Tenon or Dovetail?

Re: Tenon or Dovetail?

Dick Hines

>I don't use a dove tail since I got the new bowl jaws for my Super Nova chuck. They work best on a tenon. I feel they have a stronger hold than the dove tail jaws I was using.

Re: Tenon or Dovetail?

Sam Dean

>It depends on the types of jaws you have as well. I've noticed that the Vicmarc jaws, which I have, when clamped closed they form a perfect circle. So, to get the most strength by gripping on a tennon, it must be the exact same size as the closed position on the jaws. If the tennon is too large, the corners of each jaw actually dig in and weaken the tennon significantly.

The jaws from some other manufacturers are made so that when clamping on a tennon, the center of each jaw contacts the wood. When you crank down hard, the wood may bruise a little, but it's not as likely to tear (and fly apart(yes, I learned this the hard way!))

So, in my case, the recess works best for me. Again, because with the Vicmarc chuck, the centers of the jaws contact the wood when expanding which gives a better grip when the recess isn't made just perfect to begin with. Besides, when you turn green blanks and re-chuck them when they're dry, how accurate can you really make a recess or a tennon?

Now, If I bought some shark jaws, I would probably use them only on tennons, because their profile is made for that. A short dovetail tennon just slips off too easy.

Thanks,

Sam

Re: Tenon or Dovetail?

Dave Peebles Lyons, Ohio!

>TD,

I have not found that to be the case at all. I find a tenon is always stronger. To me it is like spliting firewood. It is easy to split it with a wedge, but I don't have much luck banging on the outside of a log. :)

I am curious why you think it is stronger? Or maybe you are really just stirring the pot. :)

Happy Holidays,

Dave

Re: Tenon or Dovetail?

RonZ

>IMHO dovetail wins hands down. As long as you make sure that the top of the tenon or the bottom of the bowl has enough flat area to mate with the chuck and thet the angle of th tenon is close enough to the angle of the check, its set. Also, I find that I can use a shorter tenon of about 1/4" - 1/2" with the dovetail jaws, depending on the wood. This holds true for the chuck gripping the tenon from the outside. On the inside, it depends on the wood but the same principles as above applies. With my own eyes I saw Dave Regester make a 2mm inside tenon to grip the bowl he turned between centers to finish the inside.

Spigot / Oneway has been a problem for me. It appears that when I tighten it, it tears the grain and I have had bowls orbit.

Re: Tenon or Dovetail?

TD

>Dave, I use the Vicmarc chuck with the standard dovetail jaws and I do not turn much end-grain. I use a stepped down mounting ring so that while it may look like I have only 1/2" or so of wood around the dovetail I actually have left twice that. I also try to keep the circle to about 1/8" larger than the closed diameter of the jaws so the jaws are in full contact instead of just one point at the center of each jaw. If I cannot fit this into a base diameter of 1/3 the max diameter then I either change to a smaller chuck, change the jaws, or go to a spigot. With softer wood I usually harden the dovetail with thin CA. Whenever I try the spigot I often pinch the wood in two or it shears off even with the top of the jaws. For me, I prefer the expanding method as it seems to give me less trouble. Once my vessel is dry and I return it for the finish turning I turn most of the dovetail off, leaving no more than 1/8" depth which is enough to hold the vessel for sanding and finishing. Since all my pieces are finished with oil and carry a life-time guarantee I must leave this ring so that I can remount the piece if it ever needs rebuffed or re-oiled. I tell my customers "no ring--no warranty". It took me a long time to find a way to make this "mounting ring" appear to be a part of my overall design instead of something that should have been cut off. This is a very interesting thread because I know a lot of good turners that prefer the spigot but it just doesn't work for me.

TD

Re: Tenon or Dovetail?

Dave Peebles Lyons, Ohio!

>TD,

Good info in your post. I can certainly see why you do what you do. If it works for you, that is all that matters.

In my work, I have found that I like the tenon. It allows me to give the piece the lift that works in my eye. I always reverse turn my pieces on a vacuum chuck to do the foot. It allows me to make subtle changes to the shape of the work.

I guess it all come down to what works for each turner. There is no right way.... Just different ways. :)

Thanks for the interesting thread.

Best wishes,

Dave