Turning a Chinaberry Bowl


Well, I’m back. First, a bit of an update on my drying process I explained in my last blog entry. So far I haven’t had a single crack appear while doing this procedure, either with the Pentacryl wood stabilizer or without it. I have two in the drying process now that haven’t had the stabilizer treatment and they should be dried sufficiently in a few days.
For this entry, I thought I’d go along a similar line. I thought I’d write an essay on turning a bowl, from blank through to finishing. I thought that would be something worth writing about. I’ve started on it today and I took some pictures so here goes. I hope you find it interesting.
An old friend who I happened to see last night at a party told me that she had a chinaberry tree in her back yard so she wondered if I could turn a bowl of chinaberry for her. She bought a bowl made of cocobolo a while back and has been real happy with it. I told her that I had one chinaberry bowl in my shop on Etsy, but it is a small one, about 4 inches in diameter. I told her that I had a larger blank just waiting to be turned. She laid claim to it so now I’m writing about it.


Here’s a picture of the small one I turned previously that is listed on my Etsy shop at http://mlcwoodworks.etsy.com
As you can see, chinaberry is a very pretty wood. It has beautiful colors and grain patterns. Another wood turner at a craft fair back in April urged me to try some chinaberry and that he just loved it. I happened to have this small blank at home at the time and got right to it when I got home. This bowl measures about 3-¾“ in diameter and 2-½“ tall. It started from a 4” X 3” blank. The blank I’m working on now is 6” in diameter and 3” tall so I’ll have a little more latitude in shaping the bowl. Chinaberry trees don’t grow that big so 6 or 8 inches is about the largest bowl blank I’ve seen. I’m limited to a little less than 10 inches maximum by my midi lathe anyway.


Okay, on with the new bowl. I started by deciding which side of the blank would be the top and which would be the bottom.. There was a knot near one edge so that was put toward the bottom.
There are a few different ways to mount a bowl blank on to the lathe. Previously, I was using a face plate and screwing it on to the center of the top of the blank with four 1” screws but recently I’ve started using a worm screw mounted in a scroll chuck. This way, I marked the center of the top side and drilled a hole about 3/8" in diameter and 1” deep for the worm screw.

Here’s a picture of the worm screw mounted in the scroll chuck.
The bowl blank is screwed onto the worm screw until the chuck jaws are tight against the surface of the blank. This holds the blank securely and he spinning of the lathe actually serves to tighten the screw, or at least, apply pressure in the tightening direction. I start off putting the tail-stock up against the blank but after any out of round condition is remedied I remove it. The worm screw holds the blank very well.
Some turners start the blank between centers with a spur drive center and a live center in the tail-stock. There are arguments for and against each method but for now I prefer using the worm screw method.






Here is the blank mounted on the worm screw with the tail-stock supporting the bottom of the blank and the tool rest set and ready to turn.
You can see the beauty of this wood. The colors and the grain can be striking, and this blank is no exception.
I start using my 1/2” bowl gouge to turn any irregularities out of the round surface, then start shaping by bringing the bottom edge in toward the center and creating a tenon on the bottom of the bowl. A tenon is a straight protrusion on the bottom that is about 5/16” thick and the proper diameter to be able to be gripped by the scroll chuck when the blank is flipped around to hollow out the inside.





The picture on the right shows the outside has been rough shaped and the tenon created on the bottom.















The smaller picture on the left shows a small hole where the knot was on the surface. It also shows the grain swirling around that knot hole quite nicely. But a hole won’t do so it has to be filled. As I usually do, I filled it with wood shavings ground to a powder and pressed into the hole. Then I drip on some Cyanoacrylate glue(super glue, crazy glue) with a water thin consistency. This allows the glue to soak into the shavings/dust and harden creating a hard filler in the hole. After the glue dried I smoothed the surface using my bowl gouge and side scraper and then lightly sanded with 100 grit sandpaper.








You can see in this picture the hole has been filled and the swirling grain is still there. This wood will look wonderful when the finish is applied, those grain lines will just pop out and practically glow. I wish I didn’t have to wait for it to dry, but that’s the way it is.


















This picture shows the top of the bowl waiting to be hollowed out. This surface still has some of the wax on it which explains the difference in the color. You can also see the marks I used to find the center and the hole where the worm screw was attached. In this case the tenon is being held tightly in the scroll chuck. The diameter at this point is just a little under 6 inches and it will be hollowed out to where the wall thickness is as consistent as possible, not counting the tenon, and that thickness should be approximately 1/10th the diameter. For this bowl at about 5-7/8” in diameter the rough wall thickness should be approximately 5/8”.









And here is the rough turned bowl The grain and color is better than I had hoped. Now, it’s time for the bowl to dry. I am still using the process I explained in my last blog entry so it goes into a paper bag to be heated and cooled every day until it has reached equilibrium with the surrounding air.














Here is one more picture just before putting it into the bag. I’ll continue this saga on my next blog entry after the bowl has dried sufficiently to finish turning and put a finish on it. This will be a pretty bowl when finished , as you will see later. See ya’.

Drying rough turned bowls for finish turning

Since I started turning pens a few years ago, my woodworking has leaned more and more toward woodturning. I still do other projects but I've found Woodturning to be very addictive, and turning bowls, for me anyway, has been even more so.

I started turning bowls last summer after I got my Turncrafter Pro midi lathe for my birthday. The lathe I had before that was a small mini lathe that barely had enough power to turn pens. Actually, that isn't really right, it is just about all you'd need if all you are doing is turning pens. But I wanted to do more, so when I got the midi lathe it was like going from a Yugo to a Lexus. It has more power and is so much more stable than the small one. Unfortunately, I'm still limited to less than 10 inches in diameter for bowls, but that's a good maximum to have while I'm learning...I suppose.

Anyway, now I've been turning bowls for about a year and I'm getting a little better at it. One thing, though, about turning bowls is that the turning is much easier if the wood is green. The moisture in the wood both lubricates the chisel as you are cutting, and it keeps the dust down a little compared to dry wood. The problem with turning green wood, is that it still has to dry before you can finish it. I've done a lot of reading online on turning bowls and what to do about drying your rough turned bowls. Most everything I've read recommends that you rough turn the bowl to an even thickness all the way around, and that should be equal to about 1/10th the diameter of the bowl. In other words,. if you are turning a 5 inch bowl, you should turn it to approximately 1/2(0.5) inch thickness consistently from edge to bottom. This doesn't include the tenon on the bottom of the bowl that is there for the chuck to hold on to while turning. After that, comes the drying process.

As the wood dries, the moisture moves within the wood. The moisture in the surface fibers evaporates to the air, and the moisture in the fibers in the inside moves toward the outside This process continues until the wood has reached what is called the Equilibrium Moisture Content, or EMC. That is the point where the air around the wood won't draw any more moisture out of the wood. One problems is that the end grain of the wood will lose moisture much faster than the face grain causing uneven loss of moisture and warping or cracking of the wood. Another problem is that in the open air the moisture will leave the surface fibers faster than the movement of the moisture inside the wood can replace it causing the surface to want to shrink more than the inside also causing degradation. Some woods will degrade more than others, and figured woods seem to be some of the worst. One simple method is to place the wood inside a paper bag or wrap in brown craft paper and let it sit for a couple months to dry. This creates a "micro climate" within the bag and keeps the surface fibers from drying out too quickly and minimizes degradation. Other methods involve boiling , immersion in alcohol, and even immersion in dish soap. One method says to place your bowl in a microwave oven on high for 45 seconds to a minute and then weigh it and record that weight. Repeat this process after it cools and again weigh it and record the weight. Continue this process until you see no weight loss for at least three cycles. This means the wood has reached equilibrium with the surrounding atmosphere, and it's ready for final turning and then finishing. I tried the microwave method but didn't have much luck with it. It may be that my microwave is underpowered, I don't know.

What I have been trying is a combination of the microwave method and another method I've tried before using the conventional oven. What I do is rough turn the bowl and then place it in a paper bag, roll the top of the bag down and tape it closed. Then I turn the oven on to 250 degrees and place the "bowl-in-bag" into the middle of the oven. Then I wait until the oven beeps, indicating that it has preheated, then turn it off. Sometimes I'll let it sit for a few minutes on before turning the oven off but I don't leave it on for very long...at least, not on purpose. After the oven has cooled down I'll remove the "bowl-in-bag" and when it is cool to the touch I'll weigh it and write that weight down. I repeat the process and continue until there is no further weight loss through three heating cycles. I've had some actually gain a few tenths of an ounce after sitting for a while which, again, tells me it's ready to finish turning.

So far, with limited trials, this has worked quite well for me. There is, however, one other factor that I've had in these trials. I had previously decided to try some Pentacryl wood stabilizer to prevent cracking which had plagued several of my previous attempts at bowl turning. So far I've tried this method with an 8 inch box elder bowl and a smaller one of bradford pear. Although both had some previous cracks that I had sealed with CA, or super glue. No further cracks appeared after I started this process. As I said, I had purchased some Pentacryl and I covered both of these thoroughly. After letting the solution dry out for a few days I then decided on trying the oven drying method.

Right now I'm in the process of drying a small maple bowl (about 6 inches in diameter) which hasn't had the Pentacryl treatment and I will try more as the results dictate. If the ones without Pentacryl start showing more tendency to crack, I'll most likely go back to painting on the stabilizer again.

I don't profess to know a lot about this subject, I'm just attempting to relate my experiences here, hopefully without being too wordy and boring the hell out of anyone reading it. But then, it could be a cure for insomnia. My results so far look promising, and I will relate further results later. I wanted to at least get another entry into my blog, and hopefully make some sense to the reader.

Feel free to comment and/or correct me on anything you read here. As I said, I'm no expert, just a guy learning and relating my experience.

See you next time...
Larry

Hey there, I'm blogging!

Hello,
My name is Larry. I am a woodworker, as you may have guessed by the title of the blog. I make things with wood and sometimes give them as gifts and also attempt to sell them. I have had some success but it's still a learning process...as is blogging. I have a Facebook page, you guessed it, MLC Woodworks (http://www.facebook.com/home.php?#!/pages/MLC-Woodworks/139250176089610); and a shop on Etsy.com at http://mlcwoodworks.etsy.com. You can also get there through my domain http://www.mlcwoodworks.com. I plan to set up a website at mlcwoodworks.com some day but don't know when that will happen.
I've been exposed to woodworking all of my life. My dad was a cabinet maker and later became an architect. The cabinet shop he owned was before I was born or at least before I was old enough to know about it. What I remember is after we moved from California to Georgia in 1957 when I was 2. There, he worked at Athens Lumber Company in Athens, Georgia. Sometime in the 60's he went to school to learn architecture and from then on until his passing in 1990 he was drawing plans for houses, apartments, banks, shopping centers, and just about anything else you can think of around the Athens area. He also acted as a contractor in the sense that he had the crews that he knew he could trust to do the job the way he wanted and he would visit the jobs regularly to make sure it was done right. He wouldn't have just anyone work on his jobs, and his reputation around town showed that he was very particular with the quality of the work he put his name on.
I have been dabbling in woodworking all of my life but didn't really start getting into it seriously until the past 13 years or so. After high school I spent 8 years in the Navy learning and working in electronics. When I got out in 1981 I went to work for a large multinational company who made typesetting equipment and later moved into general graphic arts equipment. My job was installing, repairing, maintaining and training customers on the operation of that equipment. It ranged from large(44 inch wide film) laser imagesetters to scanners to computer based editing systems to photographic film processors to printers. I spent 15+ years doing that but started having problems with my knee in the early 90's. By '96 I had essentially burnt out both physically and mentally and spent 2 years out on disablilty. In hindsight, I should have changed jobs 5 to 10 years earlier but kept trying to take care of my customers. I finally had to leave it, and them. When I went back to work I shifted gears and went to work in a cabinet shop. I really enjoyed that until the workload started getting to my knee again after a couple of years. I found I wasn't able to work the long hours that I and my boss wanted . We came to an agreement on my limitations and things would have been fine if my boss had learned one simple thing. You can't get away with lying to your customers, or your landlord. Lies will always come back and bite you in the ass. In this case, the landlord shut us down one day and I was again out of work. After a few months on unemployment I went to work at another shop making custom entry doors. That was quite interesting and I was enjoying it and learning a lot, but personality conflicts with the boss ended that after a couple of months. During that time and afterward I had been trying to start up my own shop. I'd been buying equipment for my basement shop and I had a few jobs here and there but the knee still caused me problems that limited the amount of work I was able to do. I ended up having to pass on several jobs that could have been real money-makers.
As it is now, I'm able to work in short stints, resting frequently. In the last 3 years or so I've gotten into wood turning, starting with turning pens and then expanding to bowls when I got a slightly larger lathe for my birthday about a year ago. Now I wish I could get a bigger one. Some day... but my shop isn't real big and it is very crowded so I don't know where I'd put a bigger lathe. I have a lot of wood that I got from the cabinet shop where I worked. My boss kept throwing stuff out that I just couldn't see going to waste, so I would just throw it into the back of my truck. I've gone through a lot of it but still have stacks of wood here and there. Unfortunately, because of lack of space, I have tools like a jointer, planer and a oscillating spindle sander that are buried that I have to uncover to use. Most of my tools have to be moved around to some extent to be used, but these three are seriously a pain to get to. That's something that I have to remedy one day soon. But I keep jumping into new projects, another thing that I have to work on.
Well, I just wanted to write a short piece with a brief bio and there I babbled on and on. Oh well, I didn't have anything woodworking related ready yet anyway. My next installment will be a bit more on topic. Since I'm turning bowls now, mostly from green wood, I working out a process for drying the roughed out bowls so that I can finish them off. I've been reading a lot online on the subject and trying different things. I'm on to a process that seems to be working quite well right now. When I get more results I'll write something about that. I've also got a couple of other ideas floating in my head for the future. For now, this is me. You can see samples of my work on my facebook page or on my Etsy shop. Check back here periodically for updates.
Larry
MLC Woodworks