Pith In / Pith Out ?

[wassaw998]

I'm confused on this subject, and see folks posting pics of items they have turned from a tree branch / log.

If I am turning a piece of wet wood, (between centers, grain parallel to axis), in general, do I want to use wood that has had the pith cut out ? If I get a tree branch / small log, which has the pith, that is not recommended ? That is, I can't just mount the branch / log to my lathe as it comes off the tree and start turning (bark and all) ?

I notice when I turn wet wood with the pith, it sure does check a lot as it dries, is that because of the pith being in, or, just a factor of turning wet wood ? Does that mean on logs and such, I have to mill them into squares (with pith cut out) on my bandsaw before I start out?

Thanks.

[Doug Jones]

I am no expert by any means. What I've always been told was to cut the pith out before or while turning. As you have already discovered, if you leave the pith in checking is unavoidable, especially on fruit wood.

[kwgeorge]

Without going into much detail I will quickly explain pith. Trees that have a pith area in the center use that area to carry water and food up to the top of the tree. The cell structure there is different than that of the surrounding wood and contains much more moister. This are will lose this moister much faster than other areas in the wood and the cells will collapse leaving you warps, cracks, checks and all kinds of nasty stuff. It is always best not to use that area in your turnings if possible.

[jl]

I'm new to wood turning and I don't know what the "pith in/out" rules are. But here are examples of "pith in", end grain...

http://www.aroundthewoods.com/endgrain.shtml

... and "pith in", long grain:

http://www.lynneyamaguchi.com

Note that in the latter many have cracked centers.

Two months ago, I turned two bird eye maple bowl blanks, green, end grain, 9" diam x 3" deep, pith dead center; and a 4"x4" vase, long grain, apple wood. So far none have cracked.

Using branches of diam 1" to 6" , I have also turned over 50 mushrooms since May. Very few have cracked so far.

So what's the rule?

[gerti]

The pith has many negative qualities that often have a negative influence on turning. That being said: I turn every wood that comes out of my yard (or I find elsewhere) at least once, often with decent results.

If you have some small and medium sized branches, after cutting out the pith there would not be much left. So just try it!

Here are some examples, all of which include the pith:



The left 2 are box elder, from fairly small (around 3") branches. The pith of the second one is visible just next to the tip. The 2 on the right are some kind of pine I got from the neighbor. That was about 4" diameter. You can see the pith in the rightmost bowl near the center, a little offset to the back.

Here are some more:



The 2 on the left are from a 4" diameter cherry branch I found on the side of the road (fell from some truck). The lid of the box on the left clearly shows the pith. It developed small cracks while turning, which didn't really bother me. They are barely visible and do add a bit of charme. The goblet on the right was a very quick test of some Sumac, not finished. Seemed like almost the entire branch was pith... I don't care much for it, but a few folks liked it. I'll have to try some more Sumac.

Anyhow, long story short: If you have some 'free' wood, too small to cut out the pith, by all means try with the pith! For some projects (especially goblets) it is best to have the pith a little off-center. I cuts a little different then the rest of the wood, so be prepared for that.

Also remember the grain direction. Even if you turn a bowl that way, since the grain is parallel to the axis, cutting works pretty much like it does for boxes.

Gerd

[wassaw998]

Thanks ! Makes it a lot more clear. Sorry I keep asking stupid questions !

[mudder]

quote:Originally posted by wassaw998

Thanks ! Makes it a lot more clear. Sorry I keep asking stupid questions !

Only stupid question is that which is not asked. You cannot gain knowledge unless you are inquisitive.

[guycox]

quote:Originally posted by Doug Jones

I am no expert by any means. What I've always been told was to cut the pith out before or while turning. As you have already discovered, if you leave the pith in checking is unavoidable, especially on fruit wood.

I've had really good luck with Bradford Pear. - It absolutely refuses to check under any conditions. I hear that pear is the preferred wood for model makers because of the dimensional stability.

-- It's not that I'm in an arid area or anything, but I was given a log about a year ago. We were in the process of moving so I just tossed it into the back of the garage (ends unpainted). I actually moved my wood "logs" when we moved so I brought it with me -- After the move, I put it in the shop. I cut the blanks about a month ago -- there were no checks. I turned two of the blanks -- both stayed round. The HF moisture meter shows the two remaning blanks at about 13%.

Grab some pear wood, and save the shavings for the smoker...[:I]