AVS Forum banner
Status
Not open for further replies.
1 - 20 of 33 Posts

·
Registered
Joined
·
424 Posts
Discussion Starter · #1 ·
Looking for experience in rough framing curved soffit and matching stage.


My thoughts are to take a 1x# (# being the height....but mine could be 12"...so 1x12 I guess) and curve a bunch of 'kerfs' with my circular saw 1/2 thru the wood and carefully curve around. I could cut plywood to the appropriate radius and use this as a template to cut the 'joists' the correct length and angle to wrap the 1x12 on.


The soffit will be drywalled...so maybe I could just bend some 7/16 OSB on it.


I will be adding crown to the soffit...hopefully it will be flexible enough to wrap. (The radius will be rather large given the width to be 115")


Looking for other options or ideas that work well that I haven't thought of.


Thanks!
 

·
Registered
Joined
·
3,639 Posts
For my stage, I built the rectangle framing for the main part of the satge out of 2x6 and put it in. Then I drew the curve I wanted for the stage on the floor. I first drew the curve using a dual focal point (oval) curve that extended a foot past the front of the 4' rectangle stage. Then I drew the curve to blend into the rectangle stage. ANYWAY, here's the part you want. Make a paper template of the cuve you drew so you can cut the top of the stage later. I cut the joists from the front edge of the rectangle to the edge of the curve using 12" OC joists in the middle and 6" OC joists on the ends (because of the blended curve shape).


Now for the face of the stage, some people take like 1/2" plywood, cut 1/4" grooves every inch or so to allow the wood to curve. I bought 1/4" hardwood and used 2 layers of it to bend around the curve, glueing and screwing the whole way.


Use the paper template for the top of the stage. I added 1+1/2" to the curve to make a bullnose on the stage that matches the risers. The risers have rope lighting underneath. Make sure you add 1+1/2" perpendicular to the curve, or the curve will be wrong.


Put it all together and you have a nice curve on a good looking stage. I would add pictures, but I don't have them on this computer. I can get them if you really want to see them. As for the curved soffit, I don't know since I don't have a soffit. I have been thinking about a fabric covered proscenium to hide the speakers and maybe match the curve of the stage.
 

·
Registered
Joined
·
48 Posts
I tried cutting kerfs for my stage radius board. Three broken boards later, I gave up on that idea and went with very flexible moulding that was close to the heighth I needed for the radius.


If you go with kerfs, make sure to get high quality lumber or hardwood with no knots or imperfections. Even though I cut enough kerfs by my third attempt at this, the board still broke because the wood I was using had a small knot at the breaking point.
 

·
Registered
Joined
·
3,301 Posts
Edit: Upon re-reading your post with a very large radius, 1/4" or 3/8" plywood may be all you need.


For smaller radius:



Being in Atlanta, you should have no trouble finding 'bendable plywood', from a local hardwood / plywood supplier.


There are basically two types:


Veneer plywood that has a flexable center core and comes typically in 1/4" or 3/8" thickness.


Pre-kerfed MDF board, than comes in 1/4", 3/8" maybe 1/2" or more.


Both of the above can be bought in either 4' x 8' sheets or 8' x 4' sheets, depending on which way you need the material to bend, (ie., tall curved columns (heights greater than 4 feet) vs. long lower profile cabinets or skirting (heights less than 4 feet).


Great stuff. Multiple layers can be glued together to form rigid curved shapes. Forms of duplicate curved profiled plywood (MDF) edges can be spaced Top, Bottom, & inbetween if necessary for taller forms. Glue and nail (stable, screw, whatever) in place, then finish outside face appropriately. The MDF forms present a much smoother face for painting, the 'Bending Ply' is a lower grade veneer on the face (usually a Lauan type) that would need to have some other type of facing applied, (plastic laminate, veneer etc.).




Good luck


Kerfboard:
http://www.interiorproducts.com/imag...oductphoto.jpg


Bending Ply:
http://www.clarkswood.com/images2/bendy2.jpg
 

·
Registered
Joined
·
169 Posts
Quote:
Originally posted by Tannehill
I tried cutting kerfs for my stage radius board. Three broken boards later, I gave up on that idea and went with very flexible moulding that was close to the heighth I needed for the radius.
Since I put my stage down on concrete (well, on roofing felt, but that felt was on concrete), I used pressure treated lumber on mine. The pressure treated lumber seemed like it was built for this task (maybe it was just mine?) as it was slightly flexible and with the right kerf-depth, worked *perfectly*.


I have pictures of it here: http://www.nessoft.com/gallery/stage


There may be easier ways to do this - it took two of us a full day to do the curved part of the stage (built the square part the day before), including Autocad plotting it, curving the 2X10, cutting the angled intersecting joists, cutting and bullnosing the 3 layers of plywood and assembling it. It turned out *fantastic*, but you may be able to find some shortcuts.


- Pete
 

·
Registered
Joined
·
169 Posts
Quote:
Originally posted by smithsonga
I will be adding crown to the soffit...hopefully it will be flexible enough to wrap. (The radius will be rather large given the width to be 115")
I can't even imagine how to pull this off - unless you do a "square" crown. If you do a standard 45 degree crown, this will be amazingly challenging. Hopefully one of the crown molding experts here can give some good advice on how to apply crown to a curved surface...
 

·
Registered
Joined
·
424 Posts
Discussion Starter · #7 ·
Peteness - How are you going to finish the stage? Carpet?


Certainly a STABLE stage.
 

·
Registered
Joined
·
6,697 Posts
Quote:
Originally posted by peteness
Since I put my stage down on concrete (well, on roofing felt, but that felt was on concrete), I used pressure treated lumber on mine. The pressure treated lumber seemed like it was built for this task (maybe it was just mine?) as it was slightly flexible and with the right kerf-depth, worked *perfectly*.


I have pictures of it here: http://www.nessoft.com/gallery/stage


There may be easier ways to do this - it took two of us a full day to do the curved part of the stage (built the square part the day before), including Autocad plotting it, curving the 2X10, cutting the angled intersecting joists, cutting and bullnosing the 3 layers of plywood and assembling it. It turned out *fantastic*, but you may be able to find some shortcuts.


- Pete
Hi Pete,


Very helpful photos. I notice that you left 3/8" of material on the depth of your kerf cuts. What was the width of the kerf cuts? Was it just a standard circular saw blade width, or did you use some sort of dado blade to get extra width?


Thanks.


Larry
 

·
Registered
Joined
·
169 Posts
Quote:
Originally posted by smithsonga
Peteness - How are you going to finish the stage? Carpet?


Certainly a STABLE stage.
It is finished in carpet - black carpet - and you can't really see very much of the hard work that went into the stage now that it's completed. It's excessively stable, though - no resonance from the sub at all, that's for sure.


You can almost see the finished product here (black carpet makes it actually hard to see, thus the "almost"): http://www.nessoft.com/gallery/carpet


- Pete
 

·
Registered
Joined
·
169 Posts
Quote:
Originally posted by LarryChanin
Very helpful photos. I notice that you left 3/8" of material on the depth of your kerf cuts. What was the width of the kerf cuts? Was it just a standard circular saw blade width, or did you use some sort of dado blade to get extra width?
Standard saw blade (carbide tipped). I used Autocad to calculate length of the surface of the curve on the front and back of the (theoretically) curved 1.5" board. The difference in length is how much material needs to be taken out. I divided this difference by the width of the saw blade, and then this is how many cuts needed to be made (minimum). Just to be safe, I doubled the number of cuts and then divided the length by that to say how often the cut should be made. It was close to 4", so I just did a kerf every 4". The "doubling" wasn't very scientific, but the rest was :). It turned out very well - the pressure treated lumber would have taken more bend - it almost seemed a bit "green" still - not sure if all pressure treated lumber would be the same.


- Pete
 

·
Registered
Joined
·
3,301 Posts
Standard wood crown molding does not bend while in it's angular (correct) mounting position. You will need to buy some 'polymer resin' based flexible crown molding for this.
 

·
Registered
Joined
·
7,780 Posts

·
Registered
Joined
·
3,639 Posts
I'm telling you, forget about cutting kerfs in the wood. Get a sheet of 1/4" hard wood and put down 2 or more layers on the curve. We did it in about 1 hour.
 

·
Registered
Joined
·
424 Posts
Discussion Starter · #14 ·
Ted:


Great site. Can you elaborate on the two nail, long string approach? I know my stage radius (130") but your method looks easier than trying to get one nail 130" away from my curve (I was going to nail a long 2x4 to the plywood and put a screw in 130" away).


How do you calculate the double nail placement if you know the radius? Talk about a serious trig problem.


Thx

Jim
 

·
Registered
Joined
·
7,780 Posts
The hardboard method is definitely the only way I'd ever do this. It was cake.


As far as the nail placement / string length, I just did a little trial and error. I had an idea of where I wanted the radius to go. I just moved the nails to a reasonable spot. Mostly I varied the string length to make it satisfactory, as I recall. No Trig calculations, I'm afraid.


Ted
 

·
Registered
Joined
·
3,639 Posts
Remember that the two nail method is for an oval, not a circle. I did it using trial and error with a fixed string length to make the curve. Put in 2 small nails equal distance from the center of the stage. Take a long piece of string and wrap it around the 2 nails and the center of the curve you want. Tie the string to make a circle and use a pencil as the 3rd point to draw the curve. If you want the the curve flatter, move the nails further apart and tie a new string.
 

·
Registered
Joined
·
3,301 Posts
Here's the formula for cutting elliptical shapes (or partial shapes).


First the basics:


An ellipse has two axis': a major (longest) and a minor (Shortest).


In the attached link 'a' = 1/2 the major axis & 'b' = 1/2 the minor axis.


'c' is the distance from the center of the ellipses to ONE nail.


So, lets say you wanted to draw (cut) your stage front as 1/2 of the long axis. Let's further assume that the quadrants (ends) are to be 10 feet apart. And that you want 1/2 of the minor axis to extend 2 feet.


So now


'a' = 5 feet

'b' = 2 feet


We need to find 'c',


'a'^2 (squared) - 'b'^2 (squared) = 'c'^2 (squared)


sqrt of c^2 = the distance from the center to each nail.


c = 4.58, so the distance between the two nails would be 9.16.


Plant the nails appropriately, then tie the string such that when pulled tight it is tangent to the greatest point on the minor axis (ie., center of the stage protrusion).


http://ccins.camosun.bc.ca/~jbritton/oval/oval.htm



This sight is kinda fun, click on the "brighter" icon, then click and drag on one of the two points to vary the ellipse. By clicking and dragging 'Outside the ellipse - see what happens.

:D

http://torus.math.uiuc.edu/eggmath/Shape/pins.html
 

·
Registered
Joined
·
3,639 Posts
Here are 2 pictures of the stage being built that shows what I described above.


Here's a picture of the stage curve framed. It has 2 layers of 1/4" hardwood on the face and the bend changes direction 3 times.
 

·
Registered
Joined
·
3,639 Posts
And here it is after 2 layers of 1/2" CDX with a 2" bullnose. The bullnose was finished with a 1 inch diameter 1/2 round trim. After this, the top was padded and it was all covered with a thick berber carpet.
 
1 - 20 of 33 Posts
Status
Not open for further replies.
Top