Thickness question

[Kevin McPeek]

Started to post this the other day but it got lost somewhere, anyway, I am working on a deep bowl that is de-barked burl edge. I finished the core of it already and like its proportions. Should I also scale the thickness when I scale up to the size? Thats about where I'm at but it looks really thick to me, I want a decently thick rim so the pointies are a prominent feature, but not so thick that it looks heavy.
I am also a little concerned because even at the thickness that it is (around 7/8") I have got a little chatter. I am getting a lot of tear/chip out also, I've turned with a number of gouges up and down, scraped up and down and nothing seems to work tremendously better than another. Scraping works better but not great.
This is the first time I have had these type of problems that I couldn't figure out how to fix

[Mike Vickery]

Kevin, The boxelder burl we have is pretty soft stuff and does seem to want to tear out. On my deaper stuff I did with it (though not as deep as yours) I ended up using my homemade Oland tool since it had a big long handle and a long shaft. Your Monster tool may be your best choice.

[George Tokarev]

Have you tried spritzing the inside with some water to soften the fibers and cutting it damp? You're going to have every grain presentation possible in a burl, all on the same surface, but the basic gouge rules where you let the curve of the gouge take care of deepening the cut still work best. I like the broad curve gouges because they give more bevel to steady on while the shaving slides down the edge onto the lathe.

Even if you don't do it regularly, you might consider honing the edge if the tearout persists.

[Reed Gray]

As far as the tear out, some pieces will tear more easily than others. Getting the wood wet with water or oil helps reduce the tear out. Light cuts with a sharp gouge help also. Some times you have to resort to the 60 grit gouge to get it all. For thickness, I consider 7/8 inch too thick for what I do. I prefer around 1/2 inch thick. On bigger bowls, especially if you core them, this can result in the chattering or vibrating which happens because the whole wall is rather thin. You can use a bowl steady to help counter this, or you can use your hand (light pressure) on the outside of the bowl to do the same thing, while taking very light cuts. Work your way gently down the inside of the bowl in stages, rather than taking one continuous cut. Of course, with a natural edge bowl, this can be a problem because of the uneven edge and you have to be very careful where you rest your hand.
robo hippy

[Kevin McPeek]

Mike,
I did use my monster to get the bottom of it and some of the sides. It currently has a shear scraper on it in attempt to clean up some of my not-so handy work.
George,
On the outside I used some walnut oil as a "lubricant" which helped somewhat. I'm sure a little bit of my problem is my gouge, I reground it not long ago and it isn't working the same as it used to so I am wrestling with that.
Reed, I might look into a bowl rest, or at least making one. This bowl and its little brother have already claimed some of my flesh, watching two hands might be trouble for me. Plus I have to work so far over the rest a two handed grip on the gouge is in good interest.
Thanks for the input.

[Ken M Nelsen]

Kevin,

I regularly turn 16"-24" natural edge cored bowls with bark (when I am lucky) and without. I shoot for 3/8" finished thickness but when it goes a bit eccentric may wind up with 1/4" or less. Any wood that size will move out-of-round as you turn no matter how much it is seasoned. A freshly sharpenned and honed gouge is a start - followed by a heavy scraper will move you in the right direction. If it's a big fight, a bowl steady is a big help. I frequently find myself pulling out my "60 grit gouge" with the lathe stopped to take care of the "wild end grain" before moving to the rest of the grits to finish the interior. Do all your finish machine sanding at relatively slow speed (300 - 600 RPM) so your sanding disk doesn't skip over the low spots.

I understand the opposing esthetics: "Who are you turning for? The customer or other turners?" - thicker being more "functional". But. the most frequent response from my customers is: "It's so light - it want's to float out of my hands." And, ironically, most of them are not used for salad or pop corn, but are displayed as sculpture - decoratively.

You don't mention a diameter in your post, but thickness is, in part, a design question in relation to the overall size of the finished piece. A large bowl will visually accomodate a thicker wall, but 7/8" sound a bit much.

All the best,

Ken

[Kevin McPeek]

Using George's suggestion I tried spritzing it with water and then I was able to scrape very well with a shear scrape. Thanks George!! That really worked good. I got it down to a little under 1/2 and after the sand and clean-up it should be a respectable thickness. I still want to leave it little thick to get the punch of the de-barked spikes.
It is around 10" diameter and 7 1/2" deep.

I turn for myself mostly, but it would be nice to sell something everyonce in awhile. The area I am going towards are functional pieces. I would really like to have people tell me they use a bowl all the time. Although some pieces such as this won't be real user friendly, besides I've heard a few of the "pro's" say the more useless you make something the more you can charge for it.