A Pithy Problem

[Clif Moore]

I plan to attempt my first end grain bowl this weekend. Here's the question: What to do with the pith?

I have read two positions as where to place the pith.
1. Keed it in the center bottom of the bowl
2. Avoid #1. Get it toward the side or at least off center if possible.

I plan to infuse the pith with CA glue to strengthen it unless advised otherwise.

Opinions? Advice?

Thanks!

 

[MichaelMouse]

Kind of wood is it? Certain types, like sweet birch, aspen or elm are good to go any way you like. The grain swirls and locks into itself. Others are a bit more of a challenge. The best advice I can give is to elevate the finished piece so the bottom may dry from both sides, not just the inside. It's worked fine for me for other woods like oak, cherry, beech and maple. Round your way to the bottom so the piece won't develop radial checks.

You can put CA in, won't hurt anything but the final finish, if you can't tolerate color difference.

 

[hockenbery]

Clif,

If you plan to do a stemmed turning like a vase or goblet, it is important to keep the pith out of the stem as it will make the stem weak.

The pith is rarely dead center in the log. So usually center of the log or just off center will keep the pith out of the stem.


If you are doing some type bowl, Center of the log yields the largest bowl and an opportunity to have a bark edge.

I would locate,center for the best grain pattern. Pickering the center of the heart wood will usually be a good gain patern.
This may or may not be close to the pith. In a perfectly symmetrical log it would be the pith.

Have fun
al

 

[Clif Moore]

Thanks! The wood is Texas Pecan. I will have to look to see how centered the pith is. I am thinking more bowl than vase right now.

 

[hockenbery]

Thanks! The wood is Texas Pecan. I will have to look to see how centered the pith is. I am thinking more bowl than vase right now.

On an end grain turning with pecan I would turn it to finish thickness.
A nice curve and even wall around 1/4" thick will minimize the chance of cracking.

One thing to think about is then rings around the pith have to push out as they dry.
The rings shrink more around than across so they either push out in a bump or crack.

A thin wall lets the rings push out rather than crack.

Al

 

[Clif Moore]

It is green wood so I was thinking 1/4" as well. I will post updates.

I am going to follow the directions in "Turning Green Wood" by Michael O'Donnell for a natural edge end grain bowl.

 

[Clif Moore]

So now what?

So which gouge to hollow the inside of this end grain bowl? Spindle (not roughing) or bowl gouge? Man this is slow going.

 

[MichaelMouse]

Some like a fingernail grind pulled up the sides, I like my more aggressive pointy grind for hogging. http://i35.photobucket.com/albums/d160/GoodOnesGone/a63b77ab.jpg

Moves a lot pretty fast, as you can see. http://i35.photobucket.com/albums/d160/GoodOnesGone/725a28f2.jpg I follow with the shallow - what you'd call spindle or "detail" gouge - ground fingernail. Or my Termite ring tool. The pointy is rolled when grinding so the whole edge is in the same line, with a large sharpness angle. Think a Pointed Hunter too as an analog.

If you have a ring or a Hunter tool, you should be good for all operations, as they are capable of peeling either aggressively or small and slick. They're actually a small radius gouge at 90 degrees to the shank, used at about 20 degrees skew and pulled, approximating the fingernail.

 

[Steve Worcester]

End grain Pecan, especially dry Pecan, is difficult to turn. We call it "pecancrete" for a reason.

A fingernail gouge or whatever style gouge you have will work, it is just very slow going and a bit of sharpening.

 

[Clif Moore]

Pecancrete is right

Feels like I am trying to hog out stone. Thanks for the comments. I am relieved to know it isn't all me and poor technique. It will be a long time before I try end grain anything with pecan again. :mad:

 

[Bill Boehme]

Feels like I am trying to hog out stone. Thanks for the comments. I am relieved to know it isn't all me and poor technique. It will be a long time before I try end grain anything with pecan again. :mad:

Maybe you are not keeping your gouge sharp enough. If the pecan is green like you said, the curly shavings should feel slightly damp and and they should slice off quite nicely. Sometimes wood has a lot of minerals in it and in that case there is not much hope of cutting for more than a few seconds before the tool is dull.

 

[john lucas]

sharpen frequently and take smaller bites. I turn a fair amount of pecan, Osage Orange, and Black Locust. All wood that people love to hate. I don't mind them at all. You just can't hog out wood on these. Take your time and sharpen often. They polish up so well when your done that it's worth the effort. I use either a V shaped bowl gouge with swept back wings or a Thompson detail gouge to hollow out small boxes and such.

 

[hockenbery]

Feels like I am trying to hog out stone. Thanks for the comments. I am relieved to know it isn't all me and poor technique. It will be a long time before I try end grain anything with pecan again. :mad:

Engrain turning is a bit more fun with tools and techniques designed to cut center to rim.

Ring tools, hook tools, some of the carbide tools, Ray Key gouge, the Raffan back hollowing, ....

Smaller projects like Boxes, goblets, vases all require less open Engrain hollowing than bowls and are good to start with.

Learning the Raffan back hollowing cut with a spindle gouge is well worth the investment of time. And this is a fun cut with the gouge cutting upside down on the right side with shavings pouring out.

The ray key gouge works very well for end grain hollowing He grinds of the right side of the tool to get it out of the way.
http://www.packardwoodworks.com/Mer...uct_Code=104060&Category_Code=tools-tayl-keyr

For my Engrain hollowing, I mostly use the Termite tool and then clean the surface a bit with a Hunter carbide. Almost no sanding required.
I also mix in the Raffan back hollowing but I'm not good enough with it to get a nicely shaped bottom. With the Termite I get nicely rounded bottoms.
Also with the termite and the Raffan Back hollowing I don't need a pilot hole.

Have fun,
Al