From Log to Curtain Pulls
Woodturning on my Taig lathe
The trunk looked interesting enough to me that I hauled it home and cut it into lengths that would just fit the bed of my Taig lathe, then split the logs into quarters. By splitting the wood immediately after cutting into lengths, I hoped to reduce drying stresses, end checking, and related problems. To a large extent this worked. Before starting work, I split a roughly square chunk of each log quarter, again using a hatchet.
Splitting wood instead of sawing it means you know exactly where the grain goes. In the case of mulberry, one immediate lesson is that even when the outside of the tree is straight, the wood inside isn't necessarily straight. Look at the second log from the left in the photo for a good example.
My initial goal was to make a set of decorative curtain pulls, althoug I ended
up with enough wood to give blanks to others and contemplate other
mulberry wood projects.
Mulberry wood is quite
significantly harder than sugar maple, a little
harder than hornbeam and a little softer than black locust. Even so, so long
as you take only thin shavings, a draw knife works very well on it.
I held the far end of the blank with a dead center — more about that
later. The wood is hard enough that I had to use a hammer to drive the center
into the wood before mounting the center in the tailstock.
Just about any sharp pointed tool will suffice for rough turning wood, and
it will work fairly quickly. I ended up mounting the tool twice, once pointing
right, as shown in the photo, with the toolpost in the rightmost T-slot on
the cross-slide while I cut as close to the tailstock as the tool would reach,
and again facing left, in the left T-slot, so I could cut as close to the chuck
as was safe.
Parting off the ends of the blanks at this point serves two purposes: It gets rid of the ends that I couldn't turn to size because they were out of reach of the toolpost, and it gets rid of the small end-checks that have developed while the blank dried.
On some of my shorter blanks, I only parted off the end by the tailstock,
leaving the roughly-rounded end in the headstock unchanged until later.
Gunsmiths have long used gun drills through a hollow tailstock center in order to bore the length of a gun barrel, and this technique has also been used in the woodworking community for well over a century. Here are some patents that illustrate this, one old, one more recent:
I made my tailstock center from a scrap chunk of 1/2" steel. I drilled it on axis using the lathe, with a 3/16" hole drilled from what would be the working end and a 7/32" hole from what would be the tail end. The difference in diameters is so that any small misalignment where the two holes met would not cause any hangups when drilling through the resulting hole.
After drilling the dead center from both ends, I turned a hollow point around
my hole on the end. I made no effort at precision, but the angle of the cone
around the hollow center is approximately 60° and I also made a very small
chamfer on the inside edge of the hole at approximately the same angle.
The photo shows the center mounted in the tailstock, with a very long twist
drill poking through the hole.
This technique is called peck drilling for a reason! You feel like
you're pecking away at the hole, pulling out the drill, poking it back in, and
pulling it out, over and over and over. I think one important thing about
this method is that the drill is stiff enough that, if the hole begins to wander
just a bit from the axis, the drill cuts to the side just a little bit each
time you pull it out and push it back in, correcting any eccentricity that
developed during the previous peck cycle.
At this point, the wood is only about half-dried, so it is not done shrinking.
It's a good idea to let it finish drying before doing the finish turning.
From this point onward, the hole through the center of the blank is our
reference for the center.
I ground a tool I can fit in my toolpost that meets the wood in much the way a skew chisel is supposed to meet the wood, and it was a success, as you can see in the photo. The photo shows the finished end of one of my curtain pulls. I used a parting tool to define the surfaces perpendicular to the axis, and used my toolpost-mounted skew for the parallel cuts. The finished surface is mirror smooth to the touch, with no grain tear-out at all.
The fine shavings you see in the photo are from the final finishing passes, while the coarse curls are from the quick and dirty rough cutting passes. Even the fine dust is actually in the form of little curls. Unlike the dust you produce with a scraping tool, these curls settle out of the air quickly, and they tend to stream off of the tool edge into a fairly well defined and orderly pile on the lathe bed instead of flying all over the place. In sum, this is a really nice way to work with wood.
I ground the tool so it could be mounted for both left-hand and right-hand use. Whichever way you are cutting, always adjust the tool so its point of tangent contact with the workpiece is near the center of the cutting edge.
On an unrelated note, because I was working on a drilled workpiece and using a hollow tailstock, both drilled to the same diameter, I did the finish work with a piece of drill rod pushed into the workpiece and I oiled the tailstock. Technically, it's still a dead center, but I didn't drive it tightly into the workpiece, I merely mounted it so it gently brushed the end, and when I cut the flat finished face on the end, I even backed the tailstock off enough that I could use a parting tool all the way up to the drill rod.
Also, I did all of the finishing work at the tailstock end, reversing the
workpiece in the lathe after finishing one end so that I could finish the
other end. This way, all of the finish turning was concentric with the hole
down the center of the workpiece and none of the finish turning was done with
reference to the outside surface, a surface that was cylindrical before the
wood finished drying but was no-longer a perfect cylinder by this point.
I finished the pulls with walnut oil and left them outside in the sun for several days. The UV in the sunlight both served to brown the wood and to help the oil polymerize. Unfortunately, it rained one day, and this raised the grain on the wood, so I re-sanded them with just 600 and 800 grit paper, and then added a second coat of oil and put them out in the sun again. The result was very nice, as shown in the photo.
The photo shows these pulls against the outside of the ornate wooden chest that they are now part of. Their permanent home is inside that chest, working the curtain that is inside the door of the chest. The design of the pulls, with a flange on each end, is intended to reflect the design of the wooden door hinges on the chest.
I should have left the pulls out in the sun to get a bit browner so they'd be a better match for the mahogany of the chest, but they do their job, and except when you're actually groping for one of the curtain pulls, they're out of sight inside the chest.