Needed something to move heavier pieces of small equipment, like my Dayton hub dolly. This seemed to fit the bill. Somewhat overbuilt, but still manageable. Sort of a goofy thing, but it’s good for pointing out some techniques I guess.
The hole through which the spindle fits is drilled exactly to the size of the spindle, allowing for an interference fit. This simplifies fitup. The spindle is then plug welded on the bottom side of the plate.
At this point the axle has been added. The tab securing the axle is attached via a bolt, which goes into a nut welded on the inside of the arm.
Next, a gusset is added beneath the top plate. It ties the arms to the plate, and prevents any movement. Note that the gusset falls exactly on the edge of the outside strongbacks. This ties the whole thing together as a unit. Solid, from top to bottom.
The bluish marks on the steel are from heat straightening. There’s always distortion when there’s welding. It’s best to straighten the steel at each step of the fabrication process. Heat straightening aka flame straightening is a subject for another altogether dedicated article.
The Swivel Assembly
The spindle has to be free to rotate. This requires a thrust bearing. They’re widely available.
Let’s start with the bushing that allows the spindle to swivel. I like using DOM (drawn over mandrel) tubing. It’s sized extremely accurately. In this case, I’m using 3/4″ DOM tubing, with a 3/16″ wall.
DOM is exact when it comes to the inside diameter. To fit a piece of 3/4″ round stock inside this tubing requires some machining.
The round stock measures .748 (I round up a bit).
Next you must bore out the DOM to allow the spindle to freely rotate.
The final clearance is .004. While it seems a bit tight, it’s not. A tight bushing allows for easier rotation because the spindle will be less able to wobble (I mean, were talking a few thou in runout, but it adds up over a distance).
Next the assembly the spindle will rotate in has to be made. In this case, a piece of square tubing.
The bushing is inserted into the hole, and welded. Then the weld is ground nearly flush to allow for the installation of a wear plate/pad. This is because the square tubing is thin walled (11ga), and won’t hold up to the force applied to the thrust bearing without collapsing.
Pop the wear plate over the bushing, and weld it. Note that the welds are on the shoulder of the square tubing, not across the width of the tubing. This is to prevent distortion. Welds across the tubing flange will cause the tubing to pull when the weld cools.
The thrust bearing I’m using is a completely enclosed 3 piece bearing. The races interlock to prevent dirt/water from entering.
Probably the most important thing is to wrap those welds. It’s imperative that the tubing is water tight.
Next, the floor, ramp, and other odds and ends were attached.
The hinges are off-the-shelf door hinges, adequate for the load.
Set of simple toggles to lock the ramp in the up position.
A note on small wire welding machines. I’m pushing the limit here. I would not recommend using a 110v machine on anything heavier. This weld, for example, is made with the machine cranked up to the max. It’s ok, but it’s the red line. We’re talking sch40 pipe welded to 14ga square tubing, Pretty thin stuff.
For thicker stuff, such as round stock….it’s back to the reliable stick process. 7018 is my rod of choice in this application.