Simple Jig for Reverse Turning of Tall Vases

[Dennis J Gooding]

This technique is applicable to tall objects such as vases where the inside diameter of the bottom is equal to or smaller than the inside diameter of the neck. I have only used it for small objects under about 10 inches in length, but it may be practical for larger pieces. The figure shows an example of a small vase and the jig used to turn its bottom. The jig consists of a cylinder with a tenon on one end, if required for chucking, and the other end trimmed to fit snugly inside bottom of the piece. The portion near the neck of the piece is trimmed to a loose fit. A shallow notch is turned just inside the smallest point of the neck and a coiled rubber band is forced into the notch to form a grommet. The depth of the notch and the size or number of rubber bands is adjusted until the jig can can be twisted with some effort through the neck of the piece.

 

[Bob Brown]

Is this meant to be a jam chuck in order to remove tenon and finish the bottom.?

 

[Dennis J Gooding]

Is this meant to be a jam chuck in order to remove tenon and finish the bottom.?

Bob, In effect, it is a sort of a jam chuck. However, it has the advantage of not requiring perfect sizing of the chuck at the neck of the piece. Also, the rubber band grommet, when placed a bit below the minimum neck opening, will resist withdrawal without having to jam an all-wood jig tightly into the bore, with the risk of cracking the piece.

 

[Bob Brown]

Bob, In effect, it is a sort of a jam chuck. However, it has the advantage of not requiring perfect sizing of the chuck at the neck of the piece. Also, the rubber band grommet, when placed a bit below the minimum neck opening, will resist withdrawal without having to jam an all-wood jig tightly into the bore, with the risk of cracking the piece.

Thanks, have you tried the rubber tubing used in hospitals to wrap around your arm when blood testing. They may be to big.

 

[Dennis J Gooding]

Thanks, have you tried the rubber tubing used in hospitals to wrap around your arm when blood testing. They may be to big.

No, I have not. I have on occasion found O-rings from my modest collection that worked with a bit of adjusting of groove depth.

 

[Dennis J Gooding]

The first photo shows some other examples of the jig described in the first post. Some have been used several times with trimming and new notches as needed to fit the turning. The second p;hoto shows a variant that I have used when the inside diameter at the bottom is slightly larger than the neck opening. I attach an expanding disk to the bottom of the jig. It is designed to expand to the size of the bottom of the piece yet with enough flexibility to be forced through the neck of the piece. In the example shown I have used a notched circle made from an old plastic key card. A long-jawed inside caliper is useful here to determine the required diameter of the circle. Otherwise it will be a trial and error process.

 

[Randy Anderson]

I use a similar setup to finish out vases and such. Very handy. A few different main sizes and different lengths like yours above and then wrap a 1" wide piece of the rubber drawer liner around 1 or 2 times till I get snug fit for the neck. Also put a small square of course grit tape on the end of the stick so it doesn't slip on the inside bottom of the vase.

 

[Kevin Jenness]

I've been using the Kelton mandrel woodchucker mandrel. It seems to be unavailable in the States now but it's not too hard to make a replica with a wooden shaft and neck cone secured with grub screws. The Kelton version accepts any 1/4" shank sanding pad/extension. Jamming the bottom of the workpiece directly against the tailstock works better for me than pressing against the shoulder with a cup chuck, especially on thin, flexible pieces.