The Hoisting Cart project, part 1: The Cart

I already made a few posts here about the hoisting cart, but they were rather sparse and incoherent.  The next few posts are intended to describe each of the major parts of the project.

This post is incomplete, I will come back in some
hours or days and add photos and a description
of the two counterweights, which haven't been
described here yet.

 The basic cart came to me as an alley gift, found with a bunch of other trash for the Large Item Pickup Day, one block from my shop, and less than a month after I realized I needed to make the hoist mobile.

(rather than fastened to the rafters over one end of the mill table, where it could only be used on one machine)

The cart turned out to be the bottom of a hotel bell-cart with a rated capacity of over 1,000lbs.

The deck is made of 3/4in hardwood ply, there are two steel hat sections running the length of the underside which create tremendous strength, and four casters are mounted to the hat sections. 
The casters are rated for 800 lbs each.

Finishing the cart proper involved adding an upper deck of 3/4 ply, both to give the thing a reasonable work surface and more importantly, something to hold the mast upright.

 Uprights between the two were fabricated from black pipe and flanges.

 Diagonal bracing made of 0.75in strap and welded to the tops and bottoms of the uprights transfer forces acting on the mast back down to the bottom deck.

 

  Some overturning moment calculations revealed that about 200lbs of counterweight total is required to keep the thing from falling over when a load appears on the boom.

 

 These counterweights are mounted beneath the decks at the end opposite the mast to keep it from tipping the cart when a load is on the boom.  Outriggers at the mast end, prevent it from tipping the cart when a load on the boom is swung around.

In total, about 200lbs of counterweight is required. To keep the size(s) reasonable, I decided to put some on the top deck and some on the bottom.

 The top counterweight I made from salvaged steel plates welded together (because I had the material lying around), pretty simple.  It ended up weighing 55lbs.

  That left me with a deficit of roughly 130lbs.  Worse, there was a clearance issue with the casters, so in one dimension, it could not be larger than the cardboard template seen in the photo.

Also, the closer to the mast any portion of the counterweight is, the less effective it is, so I resolved to make the bottom counterweight of lead, specifically lead shot.  This was going to be a heavy, heavy object, in an inconvenient place, and I wanted the entire cart to come apart for transport.  Using lead shot meant it could be filled and emptied as needed for transportation.

This we then do...

 

magically "optimized" image placement by Blogger

I literally can't fix image placement.

The tank for the lead shot was folded, welded, and precision-bashed from 16ga hot rolled steel.  Angle iron was added to each end to make sturdy mounting flanges.  After measuring twice, and drawing it thrice, and saying things naughty not nice, I found out the tank didn't actually let the casters rotate past.  So I beat the sheet metal into submission, figuring I would patch up whatever welds inevitably broke after I had deformed it into a functional shape.  Mirabile dictu, it stayed air tight.  I wasn't gentle, I mean I beat the living hell out of that tank.  I was using a 3lb short-handle drilling sledge.

 By the way, I did this after I had already painted it, clever me.  I used sheets of kitchen parchment paper next to the paint, and a few sheets of newsprint over that, to protect it from direct abrasion by the hammer face.  The paint deformed and is still stuck hard.  Not a chip came off.  My paint method works.  Long live Dan Gelbarth who showeth the way.  Except I'm not using powdercoat yet but still.

The tank would have been a much simpler shape if I hadn't wanted it to do a good job of draining, when the time comes, probably after my death.  Which reminds me, I should put a decal or sticker on that tank.  Mustn't assume anything.

Had to buy a large hex key to close the fill & drain ports.  With PTFE tape on the threads, the tank is air-tight!  So at least it won't dribble lead dust everywhere the cart goes.

 Because the mast needed to be as tall as possible to be useful in my shop, and because the door opening is much shorter, the mast needed to fold down, complicating the mounting of it.

 Now we need to connect the mast to the two decks in such a way that the mast can be folded down, and which won't place undue strain on the plywood deck material.

 For the top deck a hinged mount was created and welded to the mast.  The hinges are two large bare-steel "weldable" (no holes) hinges from the hardware store.  To disassemble the mast from the cart, the hinged bracket can be unbolted from the deck surface.

 Because all of the weight and bending moment on the mast is concentrated where the mast connects (at right angles, even!) to the two decks, the brackets were made very wide and deep, in order to engage a large area of the plywood.  Both brackets fit tightly on the plywood, and are clamped tightly in place with many bolts once installed.  This ensures the plywood does not see concentrated forces which could bend or break the wood fibers, leading to eventual failure.

 Since I wanted a very close fit of the mast to the bracket, a hole saw cutting out the notch would not do.  I set up a fly cutter for that diameter, and used the mill to make the notch, ala the short video which Blogger places wherever the hell it wants, nor will it wrap text around videos, it's a known problem, never fixed...

The lower bracket is designed to guide the bottom of the mast into place when it's being erected.  It has some holes and a bolt to make sure it stays put, and because the bracket creates a lever which tries to break off the edge of the deck when the mast is loaded, I added a brace under the deck to prevent the bracket from trying to twist at the edge.

This Ekranoplan won't fly

That's really about it.  Once fit and function were verified, the parts were degreased, abrasive blasted, primered, and painted safety yellow in a vain attempt to save my shins in the future.

The outriggers are not installed yet, but when they are, they will look something like this...

I really wanted them to swing out or slide out, but I couldn't make it work in the space available.  So there will be a pair of sockets mounted to the bottom deck, into which the outriggers will slide and be retained with a pin.  When not in use, I'll provide some sort of broom clip affair to stow them out of the way of work and ankles.

  The basic cart itself is mostly complete now, save for filling the lower counterweight with lead shot, and fabricating and installing the outriggers.  That will happen when finances permit.