Turning a Natural Edge Bowl - Demo - Comments??

[Thomas Canfield]

I will be doing a demo for my local club, Hill Country Turners, over in Kerrville Thursday. I have made a little outline of talking points and am posting here for any comments if you have any idea of additional things to discuss. Time will be somewhat limited and I like to take a green section to rough turn and then also remount a dried green turned piece. I plan to mount the dried piece first when I have sharp tools since sharpening during demo may not be possible. I will either be using a section of Cherry Laurel (if not too wet and slinging sap) or some Texas Ash for the demo.

TURNING A NATURAL EDGE BOWL
A loose definition of a natural edge bowl is a bowl turned from a log segment with the bark side as the rim of the bowl. It can be either with or without bark, and the time of year that the tree was cut will have a major impact on the ability to retain the bark. Wood cut in the late summer and fall have a better chance to retain the bark that wood cut in the early spring and early summer with extra sap. The first step is the selection of wood and the desired shape. A long oval can be turned from a section that is longer than wide, that is a 12” long section of a 8” log for example. A “round” bowl would need to be turned from a larger diameter log than the length and still the rim will be oval. Green wood also turns easier and is often used turning to final thickness and allowed to “warp” with some additional work later done to get a flat of sitting bottom.
Basic steps after wood has been selected are:
1. Mount on lathe with bark side toward headstock. I usually use a 2 ¾” Forstner bit to get a flat spot for either the worm screw in chuck or a 2 ½” faceplate , but you can also use a 2 or 4 prong drive center in a 1” drilled hole, and then the tailstock against the flat side of the section. The section should be balanced using a band saw to round up if balance is an issue for smaller lathe. Extra care should be used with position of the tool rest and hand position due to the wings and any air gaps.
2. Turn the outside and form a tenon with dimple (live center has done this if used). You need to cut from the bark toward the bottom to prevent pushing off the bark, and a sharp tool is required to prevent a lot of tear-out on the end grain since there is a lot of air gap near the bark outer limit. The remainder of the bowl outside is turned in normal manner from center toward outside. I prefer a tenon with dimple since I can remount later between center and true up the tenon to return if turned rough, and also to be able to turn off tenon using a jam chuck with pad. Sand the outside if turning to final dimension and hand sanding will be required at the end of the wings. With the lathe not turning, a random orbital sander can be used on the tips
3. Reverse the piece and install the tenon in the chuck. I use the live center on larger pieces until getting down to a full circle cutting of deeper. A sharp tool is required when getting near the finish diameter of the bark edge to prevent tear-out where the problem is magnified due to the air gaps and soft bark tissue. Again, extra care should be used with position of the tool rest and hand position due to the wings and any air gaps.
4. The interior needs to be turned down in stages, down to bottom of bark, and possible multiple stages on the lower due to the flexibility of the wings. Continue turning to the bottom using a sharp tool for the final cuts.
5. Sanding the interior wings needs to be done with the lathe off either by hand or using a small powered sander with foam pad. Sanding the lower interior can be done in the normal manner being careful of the wings.
6. After final sanding, the natural edge bowl is then reversed and using a jam chuck* and pad inside and the live center in the bottom dimple, the tenon can be reduced to a nub and that area sanded prior to the hand removal of the nub. I use a flush cut saw with plastic shield against the bottom to cut off the nub and then work down the remaining raised section with chisel and/or sanding.
7. *Caution – the wings add extra height requirement for the type of jam chuck used. That might be a consideration in deciding the height of the natural edge bowl that you can turn.
Tom Canfield 2-10-13

[Reed Gray]

It took me a long time to figure out that I got way more turning tool lines/marks in NE and square bowls because I would use the death grip with both hands on my gouges. Once I learned to relax my grip, those lines went away.....

robo hippy

[Aric Krueger]

When I do a natural edge bowl, I don't use a worm screw or faceplate. I never seem to get the bark edges to line up the way I want that way. What I do is get rid of some bark in the center with a bench chisel and use a large 2 prong drive between centers. I rough the outside a little to get a clearer view of where the bark edge is going to be. Then I reposition the tail stock to get the high edges level with each other and low edges level with each other (or as close as they're going to get). I check the positioning by hand spinning with the lathe off and holding a pencil (or my finger) on the tool rest to see where the 2 high points and 2 low points pass by. I reposition the tail stock so the 2 high points are aligned with each other and then the 2 low points are aligned with each other. (A little like detecting wobble in a grinding wheel.) When I'm satisfied with the repositioning, I true it up, continue shaping and turning the tenon. Using a faceplate or worm screw doesn't allow me the ability to tip it and realign the axis to "fine tune" the symmetry of the bark edge. ...Just how I do it. I hope my description makes sense.

I hope the Hill Country Turners over in Kerrville enjoy your demo! :)

[Thom Sturgill]

+1 on Aric's comment. You can use a forstner bit for the drive center, but it is better to clear a large area in case you need to move it to get the 'proper' balance.

[Fred Belknap]

Sounds like you have it pretty well covered. I do quite a few NE bowls, and one thing I have found is that the bark will dry and shrink more than the wood. I usually do my NE bowls the same as regular bowls and turn twice to get a better looking bowl. Probably just me. I also use thin CA on the bark to make it more stable. I put the CA on after sanding but before final sanding like after the 220 grit. I do the inside of the bark on the lathe then take it off with the chuck attached and do the outside with the bowl upside down to keep the CA from running down onto the wood. Hope you have a great demo.

[Thomas Canfield]

Thanks for the comments. When I use the Forstner bit, I shim up the wood to get what I think will be the best leveling of bark or other presentation on the drill press or use a bubble level in the hand drilled surface if it will not fit my 17" drill press. That does not allow for any repositioning after starting, but usually it is close enough for a nice product. I don't usually have a balance issue with my Powermatic 3520B but my demo will be on a Nova 1236. I will also show using a 2 prong drive inside a 1"drilled hole to contain the drive but show the flexibility of adjusting on the lathe.



Fred- I also will use CA on some bark edges, but will apply a light spray of shellac or lacquer prior to the CA to minimize soaking into the adjacent wood. The spray is sanded off with the final sanding. The spray also works on cracks and CA application.

[Richard Coers]

You return natural edge bowls? Why? The darn things look basically oval when turned green, so I don't see the need to return. Add the fact the returning dried bowls with brittle bark, and the intermittent cutting, makes for a rough turning session. Not saying it's wrong, just makes life a lot tougher.

[Dennis Ford]

Starting at the bark edge and cutting toward the bottom on the inside is the way I do it but this method requires that you line up the bevel before entering the cut. You might want to talk about gouge presentation in your demo. The interrupted cut prevents "rubbing" the bevel but light bevel contact greatly improves the surface quality.

[Mark Levitski]

You return natural edge bowls? Why?

Same as Fred. It isn't just to get it "rounder". You get to equalize the different shrinkage/warpage rates between the bark and wood. Also gives a chance to work on dry bark instead of wet in order to stabilize it.


to get a better looking bowl Right!

[Richard Coers]

I only turn natural edge bowls in late fall and winter if I want the bark to hold on. I don't like using CA. I don't have much shrinkage under the bark because it has basically hardened off for the end of the year. It may shirnk a little, but that is certainly taken care of with sanding.

[Thomas Canfield]

Again thanks for the additional comments.

I do return some natural edge to get the dry wood for better finishing. Also, some of the larger bowls turned to finish green warp so bad that there is no chance to bet a stable bottom.

Dennis - I agree that the tool presentation is critical along with a steady hand entering the bark inside due to the brittle nature of the bark and also the air gaps usually found. Sharp tool and gentle steady hand are required. They recently installed a plexiglass shield on the club lathe and it is hard to get a bowl gouge really swung out to get the right tool angle for that entry - part of the challenge doing a demo.

[John RStegall]

Tom's demo was very well received last night. As one might expect from such a talented guy, he did a great job. He also gave away some cherry laurel. I cannot wait to try my first natural edge bowl. Thanks again TC!

john

[Thomas Canfield]

Thanks John. I think that what he is saying is that I did not throw anything off the lathe. The demo got rushed a little, but hopefully the basics were shown. It helped to have a pretty good selection of some "natural edge" pieces, with and without bark, and configurations. Having the back end of my pickup about half full of wood did not hurt, but then some of it came home with me. Still have some to share.