bowl blank orientation in the tree

[Zach LaPerriere]

A good looking alder drifted by my beachfront cabin yesterday during a storm. I'm guessing it washed down a nearby river. The first picture is towing it back. I had to tow in reverse for the last few hundred yards for better maneuverability around a reef.



As the second picture shows, the alder is curved, presumably from hanging over the river. About 16" at the butt, almost 24" at the root flare.



So here's my question about laying out bowl blanks:

The upper (concave) side of the tree is tension wood, the lower (convex) side is compression wood. After I buck up the tree into rounds, wouldn't it make sense to rip the rounds so that one side has tension wood and the other compression? In other words, parallel to the radius of the curve, not perpendicular.

I'm thinking that the opposite would make for a very unstable bowl, being half compression and half tension wood. I'm hoping the figure in the wood will also be more balanced.

Additionally, if anyone has any suggestions for resources on best placement of the bowl in trees, I would be grateful.

Thanks!
Zach

PS My apologies for the sideways picture, I'm not seeing how to rotate it.
EDIT: Got it!

 

[Jamie Straw]

To delete photo...

Zach, to delete a photo, select Edit Post, then at the bottom select Go Advanced. You will then find Manage Attachments (as found when writing a new post). In the lower box, select the photo you want to delete, and a little "x" will appear, which you can tap to delete.

 

[Zach LaPerriere]

Thanks, Jamie! I shouldn't have been afraid to "Go Advanced"... Strange how that second photo gets turned. If only I was more tech savvy.

 

[Bill Boehme]

Your camera should have a setting that senses when you rotate the camera and correctly rotates the image automatically.

 

[Bill Boehme]

... The upper (concave) side of the tree is tension wood, the lower (convex) side is compression wood. After I buck up the tree into rounds, wouldn't it make sense to rip the rounds so that one side has tension wood and the other compression? In other words, parallel to the radius of the curve, not perpendicular.

I'm thinking that the opposite would make for a very unstable bowl, being half compression and half tension wood. I'm hoping the figure in the wood will also be more balanced.....

You are correct to a point. You definitely don't want wood that has both tension and compression. Having said that, it is not like the bottom half has uniform compression and the top has uniform tension with a sharp line of demarcation through the center. both tension and compression are varying throughout the wood. A simplistic model would say that these built in stress are maximum at the outer extremes and reach a null at the middle. This means that no matter how you cut it, there will still be a stress gradient. However, it might be worth cutting some of it into blanks and roughing them out as soon as you can. I would orient the bowls facing up or down but not sideways (if you visualize how the tree was oriented before it fell into the river). If nothing else, it can still be firewood.

The stresses are probably less as you go up the tree. So, even though the base is bigger, it might be the most problematic.

 

[Charlie Knighton]

in the spring do you get a better choice of trees.....or is it potluck????????????

 

[dbonertz]

Zack,

You are right on with how to process your log for usable bowls. The reaction/tension wood blank on top and compression on bottom. If you tried to do a blank with 1/2 on each side of the blanks they have more stress in them thus more loss to cracking. Bill is correct there will be stress even with orienting the blanks tension and compression but your success rate will be much higher. Good luck that log should yield quite a few nice blanks.

For fun I would suggest cutting a couple of blanks with 1/2 tension and 1/2 compression and wet turn them thin to about 1/8" to 1/4" wall thickness. They will warp to possibly unusable bowls but it is pretty cool seeing how they warp. If you just round the bottom on the exterior with no flat spot for it to stand on it will tip over to different sides depending on the season. I think it is pretty cool to let nature have its way with bowls like this. They become more art pieces than usable.

 

[hockenbery]

Cutting blanks with the bottom/top facing the curve will give the most balanced grain.
It also probably balances the tension directions of the wood too.
Balanced grain usually gives the most pleasing patterns in a bowl and it definitely lets the bowl dry into a uniform oval.

If you are turning natural edge bowls in one pass the curves can add interest to the rim.
You can feature the curve in the rim. I turn quite a few natural edge bowls from these often have tension.
Some of them have definite curves in them.

I mount the bowl in the chuck with the outside near to finished curve and size.
Then hollow some of the interior. So the walls are 1/2 - 3/4" thick for an couple inches.
This leaves a lot of wood in the interior to minimize vibration and let's the rim edges move a bit with the some of the tension released
I then finish turn the outside after the rims have moved.
Then turn the inside walls to thickness all the way to the bottom.
This works pretty well for me to be even walls in wood that has tension.

Al

 

[Zach LaPerriere]

Wow! Great responses again. Thank you, all.

Thanks, Al, for the tips on NE bowls. I haven't ventured far down that path, but it's exciting to think about.

Thanks, dbonertz for the idea on finish turning a few bowls with 1/2 uphill/1/2 downhill grain to see maximimum movement.

Thanks, Bill, for confirming my thoughts, and also for pointing out that the stresses will likely reduce further up the tree. Also, I checked into the camera, and I was upload a picture as a portrait (vertical orientation) but for some reason the forum is turning the photo in upload.

Finally, to answer your question Charlie, this is my first "potluck" log. I've zipped out to a number in the skiff, but let most go by. I normally get my wood either from friends clearing trees, driftwood, or going for walks in the woods. I've also turned some buried logs that came from excavating my shop.

I talked with a turner friend today who recently milled a curved alder down to 8/4. He said the sapwood especially had amazing wavy grain, similar to maple. That's pretty exciting for around here, where wood is plentiful but figured wood is rare.

I'll post some pictures after I cut some blanks. Might be a few weeks. Thanks again.

Zach

 

[Zach LaPerriere]

I cut the tree into rounds this afternoon at low tide.

The tension was splitting as I cut rounds.



Later, as I painted anchorseal on the rounds I kept hearing pops and creaks—some serious tension. Good news, the tree is full of rays.

EDIT: The forum picture uploader is going crazy! I uploaded the picture as a landscape, and somehow it got turned 180° in the uploading. Sorry...
2nd EDIT: Image corrected.

 

[Bill Boehme]

..... Also, I checked into the camera, and I was upload a picture as a portrait (vertical orientation) but for some reason the forum is turning the photo in upload....

Zach, the forum software does not do anything that would alter images that you upload, nor does it strip metadata from images. Digital images all have an embedded header text file that provides some basic information that enables software to be able to properly display it on a screen. This data is defined in an industry standard for JPG images. Part of this data includes horizontal dimension in pixels followed by the vertical dimension in pixels. Even if almost all of the other metadata is removed from the image, the data giving the dimensions remains or else it could not be displayed. However, Apple and perhaps some others that make camera phones ignore that part of the standard and, instead, specify the pixel dimensions in terms of long side first followed by short side. In order to enable correct orientation, they include another metadata tag that gives camera rotation. That is fine because most all display software knows about the rotation tag and is able to use it to properly display an image. But, what if the metadata containing this rotation angle tag gets stripped out? Well, the fallback that display software uses is to assume that the first pixel dimension given is horizontal since that is the standard protocol.

I took a look at the images and found something interesting.
The first image has all of its metadata intact as shown in the attached screen shot below. Notice that you can see the shutter speed aperture, camera name, ISO speed, date and time, file size, pixel dimensions, and much more.



The second image shown below is missing all of the EXIF data and almost all of the basic shooting data. This is the reason that the image is not being displayed correctly. So how did this happen? I can't say, but most likely it was caused by whatever software you use on your computer to display images whether Windows picture viewer or something equivalent in Apple software.

 

[Zach LaPerriere]

Thanks, Bill. I fixed the images. You're giving me an education on photo uploading, as well as turning. My wife is much more techy than me, and I've helped her from time to time. I once tried to install vBulletin on a new forum when she was super busy. Let's just say it was humbling, and I eventually gave up. Thank you for all of your time and energy you put into making this forum run well.

Best,
Zach