Tall flat on tracking wagon

[Rainmaker]

Hi all, back again.

I have some 12' tall, 10' wide, hard cover Broadway flats mounted on the DS edge of a 1' wide wagon. Framed out of 2*2 with trundle casters. I have flats on the on and off stage edges but I'm still getting some shimmy when we push them in their tracks. We've tightened up the knife tolerance so my only thought at this point is sandbags on the wagons and maybe a diagonal brace from the top of the flat down to the wagon in the center.

I can attach an image if this explanation is unclear. Just trying to figure out if I'm missing something else obvious I could do to combat the shimmy and top heaviness other than more wagon weight and that brace.

 

[Van]

When you say shimmy do you mean the cart is wiggling back and forth as it rolls on and off stage? or do you mean the flats are twisting, along the Z axis as the unit rolls on and off?

 

[Rainmaker]

When you say shimmy do you mean the cart is wiggling back and forth as it rolls on and off stage? or do you mean the flats are twisting, along the Z axis as the unit rolls on and off?

Yeah the cart is wiggling US/DS a bit. I added (3) 35 pound sandbags and a 1*3 running from the middle of the wagon up to the flat and that took some of it out but there's still some particularly if I try to move it quickly like we will in the scene changes

 

[bobgaggle]

sounds like this unit is built really light, not much inertia; any little bump in the floor or imperfection in the wheels will show up as wiggles when you move the unit. You've got the right ideas, either make it REALLY stiff or make it a LOT heavier. Another question, how many wheels do you have on it? I imagine more than 4, given its dimensions. those extra ones in the middle might be causing your problem if the floor isn't very flat...

 

[Rainmaker]

There are 6 trundle casters on it. Each is rated for 75 pounds. And yeah, our floor is far from flat, we tried to shim and level the subdeck they're riding on the best we can but it's not perfect by any stretch

 

[kicknargel]

Yeah, fewer better casters might help. Fewer will reduce high-centering and I'd prefer a soft rubber for a little shock absorption. Also, to stiffen up the flats, I'd add diagonal bracing near the top, from the return flats to the main one (diagonal if you're looking in plan view from the top). That should reduce the twisting about the z-axis that Van mentions.