# Installing flats on a turntable

#### lcole

##### New Member
Hi everyone!
High school theatre teacher here, in over her head as usual. We are just about finished building a 16 ft turntable. It will be rotated manually, in-between scenes, a spiderweb of 1x4s on stage with casters facing up. Top platform is just two layers of plywood. Center steel flanges/pipes for pivot point. Now I must install a wall through the center of the circle- so 16 ft across. Originally 10 ft high, but 8 for extra stability and ease of build.
The flats will be decorated on both sides.

I'd really like someone to tell me the best way to do this. most flats i just throw a big jack on the back, but it'd be hard to hide.

also- while we are at it- does anyone have any good guides to carving foam into crown moldings?

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#### dbaxter

##### Well-Known Member
If the wall will be used as part of the set - living room, porch, whatever - don't make it totally a straight line. Give it a little break so you have a 'V', however mild. Obviously, the bigger the V, the more stable. Or, maybe even a stretched out 'Z'.

#### almorton

##### Well-Known Member
We have sets on our revolve regularly where they are, essentially, a straight wall with a door or window in them. We don't just use flats for these, though. They're really construction depth walls, built with a cavity and seriously braced internally and securely fixed down to the deck, then clad with plywood and decorated. It's the only way to get the rigidity, really. Our last set had a wall that was about a foot deep in total. This is a shot of it partly constructed during rehearsal. It had two book cases and a double door bult into it, and it was already rigid and stable enough to be used by the cast.

#### lcole

##### New Member
We have sets on our revolve regularly where they are, essentially, a straight wall with a door or window in them. We don't just use flats for these, though. They're really construction depth walls, built with a cavity and seriously braced internally and securely fixed down to the deck, then clad with plywood and decorated. It's the only way to get the rigidity, really. Our last set had a wall that was about a foot deep in total. This is a shot of it partly constructed during rehearsal. It had two book cases and a double door bult into it, and it was already rigid and stable enough to be used by the cast.

This is what I was thinking. Start with a 2x4 base and her bolt it down through the platform. I guess I could go even wider, I have 2x8s sitting around.

#### almorton

##### Well-Known Member
We have the advantage that our (motorised) revolve is set into the deck and sits on (I think) 8 castors running on a steel track, so it's also heavy and stable in itself. The wall itself, even before fixing to the deck, would have been a very rigid structure. Even just sitting it on the deck while it was being worked on, weighted with stage weights, it would have taken quite a lot of abuse to topple it.

#### Catherder

##### Well-Known Member
Leverage other set pieces as bracing too. Furniture, a front porch, etc.

Edit: in addition to solid structural bracing inside the walls. Not as the only things keeping them upright.

#### Van

##### CBMod
CB Mods
There are tons of resource for making you own table top foam cutter but they all have similar issues; they all have a static vertical hot wire. to do crown moldings you really need a framed wire that is able to move in the X and Z axis. typically the foam billets are laid on a table, an a cutting frame follows a metal or wooden guide which is curt to the profile of your molding. This requires lots of room or the willingness to make a bunch of 24' long chunks of crown which have to then get glued together and have all those joins addressed. Your best bet is to find a local or regional producer of foam molding. They are often used as an base for Stucco. a company buys the molding and then covers it in stucco, no one's the wiser that it isn't real.
There are several large regional companies and often many small companies scattered about larger cities. Here in Portland I always used NW Foam Products. You can usually pick from a catalog of stock shapes or, if you have a really picky designer, you can submit a custom profile in a DXF or DWG and they can build custom guides for you. That, however is a much more expensive option. Once you obtain your molding you then need to coat it with something, I always suggest VSSSD, so that you can paint it. <most paints will not stick to foam, or they melt it.

#### bobgaggle

##### Well-Known Member
If you have a static hotwire setup you can carve a complex moulding in multiple passes. Lots of times plywood and sonotube have masqueraded on stage as expensive crown moulding. As for your walls, they must be thick enough to stand up on their own, or you have to brace them. An 8' high wall could be 12" thick and stand up just fine with some screws through the bottom plate into the deck. Use a sheet of 3/4" for the framing and 2 sheets of luan. I think "cabinet grade" plywood at HD is like $50/sheet now and luaun is$25 ish. \$100 materials for each 4x8 'flat'.

#### jtweigandt

##### Well-Known Member
you can get a lot of mileage by stacking foam of various widths to make a pleasing "complex" profile

Can also cut small pieces with a 45 degree edge.

I also have rip sawed the bullnose off of the tongue and groove foamula R panels to yield a nice pice of half round to use in my buildup

All my foam cutting has been with the table saw, (messy but quick) or with a razor toothless saber saw blade. or score and snap when installing "boards"

Van

#### JonCarter

##### Well-Known Member
LCole, here's an option for holding your flats vertical on the TT. You say you're in a school. OK, buy the shop teacher a six-pack (or whatever) and have him/her make a class project out of making a half-dozen of these: 1/4" plate, 2'-3' square, with a 3' piece of 1x2 channel welded vertically in the center. Drill (1/4") the vertical channels through the 2" dimension at 6" and 30" above the plate. Then drill & screw the plate to your TT (4, 3/8" lag screws near corners, maybe). Bolt the stiles of your flats to both sides of the verticals.

This should be pretty steady for flats up to 10' high. Additional bracing (furniture, etc.) as suggested above won't hurt. Save the plates for the next show. Give the shop teacher comps to your show.

#### Van

##### CBMod
CB Mods
you can get a lot of mileage by stacking foam of various widths to make a pleasing "complex" profile

Can also cut small pieces with a 45 degree edge.

I also have rip sawed the bullnose off of the tongue and groove foamula R panels to yield a nice pice of half round to use in my buildup

All my foam cutting has been with the table saw, (messy but quick) or with a razor toothless saber saw blade. or score and snap when installing "boards"View attachment 23804
Stacked Profiles are a great way to go! 30NF or 30 Neutral is a great glue for this. It is a Latex based Contact cement specifically made for foam.
Just for others that may be reading this in the future. Cutting Extruded Polyethylene, well, ANY kind of foam on a Table-saw is risky. I highly reccomend cleaning and waxing the top and the rip guide prior to attempting. Also, use a flat Push stick or planing paddles to push through blade. If the foam kicks back you cannot react fast enough to keep from getting burns on your fingers from friction with the foam. IDK why it does it but, Yow does it hurt.
Also, if your foam flexes and the blade doesn't completely come through the material do not reach up and press it down with your hand <this is Table-saw 101 but I've seen it happen more often with thin sheets of foam> You wouldn't beleive how many folks there are with missing thumbs or thumb tips.

#### jtweigandt

##### Well-Known Member
I don't know whether it's our speed, or large blade or tooth combo, but when I cut foamula R or whatever the blue brand is (both polystyrene rigid insulating board)
it cuts like buttah.. We do have a BIG table saw, so it is hard to bog.. Also relatively higher blade is vectoring more down than back. low blade is pushing back or even up.. YIKES

But yes... push sticks a must. And mask/respirator for the fine particulate dust.

Wood or foam.. the table saw wants to hurt you..

#### JonCarter

##### Well-Known Member
How did we get from mounting flats on a TT to cutting foam moulding sections???

#### jtweigandt

##### Well-Known Member
How did we get from mounting flats on a TT to cutting foam moulding sections???
Original post had the second question at the end

#### JonCarter

##### Well-Known Member
I apologize; I missed that issue in the original post. But unless the crown moulding needed is some very unusual pattern, isn't stock material from the local lumber yard cheaper than than the labor & material required to make your own?

#### jtweigandt

##### Well-Known Member
I apologize; I missed that issue in the original post. But unless the crown moulding needed is some very unusual pattern, isn't stock material from the local lumber yard cheaper than than the labor & material required to make your own?
At least around here moulding is pretty expensive.. even normal trim boards.. I can get qty 8 8 foot x 6 inch baseboard from one 18 buck 4x8 sheet of foam vs 5 1/4 width 8 foot moulding in faced chipboard for 21 bucks.. thats an > 8x cost savings