Moisture content

[Bill Jobe]

What is considered the best (or highest) moisture content to turn wood without it cracking?

[Brice Rogers]

Bill, I'm not sure if I'm understanding your post. I usually do rough turning (wet) followed by a drying cycle and then final turning. I rough turn to help reduce cracking. I find that rough turned objects crack less than leaving a round sitting and drying over an extended period of time. Also, it is possible to rough turn something and then boil it to help reduce stresses. So, when I rough turn, I sometimes turn pieces so wet that the water sprays out when they are spun up.

When I do the secondary turning, I usually try to get it as dry as I can. I don't have a moisture meter, so I just weigh the piece and record the weight. When it stops changing weight, that tells me that it is at or close to equilibrium.

When I rough turn, I intentionally round the sharp edges of the lip in order to reduce stresses.

After I rough turn I wrap the lip and much of the outside with stretch-wrap and put into a paper bag along with the damp shavings and weigh the bag. When the weight starts to equilibrate, I will often pull it out. It is still wrapped with stretch-wrap on the outside, so the inside dries more quickly than the outside. I still get cracks but not too many.

[Bill Jobe]

Bill, I'm not sure if I'm understanding your post. I usually do rough turning (wet) followed by a drying cycle and then final turning. I rough turn to help reduce cracking. I find that rough turned objects crack less than leaving a round sitting and drying over an extended period of time. Also, it is possible to rough turn something and then boil it to help reduce stresses. So, when I rough turn, I sometimes turn pieces so wet that the water sprays out when they are spun up.

When I do the secondary turning, I usually try to get it as dry as I can. I don't have a moisture meter, so I just weigh the piece and record the weight. When it stops changing weight, that tells me that it is at or close to equilibrium.

When I rough turn, I intentionally round the sharp edges of the lip in order to reduce stresses.

After I rough turn I wrap the lip and much of the outside with stretch-wrap and put into a paper bag along with the damp shavings and weigh the bag. When the weight starts to equilibrate, I will often pull it out. It is still wrapped with stretch-wrap on the outside, so the inside dries more quickly than the outside. I still get cracks but not too many.

I have a moisture meter is why I asked. I have several pieces that I roughed out, then placed in a paper sack, then inside another paper sack or simply wrap in several layers newspapers.
I just not learned enough to tell by looking at or feeling a piece to determine whether or not I can finish turn it, so I bought a meter. But I don't know what reading tells me I can finish turning it.

[Michael Mills]

It depends somewhat on where you live. The following link gives equilibrium moisture content by major cities (starts about page 6). For me in NC I consider anything under 14% good to go. I do try to bring the item in the house for a few days before final turning. I have a pin moisture meter and just test it in the base right through the paper bag.
Other cities may be higher or lower, such as down to 5.8 in El Paso or 20+ in some other places.
http://www.fpl.fs.fed.us/documnts/fplrn/fplrn268.pdf

[Steve Doerr]

Brice, another way to determine if the wood is dry is to weigh it. I turn all of my wood (wet or dry) to final thickness. If the wood is wet, I will soak it in DNA (denatured alcohol) for 24 to 48 hours (usually only 24). After I take it out of the DNA I put it in a brown paper bag and weigh it. Once it stops loosing weight I know it is dry. It usually takes about 2 to 3 weeks for a finished turned piece to hit equilibrium. For a bowl that you will be twice turning, I would say it may take a month or 2 for the roughed bowl to reach equilibrium.

[Brice Rogers]

Steve,

I agree with you.

But I think that you meant to address that comment to Bill, as I already do the consecutive weighings.

Right now in San Diego, we are having a weather condition known as a Santa Ana - - 30 plus mph winds from the desert, 90 degrees F and about 10 percent humidity. I put out one of my rough turnings all day and checked that it didn't lose any weight. It is ready for final turning.

[Prashun Patel]

Ambient moisture content can vary. I usually just test known, dry lumber (which usually comes in between 7 and 9%) before I test the blank. In practice, I find close is good enough. If it's close to 10%, in my neck of the woods, it tends to be fine for me.

[Steve Doerr]

Sorry Brice. didn't go far enough up on the thread to get the right name :-0

[Bill Jobe]

Thanks everyone . I have about 10 pieces wrapped in newspapers and then a paper sack that are hovering just above 10.
It seems like an eternity when I don't have anything to turn.

[Pat Scott]

I agree with Prashun, I have a pinless moisture meter and if it's 10% then I consider it dry enough to finish turn. I measure the bottom of the tenon where I have a flat base, and also the top rim if it's wide enough. I might measure the walls, but with a curved surface the readings might not be consistent.

[Bill Jobe]

Well, it looks like I got myself some pieces to finish.
Sure would be nice to have that new Grizzly I so want.
But this HF 10x18 mini continues to perform no matter how hard I work it.
Thanks everyone.

I also am experimenting with microwave drying. I have a slab of Osage Orange that is too big for the mini, so I decided to clean up the edges, sand it down smooth and give it to the wife who likes slabs to place other pieces on.

A couple of days ago I microwaved it for about 2 minutes at a time, letting it cool down, then back in the oven for another 2 minutes. Got it down below 10% after about 7 or 8 times. It began at about 25-30 depending where I put the meter. It's about 3" thick.

[Bill Jobe]

Update pics of the slab I'm making. Eventually I intend to turn an offset bowl in it, when I get a bigger lathe. At first I intended to just clean up the perimeter but leave the bark in the curl, but it was so crumbly I decided to clean it up as well. It measures 2 5/8" think. I'm a bit concerned now about what it might do since nowhere on it do I get a mousture reading above 7. Anyone experimented with microwaving only to go below 10% ? Will it cause problems as it rehydrates? It's been inside for 2 days and so far nothing dramatic has happened to it. It was checked when I cut it.

[Jamie Straw]

Ambient moisture content can vary. I usually just test known, dry lumber (which usually comes in between 7 and 9%) before I test the blank. In practice, I find close is good enough. If it's close to 10%, in my neck of the woods, it tends to be fine for me.
The kiln dried wood I get here in Puget Sound (WA) is in that 7%-9% range, but nothing in my shop drops below 12%, except perhaps in early September if it's been hot and no rain for a few weeks. So, like Michael, anything 12% or under is fair game. For reference, humidity in my shop the past few weeks, when unheated, is ~85%. Pellet stove will drop it to 72% or so.

[Bill Jobe]

Boy, I tell you, microwaving Is a great way to dry wood! It was in the 50s the evening I dried this piece and every time I took it out I had a warm piece of wood to lay in my lap to sand and chisel for several minutes. Couldn't be any easier. And to take a piece of my (current ) favorite wood i'd harvested just a couple of days prior is nice. That tree was standing a week ago.
What's really amazing about Osage Orange is that most pinpoint tests are around 5 or 6 and piece still weighs a ton. Sure wish I had a bigger lathe. I can't wait to cut an offset bowl in it.