Archive for November, 2010

Turning BowlWoodworking Project - Part 2 - from Jet Tools

Next step is to move the tool rest across the front of the piece, about a quarter inch away, so that the tool is cutting right at the center line with the tool handle held level. Turn on the machine. Before I cut out the center of this I'm going to make a peeling cut all the way across the face of the piece.

By placing the bevel parallel to the surface I want to lathe, and not changing the attitude of the tool, I should be able to make one continuous cut. I'm sliding off it so I'm going to come back and pick that up again. This should be a very fine, light cut, leaving a good clean surface.

Once I have that done, I'm going to mark the rim now and then I'm going to start hollowing out the center. To do this, I'm going to put the tool handle way over, about 45 degrees, with the flute facing in. By doing this and holding the handle level, I have much more control. I initiate the cut, roll the flute up and bring the handle around. As I do that we get a perfectly clean cut all the way through. What's happening is we're creating a little ridge, and then as we roll the flute up we're putting the bevel under the cutting edge and getting a nice clean surface. Holding the handle level is an easy reference to remember.

By doing a lot of shallow plates like this, you get in the habit of making these movements. Once you go deeper it becomes more difficult. It doesn't have to be a heavy cut and we don't want to go real deep. Now, if as you are doing this you find that your cut is making too deep a radius, back off and don't go all the way to the bottom. Expand your diameter and then come back and finish up by making it deeper. If on the other hand you find that you are coming too far out and not going deep enough, what you want to do is put the heel up here and pick up the fly. This will avoid a transition line. But you are better off in you can do one continuous cut all the way through.

As you are bringing the tool handle around you want to continue to roll the flute up and push it across the surface. What you are looking for is one continuous curve that goes from rim to rim.

We are approaching the bottom of the hole now and as we get closer you'll find that you'll cut right through it and the tool stops cutting once it passes the center line. Of course, that is because once you've past the center the blank is rotating up away from the cutting edge and not into it. This will leave one continuous cut all the way through the bottom.

As it starts vibrating when you get out towards the rim, you might want to put your left hand behind the piece right at the rim just to support it and reduce some of that vibration. That should leave a nice clean surface. I've got one little ridge in here so I'll make one last cut - and we are ready to sand it.

Pull the tool rest out of the way, grab some sandpaper and of course a dust mask. Okay, that's about ready for a finish now.

Turning a BowlWoodworking Project - Part One - from Jet Tools

You can draw out the circumference then freehand it on the bandsaw. The next step is to drill a hole in the plate so we can attach it to the screw chuck. But before we do that we want to measure the length of the screw so that we don't drill a hole all the way through the blank.

Adjust the toolrest so it's just below the center. Mark the center and adjust the toolrest one more time and then with our caliper set at about 1 inch, or whatever works for the particular chuck you are using, and make a mark. We'll come in with a bedan tool. We can speed this up now to about 1000 or 1500 rpm and make our recess. This is basically just a scraping cut. Then outline where our foot is going to be and leave at least a half inch. Now we can pick up our bowl gouge and start shaping the bottom of the plate.

We are going to start with the bevel up against the material and the tool handle against our body - and very slowly and carefully roll the tool over until we start cutting. And we want to keep the tool handle perpendicular to our body. Use our full body to rotate so we get a nice clean curve all the way from what is going to become the foot up to the rim. These don't have to be real heavy cuts - we are more interested in finesse than heavy cuts. Now we'll stop and move the toolrest a little closer so that I have more control, and continue that same cut.

As I get close to what's going to be become the foot, I'm going to detail that just slightly. In order to do that, I'm going to take just the tip of the tool and roll it in, just to give me a little rise. This will create an additional shadow line and make it appear a little deeper.

Once I have the basic shape that I want, I'm going to move the tool rest and lower the tool handle so that I can make a nice clean shear cut for a finish. This will produce real fine, angel-hair shaped shavings. You'll also get rid of all those little scratch marks or ridges that have been left in the surface. Once we've made that finishing cut we should be rid of most of the ridges and have a really nice surface that doesn't take much sanding at all.

Now we'll unscrew the plate from the screw chuck and we're going to place it flat on the lathe bed. We'll take the screw out of the chuck and remove the chuck from the lathe. We're going to completely close the chuck and drop it into the recess. Once we have it in the recess we'll open it just a little, make sure it's properly seated then tighten it up. It's better to put it down flat on a surface than try to attach the plate to the chuck on the lathe. This way you'll get it properly seated.

We're going to place the tool rest so that we can trim the perimeter of it about a quarter inch from the surface. Spin it a couple of times to make sure it's going to clear. Then I can turn it on and with my tool handle way down, I'm going to trim the edge. This has to be a very light cut so that you don't pick up the fibers of the wood and rip them off. Once I've trimmed the edge of the material, I want to check it by hand and make sure I've gotten rid of all the saw marks - and here we have a few. You never want to do this with the machine running, you always want to stop it. I'm making one more pass - and I believe we're clean. (Continued in Part Two.)