(Click on any picture to enlarge)

Part of my 'never-ending' deck project requires about 13 large columns. I looked at buying columns and would really have loved to purchase a maintenance free version such as polycast columns. But at costs anywhere from $250 to $500 each, I started to look for other options. The ornamental mill, shown above, produced by Legacy Woodworking is just the ticket for quickly making a variety of column-like turnings. Unfortunately, these tools are not that cheap either ranging from $900 to $2300 depending on size and options. I will say... if you get a chance to watch one in action, DO.... they are really neat machines.
The two main stumbling blocks with the Legacy machine, at least for my needs, was its maximum capacity and its inability to effectively cut a 12" column with entasis. Entasis refers to the slight bulging appearing classical columns have. It gives the impression of weight and stability to architectual columns. The standard legacy mills are limited to less then 7 foot lengths with a diameter of 10 inches. I wanted something more in the area of 8 to 9 feet that could handle diameters approaching 18 inches. Step one was to come up with a design. Off to the drawing board. Or in my case, off to AutoCAD!
Now it's time to find someone with all the equipment I need. Let's see..... a milling machine, large lathe, welder, sandblaster and more.... looks like its time to visit Dad's shop. Most of the pieces for the machine are made from steel with the addition of some aluminum extrusions where practical. The aluminum extrusion are made by Bosch and I just love the stuff. I'll admit, the idea of the extrusion came directly from Legacy's design and I would have used more of it if I wasn't so expensive.
It takes a lot of time to cut steel compared to wood! The steel parts were quite numerous and there was quite a bit of welding involved. Given that I have only welded once before, welding was not on my list of core compentancies. In an effort to level the playing field I thought it would be nice if dad got an auto-darkening welders helmet for Father's Day. You know.... one for him to loan to his son. I'll never weld without one again. After lots of grinding and a wirebrush, I managed to splatter enough metal on the parts to hold them together.
AutoCAD is great to this type of design. It's so nice to know the exact dimensions of all the parts. Here the headstock end of the lathe was completely designed before the first part was cut. This helped speed along the construction process by eliminating the tedius process of hand fitting pieces. I ended up wasting very little material due to miscut peices. These photos show the design compared to the work in progress.
These photos give you a feeling for the final look of the machine. This was taking during component assembly and fitting. I placed a couple small pieces of the extrusion between the head and tail sections to show how the back of the bed that holds the turning can be tilted up 30 degrees.
If you recall, one of the my needs was the ability to cut an entasis on a large column. The legacy is able to cut curved columns. The way they do this it to allow the cross-slide to be connected to a template guide that follows a pattern moving the router front to back. They use a long bit that reaches down the side of the part and cuts on the edge of the column facing away from the user. This works fine and dandy for smaller diameters but doesn't lend itself well to large diameters as the router bit must be more than half the diamter. Since I was looking at cutting 12" to 14" columns this would require bit lenghts between 6" to 8" which is just too much. My idea was make a bracket for the router that attached to the cross-slide but held the router on the front side of the column as opposed to the top. This way the router is moved in and out from the center of the turning and a regular straight cut bit could be used. Once I have some photos of this arrangement, it may make more sense.
One of the more fascinating features of the Legacy mill is it's ability to cut rope and barley turnings. This is done be gearing the main spindle to a lead screw that moves the carriage from one end to the other. A series of different sized gears are use to vary the pitch of the rope or barley twists. I first thought I would use some bicycle sprockets and chain to accomplish this but soon realized gears were more pratical. I looked for large thin gears like Legacy used but didn't find any off-the-shelf sources. So I opted to machine them myself. How hard could it be? It was all we could do to get the milling machine contorted in the proper arrangement to cut 10" gears using a 12" rotary table.
After a couple days of machining gears, I had 24 gears that would give me pitches from 1/8" to 12" per revolution with a lot of pitches inbetween. The gear system also included an inline gear reverser that allows me to cut right handed or left handed pitches. Even with the head stock and tail stock mostly assembled there is still a table full of parts to add before it is finished. A few more weeks and the machine should be ready for some paint and it's first trial run.
Here's the bottom view of the tail stock showing the chain drive that drives the lift screws that are located at each end. These screw control the distance between the material and the router bit and can be adjusted to cut tapered columns. With the top side rails in place, one begins to get a feel for the overall size of the machine. The carriage can be seen sitting on the rails.
To engage and disengage the carriage and cross-slide from their respective lead screws, a half nut is used. The half nut can be thought of a nut that is cut in half and placed around the lead screw. While the two halves are clamped around the lead screw, the carriage is locked in place. Let the half nuts separate, and the carriage is able to move freely from the lead screw. The close up photo shows the halfnut is both the open and closed state.
In these photos show the bed rotated 30 degrees towards the front. A bracket will be added under the carriage to position the router on its side hanging out the front between the top and bottom rails. This is to allow the router to cut from the front side as opposed to from the top. Once the bracket is built and installed, you'll be a better feel for my idea.
Progress is moving along fairly nicely, which means its time for Mr. Murphy to step in. Well, every design must have a flaw or two and it was at this point in time that I discovered my first major one. Put simply, the lead-screw's position on the back side on the front rail was going to collide with the bed as it was raised to its fully elevated position. To get around this, I opted to position the lead below the front rail but this did require a day's effort to rework the lead-screw's halfnut system. The newly positioned lead screw can be seen in later photos. In the end, this may have been the better router as it re-position the handle for the half-nut in a better position.
At last it is time paint and start the final assembly. All the parts that were to be painted were first sandblasted followed by a couple coats of Rustoleum's Hammered-Finish spray paints. The final machine is large, to say the least. These photos show the final assembly well along with only the gear-train left to assemble. The legs were angled out 6 inches towards the front, back and ends. This was more than needed and caused the machine to be extra wide. I'll likely cut the angle in half plus I need to add gussets to the angle brakets that attach the legs to the bottom rails. The 1/4 inch steel angles were still too limber to support the weight of the machine which I suspect is pushing 300 pounds. And that doesn't include the router or the material being cut. More photos will come over the next two weeks as the final assembly is completed.