Router Plane

Monday, March 18, 2019

2 Piece Turned Bowl - #3 Completing Phase 1 Turning


Turning the top half follows just about the same process as the bottom half.  However, in looking at the previous post I think there were some intermediate steps in turning the inside face of the bowl that I should have included.  Having a nearly identical piece gives me that opportunity to fill in that gap in the process.

I am going to pick up after turning the outer face and right after mounting the blank using the large jaws on the chuck.  Here it is ready for me to start turning or dishing out what will be the inner surface of the bowl.  The 2½” drilled hole used to hold the blank in the chuck using the intermediate size jaws to turn the outside face of the bottom is clearly visible.


Leaving a flat surface about 5/8” wide for gluing the two halves together I started turning away the inside of the top.  My goal here is to mirror the outside curve leaving a wall thickness of about 3/8”.  If you are really, really good you can probably gauge the thickness by feeling both sides.  Me, I rely on a gauge to get that constant thickness.  I have three different ones but here is what was used on this bowl.

Rather than take off material in layers all the way across the face from edge to center I work to a finished depth from the outside in.  That’s because as material is removed you decrease structural integrity which makes the piece less stiff which can allow the piece vibrate via harmonic chatter giving you a turned surface with all kinds of hills, valleys, ridges and even spirals.  Below are two photos showing how I worked my way toward the center roughly a third at a time.

Below on the left you can see that when I get right at the center, I leave a little nub.  The top of this nub is the bottom of original drilled 2½” hole.  It acts as a reference so I can tell how far I have dished down into the blank. Once satisfied with where the turned surface is, I take the nub off and finish sand the surface as shown in the right photo.  Don’t worry about the little hole in the center it’s going to go away soon.

To make sure the glue band at the edge is square with the bowl axis I start by marking it up with a pencil. Next, using a straight board that has some sandpaper glued to one end I hold the bare wood up against the right edge and use the sandpaper end to remove any irregularities and flatten the band.  When done I have a good glue surface square with the bowls axis.  Well, almost square as there is a tiny bit of taper toward the inside since there is only sandpaper on one side.  That’s not a problem because I want the outer edge tight and can live with a hairline crack on the inside.  If I wanted it truly square a second piece of sandpaper would need to be added to the opposite end of the board.

The last step on the top for now is to drill the center hole.  Here you can see where the Fostner bit has just started to break through the other side.  It will be finished when I flip the blank over, remount it on a different set of jaws and finish turning the top’s outside.


With both the top and bottom blanks finish turned on the inside and mostly turned on the outside below are the two halves in the same orientation as they will be when glued together.  On the left is the top while on the right is the bottom.


Setting the top on the bottom looks like this.  The bottom needs have final shaping done to the foot and the top needs to have the foot completely removed.  Also, the outer edge is a little fat so once the halves are glued together that will have to be refined.  Speaking of the edge I am thinking about doing a turquoise inlay band where the two halves come together.  No decision on that but I am considering it.


Now it’s time to switch out the large jaws on the scroll chuck and go to the extra-large jaws.  Once that’s done the bottom blank is mounted and the finish turning done to the foot.  The work here included making the foot about a half an inch smaller in diameter, cleaning up the inside of the foot to remove the hole I had drilled earlier and adding a shallow recess to delineate the rim the piece will set on when done.  The left image shows what the foot looked like earlier, right after I had drilled that hole and the right shows the finished bottom.


Next up is the top going though a similar process with a slightly different result as there is no need for any of the foot to remain.  Left photo is top mounted in the extra-large jaws before I started turning and the right photo is when the turning is completed.


Stacking the top and bottom halves together like they will be when done looks like this.  In looking at the profile I can see the top curve needs some more help.  It is not as smooth as I would like.  If you look about an inch in from the outside edge there is a little bump that needs to be smoothed out.  I am not too worried as once the two halves are glued together, I will need to finish the edge and its transition.

This completes the Phase 1 turning which is as far as I can go for now.  Next is to stain and finish the completed inside faces of both halves.  No way that can be done later through the small opening in the top half.

Next up – Inside Finishing & Making a Live Center Cone

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