Saturday, April 24, 2010

The Winch


The power for the Laddervator comes from a Warn Industries 68500 PullzAll 110 AC corded electric winch. It has forward and reverse motion and variable speed - great for fine control. There is a battery model available -- but I felt more comfortable with the grid behind me! It locks when the power is removed - a great safety feature, especially if the platform is at the top of the ladder. It's rated for 1,000 lbs - far more than I'll need. It comes wound with 15ft of 7/32" wire rope.

For the prototype its attached to the ladder with a couple of climbing slings and caribenas. The production model will hold the winch to the ladder with a custom bracket.

Here's the whole thing in action:


Since I strongly believe that the production version will not be bolted together but will be welded I took a MIG welding class at Tech Shop in Palo Alto. Informative, fun and no burnt fingers!

Option #2


Constructed the Laddervator frame using Option #2 (flanged wheels on the outside of the frame). For wheels I used 2.5" Campbell pulleys (4x). They are rated to support 550 pounds - much more than the max 200 lbs I'm planning for the prototype. Everything bolted together very smoothly. I used some old shelving brackets that I found in the as well as remnant shelf-supports and a couple of linear feet of azek. I drilled a hole at the top of the frame through which slipped a caribena for connecting the frame to the winch. Construction time was a couple of hours.

Here's a picture of the prototype Laddervator frame in place on the ladder. You can also see the winch (orange box at the back of the ladder). More about that later!


Wednesday, April 7, 2010

Design Options

I started out with a quick perspective view of the full design: ladder, platform, winch, top-pully and rope. The hardest part was how to attach the platform to the ladder so it (a) moved smoothly and (b) stayed on the ladder.

I thought about two options:

Option 1: Wheels on the inside of the ladder:

Option 2: Wheels on the outside of the ladder:



For options 1 and 2 I would need to use flanged wheels to keep the platform on the ladder.

I also considered using roller-blade wheels in a 3rd option:

Tuesday, April 6, 2010

The Model




Before I started collecting materials for the Laddervator I decided to build a model first so I could test out designs without a lot of work. I used K'nex to build a small version of the Laddervator. The good news was that I had a roller-coaster set that had a track that looks and works like a ladder, and a car that already has wheels. I used a K'nex motor (with forward and reverse gears) to represent the motor that I will be using in the laddervator. One thing I noticed is that even in reverse, the Laddervator platform has to be heavy enough to pull against the weight of the rope (or thread in the model) to allow it to return to the ground.

Project Inception

Well, the project actually started a couple of months ago when I signed up for the Youg Makers program at the Exploritorium. We meet one Saturday each month for workshops, presentations from prominent Makers and to work on our projects. The objective is to display what we build at the Maker Fair in San Mateo in May.

My Project: Design and build a prototype portable 'laddervator'.

What's a laddervator? Good question! A laddervator is a device that attaches to a standard aluminum ladder that transports items up and down. They are typically used to get heavy roofing suppliers to a roof without the need for a crane (or a lot of manual work).

Some project considerations:
  • Inexpensive (I want to keep the cost below $100)
  • Portable (as I want to easily take it to the Maker's Fair)
  • Safe (nothing drops on my head!)
  • Strong (I would like the laddervator to be able to lift at least 200lbs)
I'm only building a prototype at this time. But if it works out well then I'll take what I learn and will build a 'finished' version.