Removing The Tenon

[Brett Bobo]

What is your process for the removal of the tenon for a bowl? I've tried both the cole jaws and between centers with a bun in the bottom of the bowl but to no avail. When using the cole jaws, the rim of the bowl cracks with the pressure needed to keep the bowl from becoming a flying object. With the bun in the bottom of the bowl, it's difficult to center it in the bottom of the bowl, so the bowl wobbles. Also, the bun leaves an indention in the bowl, even with a cloth placed over it.

Can the tenon be removed (or a small diameter to be snapped off afterward) directly from the chuck when the bowl is mounted to turn the inside of the bowl by increasing the tenon length by ~1/8" to 3/16"? What recommendations do you have?

Thanks,
Brett

[John Keeton]

Brett, my guess is that most folks use either a donut chuck or a Longworth chuck. I use the donut chuck, and recently acquired a threaded adapter to go in my tailstock so that I can mount the chuck, with the bowl, on my tailstock. That way, I can easily center it on the donut chuck and gain access to the bottom for finishing.

I also use cole jaws, but I have not had a problem with cracking of the rim. Sounds like you are using a lot of pressure, or possibly too much speed. That said, I did launch one bowl from the cole jaws!:o So, I do appreciate your circumstances!

[Steve Schlumpf]

Brett - agree with John, use a donut-chuck, longworth chuck, vacuum chuck or jam chuck.

If you are going to use your cole jaws - no problem - just bring up the tailstock and apply light pressure to help hold the bowl in place. No need to over tighten the cole jaws when the tailstock is there to help secure it. Just turn the foot down until you have a small area left - then cut or carve the small piece of wood off the bottom area and sand.

Wouldn't recommend snapping the wood off as it could easily remove some additional wood with it - ruining your bowl! DAMHIKT!!

[Wally Dickerman]

Brett, if you are turning your tenon between centers as most do, leave the mark left by the tailstock. You'll need it for centering the piece when you reverse mount it to remove or reshape the tenon for a foot.

If you are cracking the rim when you're using cole jaws, you're applying way too much pressure. If you're leaving a mark on the inside of the bowl when reversing it, use more padding. A mouse pad for instance.

Wally

[Brett Bobo]

Interesting, I haven't heard of a donut chuck or the longworth chuck so I'll do some research. Any links to other threads or sites of how to make one would be appreciated.

With the cole jaws, I was conscious of not applying too much pressure and that's when the bowl caming flying off. So, I applied a little more but maybe it cracked because of the beveled edge. Also, I wasn't using the tailstock as Steve suggested so that's a great idea--seems obvious now.

Thanks!

[Mark Burge]

Brett, I a made a donut chuck and use it most of the time, but I have also simply parted the bowl off and finished the bottom with hand tools to clean up the little stub that remains. I think it really depends on how you want to finish the bottom. If it is to be a round bottom, the parting off method works well. For a foot you really need some way to turn it around.

I have never used a set of cole jaws, but I am guessing that you may be wanting to pull it too tight because you are getting catches that threaten (or actually) launch the bowl. I'll tell you the same thing I try to tell myself "take light cuts - sharpen before you start on the bottom" Maybe you will listen, I don't too well. :)

[Mark Burge]

Here is Art Leistman's version. http://azwoodturners.org/DoughnutChuck.pdf

[Mark Burge]

Here is an article on the Longworth chuck http://www.morewoodturning.net/articles/Longworth_Chuck.pdf

[bob svoboda]

I've also found, when using cole jaws, to use super sharp tools and very light cuts. The combination lessens the tendency to 'launch'.

[Bernie Weishapl]

Brett I had cole jaws for a while but like you got tired of crushing the bowls. I made a donut chuck and used a tailstock adapter that the chuck screwed on and went into the tailstock. When the bowl is brought up to the donut chuck it was centered and when tightened down could finish off the tenon with no problems.

[Thom Sturgill]

Also if using cole jaws without the tail stock, wrap blue or green tape around the bowl and jaws. I think most of us have launched a bowl or two from cole jaws. :mad:

Donut or longworth chucks are worthwhile projects, vacuum chucks are expensive but once you get used to them, you love them. They still have their issues if the bowl is too porous though, so the donut chuck still has a place in the tool kit even if you have a vacuum chuck.

If you use a wormwood screw to start the bowl and turn the tenon instead of between centers, then mark center with a skew chisel before removing the blank from the screw. Then you can use that to help re-center the bowl when you reverse it again.

[Michael Mills]

This is what I normally do.
Leave the indent from the tailstock in order to find the center point. I am not sure what a "bun" is that you refer to. It must be convex to leave a dimple in the bottom. I just take a couple of pieces of leather and cover the jaws of my chuck, then bring up the tailstock.
Only the outside edges of the jaws make contact so it is almost self-centering and distributes the pressure in a wide area of the bowl. I then form the foot down to the last 3/8" or so and then remove that with a chisel once off the lathe.
Some day I will get around to building a donut chuck as I think that would be the most useful and allow the foot to be fully completed and finished on the lathe.
Mike

[Bob Hampton]

i'll throw another way in the mix here ...
I dont have cole jaws or longworth chuck (someday ill figure that one out and make it ) so i use a very simple way ...i use a piece of the black water pipe..4inch long 31/2 od and 3"id with a piece of carpet pad on the end facing the bowl....lay the bowl over the pad and bring up the tail stock using the center hole from the tail stock ..u might have to wiggle it around a bit to get perfect center but usually it centers good ...apply a little pressure and away u go ..
turn the tenon down to a little "nub" and then just tap it off with a sharp chisel and sand ..done

Bob

[Jeff Fagen]

Do you mean black PVC pipe?

[Justin Stephen]

So far with my whopping 3 bowls finished, I have been using a jam chuck, pulling the tailstock away and using a few pieces of masking tape (to hold the bowl onto the jam chuck) at the very end to cut away the thin nub and for sanding.

A doughnut chuck is definitely on my to-do list.

[Kyle Iwamoto]

I use a jam chuck and undercut the tailstock thing. Can't remember it's name right now. Senior moment. Foot or no foot? This also reduces the foot a little. I try to make the foot concave, so the bowl doesn't wobble. I get as much of the tenon cut off as possible. Then I chisel off the nub and power sand the foot. If no foot, then it's a little easier to get the tenon off with the TS installed. I have a very shallow angle skew just to do this. A "standard" taper skew can't reach too far if you're saving a foot.

Have not gotten around to building a donut or spending the bucks on a vacuum chuck, which would be the best way.

Just another way to do it.

[Cody Colston]

I made a doughnut chuck but I don't use it. I have a piece of 4x4 fir with one end rounded and a tenon on the other end. I chuck it up, place a big sponge over the rounded end followed by the bowl and bring the tail stock against the dimple that I put in the bowl tenon...when I don't forget.

Like a few others said, turn the tenon down to about 3/8", cut it off with a chisel and sand smooth.

BTW, I've long ago loaned out my copy but I think that's the method that Bill Grumbine demonstrates in his "Turned Bowls Made Easy" video.

I do remember him saying that if you try to turn the tenon completely off and catch the bowl at the same time you will regret it as the bowl will get away and land on the hardest, pointiest thing in the shop. :D

[Scott Hackler]

I use a jam chuck and turn the tenon down to about 1/2". Most the time I will "dress" the bottom with any type of finishing recess and rim that seems right and do as much sanding as possible before removing it from the lathe. I cut the 1/2" peg off with a push pull trim hand saw and power sand any trace off with 400. Add a little BLO and ready for the wood burner with my name stamp. Works pretty good and I am really used to doing it this way, but I have been thinking about building a donut chuck as I would like to finish the entire bottom on the lathe.

[Brett Bobo]

Thanks for all of the input. As a follow-up, I have several questions based on the different methods that are used:

1. With the donut chuck, is the tailstock adapter for the four jaw chuck only used to center the bowl on the donut chuck and then removed (obviously, right?) before turning the tenon off? Should the live center of the tailstock used to "pin" the bowl in place or is the donut chuck adequate to hold the bowl at that point? Is it possible to over-tighten the donut chuck and crack the wall of the bowl?

2. With cole jaws, to avoid cracking the wall of the bowl as I seem to do, is it best to use the live center on the tailstock and then remove the remaining, small tenon off of the lathe with hand tools, sandpaper, etc.

Some others mentioned the method I was trying to use when I said "bun" but basically a rounded piece that fit into the bottom of the bowl with a protected cover to avoid marring the surface of the bowl. I now realize that I should be chucking the bun as I was using the spur center so from the headstock, I had spur center, bun, bowl, and live center on the tailstock. It's no wonder that I was getting alot of wobble and having trouble centering it.

Several very good options that I'll try and the donut chuck seems like the best option considering the bowl can be completely finished on the lathe.

[Thomas Canfield]

I have started using a jam chuck made from MDF with a piece of the cheap shelf liner between the jam chuck and bowl, and then bring the live center up against the dimple left in the tenon. You can remove most of the tenon material leaving only a small post that can be cut off with saw, chisel, or snapped off if your are luckier than I am. A little sanding with disk and then hand sanding removes any remaining dimple. You can do some recess work, round off the bottom, or make it flat, but it is hard to do grooves or marking because of the tailstock. You need to be cautious of pushing too hard against a thin bottom when you get down to a smaller stub of the tenon.

If I need to get to the bottom, then I use a donut chuck or cole jaws. In any case, holding a thin bowl requires a more delicate approach.

I have not got sucked so far into the vortex to be captured by the vacuum and think I can keep resisting.

[Wally Dickerman]

Thanks for all of the input. As a follow-up, I have several questions based on the different methods that are used:

1. With the donut chuck, is the tailstock adapter for the four jaw chuck only used to center the bowl on the donut chuck and then removed (obviously, right?) before turning the tenon off? Should the live center of the tailstock used to "pin" the bowl in place or is the donut chuck adequate to hold the bowl at that point? Is it possible to over-tighten the donut chuck and crack the wall of the bowl? A lot of turners will tell you to buy yet one more piece of equipment like the threaded centering device. I prefer to do things the old school way.

2. With cole jaws, to avoid cracking the wall of the bowl as I seem to do, is it best to use the live center on the tailstock and then remove the remaining, small tenon off of the lathe with hand tools, sandpaper, etc.

Some others mentioned the method I was trying to use when I said "bun" but basically a rounded piece that fit into the bottom of the bowl with a protected cover to avoid marring the surface of the bowl. I now realize that I should be chucking the bun as I was using the spur center so from the headstock, I had spur center, bun, bowl, and live center on the tailstock. It's no wonder that I was getting alot of wobble and having trouble centering it.

Several very good options that I'll try and the donut chuck seems like the best option considering the bowl can be completely finished on the lathe.

When using the donut chuck, the best way to center the piece is by using the tailstock and live center, and using the dimple left from forming the tenon. Once it's centered and tightend down, you can back the tailstock away. Take very light cuts with a spindle gouge or small bowl gouge. It's nice to put in some kind of design on the bottom. I can't recall ever damaging the bowl with the donut. Don't worry about cracking the bowl with the donut.

When using the cole jaws, don't over tighten, as you seem to be doing. If you feel more comfortable by using the live center when turning the bottom, by all means do it. You can back it away to finish the center of the bottom. Again, use light cuts. Don't force anything.

Yes, you should be chucking the bun as you call it. A spur center gives you no stability at all. A lot of turners merely leave the chuck on the spindle and place a piece of foam (mouse pad) over it to protect the bowl. Then bring up the tailstock and finish the bottom.

Wally

[Justin Stephen]

BTW, I've long ago loaned out my copy but I think that's the method that Bill Grumbine demonstrates in his "Turned Bowls Made Easy" video.


It is indeed. This method also allows for finishing the bottom of natural or irregular-edged pieces.

[Patrick Doody]

I made a doughnut chuck but I don't use it. I have a piece of 4x4 fir with one end rounded and a tenon on the other end. I chuck it up, place a big sponge over the rounded end followed by the bowl and bring the tail stock against the dimple that I put in the bowl tenon...when I don't forget.

Like a few others said, turn the tenon down to about 3/8", cut it off with a chisel and sand smooth.

BTW, I've long ago loaned out my copy but I think that's the method that Bill Grumbine demonstrates in his "Turned Bowls Made Easy" video.

I do remember him saying that if you try to turn the tenon completely off and catch the bowl at the same time you will regret it as the bowl will get away and land on the hardest, pointiest thing in the shop. :D


I use a very similar method, with one minor exception I have a chunk of maple screwed onto a faceplate that I use. works great. (i'm a novice FYI)

[Mike Lipke]

Do a google search for Alan Lacer Straka Chuck.
He has an excellent downloadable file on how to make a donut or Straka chuck.

[Michael Mills]

A plus of Bob Hamiltons method, using a 3.5 OD pipe section, is that you have approximately 11 inches (circumference) contacting the interior of the bowl, not just a small area in the center. A lot of area for positive friction :) and much less likely to wobble if you get a small catch :(.
I didn’t have a pipe section so I just use the chuck jaws.

Mike

[Frank Drew]

You can get tapered rubber grippers for cole-type jaws that conform better to most bowls' curves, lessening the chance for the bowl to self-launch and making too much clamping pressure unnecessary. Maybe I've just been lucky, but I've never broken a bowl with my jaws, and they're my go-to method for finishing the bottom of bowls. I occasionally use tenons but more often turn a shallow dovetail recess for the preliminary holding; when the bowl is finished, it's easy enough to remove the undercut portion of the recess to make a nicely detailed bottom, using the cole jaws, only medium speed, and a light touch with your tools.

[Brett Bobo]

As far as the material for a donut chuck, do you foresee any issues with using 3/4" MDF? With MDF, I'm curious if the outer ring that holds the bottom of the bowl would be stiff enough to avoid breaking (in tension) when the bolts are tightened down. I'd probably double up the MDF for a total thickness of 1 1/2" on the faceplate side as the article I found from Mike's suggestion does this but with plywood.

[Brett Bobo]

Bernie,
Do you know where can I find the tailstock chuck adapter for a Nova chuck? From Teknatool's website, it lists this item as new and after calling Woodcraft and Craft Supply USA, neither of the two carry it and won't carry it for a while. Maybe there's another manufacturer that sells one that's compatible with the Nova chuck. Thanks for the help!

[Brodie Brickey]

Donut chuck link:
http://azwoodturners.org/DoughnutChuck.pdf

[Karl Card]

I am wanting a set of cole jaws and a friend of mine uses them also to finish the bottom of bowls. He doesnt seem to launch any but at the same time he is very patient and sharpens his tools before doing the bottom...

I would like to start making bowls with a pedestal on them mainly because i like the looks but at the same time might make it easier to finish the bottom... have to try it and see..

[Jim Sebring]

Brett, go to Bestwoodtools.com for the adapter. I just got one for my 1 1/4 x 8 chuck. Here's the link: http://bestwoodtools.stores.yahoo.net/tailchucad.html

[Steve Trauthwein]

I have a donut chuck, a longworth chuck, a cole chuck, and a dedicated flat for jamb chuck. 99% of the time I will place a piece of pad used to route on in the bottom of the piece and find the indent from when I was turning between centers, make what adjustments necessary to have the piece running true. I then turn off the tenon at a relatively slow speed leaving a nub-a half inch nub if I am turning box elder and as little as a quarter inch or less if I am turning tight grained maple or cherry or such, then had finish the rest of the bottom. Fast and very efficient.

Regards, Steve