I have made a few vases and hollow forms over time. I usually leave them on the tenon all the way through to completion of the outside finish, and then part them off. However, in some cases, some additional work is required on the foot of the piece, which is now tricky.
The top is finished, and any contact with a hard surface will leave marks, especially when lacquer has been used. So what to do?
I cannot claim the original idea for this, I did see something very similar on another turner’s website (and if I can find the time and patience, I will quote it here). In any case, here’s my version of the bottom helper:
The main shaft is a piece of broom stick, but anything sturdy and not too big will do. The length is determined by two factors: the distance between centres on your lathe and the biggest piece you are likely to use it on. At the far end, I have mounted the broom stick in a left over tenon from a candle stick (but any tenon will do, just don’t use soft wood), thus allowing the helper to be mounted securely in a chuck. This also means you have to allow for the chuck when determining the length.
The near end is covered with a small piece of anti-slip mat, but anything rubbery and soft will do.
The sleeve is a piece of soft wood, drilled to run easily, but without too much clearance, over the broom stick, and turned into a cone on one side. Then a whole is drilled in to hold the screw. In my case, this screw was salvaged from an IKEA desk. The important bit here is to use something quite large, so that it has plenty of grip into the wood of the sleeve. Obviously the whole in the sleeve needs to be just slightly larger than the core diameter of the screw. The tip of the screw is rounded so that it will hold the sleeve firmly in place without damaging the shaft.
How to use: mount in a chuck and use your tail stock to ensure it is running true. Then move the tail stock back, loosen the screw in the sleeve and move it up against the chuck. Now place your vase or hollow form onto the shaft until the bottom makes contact with the rubber pad, but without applying any pressure. Now move the sleeve into the opening of the vase and only secure the screw lightly. Bring up the tail stock, centre the foot of the work piece until you are happy. Now apply pressure from the tail stock (this is what will allow the rubber pad to transfer rotational force), and finally adjust the sleeve so that your vase runs true, then secure the screw.
You can now work on the foot until finished. This should also explain why the sleeve has to be made from soft wood: if it presses against a harder wood, it will be the sleeve that gets impressed and not your work piece. If you are concerned about leaving marks, you can cover the conical part with the same anti-slip mat or some other cloth.
Note: This does not hold your work piece very firmly, therefore you must take very light cuts.