Been awhile since I had shop time. The last three weeks have been pretty much on call and vacation with the kids so it feels good to get back to work on some things.
As I progress on the lathe, I have been wanting to experiment with more delicate turnings. Much of my work has been more heavy handed so far and I wanted to work with curves, thinner walls, and trickier hollowing. I had a small log I discovered that had been sitting in the basement since the beginning of time so I mounted it and went to work.
Here is the log mounted after roughing the bark and working some of the knots down.
For those new to turning or not familiar with lathe operation, a piece such as this is out of round. Care has to be taken when moving the chisel into the piece because the chisel will connect to solid mass, then air, then solid mass again. One way of determining how far to move your chisel in, without jamming the chisel in too far, is to watch the blur of the piece while it is spinning.
The blur lets you know the largest diameter of where the log will have some solid mass. If you move in slowly, you can touch the edge against the piece and your chisel work will go much smoother. In the beginning, large knots and bark can play havoc if you slide the chisel in too fast. Watching the blur helps you determine the safest point in which to make contact.
Since the piece is to be hollowed, I needed to eventually mount the log on my 4 jaw chuck. The idea is for the chuck to hold the piece solid and remove the tailstock to gain access for hollowing. Rather than trying to constantly measure the thickness of the log in various places, I used a set of outside calipers to determine the max width allowed to chuck the piece and would check and recheck the log until the log was slim enough to chuck.
Couple items I learned with this project -
1. When moving a piece from headstock to jaw chuck, it is easiest to re-establish centering by keeping the jaw chuck loose and sliding the head piece into the chuck, then moving the tailstock into position and inserting the tail stock into the same entry point already established, then tightening the jaw chuck. If you mount the piece jaw chuck first, the tail portion will be out of alignment.
2. I need a spindle steady :) The log was too long for the jaw chuck to maintain a steady spin alone so I had to work on making the piece shorter. The way I approached this was to part the piece out so that the part was made in front of the piece and remounting it, rather than parting at the end of the piece.
The logic behind this is that when the log is on the spindle, I can’t make a good even surface on the end. By parting the piece towards the front, the edge will be perfectly flat for re-chucking. This will give the jaws a better grip on the piece.
I roughed out the shape using the roughing gouges, followed by scrapers and the skew chisel. The skew chisel is probably the trickiest to learn on the lathe because it can catch on the piece very easily, but they produce a very fine surface and they cut down on sanding time dramatically. I used a 3/8 bowl gouge to shape the lip and hollow it. The lip was the most delicate feature as its thickness was almost as slim as a dime. Any catch on the chisel and the lip would break off. I could only hollow about half the depth with the bowl gouge. I had no wiggle room after that. I will have to invest in some hollowing tools in the near future.
This is the piece on the lathe, shaped and partially parted -
I have read that applying a finish while the piece is in motion works well in creating an even finish. I found this to be true but learned that spraying a polyurethane is not the brightest move. The spinning causes the poly to be slothed off. On a good note, I do have a shirt now that is resistant to stains :)
This is the finished piece. I have my own personal critiques of it that I will work to correct in future turnings but I am happy with the overall design. It should make a decent weed pot or something of that nature.
Thanks for looking,
-- There is little that is simple when it comes to making a simple box.