Zip Line Brake

Project:
Designing a brake for our zip line

Difficulty Level (Easy, Medium, Hard, Insane):
Medium

Process:
The zip line brake system has gone through several revisions over the last year or two, mainly:

1. Simple tire at the end of the zip line
2. Elastics tied to a wooden block
3. Counter-weight system tied to a stopper block

The first version was semi-ok because at least it gave about a foot of stopping distance, but the stop was still quite abrupt so that sometimes it would fling the kids up and bang their legs against the cross beam. Not that getting hurt can be avoided at all times, but since a lot of neighbor kids were using it I wanted to make sure I'd minimize the risk of anyone getting hurt. That's when the second version came in.

I had originally used 1/4" steel wire for the zip line itself which would have been fine, but again, in an attempt to minimize all risk of the line ever snapping I upgraded it to a 3/8" wire which has a braking strength of over 12,000 lbs and a "safe load of about 2,500 lbs. Because of that upgrade I had about 100 feet of the 1/4" steel wire left over which I tied between our club house and the end of the zip line, tied a triple chord (braided) elastic rope to it and the other end to a wooden block which slid along the main wire. So every time a kid would go down, the zip line trolley would hit the wooden block, engage the elastic rope and slow the kids down over a distance of about 20 feet.

However, after a year of using the elastic rope very successfully, the sun and weather started breaking down the elastic so I had to come up with a more permanent solution. Such was the counter-weight zip line brake design born. I've seen these designs a lot in my university physics classes and I started thinking about how to implement this typical pulley system. Essentially, the potential energy of the zip line user at the start of the zip line is converted into kinetic energy and through the counter weight, as they hit the wooden stopper it raises the weight and converts the kids kinetic energy back into potential energy.

If the drop in height from the start of the zip line to the end is 6 feet and the kid weighs 50lbs I would have to attach a 50lbs bucket at the counter weight end and it will be raised about 6 feet as the zip line brake slows down the kid. In theory that sounds about right and the reason I used the pulley system is that instead of having a simple 6 foot stopping distance I can triple that to about 18 feet.

After casting the aluminum pulleys with my Home Foundry and my Propane Burner I put them on my Gingery Lathe, turned them down to size, welded a "cage" around the pulley, installed them on the zip line and hooked them up to a 3/16" steel wire using the "Flemish Eye" technique and some wire clamps.

One thing I noticed is that because the kids are all fairly light, my counter weight had to be equally light whose down-force wasn't quite strong enough to pull the wooden block back up the zip line to its starting point because the steel wire created too much friction against the wooden block so I knew I had to "eigenheer" something to fix that.

I had recently purchased some 1" teflon pieces at a local scrap yard so I cut up a piece about 10" long and 1" by 1" wide, put it in my lathe, turned it down to 7/8" diameter, drilled a 1/2" hole through it and cut the teflon sleeve in half with my band saw. All that was left to do is drill out the wooden block to 3/4", put the teflon sleeve halves around the 3/8" steel wire and hammer it into the wooden block. Now I had a low friction sleeve around the wire that made the wooden block slide back up the zip line with very minimal effort.

I had my son test it and after doing a few adjustments to the wire guides around the pulleys it was another project completed.

Videos:

Pictures:

The patterns for the pulleys

The pattern in the drag

After the aluminum was poured

After the cast was shaken out of the mold

The pulleys before they were cleaned up

After they were cleaned up on the table saw

Turning them to size on the lathe

One of the finished pulleys

Welding the bracket to hold the counter weight pulley

After the counter weight pulley was installed

Cutting out the wire guards

Welding the wire guards to the counter weight pulley holder

Testing it out with a rope

Seems to work

Nathaniel after he just tried the zip line brake

The turned, drilled and split Teflon sleeve for the wooden block

After the two Teflon halves were put together

The drilled out wooden stop block

Test install of the Teflon sleeve

Another view of the test-installed Teflon sleeve

Getting ready to install the Teflon sleeve

The installed Teflon sleeve in the wooden stop block

The dual pulley

A close up of the wire guards

Another view of the installed wire guards from below this time

Tools:
Home Foundry
Propane Burner
Gingery Lathe
Measuring tape
Pencil
Angle grinder
MIG welder
Table saw
Snap ring pliers
Adjustable wrench
Clamps
Drill
Drill press
Ladder
Screwdriver
Tap & die set

Materials:
About 2 lbs of aluminum
Scrap metal
100' of 3/16" aircraft cable
Six 1/2" Snap rings
Quick link chain links
12"elastic rope

Cost:
$50.00

Time:
15 hrs

Savings:
$300

Conclusion:
It works awesome. I just wish it wasn't winter soon...

Zip Line Pulleys

Project:
Building replacement zip line pulleys

Difficulty Level (Easy, Medium, Hard, Insane):
Medium

Process:
I had already tried two versions of the Zip Line Pulleys a while back. The first version was made out of a rubber caster which just split in half. The second version was made from cast aluminum which also killed one of the two pulleys so when I got my 1973 Emco Maximat V10 metal lathe I figured I'd make some out of mild steel.

The process was fairly easy. I had some 2" cold rolled metal which I chucked up, measured out the dimensions and then faced, drilled, bored, turned and parted it off. After painting the pulleys with some rust paint (they'll be out in the rain, afterwards I realized I should have made them with stainless steel instead of regular mild steel) I pressed the pulleys and set them with some loctite.

Pictures:

The finished pulley

Another view

Testing the bearing

Painting the pulley

Tools:
Metal lathe

Materials:
2" of 2" round solid cold rolled steel
2 bearings (32mm, 10 mm wide, 12mm center hole)

Cost:
$10.00

Time:
3hr

Savings:
$30.00

Conclusion:
They look awesome

Scrap Metal Bin

Project:
Building a scrap metal bin for my shorter scrap metal

Difficulty Level (Easy, Medium, Hard, Insane):
Easy

Process:
I had already built a Scrap Metal Storage Shelf last month for my longer scrap metal but I had a bucket full of smaller stuff (less than 6") so whenever I needed a small piece I'd have to dump the entire 50lb heavy bucket to find a small little piece. I had some left-over OSB from building Storage Shelves for a Coworker so I figured I might as well use it up instead of throwing it in the garbage.

I took one of the cut-offs from the shelves, put 4 small casters at the bottom, glued and nailed the sides to the base and then put in a couple of dividing walls to make 6 compartments for:

1. Square solid pieces
2. Square hollow pieces
3. Round solid pieces
4. Round hollow pieces
5. Flat pieces
6. Angle pices

After everything was built I sorted my big bucket of scrap metal and pushed it under my metal lathe. Finally I can find my stuff without having to sort through that whole bucket.

Pictures:

Cut-off from an earlier shelf project

The walls glued and the dividers installed

The scrap metal all sorted

A close up of the sorted metal

Stores away under my metal lathe

Tools:
Table saw
Chop saw
Compressor
Framing nailer
Measuring tape
Pencil
Square
Drill

Materials:
Four 2'x2x pieces of 3/4" OSB
4 Casters

Cost:
$4.00

Time:
1hr

Savings:
Probably at least $50 bucks

Conclusion:
So glad I can finally find my stuff

Storage Shelves For Coworker

Project:
Building some storage shelves for a coworker

Difficulty Level (Easy, Medium, Hard, Insane):
Easy

Process:
I've built a fair number of these types of shelves for my own house so I knew they would be fairly easy to make and extremely sturdy.

I basically cut the shelves out of 3/4" OSB material to 8' by 2' wide, cut a bunch of 2x4s down to 2x2s, glued and nailed them to the shelves, then screwed metal brackets to the vertical support legs and loaded everything in the van.

Once I was at his place all i had to do is screw the back legs to the wall, have him hold up the front leg while I lifted the shelf up on the brackets and screwed it together with some 1-1/2" screws.

It did get a bit tricky because of the garage door tracks which I didn't know were there so we ended up doing some creative supporting for the top shelves for one unit and cut some of top shelves off some of the other two units. With the extra shelves I ended up building another 4' wide fourth unit with 5 shelves.

Videos:

Pictures:

The plans for spacing out the shelves

The 2x4s and the 3/4" OSB shelves

Getting ready to glue the 2x4s to the shelves

The 18 8'x2' shelves ready

The shelves stacked up on my work bench

Getting ready to make the vertical support legs

Marking the height of the shelves on the support legs

A close up view of the support legs

A close-up of where the shelves will go

Getting ready to install the brackets

Placing the brackets in their position

After the brackets were screwed to the support legs

All the brackets screwed to the support legs

Loading it all in the van

Laying out the shelves in the garage

Two units done

Three units done

Tools:
Air compressor
Framing nailer
Table saw
Chop saw
Circular saw
Square
Measuring tape
Pencil
Hammer
Drill

Materials:
Nine 4'x8' sheets of 3/4" OSB
Forty 8' long 2x4s
Ten 10' long 2x4s
116 angle brackets
232 1-1/2" screws
20 3-1/2" screws

Cost:
$375

Time:
10hrs

Conclusion:
They are super sturdy and will definitely last for many, many years