Treadle Lathe

Treadle lathe

The Plan

I designed my lathe with the following goals in mind:

The dimensions are probably a little optimistic. I haven’t tried to make anything that large yet, so I don’t know for sure. The lathe is big enough, but whether it’s rigid enough might be a different story.

Lathe plans

The Frame

The frame is built from dimensional lumber from Lowe’s. I paid attention to picking out boards that were relatively straight and free of knots. Where there were knots, I made a rough plan for working around them before I bought them.

The foot at the end is held in place with bolts so that it can be removed for compact storage. Everything else is secured with deck screws. No fancy joinery here. This is cheap, crappy lumber anyway. This tool exists to make art — it is not art itself.

Besides being sufficiently sturdy, the most important feature of the frame is that it holds the bearings in line with each other. To accomplish this, I drilled the holes for the bearings before assembling the frame. This let me cheat any alignment problems a bit during final assembly.

The Crankshaft

The crankshaft is made from a 1/2” cold rolled steel rod. I heated up one end of the rod with a propane torch and bent a jog in it with my vise. The offset end is almost parallel with the main part of the shaft. I connected this to the foot pedal with a rod end (also know as a Heim joint) and some threaded rod. The rod end isn’t really meant for this kind of use, but it seems to be holding up well with the liberal application of oil.

Crankshaft

The Pedal

The foot pedal is just a 1x2 with a big hole drilled in one end. The reasoning is that I can easily fold it out of the way for storage, I can move it to either side of the lathe, and I can easily move it to switch feet or accommodate my position at the lathe. In practice it works OK, although a design more like the ones on old sewing machines would be more pleasant to use.

Pedal

The Flywheel

The flywheel is a sandwich of 1x10’s and 2x10’s, with the 2x10’s in the middle. Each layer is offset 60° from the one previous. I applied glue between the layers before securing them to each other with deck screws.

Flywheel

Once the glue had dried, I drilled a 1/2” hole through the center. Getting this straight is important. I got it close enough. Then I marked a circle around the hole using an improvised compass. Now for the painful part: I made a rough cut around that circle using a coping saw. It took multiple blades and a lot of time. If you have any way to do this step with a power tool, I highly recommend using it.

Next, I attached a floor flange around the center hole and drilled it to accept the retaining pin. At this point, I mounted the wheel on the crankshaft.

Flywheel pin

Now I had to find a way to cut a groove for the drive belt. I didn’t have the tools I needed, so the project went dormant for awhile. Eventually, I bought a router. I built a platform that pivoted on the lathe’s spindle and mounted the router on it. Then I just turned the router on and slowly spun the flywheel until the groove was complete.

The Drive Pulley

To make the drive pulley, I drilled a 1/2” hole through the center of a piece of 4x4 and roughed out a circle around it with a wood chisel. Then I drilled a hole in the side for a set screw. There isn’t a flat on the spindle, so the set screw doesn’t do much, but the pulley fits snugly enough to the 1/2” rod anyway.

Once again, I cut a groove with the router. I found that the belt was slipping too much on the smaller pulley wheel, so I painted the groove with some Plasti Dip. The belt now grips the wheel very reliably.

Drive pulley

The Drive Belt

I really cheaped out on the drive belt. It’s just some cotton rope with the ends stitched together. Unfortunately, it stretches out with time and use. I deal with this problem in two ways. First, I make sure the rope is a little too snug at first, so that it fits well after it’s stretched a bit. Second, I’ve found that wetting the rope helps it grip better and causes it to shrink some so that it is tighter again.

Rope splice

The Spindle

The spindle is made from the same steel rod as the crankshaft. It also rides on the same radial bearings. The bearings are mounted directly in the cedar posts, and are held in place with screws and modified fender washers. Shaft collars keep the spindle where it belongs.

The spindle also has a thrust bearing (and matching washers) to handle the pressure from the secured work piece. Some kind of thrust bearing is necessary, or you’ll lose a lot of energy to friction. For the record, I’m not totally happy with this particular bearing, and I’ll be looking for a better replacement.

The Drive Spur

Like many before me, I chose to use the Shopsmith drive spur. Because I used a 1/2” spindle, I needed a spacer. I drilled a hole in the side of the spacer so the spur’s set screw would make contact with the spindle. The spur isn’t perfectly centered, but it’s pretty close. If I want to take a piece off of the lathe and then put it back on, I make sure to mark it first so that it goes back onto the spur in the same orientation.

Drive spur

My original plan had been to hammer the end of the spindle flat and then grind it into a shape similar to a spade drill bit. When the time came, I had some extra money to spend on the Shopsmith spur, so I skipped the blacksmithing.

The Tailstock

The tailstock is fixed in place with a wedge. The dead center is made of excess rod from the spindle. I had left the spindle a few inches long, and I turned it to a point with a file. Then I lopped off the end and sunk it into a hole in the tailstock. I made sure that the point sticks out past the base of the tailstock so that I don’t lose any potential swing (there’s that optimism again).

Tailstock

The Tool Rest

The tool rest is positioned with a wedge, just like the tailstock. I used a piece of angle iron for the top of the rest, thinking it would hold up better than cheap wood. And it does, but the steel is soft enough that it still gets plenty of nicks from the hardened chisel.

Tool rest

The Chisel

I made my own skew chisel using some leftover 1084 high carbon steel and a short piece of cedar 2x4. It’s rough, and it’s too wide, and it overheats easily, but it works! Its handle is also the first thing I turned on my lathe. I’ll eventually buy some nicer chisels, but this one does the job for now.

Chisel with turned handle

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