# Giant arches

#### cvanp

##### Active Member
Hey all,

We're starting to move from the design phase to construction phase in Guys And Dolls. We've already built our stage rake and now we're starting to build several giant arches that form the sewer in the show.

Here's an image:

I've got accurate measurements and everything for how big the arches need to be, the problem is making them - we aren't quite sure how.

I want them made out of luan, as it seems that is our most cost-effective way to do things (plus if we used something like muslin that tends to ripple when people walk by it, in my experience). The problem is figuring out how to cut the actual arch. Is there a certain way we might want to approach building this?

Thanks,

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#### Charc

##### Well-Known Member
I have some plans I can look at for an arch, but it won't be what you want. Of particular interest for you though would be the top section, I think.

I'll take a look at that soon.

#### Van

##### CBMod
CB Mods
Traditionally, thie sewer scene takes place against a silly looking backdrop. I like your "Cut-Drop" look a lot better. These could be made as Cut Drops, but I think you are looking for a hard solution. I need to run home and do some drawing I'll post a suggestion in a bit, if no one else beats me to it.

#### cvanp

##### Active Member
Thanks Van. Any help you can provide is great! You're right about the silly looking backdrops... that is what I was making every effort to avoid. Of course, a backdrop would have been a lot easier. Now I have to figure out how to build this behemoth...

Thanks again

#### SHARYNF

##### Well-Known Member
Van is the master here, but sometimes taking lengths of 1 inch pvc pipe, glueing them to make the length and then bending them into the arch works fine. You can also get a material with stretch ability, or attach luan Trick is to met the side pieces to be stiff enough so that it will force the pvc to keep the bent shape.

Sharyn

#### cvanp

##### Active Member
Sharyn,

thanks for the suggestion of PVC. It sounds like it could work but it might be a bit complex to build (and seeing as how it's all volunteers, parents, etc. we have to keep it relatively simple). Plus I'm not sure if PVC would present a budgetary problem - although that's just an unfounded concern, I don't know how much 1-inch PVC actually costs.

Thanks for the suggestion though!

#### jwl868

##### Active Member
I’ll put in my two bits on this, but I, too, defer to Van.

Will the arches be hung from a pipe?

Why not use “conventionalflat construction methods: 1x4 frame with the lauan cover?

Based on your sketch, I took an educated guess at the dimensions (Semi circle, 12’ radius), but it looks like at least 8 sheets per arch. The construction may be complicated by how wide the panel needs to be at the side/base and how wide the panel has to be at the top (between the top of the curve of the arch and the bottom of the teaser.) [I assumed 3 feet for the bases and the top of the arch.] By complicated, I mean working within the limitations of 4’ x 8’ sheets and then how much lauan will go to waste.

I also think you’ll have to build it in at least two pieces – left and right. But even those may be unwieldy to move into position. May be difficult to flip over if built face down.

**

Perhaps you know your pool of volunteers: But you should be able to find a 3 to 4 people with power tools and the ability to use them. My own experience is that people are always willing to help and will do good work, they just need the instructions. In any case, construct the upstagemost archway first – errors/blemishes will have the best chance to be hidden and everyone will have learned a few things by the time you do the front archway.

Joe

#### gafftaper

##### Senior Team
Senior Team
Fight Leukemia
Once again pointing out Van's the master here. But I would go with 1x3 or 1x4 standard flat construction techniques here on the sides. Build it in four sections, the two square areas and two half arches. For the arch section, build the top like a normal flat and make the bottom come across at an angle. Then throw a few extra angle pieces in to help with some extra support. You won't have 1x4 support in all places so the Luan will be a little bit flimsy in places. Something like this below.

#### Van

##### CBMod
CB Mods
I'm no master. I'm just a carpenter. Actually what gaff put up is just about what you're going to see from me. I would add that although my drawing does not show a return on the inside of the arch one could be easily added. I threw this together real real quick so som other things to take into account. To reduce the weight of the piece you can rip down the internal pieces < toggles > to 1 1/2" - 2 " don't go any smaller or you're gonna get bowing. I'd probably use 1/8" Luan on this arch, again as a weight issue. Toggles could be moved to 4' centers but I wouldn't recommend it, If you were to use 4x12 sheets of luan you could easily go to 36" O.C. Take a look at these I'll chaeck back later for questions/ clarifications.

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#### cvanp

##### Active Member
Wow, Icewolf and Van, you guys are awesome!

Now my next question: what's the best way to get an accurate arch shape cut from the luan? I know how to frame it out now, but that's the best way to make the arch actually an arch? And make it look good? I guess what's tough is that it's a circle shape, and that doesn't seem too easy to do.

Thanks again!!

Senior Team

#### Van

##### CBMod
CB Mods
Not knowing the exact measurements of your arch I'd say Use Dereks advice.
Layout all the pieces of luan that you are going to use as cover on the floor, in the directions, and places that you are oing to frame out the arch.
Find the center line of your arch.
Project that center line as far out as your radius of the arch.
Make a mark for the Point of your trammel points.
Now scribe your line onto the face of the luan and cut it out with a jig saw or skill saw set very shallow.
Another way to do it, if you don't have enough floor space is to "grid" the arch.
Make a scale drawing of the arch on grid paper. Using 1/4" grid paper, and drawing a 1" scale drawing on it will give you an exact picture of every 3" of the arch.
Now snap lines onto each piece of luan in a 3" grid.
Draw what you see in each grid of the paper in the coresponding box on the luan and you will have a good representation of your arch.
Make a cut on the outside of the line with a jig saw, or a skill saw set very shallow then using a rasp, belt sander or what ever tool you have sooth out the line to the closest approximation of the arch line that you can get.

This second technicque is the same technicque you use to transfer a rendering of a painted drop to the full scale drop. Hope that helps.

#### gafftaper

##### Senior Team
Senior Team
Fight Leukemia
I think I would use a metal cutting blade in the skill saw. My old college T.D. who knew every trick in the book was a huge fan of metal cutting blades for any sort of detailed skill saw work or work that you need to sand down really well.

What do you think of that Van?

As for drawing the line. All you need is a long string, a pencil, and a screw into the floor at the center of the circle. If you want to get fancy these are REALLY cool. They attach to any half inch pole so it's even easier than the string to get a perfect line.

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#### jwl868

##### Active Member
Another way to draw the arc would be to use a board (like a 1x4 or 2x4) or a couple boards screwed together to make a long compass. Drill a hole near one end to pivot on and then drill another hole at your radius. After laying the wood out and locating the center of the arc, one person holds a dowel or similar rod at the pivot, and another person makes the arc with a pencil through the other hole.

Joe

#### bobgaggle

##### Well-Known Member
Since this is just for the sewer scene, I'm assuming you're flying these in. Now I'm just a high school senior, but my advice would be to use sheet foam. Its light and takes no time to cut out whatever you want. I build a giant castle silhouette for my school's production of Dracula this year. It was a 40'x16' flat that was supported with 1x3. it worked great

You could easily frame out your arch with 1x4 (or even PVC molded with a plumber's propane torch), use some foamboard liquid nails to apply the foam and stand the thing up. Because its flying, you don't have to worry about actors kicking through it while stumbling around in the backstage dark. Its also very light and takes paint well.

The only inhibitor would be the cost...a 4x8 sheet of 1/4" costs $10 at home depot. I don't know if you've used it before and have any left over. #### icewolf08 ##### CBMod CB Mods Wow, Icewolf and Van, you guys are awesome! Now my next question: what's the best way to get an accurate arch shape cut from the luan? I know how to frame it out now, but that's the best way to make the arch actually an arch? And make it look good? I guess what's tough is that it's a circle shape, and that doesn't seem too easy to do. Thanks again!! I didn't even post in this tread yet... I agree with what has been said though, scribe and cut. You will find that at viewing distance slight imperfections won't really be visible, so cutting with a jigsaw is probably fine. If you want to be really precise you can use a router. You would do this in much the same way as the long arm compass except instead of a pencil on the end you put the router. This is of course assuming that you have enough space to lay out all the pieces. Then you can just swing one arc and be done. Simple, precise arc. #### Van ##### CBMod CB Mods Premium Member Since this is just for the sewer scene, I'm assuming you're flying these in. Now I'm just a high school senior, but my advice would be to use sheet foam. Its light and takes no time to cut out whatever you want. I build a giant castle silhouette for my school's production of Dracula this year. It was a 40'x16' flat that was supported with 1x3. it worked great You could easily frame out your arch with 1x4 (or even PVC molded with a plumber's propane torch), use some foamboard liquid nails to apply the foam and stand the thing up. Because its flying, you don't have to worry about actors kicking through it while stumbling around in the backstage dark. Its also very light and takes paint well. The only inhibitor would be the cost...a 4x8 sheet of 1/4" costs$10 at home depot. I don't know if you've used it before and have any left over.

Hey This is mostly a good idea. I can see using 1/2" blue foam, it's just as expensive as a sheet of luan. The big trick is attaching it to the framing. Never trust glue alone. You would want to use drywall screws and fender washers, sink the washers into the foam a bit then putty over < or use a liberal coating of VSSSD>

No Open Flames around PVC Pipe! You can use a heat gun, and even that you need to use in an extremely well ventilated area.

Other than that last Caveat, Bobgaggle, Great Post ! Great Ideas!

< for a high school kid>

#### cvanp

##### Active Member
I didn't even post in this tread yet...

Consider it a product of me posting at 11pm, when I'm barely functioning. I meant to say thanks Gafftaper (but thanks to you too!)

We were discussing foam as a possibility... the cost is (in my area, anyway) relatively on par with luan so that's not a concern so much as the durability is, as well as making sure someone's arm doesn't get punched through it.

This might be the way to go though, especially because of the sheer size of these pieces. That may help us when it comes down to mounting them and doing the actual flying.

Re: Putty/VSSD: I'd rather use something off the shelf due to time constraints. My TD is endorsing spackle, is that good or is there something better available?

#### Van

##### CBMod
CB Mods
Consider it a product of me posting at 11pm, when I'm barely functioning. I meant to say thanks Gafftaper (but thanks to you too!)

We were discussing foam as a possibility... the cost is (in my area, anyway) relatively on par with luan so that's not a concern so much as the durability is, as well as making sure someone's arm doesn't get punched through it.

This might be the way to go though, especially because of the sheer size of these pieces. That may help us when it comes down to mounting them and doing the actual flying.

Re: Putty/VSSD: I'd rather use something off the shelf due to time constraints. My TD is endorsing spackle, is that good or is there something better available?

If you're going to use foam, you have to use scenic dope, the VSSSD recipes that I have posted on here are simple to mix, non-toxic, set up quickly, and cure quickly. Straight latex paint won't stick to foam well enough, it pools up, Spackle, by itself, won't stick to foam either. it'll just crumble off. You need either a commercially availible "lagging Compound" availible at most Insulation places or VSSSD which is my version of Lagging compound with a few Theatrical twists.