Monday, May 19, 2014

Zip Line Pulleys

Upgrading the zip line trolley to aluminum pulleys

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

Version 1: store bought bushing-based pulleys
Version 2: castors turned on the lathe with ball bearings
Version 3: custom cast aluminum pulleys with ball bearings

The first version just wasn't rolling fast enough and since the kids wanted an awesome ride I had to do something about that. I figured if I used the vulcanized rubber castors and turned them in the Gingery Lathe it would be a bit quieter and give a nicer, smoother ride. It actually worked out quite well until last night when I decided to go down the zip line one last time before going in and I just destroyed the rear pulley.

I have gone on the zip line numerous times (and so have 5 neighbor parents) and I knew that it would eventually have to be replaced because the kids were wearing it down so when it finally died last night I figured I might as well get going.

The process was fairly straight forward but it was rather time consuming:

1. Create the wood pattern
2. Cast the parts in aluminum
3. Machine them on the lathe
4. Install
5. Enjoy


Once they were installed:

Our neighbor came over with his GoPro so here are some more videos:

Zip Line à la GoPro

The arrangement of pulleys and guide rollers
The finished (version 2) trolley
After installing the (version 2) pulleys
The pattern for the pulley. Note the thin rod is to make an imprint for the core, the larger knob on the left was only so that I could mount it on the lathe and the right, big part, was for the actual pulley
Another angle
The freshly made core
I found that making 1/2" cores was really difficult because they kept breaking. The way to make it almost 100% successful is by putting a rolled up piece of paper between the core and the core box.
The pattern in the sand mold
The furnace going and the 3 mold boxes in the back
Taking out one of the casts
After it was cleaned up but still with the risers and runner attached
Another angle. You can see the raw cast of the pulley at the left
The last cast before shaking it out
The pile of reclaimed green sand before stowing it away
The raw cast mounted on the lathe
Another angle
After cleaning it up it turned out quite nicely
Almost done with the groove of the pulley
Parting off the pulley
I made 3 casts, two are clean-turned, the third one is done
Close-up of the finished pulley
Another view
The second pulley before cutting off the collar
The drilled out pulley before reaming it
The third pulley
This is the second pulley that snapped when I tried to install the bearings with the vise. Note to self: Make sure you ream the hole big enough!!!

Ange grinder
Measuring tape
Bench grinder
Drill press
Gingery Lathe
Bi-metal hole saw kit
Socket set
Adjustable wrench
MIG welder
Home Foundry
Hack saw
Tap & Die set
Alan keys

3/16" metal for trolley sides
2 casters
12 washers
Nuts & bolts
Four 1.25" bearings

About $20.00



The 3rd version pulleys are INCREDIBLY fast! The kids (and I) LOVE it!

Re-Fabricate BBQ Drip Tray

A friend of mine asked me if I could have a look at his BBQ drip tray and fix it so after I got it I was quite shocked to see that there wasn't much left of it. Originally I thought I could patch it up but after I saw the state in which it was in the only option was a complete re-build.

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

After I laid the drip tray on my work bench and straightened it out as much as possible I took the measurements and went through my metal storage bin to see if I had any suitable material to make a replacement drip tray. Luckily I had a few metal shelves lying around that I had picked up a few years ago that was made out of heavy duty metal (probably at least 2mm thick). It just happened to be the right width (12") and was almost 4' wide (I needed 34.5").

After cutting the shelf to size I took a 3/4" square tube and cut it diagonally to give me two 12" pieces of 3/4" angle iron (I didn't have any angle iron in my stash). Using my trusty MIG welder I tacked it in a few places to make sure it was square, then finished tack-welding it at the bottom.

Needless to say, this drip tray will last for a LONG time. At least as long as the BBQ.

The rusted out drip tray
From the top
The shelf I had lying around
After it was cut, bent and the sides welded on
Another view
Close-up of the tack welds
The tack welds on the bottom
The finished drip tray

Angle grinder
Measuring tape
Ear muffs
Bench grinder
MIG welder

1 steel shelf
12" of 3/4" steel tubing


1.5 hrs

No idea, probably at least $40

I've already received some nice pictures of BBQ'd meat so it seems to work just fine