Recess or tenon?

[Lawrence Tarnoff]

What factors dictate whether one should use a tenon or a recess on a bowl? I'm currently working on a 10-inch by 4-inch ash bowl. I've managed to have previous efforts fly off the chuck using (or mis-using) both methods.

Larry

[Brian Kent]

I think a recess is stronger. The tenon works if the wood is strong enough and you want to end up with a thinner bowl bottom.

[Jamie Donaldson]

The recess is not as reliable as a tenon because of the tendancy for weak end grain to split out on 2 sides, especially in dry wood. This is more true for bowls with smaller bases than platters, which usually have larger bases than bowls.

[Harry Robinette]

Lawrence
Check out Stuart Batty's video's on vemio?. Just google Stuart Batty woodturner and look for videos. he has a bunch of them that are all excellent. One is on the same thing your asking.

[Clint Merrill]

There are many good chucks on the market for both tenon and recess mounting. My preference is the recess, better holding power and easier re-mount, with minimal depth, often as little as 1/16 in. I have used a '6in1' for 20 plus years without a failure or flying saucer thingy. This is what I would call reverse collet ie. the 4 1/4 sections expand into the recess and are in 3-4 sizes to range from about 2 - 4 in. Possibly under the 'Sorby' label.
I have seen them on ebay recently under 'wood lathe chucks', or vey reasonable prices, might be worth a look ?? Good luck and be safe. Clint Merrill

[Reed Gray]

I feel like I should make one as well as this question comes up so often. I do need to check out Stuart's version too. The only time I would say never use a recess would be if you were doing an end grain turning. If you expand into a recess on an end grain piece, you might as well put a splitting wedge into it. The only important thing is to have a tenon or recess that is properly made.

First, it has to be sized to fit the piece you are turning. Tenon needs to be about 1/3 to 1/4 the diameter of the bowl, so a 12 inch bowl should have a 3 to 4 inch tenon. You can get away with less, but then it is more risky, especially if you are doing production turning with heavy roughing, and/or coring. If you are using a recess, you need about the same size foot, with a recess to fit inside so there is plenty of shoulder to push against. My big chuck has 2 5/8 inch wide jaws when closed. Perfect for this size, and good up to 14 or so inches. Beyond that and I go to bigger jaws.

Second, the recess or tenon needs to be very close in size to the chuck jaws. For a tenon, if your chuck jaws close down to 3 inches, then your tenon should be 3 1/4 inch wide, maybe a bit more or less depending on how accurately you measure and cut, and how wet or dry the wood is. For a recess, if your jaws closed are 2 inch diameter, the recess should be about 2 1/4 inch max diameter. This puts more steel on the wood so the grip is more secure.

Third is how tight do you need the chuck to grip. With both tenon and recess, you can over tighten to the point that you break the tenon or recess. You can also over tighten to the point that you have so much stress on it that even a tiny catch will be more than it can handle, and it breaks. Of course, too loose and it can also fly off. You want it snug. I snug it up in one key hole, roll around to the other key hole and snug it up again. On a really big piece, I will go around a couple of times. I never tighten it up as much as I possibly can. I have broken a few handles and some gears in the chucks.

Forth, the angles of the chuck jaws and recess or tenon need to match. If you have straight jaws, the sides need to be dead square. You can eyeball along the ways of the lathe, or have a square scraper, or line the shaft of your tool up with the ways of the lathe for your recess. If you have dove tailed jaws, I prefer a specialized dove tail tool that is cut to the proper angle. I line the shaft of the tool up with the lathe bed ways, and plunge in just inside the line I mark (dedicates set of calipers/divider that are super glued into place so they don't vibrate open), then just barely take the line. You can use gouges and skews, but they don't tend to be quite as accurate. I do feel that the dove tail jaws give a better hold. It forms a locking wedged joint. Dove tail joints are the strongest joint in woodworking for that reason.

Depth wise, 1/8 to 3/16 inch is plenty. I used to make them 1/4 inch deep or so, and that is over kill. You may feel more comfortable with the extra depth, but it really isn't necessary. Please note here, this is for good solid wood. If there are existing cracks, I toss the piece of wood. If it is a piece I need to turn especially for some one, on a bowl, I would then use a tenon, or if I used a recess, then I would turn much more gently, and make extra sure to stand out of the line of fire. If the wood is punky, again, I won't turn it. A glue block on a face plate is probably the most secure grip. Harder and more brittle woods tend to crack off more than more medium hard woods. With softer ones and wetter ones, you may need to stop and tighten up once or twice as you are turning because the wood will compress.

I almost always try to line up the chuck jaws so that they are not directly lined up on end grain and side grain (say like 12/6 o'clock, and 3/6 o'clock), and rotate it 45 degrees. This way all jaws are on the same grain orientation. This is more important on wet wood than dry. End grain, does not compress very much. Side grain does, especially when green. It isn't necessary to do this all the time, but it has become habit for me, just like turning down the variable speed before I turn on the lathe.

robo hippy

[Brian Kent]

Thank you for being a great teacher, Reed.

[Geoff Gaudet]

Wow, there's a lot of information in some of these posts.

Personally, I'll use either tenon or recess, with a fair part of my decision based on design--whatever's going to be easiest to clean up at the end. For example, if the piece is going to have a small foot, a tenon might be best...if it's going to have a wide base, then a recess might be better. If you can't reverse the finished vessel, then a tenon might be easier to remove.

[Mike Cruz]

Larry, for me, most of the time, I go with a tenon. The main reason is that it is easier to gauge the bottom of the bowl. And since I do tenons most of the time, when I do a recess, it is very easy to go too thin on the bottom. Other than that, I don't see a huge difference. I've turned 20+" bowls on 4" tenons. If the wood is strong, and you cut a good tenon, it really shouldn't break or launch out of the chuck. If you are launching 10" bowls, I'd take a good hard look at your chuck...might be something wrong with it.

[Leo Van Der Loo]

Previous thread on this with also my answer on the use of recess rather than tenon, just from my 50+ years of turning experience .

http://www.sawmillcreek.org/showthre...58#post2211458

[Lawrence Tarnoff]

Friends ...

Thank you, all, for your thoughtful responses. I learned a lot tonight. I have 40+ years of hobbyist carpentry behind me, but am just getting into turning and am hooked. The SMC turners are terrific teachers!!!

Larry

[Dwight Rutherford]

Check out this U-Tube tutorial on various ways to chuck your work. http://m.youtube.com/watch?context=C...ubJI0NSJ0%253D

[John Keeton]

Aside from the great answers provided already, I prefer to have a finished and detailed bottom on my work, and it would seem difficult to reverse a recess turned bowl to achieve that without getting out my vacuum system, using a donut chuck, or a longworth. That wouldn't be a problem for you guys that have an installed vacuum pump system available at the flip of a switch, but I use the Holdfast. While it is easy to set up, I find using a tenon much easier when reversing and doing the bottom - particularly on hollow forms. I actually use a glued on waste block on nearly all my work, unless I have enough wood to spare, or it is an end grain turning.

Just call me lazy, I guess!

[Michelle Rich]

because I sold bowls for many years, I found many times I had to bring them back to the shop for repair/refinish, etc. Having a recess, made it VERY easy to get it back on the lathe. I usually turned a disc ,to finish the recess ,with the info and my signature & glued it in with a tiny drop of glue..it was easy to pop it out.