How do YOU turn a bowl thinner than 3/8"?

[Matt Hutchinson]

As I continue to finish more and more bowls, I keep running into the same problem: chatter on the inside of bowls. Many of my bowls have walls less than 3/8" thick. On every single one I get chatter at the rim of the bowl. I use a sharp tool, I try different cutting angles, I take super light cuts, and I even support the rim with my hand. I am getting better at it, but I still get chatter that I have to power sand away. Is this a technique that I will improve the more I turn, or is this a continual issue? How do each of you all turn at the rim without creating chatter? Thanks.

Hutch

[Doug Miller]

There are many issues that could be coming into play. One that seems to be my biggest issue is to leave the supporting wood until it needs to come out. The way to do this is to hollow your bowl from the outter edge in. Let me explain a bit.

Once the bowl has been formed on the outside and you have reversed the blank on the lathe, begin the hollowing process as normal. However, leave the walls very thick. Once the bulk of the wood has been removed you are ready to begin thinning. The big difference from the way I was tought is that I have since learned to thin the piece 1 inch at a time. In other words you take the blank from an inch or so thick down to that thin wall your after only 1 inch deep into the bowl. At first it will seem like a huge waste of time, but trust me, the extra wood just under your work area will halt any chatter that you may be getting.

Once the 1 inch section is as thin as you want it you move on to the next inch. This inch by inch procedure continues until you reach the bottom. Make sure you blend each successive inch as you go. Once you get to the bottom there is no going back to the rim to get that little bump. Only bad things can happen if you attempt it.

Good luck

[Matt Hutchinson]

I don't know if I would really be able to use that technique most of the time. You see, I thrice turn my bowls, not just twice. When I am ready to finish a bowl, I skim off the surface layer to remove all sealer. Then I wait, letting the bowl get as dry as possible and let it move/acclamate a final time. This is a great way to do things, but the down side is that when the bowl goes on the lathe for the third time, its wall thickness is diminished.

But I will definitely try that technique as much as possible. For some reason it had slipped my mind, but I do have a few bowls for which that would work well. Thanks!

Hutch

[Frank Kobilsek]

Matt,

Doug is absolutely correct but I will add that the guys that turn real thin, under an 1/8", turn green wood start to finish.

I saw Bin Pho demo in Chicago a couple weeks ago. He turn a box elder bowl to 1/16" thick. He positioned his work light against the oposite side of the bowl and used the light that shined thru as his thickness gauge.

Frank

[Steve Schlumpf]

Matt - the only thing I can add to what has already been offered is to use a bowl steady. Your hand will work but will vary in it's position - a steady rest won't. You'll still have to use a sharp tool and very light cuts but it should help eliminate most of the chatter.

[Matt Hutchinson]

I feel kinda silly, cuz I knew that technique, but then I forgot about it when doing this run of bowls! :rolleyes:

I will let you know what happens on the next couple of bowls. However, I think I may still have some issues, cuz the rims on large diameter bowls are so flexible.

Also, I have only been using a bowl gouge, but I know some like to use scrapers. I have a heavy scraper, but I have not been successful with it so far, and it kinda makes me nervous. (Lots of tearout and such.) How effective is a negative rake scraper? Thanks all!

Hutch

[Bruce McElhaney]

Doug's tech. is a good way to go. Of Course some woods will easily turn thinner than others. I can turn Maple and Cherry very thin. A bowl steady also works great for thinner bowls. I use the Oneway bowl steady with its two wheels against the outside of the bowl near the rim. A very light touch of the wheels on the bowl is all that's needed. I often use a scraper on medium and larger solid wood bowls bowls but never near the rim.

[Jim Becker]

I've rarely gone that thin, but when I took David Ellsworth's three day, the technique was explained as doing it in steps. Once the exterior is finished turned (outside of the tenon, obviously) and reversed, you hollow it, but leave it thicker (but even thickness) and then starting at the rim, thin down perhaps the first inch including finishing cuts and then start the next inch. Outside of very careful blending between each step, once you have an area to the intended "thinness", you do not revisit it with the tool. Hence, no chatter at all. I have used this technique with success.

[Bernie Weishapl]

I use the same technique as Jim does except I do use a bowl steady. Gives you solid support and relieves the chatter.

[Reed Gray]

A scraper does work, but you have to use it at a shear angle of about 45 degrees. If you use it flat, even with a fresh burr, it will leave more tear out, and is more grabby/catchy. It does work well for roughing cuts, and I prefer it to a gouge, if for no other reason because it sends the shavings up over my hand rather than across the top of my little finger and my hand, OUCH! I frequently use a shear scrape, as it is more reliable to me, but some times I can get a finish cut from a gouge that even I won't complain about. You can do it all the way to the rim, but you need to steady the rim. Too little pressure, and it will start to vibrate, too much pressure, and it will do the same thing. I always use my hand. Also, always make sure to round over the rim edges of your bowl. If you leave them square, they make very neat little razor saws.

I am not sure why you thrice turn a bowl. I am one of the turn it once, and let it warp people. I can understand the twice turned bowls as they will be rounder, but three times? There will always be some movement as you turn because of grain orientation. After the first drying, there should be almost no residual stresses in the wood, and it will be almost no movement. There is also movement because of humidity/seasonal changes. Please understand, I am not criticizing your work, I am curious as to why you do it that way.

robo hippy

[Leo Van Der Loo]

Matt the advice given to go in steps is the best way IMO, and a good reason for that is the movement of the wood, (no not the shatter), and that's also one of the reasons not to use a scraper on real thin wood (scraper also has no bevel and the wood can/will flex and grab).
While you turn a bowl to a thin wall, the wood is drying and warping, by going a step at the time you keep most of that from happening with the thicker wall resisting this, this also makes it a necessity to make sure you are done with that step before going to the next step as you should NOT come back to it, (reason given above), learned this all the hard way, as I turned many years before the bowl gouge invention, and the scraper was the tool of choice (no other choice), and for me no other wood turners to teach or help me, boy you guy's got it easy :D :D :rolleyes:
And I'll ad some pic's just to show I do some thin turning, but do remember that the public does not appreciate the fragile bowl and the skill needed to turn it thin :eek::eek::eek:

[Matt Hutchinson]

Ah yes, I was wondering if someone was going to question the triple turning method. :D

The internal stresses are not the issue. It's acclamation. I do this for the same reason people let hardwood lumber stand in their shop for a while before they machine it. The lumber is completely dry, but the new environment can cause movement. The same thing happens with bowls. The formerly sealed rough bowls that I second turned 10 days ago are now wobbly once rechucked, and this isn't due to an eccentric axis of rotation. Even when they are at 8% moisture content they still move enough to convince me that turning them 3 times is worth it. Also, the larger the bowl the more important this extra step is. I can see when a bowl is out of round, and even though others might not notice or be bothered by it, it's something that I feel I would prefer to eliminate if possible.

So this gives you a little more info as to the "why". And no, I don't take it as a criticism. :) Thanks for the input!

Hutch

P.S. It's also something I do because that's what I learned from a pro. I figure if he makes bowls over 2 feet in diameter that are only 1/16th out of round using this method, then I feel compelled to follow suit.

[curtis rosche]

wow mat! you got a new picture, i didnt realize who it was until i read the name. you could turn them like doug said, but the second time you turn them leave them 1/2-1 inch thick, then when you do your third turning of it, do what doug said

[Harvey M. Taylor]

Simple, Matt, just keep cutting till the gouge comes out the side.Max

[Matt Hutchinson]

Thanks for the info. I kinda feel that at a certain level it may just be my techinique and/or grind angle. But I will try what everyone has suggested.

Curtis, most of my bowls are rarely 1.5" at the rim when rough turned. When twice turned they are usually closer to 3/4". But I will keep experimenting, and hopefully I will come up with a solution.

Again, I think that my technique has been improving, as I am finishing multiple bowls a day at times. This 'trial by fire' may be enough, along with your suggestions, to refine my technique to a chatterless level.

Hutch

[curtis rosche]

i ment .5 inches upto 1 inch, try doing it like doug said, it should work going from 3/4, thats what i do,

[Matt Hutchinson]

Curtis, I was reading hastily and misread your post. Oops!

I also want to complete a couple NE forms. I have a number roughed and dry, but finishing the 'wings' has me a little concerned. But like most things I do, I'm gonna dive right in and see what happens. :)

If you hadn't guessed, I tend to learn my lessons the hard way. ;)

Hutch

P.S. Leo, you are very right. I feel fortunate to be able to learn from others. Up to this point I have done what I can to gain knowledge, and my current skill level has allowed me to produce some very nice things. But I feel that it's not just about the finished product for me. Sure, a certain piece may appear excellent, but I know how I got it that way, and it isn't always pretty. I want to be successful, but also skillful. In fact, I have been feeling very humbled lately by how many seemingly 'novice' questions I have needed to ask. But then again, I am a novice. :)

[Richard Madison]

Matt,
Am familiar with all those feelings you mentioned. Many of us feel like novices when compared to folks at the next level and beyond. Nothing for it but to continue trying to improve our capabilities, and hope we are having fun. An old saying comes to mind. Press on as if you know what you are doing, and eventually you will.

[Matt Hutchinson]

Richard, thanks for the encouragement. Never heard it before, but I love that quote. That's kinda how I have been living my life over the last year, and it's conciseness and spirit really hits home. Thanks!

Hutch

[Jon Lanier]

How do each of you all turn at the rim without creating chatter? Thanks.

Hutch

Personally, its against my religion, thus, all those who turn that thin are sinners in my eyes. :eek:

Okay, I'm kidding... but really, I think that is where these guys start getting reputations... the good kind.

[Leo Van Der Loo]

Curtis, I was reading hastily and misread your post. Oops!

I also want to complete a couple NE forms. I have a number roughed and dry, but finishing the 'wings' has me a little concerned. But like most things I do, I'm gonna dive right in and see what happens. :)

If you hadn't guessed, I tend to learn my lessons the hard way. ;)

Hutch

P.S. Leo, you are very right. I feel fortunate to be able to learn from others. Up to this point I have done what I can to gain knowledge, and my current skill level has allowed me to produce some very nice things. But I feel that it's not just about the finished product for me. Sure, a certain piece may appear excellent, but I know how I got it that way, and it isn't always pretty. I want to be successful, but also skillful. In fact, I have been feeling very humbled lately by how many seemingly 'novice' questions I have needed to ask. But then again, I am a novice. :)

Curtis don't ever feel humbled asking questions so you can improve yourself, there is no-one that is perfect, we all do learn from each other, and occasionally the hard way too :eek:.
My grandfather said, and he was pretty old already then, "you are never to old to learn" to which I would add "If you want to":)

[Dick Gerard]

Leo has an excellent point about the public notreally appreciating the 1/16" inch thick walled bowls. When I first started turning, Del Stubbs was THE MAN for super thin turning. SO naturally I had to learn how as well. I eventually got pretty good at turning so thin the walls would glow and flex. But, after seeing people pick them up at shows and then set them back down again without buying, I began to question why? So I asked around (other turners) and I polled my customers as well. The result: except for turning collectors and other turners, no appreciated thin walls. The general buying public (on which we all depend) still want that feel and heft of a somewhat functional object, even though it may be burnt, painted and/or carved. When I next started leaving the walls a bit thicker, my sales went way up. One day, an older turner told me "I have never seen a transluscent tree. Why would I want a transluscent bowl of wood? If I want transluscence, I'll buy frosted glass bowls." Put that way, it started me thinking again (very dangerous thing!) and now I rarely turn less than 1/4" thin many times only down to 3/8". I let the overall scale of the piece and the nature of the wood tell me what the wall thickness/thinness should be.

bowlman

[Matt Hutchinson]

Dick and Leo, that's some very helpful info. I am not actually trying for thin walls, but at least now I know not to bother unless I am doing it for myself. What happens with my bowls is that I end up not being pleased with the inside, so I take of a bit more and modifiy the curve/cut slightly. But with this method it doesn't take long to get the rim flexing under the cut. So now I will have to work on the "step cut" technique, and hopefully I won't be as hit and miss on things. Thanks for all the great information. It's been VERY helpful.

Off I go to try the new technique. :D

Hutch

[Jim Becker]

Dick is spot on...and I'll add that only a turner would check how smooth something like a hollow vessel is inside. The average person wouldn't venture that far... :)