Making a Petal Bowl, Part 1
01 / 20
In the spring of 2004 my work and studio was featured on the cover of the American Woodturner magazine. I received numerous inquiries as to how I made the forms that appeared. The two folders in this set attempt to describe…
02 / 20
…this processes. The first two photos are of the lathe, with the equipment and modifications showing. The lathe is a "Stubby 1000." The bed has been modified by cutting a passage from the auxiliary bed to the main bed. an indexing bar has been added to the side of the main bed, with adjustable stops. A low speed drive motor has been added with a foot pedal to control rotation. The spindle has been ex-tended to permit the router to get behind the…
03 / 20
…work piece. The spindle drive is also a indexing head with 96 stops. The plastic gizmo enables me to control the exact location of the cuts. The router jig enables me to control the depth and location of the cuts. There are various attachments that set limits to the cuts. More on that as we go forward. Picture three is the wall to the left of the lathe. There are three magnetic bars holding the small tools that I use, wrenches, keys, etc. So now we start.....
04 / 20
Being that my work is so precise, usually +/- .010", I always use kiln dried wood. The first step is to band saw the blank and run it through the planer. I fasten a 3/4" waste block to the face plate and mount it to the work. I have developed a system to get the faceplate located in the center of the work.
05 / 20
After mounting the faceplate, the piece is mounted to the lathe and turned to the desired diameter. I usually band saw about 1/4" oversize. An amount of waste wood is removed from the back to speed up the processes. Being that the piece is "hanging out" about 12" there is some variation if I attempt heavy cutting. I also square off the face edge. This can be seen two pictures on.
06 / 20
This is the design drawing. I have done dozens of these so I normally don't have all these dimensions. the piece measures 6" diameter x 2" thick. The drawing shows the center line and half of the piece. From past experience I have concluded that the "petal" should point to a place on the center line about 1/3 up from the base. Trial and error and experience locates the 4" point. The size of the "petal" and depth of bowl, locates the 2 1/4" point.
07 / 20
Using a measuring jig I set the stops at the predetermined locations. It is 3/4" from block to pivot point. See next picture. Here you can see the face cut. I always start out with a perfectly clean edge.
08 / 20
When working I always wear a air helmet with outside air and a noise canceling headphones with music. The actual cutting processes is sort of like watching paint dry. Press pedal, work turns, router cuts.
09 / 20
I usually remove just enough wood to enable me to do the work necessary. The remaining mass reduces vibration and prevents warping. The sequence of cutting is critical to the success of the piece. Sanding is to 180 grit to ensure a usable finish.
10 / 20
All wall thicknesses on this piece will be .100". I usually cut to .110" to leave sanding room. The router is on a slide that can be adjusted using the large nut and locking nut. The thread is 1/4-20NC. This equals .050" per revolution. I start cutting the "petals" by plunging the router to the finished thickness and lock the nut. I then continue the processes until the width is reached. In this case 3/4".
11 / 20
At this point I cut the first of the petal lines. This will give me a reference point later on when I do the undercut. On this piece I am using a .064 bit. The first cut is ALWAYS made crossways to the grain. If not the undercutting usually knocks off the bottom corner. A word about my sanding system. Three frames back you will notice that the sanding pad is on a long shaft. Usually the router jig is in the way and that gives me extra…
12 / 20
…space. I keep the pads in this cabinet. The grits go from 80-1200. Each bin has a piece of velcro on the front. I use the pad until it is done, then replace it. This also lets me know exactly which grit I am on, as there is usually no marking on the pad.
13 / 20
I then cut the back to its finished size. In this case until i reach the .150" dimension. What I haven't said is that as I go between cuts I move the jig to the proper stop. In this case I moved in in to the 2 1/4" stop. The bar extending out the back is a stop to control the outward travel of the router. This prevents accidentally cutting the rim. I use this stop for many details. By using two stops I can cut slots as seen in my 2004 folder # ???
14 / 20
The edge, where the bowl meets the rim, is rounded over. Sometimes I square it off and sometimes I leave it as is. In the next frame, the foot is formed using a round nosed scraper. I leave a small lip between the foot and the bowl for detail. At this point I re cut the scrap block to be concentric with the piece. This is important later on when I remount the piece in the vacuum chuck the finish the bottom.
15 / 20
Going from an inside cut to an outside cut requires resetting the holder and reversing the router. In the second frame you can see the router holder. The yellow pointer is used to adjust the tangentcy of the cutter to the wood. With proper adjustment I usually can get a finish that starts at 120 grit sanding. Inside curves and outside curves have different settings, due to different cutting requirements.
16 / 20
With the rim and back cut I start on the inside of the bowl. Here the bar controls the width of the rim. I create a groove about 1" wide and continue in until the wall thickness is .110". The next two pictures show how I measure the thickness.
17 / 20
I use a standard caliper that I have modified slightly. I have ground the fingers on the measuring end to give me exactly the the measurement that is at the gap. In the past I have cut a sample piece in half to verify this dimension. I have gone through too many pieces.
18 / 20
At this point I remove the positioning screw and move the jig to the back of the lathe. I install the harp and a tool rest to prepare to make the undercut. I have made a special tool for this. The tip is .040" thick and can reach in about 3/8".
19 / 20
This one is a concave curve. Others are straight, convex, and sort of a reversed hook. The only part that cuts is the tip and 1/32 on either side. All the rest is rounded and won't cut. Using the single .062" cut as an visual gauge, I start the cut. Stopping frequently, I proceed until I clear the wood in the slot to a depth of 1/32".
20 / 20
I then locate the inside bowl face and proceed cutting until there is .100" holding the rim to the bowl This is measured using my caliper that has been ground down to about .050" as can be seen two frames back. To see how this all turns out, go to the next folder, Petal Bowl 2