hollowform advice

Re: hollowform advice

Wally Dickerman in Arizona

>Yes, dry wood is usually a little tougher to turn, expecially in some of the hard, tough woods. However, that is somewhat offset by the fact that the wood chips are much easier to remove from a hollow vessel. I always twice-turn my bowls and hollow vessels, wet or dry. I rough turn, outside and inside,then finish turn,outside first. This helps eliminate some of the wood movement as the piece is being completed.

Wally

cracks?

John K Jordan

>If you are having things come apart (did I read that earlier?), make sure there are not tight, invisible cracks extending into the wood from the end grain. These cracks or checks are often found in green wood that has been drying for a while, especially if it is not sealed but even when sealed I've seen some. It might be more of a problem with wood that was not sealed right away.

Some advice I read somewhere that I always do before turning dry or partially dry wood: cut a slice off the end grain to expose fresh wood then cut another thin slice (1/8" or so, depending on the size). Bend that slice a bit - if it breaks easily, usually along a straight or curved line, then cut and test more slices until you find solid wood. Sometimes there is no solid wood, even deep into the center. I've seen this on some very old bone dry spindle turning squares as well on some freshly cut green wood. I was once given a "nice" supply of green walnut that looked fine when sectioned but with the slice/flex test turned out to be worthless for any kind of turning - turns out it was reaction wood from a large limb that was riddled through with shakes, circular separations between the growth rings running down the length of the wood.

It some cases, it helps me to track a crack into the wood by placing one of the broken pieces on the wood and drawing a line on the newly exposed end grain, then paying special attention to that line when flexing the next slice.

When I cut blanks, I use a blue or red Sharpie to highlight any noticable cracks on the surface so I won't miss them and can deal with them later when I use the blank. I also find that highlighting the cracks on the end and sides helps me to visualize how they might be oriented deep inside the wood, helpful when deciding how to best divide the wood into facework chunks or spindle squares.

I've had more trouble with these cracks on spindle stock, but you might try the same thing with your bowl or hollow form blanks. If the wood is valuable enough to use even with cracks, you can try flooding the cracks with CA glue. As wood is turned away, it may need more glue.

Finally, something a buddy of mine does when successfully hollowing wood that is full of holes and cracks - he wraps the outside with strapping tape to hold it together. Makes it hard to judge the thickness (unless there are lots of voids and the opening is not too small).

I'm not suggesting that your problem is due to cracks, just that it's something to look for.

JKJ in East TN

Re: hollowform advice

ken chase

>Thanks Wally. do you let the piece dry a long time in a bag or finish as soon as you've done the rough turning? I see you live in a similar climate to mine in Palm Desert CA. Does the dry heat make it difficult to keep your projects from cracking?

Ken

Re: cracks?

ken chase

>Thanks so much for all the time you took responding to my post. Now that you mention it I've been getting cracks in every piece I've made except some white ash which I purchased. All the wood I have is local and given to me by a friend. Some of the mulberry was so bad I couldn't even use it. Dry and crumbly. Too bad, it's really good looking stuff.

Ken

Re: hollowform advice

Wally Dickerman in Arizona

>Hi Ken,

I almost never finish turn wet wood pieces. Nothing wrong with it, just not my method. I rough turn wet, let it dry, then finish it. After rough turning, I very liberally coat the piece with Johnson's Paste wax, even if it's almost dry, put it on a shelf and let it dry. Drying time can run from 1 to 6 months, depending on how wet it was. I usually have from 30 to 70 or more, rough turned vessels in my shop. I almost never experience cracking after rough turning. My shop has no AC. I live in the desert, but at 3000 ft., so I have cool nights and mornings. Days are hot in the summer. I don't rough turn in the summer months however. Usually do it in the Fall and Winter.

Wally

Re: hollowform advice

Keith Tompkins

>Hi Wally, I also seldom lose a piece due to cracking. Like John stated, finding the defects in the stock in advance helps.

If a piece seems like it may be suspect, I either cut it up for smaller projects, or send it to the wood pile.

Do you have any tips to share on your success rate?

Re: hollowform advice

ken chase

>Wally:

Thanks for the help. That is the first I heard of using wax. Do you bag as well? I have air conditioning in my shop which I use during the hot months. Will this cause problems in my turning?

I tend to be impatient and started soaking rough turned bowls in alcohol. Have you tried this? If so, what do you think?

Thanks again

Ken (Palm Desert CA)

Re: hollowform advice

Brad Vietje

>Ken,

I suspect air conditioning would be a help -- should be adding humidity as well as taking out the heat.

Also, in response to your other post a little further down -- not all woods are created equal, so far as cracking goes. Some woods are much worse than others, and you will often find one tree of a species that's full of cracks and ring shake, while another tree of the same stuff, from just a hundred feet away is much better. Many trees are shattered when felled, adding yet another variable. I think Apple sometimes self-destructs in mid-air ! I had a medium sized, slightly twisted Black Cherry tree trunk that was full of checks -- another, straighter tree from a few yards away was beautiful. Even the cracked stuff burns well.

Safe Spinning,

Brad Vietje

Thetford, VT