On Mon, 16 Jul 2007 17:20:23 GMT, "Toller" wrote:
I found an unidentified root in the road (it is light colored, but turns
yellow brown about a day after being cut; anything jump to mind?) and
decided to make my first vase. It is about 4" diameter and 8" high. I ran
into three problems.
1) I could only manage to hollow out about 5.5". And even then I left a
little uvula in the middle that I couldn't get out noway. I don't think I
can go deeper than 5.5", but how do you get the center part out?
I've hollowed a couple dozen vases (for some reason, I tend to like
them better than bowls, YMMV), and what I've found works pretty well
is a lathe tool spin-off of the forsner bit idea. I've got a smaller
round-nose scraper (about 1/2" x 3/16") that I set directly in the
center, and use like an auger bit to get to my depth. That
effectively "drills" a hole with a slightly concave bottom that I can
work down to with other tools, and there is no nub to remove at the
end. The other suggestion you've already gotten about levering the
tool up into the nub works well also, but that is what I do with
bowls, not vases, as there is more room to work.
2) I had to leave most of it rough inside because I couldn't manipulate a
tool in there, and certainly couldn't get sandpaper in. Any tricks here?
I had a rough time with this as well for quite a while, and tried all
sorts of things to get sandpaper in there. What I found was that a
combination of two scrapers gives me the best results. For the sides,
I ground a scraper out of used M2 punch tooling (basically just a 1/2"
round piece of HSS) with a profile similar to the end of a
butterknife, and slid it into the end of a 4' piece of black pipe.
The cutting edge is a little different than you might imagine, and I
confess I stumbled on it by accident- rather than being relieved on
the bottom, it is actually a slightly convex angle (about 93-95
degress when looking from the edge.) I use it freehand (without a
tool rest) and let the bevel ride slightly below the center line. If
you move smoothly at the waist, you can get a really, really smooth
inside face with this method.
The bottom is done with a regular fingernail-profile scraper. the
only thing that will help you blend the intersection between where the
two tools is practice, but once you get it, it will be plenty smooth
for the inside of a vase.
3) I nearly lost it because the bottom became extremely uneven when it
dried. I did the best I could to get it back on the chuck square, but it
wobbled and I had to take more off the outside to get it round than
anticipated. I almost ran out of material. How does one handle that
properly? I am not sure a chuck (if I had one) would have helped, because
the top probably wasn't square either.
The way I handle it is to turn from wet to finished in one session- I
can see the arguments for the turn-dry-turn method when it comes to
bowls, even though I don't do that myself, but with something like a
vase, every little distortion is magnified signifigantly in proportion
to it's length. You do risk distortion in the finished vase by
finishing from green wood, but that's not always a bad thing. The big
trick is to avoid getting the lip around the top too thin, which will
allow cracks to start and travel down the length of the piece (in the
case of end-grain vases, at least)
If you really feel that you need to dry before doing the final
finishing, and I'm certainly not going to tell you that there is
anything wrong with that, I would remount the dried vase between
centers before trying to stick it in the chuck. Hopefully, you have a
spur center mark in the foot from your original roughing before you
put it in the chuck to use a a reference, and on the open end, you'd
need to turn a cone that you can stick into the mouth of the vase to
have something to press the tailstock against.
Once you have it between centers, it should be pretty easy and
straightforward to true up the foot and the the rest of the vase with
good support in place before remounting it in the chuck. Doing it
that way would not only be safer, but will preserve more of the wood,
if that is what you're trying to accomplish.
On the whole it turned out nicely though.
http://www.frontiernet.net/~toller/vase.jpg