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Sunday, February 9, 2014

Making Bowls - Part 2

If you are just tuning in, here is part 1 if you wish to catch up.
So let's turn a bowl!
I decided to start with something simple.
This is a sapelle block. It is five inches square, less than two inches thick and has a piece of three quarter inch thick cottonwood glued to it for a waste block.
I start by finding the center. There are many ways to accomplish this, but for a square block, I find it easiest just to take a steel rule and mark a line across the corners.
Next I use a compass and mark a circle as big as I can, or smaller if I don't wish to use as much of the block as possible, around the block. For this bowl I am marking all this on the waste block, which will later be the bottom of the bowl. Later I will be showing another method. This is but one way to do it.
There is a variety of ways to make a hole to mount the wood to the chuck. I use this two and one eighth forstner bit in a drill press. I will tell you a way in the next installment to do all this if you don't have a drill press. As I've said, there are many ways of doing all this. You can follow along and use a combination of things to get the job done. Turning can be fun. Use your imagination and anything is possible.
Next, I like to, when possible, round the blank on my band saw. If you don't have a band saw, this step is not even completely necessary. It reduces the roughing out stage and makes the blank more balanced when you first start turning. You can absolutely though mount the square block and simply start turning until you make it round.
Also, the band saw is not the only way to take the square corners off. There are many, many ways. I even seen one guy on the internet that takes the corners off of something like this with an chainsaw or hatchet.
Now you mount it on the lathe. As you can see, for this example, the bottom of the bowl, or waste block, is mounted to the chuck. The tailstock is brought up to support the wood. ALWAYS use your tailstock until the wood is balanced well and turning until you are absolutely comfortable with turning it with no support. I have had some knotty pieces of wood that I even done most of my hollowing with the tailstock in place.
I repeat, DO NOT turn without the tailstock supporting your work until you KNOW that you are comfortable to do otherwise. Off balance pieces of wood, or pieces during a bad can, can and will leave the lathe at high speed. The tailstock will keep it from doing so.
There are differing opinions here, but I like my tool rest to be at about the center line when truing up the outside of a bowl. That puts me tool edge just above center.
I will be specific about this point as I go because I used to have a little confusion when learning how to turn bowls. Some people will say bring the rest to center when what they mean it tool edge to center. Because of the way we hold the tools, your tool edge is not going to always be necessarily at the same height as your tool rest. It will be a little above or below it.
Now you're ready to turn!
Right?
STOP!!!
Remember what I said about the full face shield. I do not recommend anyone EVER turning on the lathe to turn a bowl without a face shield on.
Have I ever turned a bowl without a face shield?
Yes.
Have I ever been hit in the face with a piece of wood?
Yes.
Do I know better now?
Yes.
Should you always wear a face shield when turning bowls?
Yes.
Yes.
And Yes.
With the tool rest as close as I can get it without coming into contact with the wood, I take my gouge and make the blank and waste block round.
I use my gouge, put the tip above the cut line so the bevel is riding on the piece of wood. Slowly bring your tool handle up and the cutting edge down until your edge starts cutting. Then, with your hand supporting the shaft on the tool rest, move it across the rest in one steady line. Keep doing this until your piece is round.
In time, with enough practice, you'll be able to just stick the edge to the wood in a split second without all that lowering your tool slowly and all. You'll just get a feel for where the good cutting starts. Just remember that a gouge cuts if the bevel is rubbing and the edge is shaving. That same gouge though can make rough scrapings if you lower the edge enough that the edge can't cut. You can still turn that way, but it just won't be as clean and you'll have to do extra sanding to make it look good later.
I am explaining this as best I can. I do not have good enough video equipment to truly show how to do all this. If in doubt though, the internet is your friend. There are many many videos on YouTube that will show you the basics of bowl turning if you're unsure of any of the technique I am explaining.
One of my favorites is Cap'n Eddie Castelin. Here is a link to Cap'n Eddie's YouTube page. Take a while, a few days if you need, and watch his videos. I have learned more from watching his videos than anything else besides practice.
Anyway, after the blank is round, I shape the outside of the bowl. Notice that if any of the waste block interferes with the shape of the bowl, turn it away. It is a waste block after all. You will be wasting it in the end. As long as you leave enough material for the chuck to hold it, you're fine. Just turn away anything that is in the way of getting the result you want.
Next thing I like to do is to face the front of the bowl, or what will be the top.
To face a bowl, I use my gouge, take very light passes from the outer edge working towards the center, and shave off material until the face is flat.
Let me stop here and answer a question I am asked often.
If you look at this photo, the grain runs across the bowl. This is how a bowl is usually turned. You work a bowl like this from the outer edge to the center.
When I first started turning a bowl for the first time, I had the grain running with the lathe bed. Somehow it just made since to me that since a tree is round, and a bowl is round, then that was the way it should be oriented.
Now, you can orient the grain the way I described, running the direction of the lathe bed. That is called an end grain turning. It is done, but it is even harder than turning a regular bowl. I do not recommend beginners attempting end grain turnings. End grain turnings you hollow by working from the center towards the outer edge. They are harder to work with than a regular bowl. They take more practice in my opinion. Also, the end grain is harder on tool edges, requiring you to have to sharpen more. Since sharpening is something that I think most beginners are still trying to learn as well, I don't thing something that make even more sharpening needed, like end grain turning, is something that needs to be tackled at this time. Let's just stick with regular bowls for now.
Now, do you remember my depth gauge from my first post?
This is nothing more than a long drill bit that I turned a handle for and epoxied the drill bit into.
Then I rummaged through my junk drawer and found a large rubber washer to go over it snugly.
Now I will show you how I use the depth gauge.
Measure how thick the bowl blank is. This one is one and three quarters inch thick. So if I want a quarter inch thick bottom, I need to hollow out about an inch and a half deep.
So I remove the center point from my tailstock and run the depth gauge through the tailstock. This is the reason I used such a long drill bit. This gives the bit support and the tailstock helps assure that I am at least near center when I start drilling.
I measure and place the rubber bushing an inch and a half from the tip of the drill bit. This is how deep I want my bowl. I usually go just shy of what I want my bowl to be. This allows me extra material at the bottom should I need it for cleaning up my cutting marks and such.
Next, with the lathe on at it's slowest speed, advance the end of the bit into the bowl blank.
Go slow and back it out often to eject the chips out that the bit has cut. If the bit happens to catch and hang up inside the bowl blank, let go of the handle. The tailstock will support if while you reach for the shut off switch. Worst case scenario, it is better to ruin a three dollar drill bit than to take a chance on hurting your hand trying to hold it.
I've only had the bit bind once in all the time I've used it (about a year now) and it did not damage the bit. I just had to shut the lathe off and slowly work the bit out of the blank before I could continue.
After you have drill with the depth gauge till the rubber washer is up to the bowl blank, remove it, move your tailstock out of the way, and start hollowing.
Work slowly. In time, you'll find that groove where you know how much material you're comfortable taking at one time. For me, I am comfortable taking huge swipes of wood. I have burned one lathe up that way though. So for the sake of your lathe, unless you are lucky to have one of those huge beasts of a lathe, take small cuts.
Work from the outside in. Use the edge of your tool to "catch" where you want to start, ride the bevel to the center, and keep working it like that until you hollow out the entire bowl. As I said earlier, there are many videos online showing the proper technique to do this.
Here is a video by Cap'n Eddie. At about the ten minute mark he started facing and hollowing the bowl. The angle of the camera I think shows real well in that video how to hollow.
Now, as with a lot of things in turning, different people have different techniques they like or dislike. Some people at this time would work a little at a time starting at the center and working out. Some people will cut into the bowl exactly where they want the inside edge of their sides to be and go from there. I like to take wide paths out from near the edge to the center and just keep working deeper and deeper. I leave the sidewalls thick until I am almost through hollowing. Then I pick up the sides and work them down as thin as I want them as I clean up the bottom.
As I work deeper, the deeper I go, the smaller the cuts I'll make. If I try to take too much at once while working more than about an inch past the tool rest, I get a lot of chatter. Chatter is the tool "bouncing" on the rest. With chatter, crazy things can happen, the least of which is a messy looking cut that will be hard to clean up later. So, the further you go over the rest, the more you need to slow down.
Actually, you could get a curved rest into this bowl. That would get you closer to the work and you could take more material at a time. Often though with shallow bowls, I don't bother. I'm not in a hurry and just take small cuts and enjoy myself.
When you can no longer see a recessed dimple in the center where you drilled the hole earlier, you are at the bottom of the bowl. Now you need to be careful or you'll turn right through the bottom. I have done that more times than I care to admit.
ACTUALLY
If you notice on this bowl, I was so busy trying to get good pictures that, if you notice the outer edge of the bottom, I turned through the bottom of the bowl on this one.
All is not lost though. Always look and see what can be done. Remember that a lot of things can be fixed when turning. I have even taken bowls off the lathe, sanded and added new bottoms to save an otherwise ruined bowl.
In this case, using a waste block saved me.
I just turned through the sapelle to the waste block. This left me with a sapelle bowl with a light colored cottonwood bottom.
Next you sand the bowl, everything that you can get to. This will be the sides, and inside. I am not getting into sanding techniques here because at this time I am not even happy with the results of my own sanding techniques on a regular basis. That is a work in progress that I may blog on in the future when I find something I am happy with.
After sanding, you finish what you can get to. There is any variety of finished you can use, varnish, oils, or some food safe finishes such as salad bowl finishes.
For this bowl, I plan on it being just a simple dish my wife likes to put in various places around the house to hold small items. For these, I use Johnson's Paste Wax.
After the finish is applied and buffed out, or dried if you use a finish that needs drying, remove the bowl from the chuck, and put on your flat jaws. I am lucky enough that I have two chucks so I can leave flat jaws on one of them just for this purpose. If you have only one chuck, you'll have to remove your regular jaws and put on your flat jaws.
Then you hold the bowl in the flat jaws upside down.
Be careful here and practice. Realize that the rubber on the jaws will hold bowls better than you think. Long ago, I cracked several bowls by clamping down too tight with the flat jaws. The thinner your sides, the less force you'll be able to apply without cracking your bowl.
However, the flat jaws do not hold a bowl as sturdy as your regular chuck. So take your time, take tiny cuts at a time, using the same method as you did earlier when you faced the top of the bowl, remove the waste block.
On this bowl, remember because of my mess up, I am leaving a bit of the waste block.
You can remove the waste block and make it flat. You can leave a ridge around the bottom to allow the bowl to appear to "float" on the table, or pretty much anything else you can imagine.
After getting it where you are happy with it, sand and finish the bottom.
And that is a completed bowl.
.
Next, I'll show another method of making a similar bowl.

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