Scaffolding towers

[maladroit]

Ratchet straps really are great for this stuff. You can get them in almost any required strength...sometimes you see them holding down a flatbed full of concrete culverts going down the highway.

While the ratchets are great for cinching things down, the real utility comes from the strength and durability of the strap. Googling around, I've found some places that will sell bulk tow strap, 2" polyester 10,000lb, 300 feet for $80 as an example. Might be able to find even better prices.

[The Rod]

I was going to suggest ratchet straps as well... Easy, multi-purpose and way easier to see. And as things 'settle' throughout the week you can easily give them half a crank or so to keep things tight. I always liked the fact that the same ratchets that secure our tower to the playa also secure it to the trailer for transport.

Put reinforced grommets in your shade material and clip a carabiner through the grommet and around the strap. The rigging from cloth to strap is then dynamic to a degree, and the rigging at the apex of the pyramid shape and between the cloth and the ground can be static.

Carabiners are much stronger, more reliable, uv resistant and re-usable than zip ties.

We got a bunch of free climbing rope from a rock gym a couple years ago, thought it was a great score for BM. Once we got to the playa it proved to be too stretchy for reliable guy lines, to wide in diameter to use for lots of purposes and mostly useless... This last year we went crazy at Harbor Fright and bought a ton of the little orange ratchet straps to use as guy lines for carports and other small structures, those along with lag screws made securing crap to the playa a breeze....

Check out the lag screw thread for ideas on how to anchor your guy lines, all sorts of great stuff in there.

[mattcamp]

So... ground anchors for something on this sort of scale.

I've had a read through the entire lag screw thread and there was some very useful info there but it's mostly for dealing with smaller structures. Bigger structures seem to refer to really large augur anchors, or lots of rebar.

I had been thinking something along the lines of a scaled up version of the below, approx 6" across, using 1/4" 18" long lag bolts in the corners.



Overkill? I'm not sure a single 18" or even 24" would be strong enough without such a plate.

Would drilling 4 lag screws down in such close proximity to each other weaken the overall ground around them?

[EspressoDude]

Earth anchors http://www.homedepot.com/p/ShelterLogic ... 719050-_-N

A-Rock's grommet plan is good if there are enough layers of fabric. We use zip ties, way cheaper than carabiners and lighter. when done don't cut the head off, cut the straight part..... re useable. Sail boat sheets work good, Kevlar core, almost zero stretch

[Elliot]

...
...using 1/4" 18" long lag bolts in the corners.
...

Too thin. You will twist them right off. I use 1/2" for the 18" length, and 3/8 for 14".

[The Rod]

I thought there was also a link to the earth anchors linked above in the lag screw thread... And another link to an earth anchor brand that actually had a picture from BM in their brochure (don't tell Media Mecca.....)

Couldn't find them.

Anyways, as far as putting screws in close to each other, I don't think it'll make much of a difference unless they're right next to each other, like the threads almost touching.

I don't think our tower was as tall as the one you have planned and it didn't have a large sail attached, but we used 18 inch bolts for four internal ratchet strap guy lines. One bolt per line and we drove them in until the heads were about 4 inches or so under the 'fluff' of the surface. Those things did not budge. There were also ideas in that thread for using multiple anchors per guy line, Fossa's 3 bolt setup for example. Another plus to the screws is that they work best driven at a 90 degree angle to the playa, so you get a deeper purchase than say an 18 inch rebar driven at an angle.

[maladroit]

...
...using 1/4" 18" long lag bolts in the corners.
...

Too thin. You will twist them right off. I use 1/2" for the 18" length, and 3/8 for 14".

Not to worry, I'm pretty sure you can't even buy 1/4x18 lag screws.

[LionsNzebras]

...
...using 1/4" 18" long lag bolts in the corners.
...

Too thin. You will twist them right off. I use 1/2" for the 18" length, and 3/8 for 14".

Not to worry, I'm pretty sure you can't even buy 1/4x18 lag screws.

You can, just not from home depot, or you special order them.
Here in town we have a place called "the nut and bolt house" they carry everything.

[mattcamp]

Yeah, that was a typo.

I meant 1/2" x 18" or 24" long... (or I see there are even 3/4" x 24" screws available in some places)

[maladroit]

Not to worry, I'm pretty sure you can't even buy 1/4x18 lag screws.

You can, just not from home depot, or you special order them.
Here in town we have a place called "the nut and bolt house" they carry everything.

I really don't think so. I don't think anyone makes them because they'd be virtually useless. I researched a lot of places online last year, ordered 50 3/8x14 screws, and never saw anything 18" long below 1/2" diameter. You usually can't even find lag screws above 10" long at Home Depot. I guess you could have them custom-made at great expense and they'd still be worthless...people have snapped off the 1/2" ones in the playa.

[LionsNzebras]

Not to worry, I'm pretty sure you can't even buy 1/4x18 lag screws.

You can, just not from home depot, or you special order them.
Here in town we have a place called "the nut and bolt house" they carry everything.

I really don't think so. I don't think anyone makes them because they'd be virtually useless. I researched a lot of places online last year, ordered 50 3/8x14 screws, and never saw anything 18" long below 1/2" diameter. You usually can't even find lag screws above 10" long at Home Depot. I guess you could have them custom-made at great expense and they'd still be worthless...people have snapped off the 1/2" ones in the playa.

I can get the 12s locally and they are working on finding longer ones.
Been told that the first 4 inches of the playa is very soft, after that it gets harder as you go down, think of compacted powder. So how deep are people going into the playa?
One would think that 12 inches would be enough.

[The CO]

The structure is remarkably similar to what we built for center camp in 1996. We used 8 guy wires, 3/8" I believe, auger type earth anchors, and strips of cloth rather than whole sheets.

[torrey.smith]

I'm about to grab a set of these "Penetrators" from American Earth Anchors.

I'm thinking the 26" for basic structural anchoring, and the 46' to handle the heavy loads from our Zip Line guys.

[maladroit]

Those "Penetrators" look amazing, though expensive compared to lags...not too many other options if you need to go that deep though. Their slogan is pretty burner friendly: "The best screw you will have in the dirt!"

[maladroit]

I really don't think so. I don't think anyone makes them because they'd be virtually useless. I researched a lot of places online last year, ordered 50 3/8x14 screws, and never saw anything 18" long below 1/2" diameter. You usually can't even find lag screws above 10" long at Home Depot. I guess you could have them custom-made at great expense and they'd still be worthless...people have snapped off the 1/2" ones in the playa.

I can get the 12s locally and they are working on finding longer ones.
Been told that the first 4 inches of the playa is very soft, after that it gets harder as you go down, think of compacted powder. So how deep are people going into the playa?
One would think that 12 inches would be enough.

Well let us know if you do find them. Most of us FIGJAM fans are buying 14" to 18" lags from online suppliers.

When installing my lags last year, I found that the playa was soft 8-10 inches down. As in, the hammer drill just spun the lag down without any hammer action. The last few inches really got the hammer going (100+ ft-lbs torque), they were immovable when flush to the playa. I wouldn't go with less than 14" though.

[The Rod]

When I go into the playa, I go DEEP.



Real deep, man.

[mattcamp]

Has anyone ever calculated the ballpark force required to rip a correctly-installed 14" or 18" lag bolt from the playa?

It wouldn't be exact of course, but would be good to know if I'm looking at say 1000lb vs 5000lb.

[Elliot]

Has anyone ever calculated the ballpark force required to rip a correctly-installed 14" or 18" lag bolt from the playa?

It wouldn't be exact of course, but would be good to know if I'm looking at say 1000lb vs 5000lb.

One tool I would love to have is a hanging scale, so we could do some tests. We could use an engine hoist or the like. But I imagine such scales cost a fortune.

[ygmir]

Has anyone ever calculated the ballpark force required to rip a correctly-installed 14" or 18" lag bolt from the playa?

It wouldn't be exact of course, but would be good to know if I'm looking at say 1000lb vs 5000lb.

One tool I would love to have is a hanging scale, so we could do some tests. We could use an engine hoist or the like. But I imagine such scales cost a fortune.

you could do it with a fulcrum/balance scale.........equal length levers, and add weight to one side until it comes out.

[Elliot]

Has anyone ever calculated the ballpark force required to rip a correctly-installed 14" or 18" lag bolt from the playa?

It wouldn't be exact of course, but would be good to know if I'm looking at say 1000lb vs 5000lb.

One tool I would love to have is a hanging scale, so we could do some tests. We could use an engine hoist or the like. But I imagine such scales cost a fortune.

you could do it with a fulcrum/balance scale.........equal length levers, and add weight to one side until it comes out.

And carry thousands of pounds of rocks or iron or lead to BRC? Well, maybe with unequal length levers.

I once watched a guy pull rebar with a cherry-picker (engine hoist). Now that was neat.

[ygmir]

or have a few people and vary the fulcrum.........most know about how much they weigh.

[LionsNzebras]

Can anyone explain why 14 - 18 inches?

why not 12? or 10?

[maladroit]

Can anyone explain why 14 - 18 inches?

why not 12? or 10?

When installing my lags last year, I found that the playa was soft 8-10 inches down. As in, the hammer drill just spun the lag down without any hammer action. The last few inches really got the hammer going (100+ ft-lbs torque), they were immovable when flush to the playa. I wouldn't go with less than 14" though.

[mdmf007]

check your anchors daily as well - the constant motion is known to egg out the hole and they loosen up considerably. Rebar is cheap, you can get it cut into whatever lengths you want and it holds extremely well.

later

[mattcamp]

Apologies for dragging up an old thread here but I thought people might be interested to know how this project actually panned out, and what the result was.

In a word: Awesome.

We ended up building a fully wooden 26 foot high tower to support a vast amount of aluminet fabric.

http://i.imgur.com/3c0YehU.jpg


We used a combination of 4x 1/4" wire rope guy lines on the down-wind sides plus two 10,000+ 2" HD ratchet straps on the windward sides as these took most of the load. The 4 main corner guys were secured with 3x 24" lag screws interconnected using lengths of heavy chain. Side guy lines were secured with 18" lag screws and either wire rope or mule tape.



We had some minor issues with the ratchet straps vibrating in strong winds so used some smaller straps to negate this (you can vaguely see the orange straps in the horribly blurry pic above).

The tower was incredibly solid and never moved an inch even in the strongest winds. We had hundreds of people visit us to climb to the top, including BLM rangers to witness their memorial procession to the temple. The BRC ranger who came by and did a structural assessment said it was massively strong and we could happily add two more levels to the top and support twice as many people at a time as we were currently allowing (we were limiting it to 6 on the top deck at any time). We had a couple of pieces of aluminet rip their grommets out during the worst of the wind but this was our fault due to not having enough of tie-down points.... it was always designed that the fabric would rip before anything structural gave way.

Overall a massive success... and given that we built the entire thing in the driveway of a Reno AirBnB in the 5 days before the event we were pretty happy with how it turned out.

Gallery of build pics is available at http://imgur.com/a/SHUNF