I thought that I could do a large curved panel (6 foot wide by 17 foot tall with a 6 foot radius) glue up… OK so call me dumb.. I failed.. My first attempt was to palne everything to 1/2 inch thick and put it up green while it was still flexible..
Where the glue held the wood cracked.. other places the glue failed.. I used white hard maple 1/2 thick.. it bent about as well as a baseball bat, so I resorted to using hydralic jack and curved blocking behind it.. It got in place with the cracks and glue joint failures I mentioned..
I then tried to do a coopered panel and found that it was nearly impossible to get the joints all to line up. The results looked terrible!
Now I’ve seen raised panels that elegantly curve around a wall and I wonder how it’s done.. any suggestions?
Replies
It's usually done one of two ways.....bent laminations....that's layer after layer of veneer with glue between the layers, layed up over a form (this is how they make radius doors also).....or it's a built system similar to a stud wall (even uses the same terminology.......plates top and bottom that describe the radius......studs fastened in place on whatever centres you need along the plates.....then bendable ply or kerfed MDF 'skins' are attached....then the face veneers on top of that). 6' x 17' feet tall is going to be challenging no matter how you do it; solid wood would not be advisable, and maple is not a good bending wood......I think it would be virtually impossible to cooper something that size.
If it has to be solid wood, and you want to use maple, your only hope is, again, bent laminations....resaw the boards into lots of thin boards, and laminate them up. Or, kerf the backside of the boards, bend, and fasten as you go....the backside has to be hidden this way though.
cabinetmaker/college woodworking instructor. Cape Breton, N.S
Frenchy, this was in the local paper this morning.
BIG 36'' OLIVER BANDSAW, 5HP/3PH Power, Will Resaw 22'' Material. Machine Needs New Tires & Paint But This Is One Solid Saw. Sacrafice,Must Sell NOW. $1500.
One of these, 1000 clamps and a little ingenuity & you'll be in business.
Post some pictures when you're done.
Joe H
PS: The way you'be done most of this project, I'm surprised you just don't get a 12' diameter log and hack off what you don't need. Might be easier........
I'd go with Adrian's suggestion, or, use a bending plywood made for this application.It's still possible to get 1/8th ply from some distributors if it has to be wood.Otherwise, layers of1/4 sheetrock and flex-i-trak (metal bendable plates).
Go thinner then 1/2 inch. If you must use 1/2 inch run kerfs in the side that will be compressed. what about using Urea Form. glue
Which direction does the grain run? Vertical? Huge water tanks, wine vats, etc. were coopered with thicker timber and after the industrial age started, T&G or similar joinery made it that much easier. the trick is in true lumber, the right layout, a strong, acurate table saw, and a router set up to cut slots for splines.
Cut your bevels, rout the grooves, cut splines to fit, and don't forget to do a dry run fit.
Bending ply and veneer is the way to go.Make sure u order the bending ply oriented in the rite direction(it comes either way).Fun stuff to work with,youll get all kinduv ideas once uve worked with it.
First mistake..green wood..gonna split.
second mistake...maple..it's too dense for that kind of glueing and it was green..
third mistake..forcing with anything like a jack..it will explode sooner or later..
Now what you say? Let the wood be somewhat dryer..use a mositure curing glue like a poly type..add some sort of tooth for the glue to bite on, like a spline, or even biscuts..(this helps a bunch with alignment as well.)
I am guessing here..17' tall? grain going that way? A 6' radius is not much at all..you may be able to glue it up flat, then add back kerfs ( if it is not shown) to bend it..is it held by curved rails?..is the desired thickness to be 1/2''? Cuz yer next method may well be to cooper it..But, they sell a set of CANOE bits for the router..like a cove and bead that mate..you will want a form to wrap the pre coped and rounded parts around..and can clamp with wedges alone if you do it in segments..do not try to do the whole shebang in one fell swoop..unless you are an octopuss..
fill in some blanks here and we'll walk ya right through it.
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Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
I can do anything because the wood was next to free (several thousand bd.ft. cost me $30.00) I tried the green approach first because green tends to be more flexible I tried the coopered approach but tried to do the whole thing at once and it was just too much for my two hands to get right.. I think if I follow Daves approach and use splines to ensure that the joints are together I stand a really good chance of success..
I can make the wood whatever thickness I need to but I think 1/2 inch thick will work.. (yes the grain goes along the 17 foot length)
I expect to hold it in place with curved rails (and cover the vertical seams with styles)which I should be able to steam bend into shape.. I guess at that point my only question will be how much to overbend to allow for spring back.. I guess I can do some trial and error appraoch if nobody has those kind of numbers available or can tell me where to look them up..
I'm thinking of using Cherry for the rails and styles. about 3/4 of an inch thick..
It is very easy to bend if you cut your rails into 1/4 or 3/16 strips . Keep them in register by marking them before cuting. then glue them up to radius . I like to start clamping and bending from the center so that there is less misalignment at the ends. Clamp them tight and most people will not know that you laminated the rails . On the stiles ,make a hefty scraper to the radius and scrape them to shape. If you have a lot to remove from the edges ,make a few passes with your no.7 to speed things up a bit.
I would lose the whole steam kiln idea altogether, it takes a long time to get the steam to penetrate and when you pull it out of the kiln, you have merely 2 mins, and you gotta get it all clamped into place or its not good, it won't take...you would need five men and a small boy to get those lengths done in the time you have. polyglue..gives you time
The only thing that I will steam bend is the rails.. the panels themselves I think I will put splines in and then glue up each strip keeping it about 4 inches wide. The splines will keep everything aligned and I'll use like gorilla glue which is a nice slow drying glue leaving me pleanty of time to work things into position. a few brads stuck in with the nail gun will hold everything in place to allow the glue to set up properly and then I'll cover the nail holes with the rails. the only holes that will need to be filled will be the ones in the rails and styles..
Dave,
I think you have hit a solution for me.. I refuse to use plywood.. I absolutely refuse to use MDF or any other "engineered" product.
However if I follow your suggestion and put a spline on each board then I can carefully glue each board together and use a clamp to get each joint tight.. plus I won't have to go thru this panic attack when I attempt to assemble it.
Thanks very much!
I have done alot of bending in the last ten years and I would vote for laminating with 1/8" plywood(bending poplar, it comes in 4'X8' and 8'x4') or 3/8" wiggle/bending luan. There are some other products that come pre-kerfed on one side and very flexible, but these are usually a mdf/particle board. All the above are "engineered products" Any of the above work great especially if used in a vacuum press. The advantage of the engineered products are that they are more stable than any green or kiln dried lumber. I have had a 24" kiln dried maple top move more than 3/16" in less than a few days. This was in Calif(desert) where the humidity levels are a bit more even than other areas of the U.S. Plus getting ahold of some long veneers shouldn't be that hard. Paper back veneer would be ideal, especially if the seems could be hid with the stile/rails.
Resawing the rail pieces into 1/8"-3/16" and clamping them in a mold would not take too long either. I prefer using clamps over vacuum pressing for this process.
To make a 4' x8' mold for a vacuum press, and a cold press mold for the rails would take less than a day. You would have less than $100 in materials for the molds. Worse thing about this whole process is disposing of the molds when you are done. The larges mold that I have made was about 5' wide by 10' long. You can build a press for under $500. Another tip would to invest in a 7" glue applicator that has the hopper on top. Beats a paint roller any day.
Another method would to make a form/mold for solid lumber to lay on and cooper each piece to match the curve. Clamping is done with bar clamps that are bent to match the radius needed. I've done it this way too. There is ALOT of time spent in hand shaping the panels and it is hard to get a consistant surface. I would personally omit the splines. The reason I did it this way was because the panels needed to be solid and a raised panel profile ran around the edges. The sizes of these were around 4'wX5'-7'h. and some were convex and some were concave. They were for a staircase.
i would suggest looking at George R. di Cristina's book "A simplified guide to custom stairbuilding and tangent layout". i am not sure if this book will solve your problems, but it may give you some good ideas. it is a fascinating book on using the tangent principle to make exact joints and patterns for incline turn handrail sections. the man is a genius IMHO. these principles may be just the application you are looking for.
Frenchy having done a number of radius work ie: crown, molding, arches etc.,just some tips and experiences I have had.
build a template and and use blocks for clamping to it
use 1/4" -3/8" stock for bending
apply glue with 4" paint roller I use titebond
make widths 1/2" wider than finished product your bound to get some creep up and down, hand plane backside after you remove from forms and then run thru thickness planer, jointer, router table or hand plane to finish front.
get a second pair of hands to assist in glue up
another technique I have use is similiar to using templates clamps and blocks, except I use air pressure with a fire hose between glue up and blocks, get the strips in forms apply air pressure bada bing bada boom
use kiln dried lumber
splines will have you pulling your hair IMO
good luck with all the wood you have a the info your recieving your bound to get one of the techinques to work
Edited 3/23/2004 10:47 pm ET by DANUSAN11
I've never been very happy with the result of my glued up work.. Glue lines are too glaringly obvious to my taste, I might be forced to use them for the crown molding at the top but hopefully I can turn something out on my shaper that will achieve the same thing.. As for doing the rails as a glue up, that's gonna be my last appraoch. Maybe somebody with real skill can achieve a decent result but so far all of my attempts have looked like glue ups.. BAD!!! glue -ups