1st Bowl and Question!

[ke4rdb]

Turned my 1st big (6") bowl this weekend...cheaped out and used popular....it came out OK, along way from great, it gets a little scary when whe you start to hollow deep. And I do have to admit I had to chase down the bowl when it came free from the chuck and went spinning like a top across the shop (also screwing up the tendon) note to self ...when you start to hear wried noise when hollowing, stop and check.....

I bought a 3/8" Ben. Best bowl gouge and hated the way it was ground...reground into a stright accoss profile with swept back sides and didn't have a catch since most of the cutting is with the sides anyway...will try to get a photo and upload a pic of the gouge.

A quick question! Do you turn a tendon (spigot??) on the bottom of the bowl to place in a chuck to hollow...and if you do how do you keep the chuck jaws from marking the tendon?

James

[Russianwolf]

While I'm no expert (turning one hollow form myself), I think you are talking about a tennon. The way I've seen it done is that once you have the outside turned to your satisfaction, you then turn a circle into the bottom about an 1/8th inch deep (you now have three circle to make up the bottom, two that would touch the counter and one that is recessed).

You then have a choice to use your chuck to compress the inner portion, or expand against the outer portion. either way your chuck is in the recessed circle and will not mar the visible bowl features. Any marring that does occur to the non-visible portions can be sanded away later if you wanted too.

[RayintheUK]

You can vary your holding technique only according to the type of chuck and jaw sets that you have. A spigot (or round tenon) needs turning as the outside is shaped - either when the bowl blank is mounted on a faceplate or a screw chuck. When it's reversed for hollowing, you can then either pare it off, or pare through until you're happy, then saw it off and sand flush.

I've got a set of external dovetail jaws for my chuck, so I tend to use a dovetailed recess to expand my jaws into. These can either be left as a "feature" (good place to sign the work and note the species and date), or turned off with the bowl held in a set of Cole jaws.

Here's a picture of a 15" diameter holm oak bowl with such a recess shown. I tend to dish the base, so that it will sit nice and flat.

HTH Ray.

[gerti]

I usually use a Longworth chuck to clean up the bottom. That allows me to use a beefy tennon and remove it (carefully, that chuck is mean) afterwards. See here:

http://gerd.knops.org/shopnotes/?p=13

[guycox]

You can vary your holding technique only according to the type of chuck and jaw sets that you have. A spigot (or round tenon) needs turning as the outside is shaped - either when the bowl blank is mounted on a faceplate or a screw chuck. When it's reversed for hollowing, you can then either pare it off, or pare through until you're happy, then saw it off and sand flush.

I've got a set of external dovetail jaws for my chuck, so I tend to use a dovetailed recess to expand my jaws into. These can either be left as a "feature" (good place to sign the work and note the species and date), or turned off with the bowl held in a set of Cole jaws.

Here's a picture of a 15" diameter holm oak bowl with such a recess shown. I tend to dish the base, so that it will sit nice and flat.

HTH Ray.

[ATTACH]7362[/ATTACH]

Nice bowl --

One comment that I'd like to make about the tennon is that larger is not always better. Notice the depth of the dovetail recess in Ray's piece with respect to the overall size of the bowl? My guess is that it's only about 1/4" to 3/8" ...

A tennon for fairly good sized bowl needn't be much "deeper" than that. With the dovetail, squeezing down an a really deep tennon will have a tendency to get pried off the base of the bowl. especially if the tennon is near the max capacity of the jaws.

What is important though is that the tennon and chuck be all squared up.. One good technique is to turn the tennon with a 1/4" step. This step provides a paralelll surface that will mate to the outemost edge of the jaws. _____
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{actual bowl bottom}