Today's Turning: Walnut Bowl. Also some technique questions

[Jeremy Leasure]

This is what I turned out today. About 7-7.5" at it's widest point. Now, these type of bowls are a real pain for me. To do the undercut I figured out today it's much easier to go on the opposite side of the lathe I normally stand on. Dunno if that's the best way or not. The fast transition at the bottom is what gets me. I can't make a good job of it with my bowl gauge, no matter what wacky stuff I try or which side of the lathe I go on. What I've been doing is getting my smallest scraper and trying to smooth it out with that, all the while praying I don't get a catch. I guess I don't pray hard enough because invariably I get just that. Seemingly out of nowhere, doing the same cut, light as possible, smooth as I can move, sharp as I can sharpen. Catches. What is the correct way to do this? I'm starting to see now why the nice shallow bowls are so popular to turn. I always end up with something deep somehow though.

http://i970.photobucket.com/albums/ae190/Chaoticfree/walnutturning2.jpg


http://i970.photobucket.com/albums/ae190/Chaoticfree/walnutturning1.jpg

[Brian Brown]

Wow, thats really nice! *I like the form, and the depth of that wood is beautiful. *I still have the same problem with the fast transition, but there are many here who I am sure can describe how to do that cut without a catch.

[Thomas Heck]

Looks nice to me. I'm just learning too. I have learned alot by trial and error. I am learning a bit to use a bowl gouge. They work the easiest on wet wood and you dont get the catches as bad.

[Roger Chandler]

To make the transition in the bottom of the bowl, you should switch to a gouge with a traditional grind, not the swept back wing profile........you should have more than one bowl gouge if you are going to do a lot of bowls.........the traditional grind makes it easier to transition from the sides to the bottom of the bowl.

[Bob Bergstrom]

That bottom transition in this type of form is one of the hardest to cut cleanly with a bowl gouge. There is a quick tight curve at the bottom of that bowl. One second you are pushing out from the center with the gouge, and the next you must make the gouge head a 180 degree change and head toward the center and hope the side of the gouge doesn't rub on the rim. A blunt bevel (80 degrees) could run the corner without too much movement but may be much like a scraper cut. . A wide heavy scraper with light cuts would work if you really swing the handle and avoid using the side of the scraper. Old timers would use a long bevel gouge and point it almost straight up keeping the handle down. That would take the big swing out of the cut but may leave many ripples and groves if not controlled. Another technique is to switch the cut from a push cut to a draw cut on the right side of the tip of the wing being carful not to catch too much of the right wing. As I stated before the rambling it isn't a easy form to cut cleanly. Your finished bowl passes on all accounts.

[Dan Forman]

Well, you seem to have done a very good job on this one. The color of the wood is gorgeous, the transition area looks clean, like the shape, understand the difficulty. Nothing to nit pick on this one, at least that I can see. :) Might be easier with a specialized tool rest that will support a small round nose scraper close the the transition area. A negative rake scraper is not likely to catch, can be used to clean up the area. https://www.storesonlinepro.com/files/2043913/uploaded/TheNegative%20RakeScraper2.pdf

Dan

[Dan Forman]

Roger --- Is there room in that shape for a traditional gouge? Looks to me like working into a tight corner like that would be result in even more catches with those wings sticking up. Would be good for the flat bottom though.

Dan

[Kathy Marshall]

Very nice bowl Jeremy.
This probably won't be much help, but when I do bowls like that I use my EWT Easy Finisher, or if I really want to make it easy I use my captive hollowing system.

[Faust M. Ruggiero]

Jeremy,
You won't find anyone here to tell you an easy way to cut that interior shape. You did a great job with it because it is inherently difficult. You can surely work from the back of the lathe for the walls but for the transition and bottom you have to work your way back left. I'm spoiled because my lathe has a sliding headstock and I cut interiors at the end of the lathe. You can grind a tool just for the transition area in this type bowl. Trent Bosch ground a tool for me during a demo day that works as well as any I have found. The tool must be ground by hand since a jig just won't do it. It is a steep grind like Bob mentioned (80 to 85 degrees) but the right side of the tool is not swept back and the left side is. That lets the "conventional" grind portion on the right cut the corner while the swept back side stays out of the way. As you progress from the transition toward the bottom the tool can roll back toward the left still riding the bevel and finish. The grind is made by starting with the tool rest set to the proper angle and the tool handle held about 45 degrees left and rolled counterclockwise so the flute is slightly closed to the left.. Begin that way and as you swing the handle to the right, roll the tool until the flute is straight up when the handle is straight from the wheel. Stop swinging the handle there and just roll the tool clockwise to complete the grind. The bottom of the gouge must stay on the platform to maintain the grinding bevel. You will end up with an asymmetrical grind, swept slightly back on the left and straight across on the right.
Don't use more than a 1/2" bowl gouge.
To use it, you stop your wall cut with the normal Irish grind when you can no longer ride the bevel. Switch to the steep ground and with the flute at least 45 degrees right pick up the cut and ride the bevel around the bottom. When past the transition you will need to slide the tool along the rest to maintain the bevel position but it will be a controlled cut. I can't guarantee being able to begin shading with 120 but at least you might avoid the really nasty digs that are so hard to remove.
faust

[Justin Stephen]

Very nice bowl Jeremy.
This probably won't be much help, but when I do bowls like that I use my EWT Easy Finisher, or if I really want to make it easy I use my captive hollowing system.

Yup, an inside transition like that has Easy Finisher written all over it. I also have a very small round nose scraper from Sorby that can do the trick in situations like that as well.

[Chris Barnett]

Wish someone, sometime, would correct the diagram to which Dan references; it surfaces too many times to not be correct and could give someone real fits trying to grind a negative rake scraper. The diagram shows an obtuse angle [an angle greater than 90 degrees] for the 65-70 degree acute angle [angles less than 90 degrees are termed acute angles]. But which is correct: is the angle in question is really obtuse, or is the angle really 65-70 degrees? One must correctly know what a negative rake is before it can be shown correctly in a diagram. Anyone willing to do this, who knows? I don't.

[Dennis Ford]

Wish someone, sometime, would correct the diagram to which Dan references; it surfaces too many times to not be correct and could give someone real fits trying to grind a negative rake scraper. The diagram shows an obtuse angle [an angle greater than 90 degrees] for the 65-70 degree acute angle [angles less than 90 degrees are termed acute angles]. But which is correct: is the angle in question is really obtuse, or is the angle really 65-70 degrees? One must correctly know what a negative rake is before it can be shown correctly in a diagram. Anyone willing to do this, who knows? I don't.

Chris; I have attached a sketch of how I grind my negative rake scraper. I started with an old 3/4" spindle gouge; it is used upside down. The top angle is shown somewhat exaggerated in this sketch, it is actually about 15 deg below horizontal. I hope the description and sketch make sense.

[Fred Belknap]

First off I'm no expert. Now I will tell you how I do those most of the time. If the bowl shape is so that I can get the toolrest close to the bottom corner I use my regular bowl gouge with the swept back wings and I get into the transition I raise the cutting edge higher in the bowl and roll the gouge either right or left depending if it is a push or pull stroke. Now if it is to far off the toolrest I use a 1" round nose scraper with a negative grind. My negative scraper is a little different than Dennis, the top angle on mine is more acute like maybe 10° but I don't measure it. I clean up the bottom and sides with a large scraper with a very small negative grind. I guess there is a lot of ways to skin a cat. BTW the walnut bowl looks great and nice job on the finish. Keep trying and you will find a system that works for you. :D