I've seen people use pvc pipe cut so it could close around a tenon and protect the wood in a chuck. My tenon is smaller than a pvc application. Has anyone tired anything else to protect the tenon in a chuck with success.
Dave F.
Dave F.
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tenon protection
- Thread starter Dave Fritz
- Start date
Dave, I'm not picturing what you have in mind.
What size tenon are we talking about, and what is its application? You mention "protecting" the wood ....
Are you talking about something that will be a part of the finished piece and you don't want to ding it up with chuck jaws sized differently, or is the tenon just smaller than any of your jaws can clamp down on, or is it something else entirely?
It could just be me just being a little dense today; wouldn't be the first time.
What size tenon are we talking about, and what is its application? You mention "protecting" the wood ....
Are you talking about something that will be a part of the finished piece and you don't want to ding it up with chuck jaws sized differently, or is the tenon just smaller than any of your jaws can clamp down on, or is it something else entirely?
It could just be me just being a little dense today; wouldn't be the first time.
Sorry I wasn't clear. I want to protect the wood from getting jaw marks in it.
Dave
Dave
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Dave, most of my tenons get turned off.
When I decide to keep some or all of the tenon I just clean it up with a small bowl gouge or a 3/8" detail spindle gouge. I asume you are talking about a bowl? Generally you do not want your foot design to be constrained by the size of your chuck jaws.
My basic procedure is turn the outside of the bowl and add a tenon. Then I reverse chuck and use the tenon in a 4 jaw chuck while I hollow out the inside. Then I reverse chuck again by putting the face of the bowl against some type of jam or friction chuck. This could be your chuck with padding like old mouse pad to protect the inside of the bowl. You use the TS for support and gently reduce the tenon to a very small nub down to perhaps a quarter of an inch or less. Take the bowl off and lathe and knock off the nib with a gouge handle if it is a standard face grain bowl or cut it with a small flush cut saw. Sand away the minor signs of the nib if any.
At least that is how I use to do it. Now I use a vacuum chuck for finishing off the bottoms.
When I decide to keep some or all of the tenon I just clean it up with a small bowl gouge or a 3/8" detail spindle gouge. I asume you are talking about a bowl? Generally you do not want your foot design to be constrained by the size of your chuck jaws.
My basic procedure is turn the outside of the bowl and add a tenon. Then I reverse chuck and use the tenon in a 4 jaw chuck while I hollow out the inside. Then I reverse chuck again by putting the face of the bowl against some type of jam or friction chuck. This could be your chuck with padding like old mouse pad to protect the inside of the bowl. You use the TS for support and gently reduce the tenon to a very small nub down to perhaps a quarter of an inch or less. Take the bowl off and lathe and knock off the nib with a gouge handle if it is a standard face grain bowl or cut it with a small flush cut saw. Sand away the minor signs of the nib if any.
At least that is how I use to do it. Now I use a vacuum chuck for finishing off the bottoms.
Dave,
One of the easiest ways to protect the tenon is to make sure that the diameter of the tenon is only minutely larger than the smallest diameter the chuck will hold. That way, almost all of each jaw will be in contact with the tenon, and the gaps in between the jaws will be so small there will be almost no marking.
One of the easiest ways to protect the tenon is to make sure that the diameter of the tenon is only minutely larger than the smallest diameter the chuck will hold. That way, almost all of each jaw will be in contact with the tenon, and the gaps in between the jaws will be so small there will be almost no marking.
I pretty much go at it the way Mike described. With a few bowl forms that I make often I actually do finish the foot at the same time as the outside profile and make it exactly the right size with just the right sized bead or groove or something for a jaw set to fit, so when the bowl is reversed to finish the inside the foot is not dinged up at all, even though the jaws are gripping it pretty tight.
It saves another reversal to do the foot which is a time saver in a run of utility bowls that are headed to a kitchen store or whatever.
Mike's right though, it's not good to get locked into a design corner by the size of the chuck jaws, but if I was going to make the foot that size anyway, well what the heck.
I have tried to protect the wood from being marked by the jaws, (rubber pads, tape, rags etc)which happens when the tenon is a touch bigger than the true circle size of the jaws, the corners bite in, but have not really found any way to do it that I was comfortable with. Anything that was stout enough to actually protect the wood always felt a little unstable to me and introduced vibration that I didn't like.
Nowadays, when I want a foot that's not the right size or shape to be grippable with of any of my chuck jaws, and that's pretty often, I do what Mike suggested and reverse the bowl one more time and finish the foot as he said.
One day when I grow up I'll get a vacuum setup just like the big boys (& girls) have; I used one for the first time a few weeks ago and they are pretty slick.
It saves another reversal to do the foot which is a time saver in a run of utility bowls that are headed to a kitchen store or whatever.
Mike's right though, it's not good to get locked into a design corner by the size of the chuck jaws, but if I was going to make the foot that size anyway, well what the heck.
I have tried to protect the wood from being marked by the jaws, (rubber pads, tape, rags etc)which happens when the tenon is a touch bigger than the true circle size of the jaws, the corners bite in, but have not really found any way to do it that I was comfortable with. Anything that was stout enough to actually protect the wood always felt a little unstable to me and introduced vibration that I didn't like.
Nowadays, when I want a foot that's not the right size or shape to be grippable with of any of my chuck jaws, and that's pretty often, I do what Mike suggested and reverse the bowl one more time and finish the foot as he said.
One day when I grow up I'll get a vacuum setup just like the big boys (& girls) have; I used one for the first time a few weeks ago and they are pretty slick.
Back to your original inquiry, what size tenon do you have? PVC pipe is available down to about 9/16" ID (actually 0.602") in 1/2" nominal size. Vinyl tubing could be smaller yet, but see below. *
For drilling golf balls, I've used a fixture with slightly variable diameter, consisting of a bottle cap from Scope mouthwash, with the locking tabs whittled away to make a concentric cone, and four slots cut in the walls. The cap is screwed to a base board, and a hose clamp pinches the fingers to embrace the ball.
* But like Dave Moore says, anything that cushions the work enough to avoid marking it makes for a wimpy attachment, and the cure could be worse than the disease.
If you can describe your project more fully, there might be an alternate, and better, process.
For drilling golf balls, I've used a fixture with slightly variable diameter, consisting of a bottle cap from Scope mouthwash, with the locking tabs whittled away to make a concentric cone, and four slots cut in the walls. The cap is screwed to a base board, and a hose clamp pinches the fingers to embrace the ball.
* But like Dave Moore says, anything that cushions the work enough to avoid marking it makes for a wimpy attachment, and the cure could be worse than the disease.
If you can describe your project more fully, there might be an alternate, and better, process.
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I believe you're using the tubing as a split collet. They make commercial collet chucks that are non-marring if you want to spend. Or, you can make some on your own by turning a long grain piece, boring your hole, then kerfing to provide the room to squeeze with something like a spring clip or hose clamp. Here's an elaborate way of going. http://www.davidreedsmith.com/Articles/AllWoodColletChuck/AllWoodColletChuck.htm Teknatool pin jaws are also pretty friendly, if you have a nova chuck.
I have dairy vacuum tubing made of white plastic down to 1/8 ID, so I suspect if you looked you could find similar. Could be tricky kerfing it to fit, but not too much for someone with a proper fixture and a razor saw, I'm sure.
I have dairy vacuum tubing made of white plastic down to 1/8 ID, so I suspect if you looked you could find similar. Could be tricky kerfing it to fit, but not too much for someone with a proper fixture and a razor saw, I'm sure.
Thanks for the information. I was trying to finish a pepper mill top that I felt needed to be redone without marking the tenon. I guess it wouldn't matter anyway since the tenon is inside the mill but you know how it is. I finally started over and made a new top.
There are some great ideas here - thanks.
Dave
There are some great ideas here - thanks.
Dave
Dave,
If you're careful, (or lucky), you can attach the washer with the square hole to the head of the peppermill, and rechuck along with tailstock support. It will all depend on how well you can center the washer.
If you're careful, (or lucky), you can attach the washer with the square hole to the head of the peppermill, and rechuck along with tailstock support. It will all depend on how well you can center the washer.
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For the task that you describe, chucking a piece of waste wood, and boring a hole that the tenon will be a snug push fit into will hold the tenon fairly secure, and putting a cone point on the live center and placing it in the hole in the knob will ensure that it stays in the bored out waste block.
If the very top of the knob needs to be returned, cut as much as possible around the cone in the center hole, remove the live center, and while holding the knob in the waste block with a couple of fingers, the last bit near the center can be cut away using light cuts.
Later,
Dale M
If the very top of the knob needs to be returned, cut as much as possible around the cone in the center hole, remove the live center, and while holding the knob in the waste block with a couple of fingers, the last bit near the center can be cut away using light cuts.
Later,
Dale M
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If it isn't too late,
I learned a cute trip from Mark St Leger awhile back.
it is just a modification to what Dale suggested above but you won't need the tail stock.
turn a tenon on small block of wood 3x3x1.
Mount it in a 4 jaw chuck face it off and drill or turn a hole in the center for a tight fit.
mark a spot between jaws 1 and 2
remove it from the chuck an cut a saw kerf from the mark to the center
remount the block in the chuck loosely.
put the tenon in the hole tighten and the wood will close enough to lock the piece tightly.
this is also useful with an off center hole for doing small off center pieces.
have fun,
Al
I learned a cute trip from Mark St Leger awhile back.
it is just a modification to what Dale suggested above but you won't need the tail stock.
turn a tenon on small block of wood 3x3x1.
Mount it in a 4 jaw chuck face it off and drill or turn a hole in the center for a tight fit.
mark a spot between jaws 1 and 2
remove it from the chuck an cut a saw kerf from the mark to the center
remount the block in the chuck loosely.
put the tenon in the hole tighten and the wood will close enough to lock the piece tightly.
this is also useful with an off center hole for doing small off center pieces.
have fun,
Al
Last edited:
Tendon collet
Dave,
I used corian counter top scrap it starts out an inch or so thick.You start between centers with a 3 X 3 or 4/4 sq piece. Turn it round, stick it in the chuck and drill or turn the center completely through and out to slightly larger then you need to hold.
On the band saw or by hand cut a 1/8 slice from the outside in. Its flexable enough to compress when squeezed and no marks. Not my idea but it works great.
Rob
Dave,
I used corian counter top scrap it starts out an inch or so thick.You start between centers with a 3 X 3 or 4/4 sq piece. Turn it round, stick it in the chuck and drill or turn the center completely through and out to slightly larger then you need to hold.
On the band saw or by hand cut a 1/8 slice from the outside in. Its flexable enough to compress when squeezed and no marks. Not my idea but it works great.
Rob
Wish I had see this thread before I posted a new one
I just created a new thread talking about using mouse pads for re-chucking. It is in the tips and tricks section.
I agree with the comment to the effect that "anything that does not mark it will give a wimpy grip". I would not recommend the mouse pad approach for anything over 2 inches long and / or 2 inches thick.
At these diameters and a reasonable speed I feel it is a safe grip. You will have to use your own judgement.
I just created a new thread talking about using mouse pads for re-chucking. It is in the tips and tricks section.
I agree with the comment to the effect that "anything that does not mark it will give a wimpy grip". I would not recommend the mouse pad approach for anything over 2 inches long and / or 2 inches thick.
At these diameters and a reasonable speed I feel it is a safe grip. You will have to use your own judgement.