Hanging Strap Cage (see Page for pictures)

http://www.saroftreve.com/wwl/strapcge.shtml

Hanging Strap Cage


I used one of these a looong time ago, and it was cool! The Hanging Strap Cage works like a Chinese finger trap: a tube shape that closes tight on what's inside. Entirely stress-free suspension. Please note that you need about 10 feet of vertical beneath the attachment point, 'cause it gets really long and stretches a bit. Also, this project involves a LOT of work. It seems like you bevel and EdgeCoat miles of leather. You'll also need rudimentary woodworking skills, or want to know someone with those skills. (There's a wooden base.) And find a metalworking shop that will do a little custom work.

This project is not for the faint-of-heart. I'm a little anal about using leather efficiently, and the lengths reflected here were selected based on a specific side of leather. You may need to change them significantly. The project consumes a little over half of a large side of latigo, and it's the best half.. the top (back) portion. Try to get a long side for this project because it makes a real difference. I've had great service from Siegel on special requests like this. Finally, it would be insane to try this project without a strap-cutter.

This design is derived from a similar item sold by Mr. S in San Francisco. They'll sell you one for $600. This project will cost a little over $100 (if you get leather cheap), but does take 15-20 hours of planning and work. It should be strong enough to hold any TWO people, since the effective weight-bearing components are equivalent to a full foot of heavy latigo. Not that I'm advocating anything funky (although I've tested mine with three people ;)

Difficulty: Difficult
Tools
Mallet, Utility Knife, Rivet Setter, Punch, Edge Beveler #2, Strap-Cutter

Parts Checklist
1" Welded D-rings (6)

Medium Rivets and ¼" Key Posts (24/36)

3/8" Key Posts (78)

Durable Dots (Snaps) (6)

Leather Checklist
Round Base: 8" x 8"

Straps (6): 212" (218" with overlaps) x 1" (note: each strap is really three pieces, unless you find a REALLY long cow)

Ring Retainers (6): 4" x .75"

Steps
1 - Understand Diagram 1
Take a really good look at Diagram 1. You'll probably need to complete something similar. Each individual (of 6) strap is in red going up and purple going back down. The numbers at the bottom tie the two together: 1(red) is the same strap as 1(purple).

Each blue box indicates a joint between two pieces of the same strap. Leave 1.5" extra on each piece at these points. The black boxes at the top represent to D-ring locations.

Leave 6" of excess at both ends, at the BOTTOM of each strap, extending beyond the location marked 'Base'.

There are eleven distinct layers, indicated by the spaces between the horizontal black lines. Each layer (except the top one) is 8" high, and represents 9" of strap, resulting in a diamond pattern. This design is quite tall. You could probably eliminate one layer if you play only with the vertically challenged ;) The top layer is 10" high.

Numbers running up the right side, associated with thin green lines. The green ones represent the length of leather required to get to the indicated point from the bottom, including 6" at the bottom and 1.5" for overlap. The blue numbers are the distance down from the D-ring. Note that you'll always add two of these numbers to get the length of a piece, since we don't want a joint at the D-ring.

'Base' is the location for the wooden base. 'Ring' is the top-most possible location of the metal hoop.

Got it?

2 - Plan Your Straps
Using some planning mechanism similar to that described above, plan your straps. This shouldn't be too hard if you understand Diagram 1. Here's what I ended up using.. see it you can map these measurements back to the Diagram: (hint: they read from red to purple)

Strap 1: 93" - 86" - 39"

Strap 2: 93" - 41" - 84"

Strap 3: 39" - 86" - 93"

Strap 4: 75" - 86" - 57"

Strap 5: 57" - 86" - 75"

Strap 6: 84" - 41" - 93"

Obviously, you need to plan this in light of what you can get out of your side of leather. Check this step three or four times before proceeding!

3 - Cut Leather
Start cutting straps! Cut lots of 1" straps, then cut them to the lengths you identified in the previous step. The ends at joints can be finished as desired.. I use a 1" end-rounder ($20 at Tandy) for a nice clean finish. The bottom ends should be shaped like the 'Strap Outline' in Diagram 2.

Next, cut the round base as shown in Diagram 2. Find a plate about 8" around and trace it.

Finally, cut the little ring retainers. These are just 4" x .75" strips that will snap on to hold the metal ring at one level or another.

4 - Punch Holes
Punch all required holes. The round base should be self-explanatory. The straps are a bit trickier.

The bottom ends should be punched as shown in Diagram 2. The joint ends require two holes, .5" and 2.5" from the end. Note that 3" will overlap.

There should be a hole every place two straps cross, which should be every nine inches. The 20" surrounding each D-ring get divided 7" - 6" - 7". This too takes a little calculation. Let's look at an example using Strap 1 from mine. Remember, this strap has three pieces, 93" - 86" - 39".

Piece 1 (93"): (bottom) - .5" - 1.5" - 2.5" - 15" - 24" - 33" - 42" - 51" - 60" - 69" - 78" - 86" - 90.5" - 92.5" - (joint)

Piece 2 (86"): (joint) - .5" - 2.5" - 6" - 13" - (D-ring) 19" - 26" - 35" - 44" - 53" - 62" - 71" - 80" - 83.5" - 85.5" - (joint)

Piece 3 (39"): (joint) - 5." - 2.5" - 6" - 15" - 24" - 36.5" - 37.5" - 38.5" - (bottom)

Finally, holes at both ends of each ring retainer. .5" back from the ends will do.

5 - Finish Edges
Get comfortable. Bevel all of the edges, and finish with Tandy EdgeCoat.

6 - Assemble Cage
Start from the bottom, and work you way up. First, number the positions on the round base, 1 to 12. Mark or scratch numbers right on the round base somewhere you'll be able to see them with the straps in place.

Attach the bottom straps to the round base using 1 medium key post and two rivets each. Follow the pattern of numbers at the bottom of Diagram 1 (or your equivalent).. it's vital that the pieces are attached in the right order! Picture Diagram 1 wrapped around your round base.

Start working upwards, attaching each joint with a 3/8" key post. This longer post will leave the joint loose, allowing the cage to constrict. Always go 'over' in the same direction: the strap going from left to right should always be on the outside (or the other way around). Complete one level all the way around before moving on to the next.

Eventually, you'll get to a joint. The first six joints you hit, attach the next appropriate piece. You'll need to track back to the base and look at the number scribed there to do so. However, once you reach the seventh place for a joint, guess what? No more pieces! All of the six remaining long ends go up and through a D-ring, then back down to meet a partner end. It's impossible to describe this process, so use trial-and-error! Just don't super-glue any key posts until you know everything is right (i.e. in place). It's a little more work, since you have to screw-unscrew-screw all 100+ key posts, but have you ever tried to remove a glued post?!?

Don't forget to put the D-rings on the straps. Secure them as shown in the Finished Product pictures below. This should be a 3/8" key post as well.

7 - Attach Snaps
Secure the Durable Dots to the ring retainers, half of a snap set on each end.

8 - Wooden Base
Grab your favorite power tool (put down that vibrator!) and cut a 12" circle of your choice of wood. .75" or 1" thick, plywood or particle board. I favor particle board, but either works. Smooth the edges of this circle with a file, and paint it black.

9 - Metal Ring
Run down to your local metalworker (unless of course you can do it yourself), and have them fabricate a 12" hoop out of 3/8" rolled steel stock (round). For safety, please get this hoop welded closed. Note that you can forego the ring (and ring retainers) if the target person wears a sturdy helmet. The strap cage can put significant pressure on the head, and one or the other should be used.

10 - Final Notes
You're actually done! Congratulations! Some parting thoughts on use:

As described earlier, you need a really high ceiling (or tree) to use this baby. A winch, block-and-tackle, or come-along is also handy.

There are six rings at the top. What's up with that?!? Well, that's part simplicity and part requirement. You certainly COULD attach all the straps to one big ring at the top, but then you couldn't get IN. The cage will stretch out to go around something 8 feet in circumference, but only if the top is open. Use three heavy quick links. The first through three adjacent D-rings, the second through the other three, the third through the first two. Got that? Don't feel bad.. I had to read it twice, too.

This is an extremely safe way to do suspension. The only possible danger is circulation, since the occupant can't move around and the straps can press in rather firmly. Don't leave someone unattended in here for too long.. there ain't no way out! I hear folks get bored, too ;)

Diagram 1

Diagram 2


The Finished Product