Bowl turning

[Dan Williams]

When turning a bowl or for that matter anything. Do you get a better grip with a tenon or expanding the chuck into a recess ?

[Mark Cothren]

Tenon for me...

[Gordon Seto]

Dan,

The most important factor is the shoulder that sits on the jaws.

Gordon

[Dan Williams]

Gordon can you explain that. Sorry but I am nwat turning

[Dan Williams]

New at turning

[Stephen Hibbs]

I've never tried expanding outwards, but it seems a tenon is best since you risk ripping the wood apart if you expand, but just compress it with a tenon.

[Neal Addy]

I have used both ways depending on the situation but a tenon is my preferred method.

[Keith Burns]

Tenon.......

[Gordon Seto]

We all know that steel jaws are much stronger than the wood they are holding. If we grip too tight, we can crush the wood fiber in compression mode; or split the bowl in expansion mode. When the wood blank is subject to lateral force, the side that is subjected to the pushing is pulling out from the chuck. The opposite side is subject to pushing force towards the chuck. The shoulder that sit against the top the jaw would give you the leverage to resist the compression force. When chucking fails, I have never seen any jaw damage; it is always the failure of the wood. Therefore the wood needs all the help it can get.
Probably someone can explain better than I do. Hope I didn't confuse you more.
The importantance of the shoulder in chucking probably is included in most of the bowl turning videos - Bill Grumbine, Mike Mahoney etc.

Gordon

[Malcolm Tibbetts]

Dan, for bowls, a tenon is probably better, but don't create a tenon that "bottoms out" in your chuck. The outside portion of your chuck jaws should make contact with your bowl bottom, instead of the tenon end making contact with the inside of your chuck. For large platters, an expanding grip seems to work well (the larger, the better); it creates a wider grip, closer to the outside diameter and therefore provides more stability.

[Steve Schlumpf]

Like Neil I have used both methods but find the tenon works best for me. When I first started turning bowls I only used expansion and if I had a bowl come off the chuck it usually blew out a piece of wood preventing me from using that blank again. If a bowl came off while using a tenon I could glue the tenon back together or just turn the tenon down a little and re-use.

[Bernie Weishapl]

Most times I use a tenon but if I do plates or platters I expand the chuck into a recess.

[George Tokarev]

When turning a bowl or for that matter anything. Do you get a better grip with a tenon or expanding the chuck into a recess ?

I hate the word "grip." It's thinking grip that causes you to crush or split out wood by cranking the handle or Tommy bars. You want to think rigid mount, and that is the result of right angle faces mating with the chuck. The shoulder on a tenon or the bottom of a mortise should be firm on the wood, and the jaws firm at 90 (+ or - for a dovetail) the other way. Firm and rigid.

I like recesses because they help me visualize the piece better. No extra stuff in the way, just a smooth transition. They also maximize the depth of the average bark-out bowl, because they're gripping already where a tenon would still be looking for a shoulder. There's also no need to reverse after hollowing, because I can finish them before I hollow.

I think most people got into tenons because they start between a drive center and the tailstock, and it's tough to get a good mortise done that way. My first chuck had a pin chuck as an option, and I quickly learned that it was both secure against dismounts and capable of holding the rounded piece on its own while I made a mortise. It was, however a collosal PITA to dismount the pin chuck and transition to the dovetail jaws, so I bought my first scroll chuck when I began turning bowls steadily.

I do a lot of weird things like turning outside/inside/outside on pieces like the dishes and boxes, so I favor smooth wedged grips over those which mark the wood. Means never having to "settle" for near-center on a remount, because the smooth jaws seek the best average, and don't fall into prior dents.

[Glenn Hodges]

Dan, I use tennons. On very large bowls I use faceplates because I have had tennons break, and had the bowls go flying. This adds excitment to the job of turning, but at my age I have no use for this kind of excitment. You might like to glue a piece of wood on the bottom of certain pieces to make a tennon.

[Christopher K. Hartley]

Dan, on most of my bowls I use a tenon grip; however. there are those cases where the tenon material may be a bit soft and there, I use the expansion grip. I have started turning my bowls so that I can use either tenon or expansion at the start. In this way I don;t get caught off guard.:)

[Bill Grumbine]

I am a strong advocate of tenons for bowls. A tenon gives you a very good grip on the blank, and you know exactly where you are with the chuck and the bottom of the bowl without any guesswork. With a little bit of planning, the tenon can be incorporated as a foot or other type of feature. It can be turned down to follow the curve of the bowl, or it can be turned away.

For plates, I like a recess for the same reasons Malcolm has mentioned. If it is a small plate, I will go for a tenon, but for most plates a recess works better because of the stability issue.

Bill

[Paul Engle]

I use recess 99.9% of the time I have so little wood that every shaving is signifacant, so a tenon just gets in the way of my artistic development of the form.... use up too much wood:eek: ? i dunno I just like the look of a recess or rabbit.....:rolleyes: :eek:

[George Tokarev]

Stability? Seems intuitive that grabbing outside provides a broader footprint than inside, if only because the outside diameter of anything must be larger than the inside. Wider gives better vibration insurance, as does greater contact area between the wood and the steel. I can only presume folks are talking about the difference between serrated and smooth holds.

Whichever you use, strive to spread the load and the leverage. I favor load over leverage, so I keep my tenons or mortises as close to minimum circularity as possible, choosing the diameter of jaw to provide the leverage, rather than broadening their opening. NOVA chuckers might want to look at the 75mm jaws as a good all-round set. Thick metal makes a lot of contact at right angles to the faceplate cutting direction without demanding a large diameter tenon.