and you aren't rubbing on that sharp bottom edge. I hold my gouge level, and roll it away from the cut, to about 2 oclock. Some lower the handle to get a better shear angle, but that never felt comfortable to me.

I haven't tried the continental gouge like Michael uses. There are 2 main differences between it and a spindle roughing gouge. A spindle gouge has a deeper flute, and is ground more square across the front while a continental gouge is shallower, and the front profile is more of a ) shape. It is not a good idea to use a spingle roughing gouge on a bowl, especially on the inside. With the square profile, the corners of the gouge are very likely to dig in, and you get big catch and can also break your gouge.

I use scrapers a lot on bowls, both for roughing and for finish cuts. The thing to remember here is that a scraping cut, where the scraper is flat on the tool rest is better suited for roughing cuts. A scraping cut does tend to 'pull' on the fibers and you will get more tear out. For a finish cut with a scraper, you need to have it at a 45 degree angle (up on its edge) to the wood rotation. This is a very light pressure touch up only cut, and you will have to make several passes to clean up even small ripples, hills and valleys. With a shear cut on the outside of a bowl, I pull from the base of the bowl to the rim. Note, this cut can be done with both the scraper or a gouge. On the inside, I pull from the center to the rim. I know this is backwards, but the cuts you take are so light that you get no tear out. Using a scraper flat on the tool rest on the inside of a bowl, especially if you are near the rim is asking for an explosion. When most of the inside of the bowl has been removed, the walls and especially the rim is very flexable. Think of a soap bubble here. Left to itself, it will stay round, but any small draft will start the outside of it to rippling. It will start to oscilate/vibrate with only slight pressure. A scraping cut will make it vibrate more, you will hear all sorts of howling noises. If it doesn't vibrate to the point of explosion, when you turn off the lathe, you will see regular divots around the rim of your bowl. When the vibration is severe enough, it can oscilate to the point where you get a big catch and your bowl explodes. This is more of a problem on bigger bowls than on smaller ones. If you are doing a big bowl, take it down in stages. Remove most of the bulk for an inch or two, then clean it up with a shear cut. Take it down another inch or so, then again clean it up. Do this all the way to the bottom. You can do a finish cut on the outside of a bowl from base to the rim in one pass because there is the mass of the inside of the bowl to keep everything stable and vibration free. You can seldom do this on the inside of a bowl because it moves as you remove wood, and the walls become flexable.

For the best cutting edge on a scraper, I prefer a straight off the grinder burr. First, I hone off the old burr on a flat diamond stone, then grind a fresh edge. I use a finer grinding wheel for this, and apply some 'push' into the wheel rather than just kissing it. I have tried a burnished burr, and didn't find it to have any benefits.

I do prefer the swept back grind on a scraper, mostly what is refered some times as an inside scraper which is swept back to the left. This is a some what specialized tool. A round nose works, and is a more versatile tool if you are trying to true up the outside of a bowl (which you can't do with an inside scraper) that has been reversed and is ready for hollowing out the inside. For me, I have the outside done before I reverse, and don't mess with it. Having it perfectly round/even on the outside with no run out is only important if you are turning very thin, in the 1/8 inch or less range. If you have 1/16 of run out, that is plus or minus 1/32 of an inch. Not enough to notice without measuring. Whether using a recess or a tenon, I use a finish cut on the surfaces of it, a very light scrape that only removes dust particles. I can easily get run out of less than 1/16 inch.

robo hippy
Click to expand...

Good post, robo hippy......

I find myself agreeing with you on several points. I enjoy it when someone puts effort into explaining what they mean so there is no confusion......and you, obviously, took some time to apply it to words......


One thing I'd like to add is there seems to be no hard rules about how to do the inside of a bowl. Different woods, and even different examples of the same species, or size, or shape, will react to your tools totally different at different times. I find myself trying one way (both bowl gouges and scrapers) and may end up doing it completely different than I thought I would!.....then again, sometimes things go exactly as planned, but that's less often than I'd like!....... 😀

otis of cologne
 
You must log in or register to reply here.
Back
Top