What size Tennon

Re: What size Tennon

john Lucas

>Gil

What kind of glue were you using. CA glue is fragile to impact so a good catch will often break the joint. Try yellow glue or gorilla glue. If you in a hurry try 5 minute epoxy or hot glue.

My tenon's on a bowl that size are about 2". I have the Vicmarc chuck and with the medium jaws this is a good size.

Re: What size Tennon

Mike Schwing from Md.

>Gil, it sounds as if technique rather than tenon size is the issue here. Any turners nearby that you can watch? That will go a million miles towards reducing catches.

For an 8" x 6" blank I would use a tenon in the 2" range while hollowing the interior. To do the exterior I'd use a faceplate. My use of glue blocks is limited to blanks that are too sparse to waste on a compression tenon, and I never use my chucks in expansion mode with recesses. I use 5 minute epoxy with my glue blocks, as I don't trust CA (but know many who do successfully) and don't have patience for yellow glue to dry.

When it goes over 12" wide I use the 4" jaws and an appropriately larger tenon.

Re: What size Tennon

Bill Hale

>Gil it sounds that you may not be a very experienced turner. If this be the case you may want to hold off on the end grain turning until you get more experience. End grain is the toughest to do. You also did not say what type of tool and size. That could also be part of the problem.

I agree that 2" is good up to about 12" and then a 4". With good tool controll you can go to 24" with the 4". Again as previously said never in expansion.

Make the tennon on an angle to match the inside of the jaws and deep enough that it almost touches the bottom of the jaw on the inside. If the wood ie either brittle or soft I run thin CA along the inside of the tennon to make it stronger. After the CA just retouch the bottom of the tennon so it is smooth and clean.

Good turning anad be safe

Bill in Casa Grande, AZ.

Re: What size Tennon

Sam Dean

>Some interesting comments about gripping with a chuck. I have a vicmarc 120 chuck and about 99 percent of the time grip my bowls from a recess in the expansion mode. I like it because if done right you can end up with a finished foot and hide the area where the chuck gripped. I only have a 12 inch swing, but even roughing a 12"x6" bowl held on by nothing more than a 1/4" recess for the 2 1/2" jaws has never been a problem. (there are, of course, common sense exceptions with punky, rotten wood, etc..). I think that out of the 200 to 250 bowls that I've turned this year, I may have lost one or two. I hear everyone talk about gripping a tenon only, but I never could understand why. Just my 2 cents.

Thanks,

Sam

Re: What size Tennon

Les Robison

>I agree with Sam on the use of an inside grip using the Vic 100/120 chuck. However, the Vic uses angled jaws and not straight jaws like some chucks. I believe the jaws of the Vic allow it to grip the inside ring of a bowl/vessel/plate is a real advantage and provides a finished look without a lot of sanding or rechucking.

Re: What size Tennon

Gil

>This is a very weird piece of wood. I'll take some photos of it and post them here. I'm experienced/inexperienced. I was turning every day from 1994-1997 mostly green wood bowls. Then I took a 4 year break while in college, and started turning in 2002 again.

On that note I would love to watch someone near by turn. I always believe there is room to improve tool use and technique. I'll take a photo of this piece of wood and see what everyone thinks. There was an inherent flaw in the base which caused the glue block to crack off, and I'm not sure how to go about fixing that..

-Gil

Never in expansion?...

BubbaBob

>...hmmmm....I've never turned a bowl any way EXCEPT using expanding jaws in a dovetail recess...hey TD, did ya teach me wrong?

BubbaBob

Re: What size Tennon *LINK*

Mark Kauder, Phenix City, AL

>Gil,

As you know, I mostly do segmented work, and that is whole 'nother animal, but I too prefer a glue block, and if I had enough of the, I think I would use mostly faceplates.

That said, even with a glue block, I use a tennon in compression mode. The Tennons are only about 1/4" high. I happen to have a set of Supernova Powergrip jaws. Since I make up glue blocks in batches, I turn them all the same, and do about 3.5-4" diameter tenons. Better safe than sorry. (no I probably would make a different sized glue block for a small turned box)

The thing I dislike about using chucks in the expansion mode, is that if you are expanding into a 3" hole, the minimum foot size will be about 3.5" in diameter. That means for decent proportions, you would not want to use it on bowls less than 10.5" in diameter (3:1 diameter to foot ratio).

Glue block to not restrict you in this same manner. Plus, though I usually reverse chuck my bowls to clean up the bottom, If need be, I can just part a bowl off and sand the bottom clean. With the expansion method, you really need to be sure and have a way of reverse chucking to clean up the bottom at least a little.

BTW, I think Mike Mahoney says in his video, that you should be chucking to 1/4 the diameter of the finished bowl. Though that is a little large in my opinion, I do not have nearly the experience that he does.

Just my opinions.

Mark


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