Bowl Tenon vs. Foot

[Brett Bobo]

When is a tenon used as the foot of a bowl or is it common to create both a foot and a tenon for all bowl diameters? For example, with the Nova 4 jaw chuck, the maximum diameter is about 2 1/2" so in order to have a larger base/foot for a larger bowl, do you turn a secondary tenon, now the foot, for bowls of a larger diameter and then remove the tenon after the inside of the bowl is complete? Can a 2 1/2" tenon be used (is it safe?) for bowls as large as 16" in diameter? Also, is there a standard for the size of a bowl's foot in relation to the bowl's diameter or is it just preference based on the look of a bowl?

Is the primary use of the cole jaws intended for removing the tenon, assuming you have a separate foot?

Thanks,
Brett

[Thom Sturgill]

Generally the rule of thirds would kick in so a 15" bowl would have a 5" foot. That said many turners prefer little or no foot at all. Depending on usage - art piece or tableware, you may not want any foot.

If making a large foot such as mentioned above, consider using a mortise rather than a tenon if you have dovetail jaws.

[Scott Hackler]

Typically I dont leave a tenon on the bowl/projects. It almost always gets turned off as a finishing step. Someone once meantioned that the sign of a "beyond beginer" turner is leaving no trace of how your project was attached to the lathe. I would agree and it really dresses up the work as well.

Now having said that, I have left part of a tenon on a bowl as a foot for several reasons. For example, I recently did a wood trace with a fellow member in Hawaii. In this trade he graciously sent a small square of dried Koa. Well to me (in Kansas) Koa is like having a chunk of wooden gold, so when I made a "pocket change bowl" out of it, I savaged most of the tenon and finished it off as a foot. Worked well for this project, but as a whole I dont leave the tenon on or make a foot. But that is just me.;)

[Wally Dickerman]

What you really need for turning larger bowls is a larger set of jaws for your chuck.

Sure, lots of folks re-turn what was once the tenon into a foot. Why not?

Wally

[Ryan Baker]

A chuck tenon never makes a suitable foot IMHO -- very ugly. It is common to return the tenon into the desired foot/base once the interior is done. That holds true if a recess is used as well. For larger turnings, you need a larger tenon to be safe. 1/3 to 1/2 the diameter is a good range. That means you need larger jaws for your chuck. Lots of people have turned a 16" bowl with 2" jaws, but no, it is not a safe thing to do. Cole jaws are one of many ways to hold the work to return the base, but to me they are one of the least useful methods.

[Michael Mills]

You don’t say what chuck you have but if it the Nova SN2 you may want to take a look at this ebay listing. Search "Jet Nova Premier Powergrip Jaw by Teknatool" they are about $45 with shipping, in a store they are about $70 with tax and shipping.
Yes, I know it says Jet (Jet is a distributor for Nova chucks, they are in the original Teknatool box). I bought a set a few months back and they are great. I have them on my SN2 and the 50mm set on my G3. The powergrips are NOT for the mini or G3 chucks.
Per the Teknatool website for the SN2
50mm jaws-up to 12" diameter for a bowl, or up to 6" length & 4" diameter for a spigot.
PowerGrip-up to 29" diameter for a bowl, or up to 19" length & 6" diameter for a spigot.
Mike

[GLENN THOMAS]

Bret,

Here's what works good for me.

Once the blank is round I start at what will be the bottom.

1st I turn the tenon, next I turn the foot of the bowl and then the body of the bowl. This basically gives me a solid bowl with a foot and a tenon on the bottom of the foot. Having a seperate tenon and foot allows you to make the foot any size you want.

After I hollow out the bowl I mount it on my Cole Jaws and support the tenon with the tail stock. With the support of the tail stock I remove 90% of the tenon and then remove the tail stock.

The cole jaws usually hold good enough to remove the little button that is left over from the tenon. If my foot is going to be smaller than the tenon sometimes Ill just cut away part of the tenon and blend it into the body of the bowl.

If you remove the tenon from the bottom as opposed to removing it from the side the force of your tool will push the bowl into the cole jaws. If you tried to remove it from the side you risk pushing the bowl out of the jaws. Besides cutting into the bottom will allow you to cut the side grain as opposed to cutting from the side which will have you cutting into end grain.

Be sure not to exceed the max speed for you cole jaws. They tend to let go if your RPMs are too high.

Hope this makes sense.

GT