One of the things I really like about owning a machine shop is that it lets me find creative solutions to difficult problems. And often along the way I find myself forced to find creative solutions to new problems that crop up while solving the first problem! Today’s project provided a little of both.

Michelle and I were recently doing some upgrades in the garage. One upgrade was to replace some shelving units. What we wanted were shelf sets on casters, so we could move them around when we were working on bigger projects.

We found plenty of examples online, but all of them were prohibitively expensive, and all of them would take a week or more to arrive. Nobody had them locally. But there were plenty of shelf sets without casters available, for much more reasonable prices. Casters are cheap too. And I own a machine shop. Thus another project is born!

Plan of Attack

First, we had to procure shelf sets and casters. We found shelf sets that had wire shelves (so mice have no place to nest), and a tubular frame (easy to adapt to casters). A stop at Harbor Freight yielded casters with threaded stems (these and these, specifically).

All I had to make was a little top-hat shaped bit of metal that would slide into the frame tube. The “brim” would support the bottom of the frame. I would drill a hole down the center of the part, and thread it to match the threads on the caster. Then I could screw the part onto the caster, insert the whole thing into the end of the shelf frame and, voila! A rolling shelving unit for about half the cost of the ready-made ones!

Off to the machine shop!

A few quick measurements gave me the dimensions I needed. I cut eight blanks in the bandsaw (we got two sets of shelves and casters). I faced off both ends of each blank square. Then I turned down the smaller section to a size that would just slip into the frame tubes.

Turning the small part down to size.

Since I had to make eight pieces, I did them batch-style. So first I turned down the small diameters of all eight parts.

As usual, my lathe bench is an unholy mess, but you can see I’m working on the sixth part at the moment.

Next, I drilled a pilot hole partially through the length of the part.

I don’t remember what size the drill was. And it doesn’t matter anyway. It’s only purpose is to make it easier to drill a bigger hole.

Then I drilled a 9/16″ hole, again partway through the part. The stem of the caster is 1/2″ diameter (threaded 1/2-20), so 9/16 is bigger. I did that on purpose: the other end will be threaded, but there’s no good reason to thread the whole part. By drilling the top part oversize, it wouldn’t get threaded when I tapped the hole later.

A big drill can move a lot of metal in a hurry.

A Setup Problem

Now it was time to work on the bottom of the parts. I had made the blanks longer than the finished parts would be, so that there was something for the lathe chuck to hold onto while I turned down the top end.

But now it was time for the excess to go away, and that caused me a bit of a problem. You see, I wanted the thickness of the brim to be consistent for all of the parts. The shelf sets were going to be essentially sitting on those brims, and I wanted the shelves level, at least insofar as the garage is level.

But the blanks weren’t all the same length. Because of the way I mounted those blanks in the lathe, the top ends weren’t all quite the same length. That doesn’t matter to the function of the part. But it gives me a setup problem: I can’t reference the cut line for the bottom end off the top end. I have to find another reference.

Since the distance from the shoulder of the part to the cut line was the important thing, I wanted to reference from the shoulder. The top end wouldn’t pass through the chuck, so I couldn’t just put the shoulder against the jaws of the chuck either.

A Solution

I used a setup tool called a parallel to solve the problem. As the name suggests, a parallel is a strip of metal that has two faces parallel to one another to a high degree of precision. They’re made in pairs, though in this case I only needed one.

The parallel is caught between the faces of the lathe chuck jaws and the shoulder of the part. It ensures that the shoulder is at a known location in space.
Be sure to remove the parallel before you turn the lathe on, lest it be embedded in your forehead.

Now I could cut off the extra part and have a consistent size where it matters.

The red thing just to the right of the spinning part is a work stop. It’s bearing against the lathe carriage, so the parting blade is always in the same place. Since the shoulder of each part is also always in the same place, the resulting cut will leave a part of consistent size.

Final Machine Operations

Next up, we drilled the hole to 29/64″. That leaves just the right amount of metal so that we can tap the hole with a 1/2-20 thread later. I looked that value up in a book.

Finally, I used a file to round off the sharp edges. Unfortunately, I didn’t get a picture of that.

I tapped the parts at the bench.

You can see some finished parts on the blue rag.

Another Success

The castors make it easy to move the shelves around.