>I was turning a goblet last night. The stem wasn't that thin but the wood moved and the goblet started dancing. I felt like this could lead to problems so I put a piece of wood in my live tailscenter and covered it with cloth. Inserted this in the goblet to keep it from wobbling too much. I got to wondering what others do. This wasn't a particularly thin or very tall goblet.
Just for fun I would like to try one that's maybe a foot tall or more with a stem less than 1/4". My tailstock support wouldn't work for this because the force to keep the tailstock rotating would rip the stem apart(learned this is from previous experimentation on a different project).
My thoughts are to use the string support used when making tremblers. I also figure that I would need a steady rest when first hollowing the goblet head.
Loosely pack bathroom tissue in the goblet. Bring the tailstock up and apply just enough pressure to make the live center spin. You should be able to stop the live center with light finger pressure. Use a fair sized cone center so there is a good surface area of contact between the tissue in the live center.
Of course work from the tailstock towards the headstock in short increments completing the stem (sanding and everything) as you go. Work with sharp tools that apply pressure towards the headstock as you cut.
It is best to work with straight fine grain woods.
The goblet part is interesting. You need of good grip on the stock to hollow out and shape the goblet. Even so there is bound to be a fair amount of flex in the unsupported end of the wood.
Make the stock round with the tailstock used for support. Move the tailstock out of the way and start hollowing. If there is any vibration (there almost certainly will be) have someone apply pressure to the round turning about 6" from the bowl of the goblet. The pressure can be applied by sticking a piece of wood between the ways and leaning against the spinning wood. You could also use a steady rest but having an assistant is more fun and makes for a quicker job.
I regularly make wands of small cross section with light stabilizing pressure from the tailstock. Most are 3/8" x 10" but on occasion I have done 3/16" x 14". I say this because I know if I can make a turning like that then anyone can.
>I like to use the live center. I use a Oneway live center with a bull nose cone. It seems to give me no problems, but then again don't turn my stems really, really thin.
I try to make the stem the very last thing I cut.
This gets into some obvious problems, but I try to work most of the base prior to thinning the stem.
>When I do a goblet, I hollow and finish the inside of the bowl first. I Then use a large cone tail stock that I insert into the bowl. Then I turn and finish the outside of the bowl. Now I thin down the stem and start forming the base. Once the stem is about 1/2" thick or so, I concentrate on the base and finish it. Now I hold my breath and use 60 grit sand paper to finish sizing the stem. I hold the two ends in each hand with the stem held in the loop which makes sort of a "spindle support". The longest stem I've turn was 8" and 3/16"-1/4" thick.
>At the IWCS meeting in Tacoma last August, Jim Osenton of Canada demonstrated turning very thin stemmed wedding goblets. Jim used a tennis ball with a + cut in one side to accept the live tail center. The tennis ball was then inserted in the mounth of the goblet bowl to help stabilize it and prevent the vibration you are talking about.
After returning home, I tried this on several goblets and found it worked every bit as well as he made it look.
I assume he applied just enough pressure to stabilize the goblet without making the tailcenter spin. I've heard about the Tennis ball but didn't have one handy. The stem wasn't thin enough to be a problem on this one but since the goblet top was moving off center I was concerned that it would decide to go really off center and break off as the rpm's came up.
>I don't remember whether he had the tail center spinning or not, but I did have it spinning when I tried out the technique on a couple of goblets that I was making. Too stiff of a tail center, however, might prove a problem.
I don't remember exactly what I was turning but I stopped the lathe to look at the piece and when I turned it back on the headstock started the tailstock didn't start as quickly and it twisted the piece in half. The powermatic is variable speed and I may be able to gradually raise the speed and not have the same problem. I'll hang out at the tennis courts and chase balls until somebody has pity and gives me one.
>John, another way to do it is to turn and finish the cup, then bring up the tailstock and tape the cup to the cone center (the Oneway is great, but you can fashion your own to meet your needs). Then the piece by backing off the cone just a little. Works great.
I got this from Pete Buccellato at our chapter meeting. There's a write-up in our March newsletter, follow the link.
I'll have to give that a try. I experimented with tension years ago but again had problems with the live center twisting the piece apart. I now have the Powermatic copy of the Oneway and it spins with less force so it might work. Obviously it did For Pete. I actually considered gearing the tailstock to the headstock so they spin at the same rate but I'll have to retire to have enough time to do that.
Jean Francois Escoulen turns trembler goblets using nothing but a Bedan and some string supports. The cups on his goblets are much smaller than mine and that may be part of my problem.
>Pulling tension on ANY long spindle turning between centers is the better way to go. The problem is doing it. The adapter for the Oneway tail-center and a scroll chuck are the easy way to do it for long spindles. For a goblet, you can make an expanding internal chuck out of wood with a center-screw that is held (and pulled) in the tailstock with a Jacobs chuck.
If you are going to use light pressure to hold the goblet, rubber balls from the toy store are better than tennis balls because they are softer. Hollow ones work really well. Use a penny for the center contact and enough tail pressure to expand the ball into the goblet. Punch a dimple in the middle of the penny for the center. Don't worry about the tail center spinning or not. Put some beeswax on the tip if it doesn't.
There are times when a dead-center works better than one that spins with the wood. The slight twisting (torque) on the wood can serve to make it stiffer and easier to turn. I would always try both before making up my mind that the live-center is better.
Using a wad of paper towel is too simple. There are other ways to do it. Some of the things that I have used are:
- those "Goblet Buffs" from Bealle
- sponge dishwashing pads
- sponge cosmetic pads
- a ball of rubber bands (size is variable with the number of bands and how many years you have been collecting)
- a soccer ball (for very large goblets and thin bowls)
- foam insulation tape wrapped around a ball of masking tape
- double thickness of toy baloons with a penny for the center contact.
- a potato carved to proper shape and size with a peeler. This one is the 1st choice in Idaho and spelled "potatoe" if your last name is Quale. Use a bottle-cap to support the center.
Some of these have the advantage that they can be shaped to fit the inside of the goblet. That can give enough support that the bottom of the goblet to be turned very thin from the outside.
>Another way that I have heard about but haven't actually tried.(that never stops me!) Spray urethane sealing foam into the bowl. it's form fitting and light weight, but has adequate density to drive the goblet and hold to the tail center. Probably another method too much sugar for a dime. Arch
>Make sure you put a piece of SaranWrap inside the goblet before using the foam, or use the foam the won't bond to the wood. Otherwise it will take a lot of sanding to get rid of it.
a string steady rest is very easy to do in less than 5 minutes, and works fine. there's no pressure on the piece, and you can turn long and thin pieces by adding as many steady rests as you need.
I have a page on my website which explains how to build this kind of things.
follow the link, then click on "trembleur" in the left menu (page in English of course)
