Paper Joint Faceplate of Cole Jaws?

[Jim Bennett]

Hi - I’m getting ready to start gluing up a segmented bowl. Bottom is about 4.5” diameter, top ring about 10” diameter, seven total rings, 5” height.

I have the bottom paper-joint glued to a 5” face plate, and had intended on adding a ring at a time, truing it up, adding the next, and so on. Is there any reason why I can’t do it this way? I’ve seen in various books where the author built up the bowl that way, but after truing up the last ring, the interior was cleaned up and sanded, then the whole thing was removed and reversed onto a jam chuck for finishing the exterior and bottom.

I don’t have a jam chuck and certainly not one large enough to capture a rim of 10”. I had thought I could use my SuperNova 2 chuck with the 12” Cole jaws attached to accomplish the same thing. Does this seem like a doable procedure, or am I going to have to build a huge jam chuck?

 

[Bill Boehme]

A jam chuck is just a piece of wood. You could even use a bowl blank if you have one that is larger than the top of your segmented turning. You can hold the jam chuck with a chuck or a faceplate then true up the opposite side and turn a groove that fits the rim of the bowl. You could also use a piece of plywood or 2X12 lumber as your jam chuck.

I have the bottom paper-joint glued to a 5” face plate .....

I hope that you have a glue block screwed to the faceplate and then using a piece of brown paper sack or equivalent make your paper glue joint between the glue block and the bottom of your turning.

I don't do segmented turning so I am not an authority on the best way to do things, but whatever you're making never glue anything directly to a faceplate.

 

[Jim Bennett]

Hi Bill, thanks for the quick reply. I almost had my wine shoot out my nose when I read what you said about gluing the base directly to the faceplate. Now THAT would be something to see!! No, I used a piece of brown paper, glued between the base and a sacrificial round disk, which in turn is very securely screwed to a faceplate that can be reversed. I’ve used that method on a couple other bowl turnings and like the way it works.

I guess maybe I was overthinking the jam chuck thing - the ones in those books are nice, large cones made from several laminated pieces of MDF. Making one that big probably would use up a very large part of an entire sheet of MDF, not to mention weighing as much as the Queen Mary II. The cone approach is nice, as it could be used for quite a variety of bowl sizes. I suppose I could sacrifice a 12x12 hunk of plywood for this project... but, would the Cole jaws approach work?

Jim

 

[john lucas]

Jim A jam chuck can be just about anything. I take a spare faceplate and screw a small waste block to it. The I use anything I have that's large to accept the bowl, plywood, glueups of 2x4's, green wood for the next big green bowl, etc. Your only going to cut a small depression just big enough for the bowl to fit over. Right now I have a piece of 3/4" plywood that is about 15" in diameter that I have used many times. It is about 3/8" now out toward the edges because I have reshaped it so many times. It still works for a lot of things. I have an article on our club website called methods of reverse turning bowls. One of those methods should work for you. It's under tips and projects I think. go to www.cumberlandwoodturners.com

 

[Jim Bennett]

John - thanks for the link - very good info in that article.

 

[Bill Boehme]

Here is a link that goes directly to John's article on the Cumberland Woodturners website: Methods and Jigs for Reverse Turning Bowls. It's an outstanding article and the Cumberland Woodturners have an excellent website with lots of other tutorials that are worth perusing.

 

[Dennis J Gooding]

Here is a link that goes directly to John's article on the Cumberland Woodturners website: Methods and Jigs for Reverse Turning Bowls. It's an outstanding article and the Cumberland Woodturners have an excellent website with lots of other tutorials that are worth perusing.

[
Link doesn't seem to work, Bill.

 

[Dennis J Gooding]

Here is a link that goes directly to John's article on the Cumberland Woodturners website: Methods and Jigs for Reverse Turning Bowls. It's an outstanding article and the Cumberland Woodturners have an excellent website with lots of other tutorials that are worth perusing.

Sorry, it does work, but not as expected. It spits our a PDF with no indication that contact has been made with the site.

 

[Bill Boehme]

[
Link doesn't seem to work, Bill.

It works on all of my computers and my iPad. On my Windows 7 PC running FireFox I have FF set to open PDF files using Adobe Acrobat. On my Windows 10 PC running FF it is able to open to open it inside FF. My iPad is running Safari and opened the PDF without any problem. Internet Explorer also works. You might have your preferences set to download PDF files rather than opening them.

 

[Richard Coers]

I'm no fan of a paper joint to hold on a bowl. Too much weight and cutting pressures for a joint with a purposely design weak spot. Turning half and quarter columns is perfect for that, but not a bowl. It's just too easy to turn off the scrap block when your done to take those kind of chances when you have so much labor in the segmenting work.

 

[Dennis J Gooding]

Hi - I’m getting ready to start gluing up a segmented bowl. Bottom is about 4.5” diameter, top ring about 10” diameter, seven total rings, 5” height.

I don’t have a jam chuck and certainly not one large enough to capture a rim of 10”. I had thought I could use my SuperNova 2 chuck with the 12” Cole jaws attached to accomplish the same thing. Does this seem like a doable procedure, or am I going to have to build a huge jam chuck?

I use a variant of the first method described by John in the referenced article. Instead of cutting directly into the plywood or MDF disk to fit a particular bowl, I screw four (or more for really big bowls) small sacrificial pieces of plywood into the mother disk so that they slightly overlap the perimeter of the bowl, using two screws each. Then, using a parting tool, I trim the plywood pieces to the fit the diameter of the bowl, cutting in just until one or more plywood pieces has been cut through. (This will automatically compensate for any small warps in the disk.)

For a conventional bowl, the plywood piece are trimmed to fit the outside diameter; for a hollow form they are trimmed to fit the inside diameter.

To hold down a conventional bowl so as to have unhampered access to the bottom, I screw a small strip of plywood at each of the above anchor points such that one end rests on the disk and the other rests on the side of the bowl far enough up to safely capture the bowl. I have used this technique for pieces of all size, including a 20-inch tray.

With this approach, the plywood disk will last practically forever and the plywood strips usually can be used several times and are quickly made from scrap plywood on a bandsaw.

 

[Mike Johnson]

I have a box full of different sized jamb chucks and left over pieces parted off of work pieces that I can always rummage through to use for a new project. Each piece can be reused multiple times until you run out of wood to use as a jamb, at that point I usually just turn the piece into several glue blocks.

 

[Leo Van Der Loo]

Jim I get the feeling nobody does want to answer you cole-jaw question, well, I do use the Cole-jaw extensively especially with the larger turnings I turn.

I will add some pictures so you can see what or how I use the Jumbo Jaws as Oneway call them, I have 3 different sizes for my lathes.

Here are two pictures the Black Walnut I have just returned the recess that I used on that bowl, stacked the steel center rubber covered buttons so I could hold the higher round rim securely, the next one is a old dry Applewood bowl where I am flattening the bace and then cut a recess into it, buttons on the inside.

The next two Applewood bowls I turned the recess and also the outside of the bowl while held in the Jumbo Jaws, the 20 year old one under that bowl I also returned both the recess and the outside of the bowl, the green tape is holding wedges I place to prevent the slight warped bowls from wobbling as I turn it.


The next Black Walnut has the recess returned so one will not be able to tell there was a tenon or recess, the large Elm platter is too large to hold on my Mega Jumbo jaws (15.5” max iirc) so I made a large extension to handle the extra large pieces.

And yes there are other ways to hold a bowl for returning the recess or tenon.

Piece of pinewood or other wood screwed to a faceplate, and then a slight recess turned where the rim will fit into, then frogs screwed like these holding the bowl securely works well and returning it is done very safely this way as well.

 

[Bill Boehme]

Jim I get the feeling nobody does want to answer you cole-jaw question, well, I do use the Cole-jaw extensively especially with the larger turnings I turn.

@Leo Van Der Loo , it may not be a matter of not wanting to answer the question, ... we were just waiting on you to answer it.

I think that Jim's question was asking about using his Nova Cole jaws for an "off label" purpose ... to apply pressure during the glue up of rings in a segmented turning. I'm not a segmented turner so I could be all wrong, but I don't think that these big thin aluminum jaws are meant for that type of service and might bend. Even a tiny amount of bending wouldn't be good. Anyway, I see jam chucks lying around everywhere in my shop ... almost every piece of wood is a potential jam chuck.

 

[Jim Bennett]

Folks - thanks for all the replies to my posting. My initial intent was to paper glue the base to a sacrificial piece of plywood disk, attach it to a faceplate, and then add a couple rings, turn them and add more, etc. When done, I was going to remove the faceplate and reverse the entire thing, holding the top ring in my large Cole jaws. I could then clean up and finish the base. But.....

I already had the base glued to the plywood disk and faceplate attached. After further consideration, I turned a dovetailed recess in the base, removed it from the glue block and mounted it in my chuck. I am now adding rings to the base by using a 15” disk, with a bunch of concentric circles drawn on it (for centering) in the tailstock. After adding a couple rings, I’ll turn them, add more, turn, etc. So, if I do need to touch up the base I’ll reverse the bowl into my Cole jaws, but at this point it might not be necessary - I was able to address the base after getting rid of the paper residue.

 

[Mike Johnson]

Jim,

Using the method as you have described is commonly used for segmented work, after adding each new additional ring to the blank you can usually start working on the piece after an hour or two of dry time for the glue. If you have a support from the tail stock end pressed against the stack of rings you can be more aggressive with your tool when rounding the stack. If you don't have a tail stock support for the freshly glued blank you need to take it slow and use more care and sharp tools when cutting and leveling the face of the last ring. A bad catch on the last ring of the stack can cause problems, if you add a large number of rings to the stack you might also want to use a steady rest with wheels to support the vessel midway to keep it centered and remove stress from the base. You also want to slow the speed of the lathe to reduce the centrifugal forces on a larger or longer hollow segmented piece when turning without any support from a tail stock or steady rest. Excessive RPM's can pull the unsupported piece from a bowl chuck or separate a weak glue joint. A lot of hours can go into a segmented piece and it only takes one mistake to destroy the effort. Take your time, don't get in a hurry, don't take any short cuts when you get close to the finish line, just like driving a car most accidents occur when you are only a mile or two from home..

 

[Jim Bennett]

Mike - thanks for the reply.

Glad to know that my approach is not out in left field! I was surprised to read that part about working on a glued up ring (or two) after only 1-2 hours of drying time. I guess I'm not that brave - I let mine sit overnight before attacking them. Since the majority of my work is done with carbide tools, I'm almost always using pretty sharp edges. Perhaps I'll try some shaping after 4-5 hours, but not too heavy-handed. As you say - a LOT of work goes into making a segmented piece and having it "decompose" on the lathe would be heartbreaking, to say the least.

 

[Mike Johnson]

Jim,

When you use the tail stock to compress the segmented ring onto the bowl you squeeze most of the glue from the joint and the wood quickly absorbs most of the moisture from the wood glue and it begins to set fairly quick. If you have your tail stock support pressed against the piece you can start turning on the piece in a short amount of dry time, without the support you want to wait at least several hours depending on the diameter of the piece. The larger diameter rings create more pressure on the cutting tool as it rotates on the lathe, a good catch on a glue joint not completely dry and un supported could cause it to break free. I sometimes use a bowl chuck or face plate on both ends of the piece using an adapter that fits into the tail stock quill, this provides a very secure method of hold a piece between centers and putting pressure on the glue joint.

 

[Jim Bennett]

Mike,

I'd rather be safe than sorry and am not in a big rush on my turning. I've glued up two rings at a time to the base and am waiting five hours. As I mentioned, I'm using carbide tip tools and they cut through the maple and padauk like butter w/o pushing hard at all. With two boys at home (ages 5 and 11) I've got plenty other things to keep me busy while the glue sets!

 

[Doug Freeman]

If you are going to continue with segmented turning you may want to consider a “bowl press” (can use it for most shapes). It doesnt tie up the lathe. Depending on the total depth and shape I typically glue up all rings then glue all rings in a stack. 4-5 rings get stack glued at once, dry several hrs, then 4-5 more etc. the whole piece then dries at least overnight, then gets turned all at once. Some shapes may be done in upper and lower halves, rough turned round, glued together and finish turned. The tenon or glue block is included from the start. More then one way to skin that cat.

 

[Jim Bennett]

Hi Doug - I used that method on my first couple bowls and it worked out OK. The only issue I had was that I was "eyeballing" the alignment of each ring on the stack. This last one I did on the lathe, using a 15" MDF disk with a bunch of concentric rings, put in the tail stock. It gets the rings very, very close to being right on center when I press things together. I've also found that I can get an entire bowl glued up in one day and have it ready to turn the following day. At first I was waiting 4-5 hours before gluing on additional rings, but have found that they are really well adhered after a short amount of time. Gives me time to get other things done while the last group dries.

Jim