Octagon Tool Handle Construction Tutorial *LINKS*

Octagon Tool Handle Construction Tutorial *LINKS*

William R. Duffield on the Cohansey

>Todd of Dead Horse Forge posted a photo and started a thread about a beautiful antique screwdriver with an intriguing handle, that he found at auction.

Click on the pic to view Todd's thread.

This piqued my curiosity, and I decided to try to reproduce the effect of the octagonal handle with ogee curved facets, using a minimum of power tools, and more importantly a minimum of precision jigs and fixtures. In other words, I tried to tailor my techniques to weigh heavily towards what David Pye, in The Nature and Art of Workmanship, philosophically calls "The workmanship of risk."

I posted a photo of the results of my first attempt in that thread, critiqued them, and promised that this exposition would follow. Here is that photo again.

I started with a scrap block of figured walnut. It was just over an inch square, and about 5" long, a cut off from a claw and ball chair leg, salvaged from the trash. Thus, it already had two faces flat and square, and a subtle indication of the figure hidden inside. I had already used up or given away all the rest of the scraps that showed special figure. I set my cutting gauge to 1 ¹/₁₆" and marked two opposite faces, referenced from one of the flat sides. I'll explain how I chose that important dimension in a bit.

I planed the rough bandsawn face flat and parallel to the first face.

I repeated the above two steps to flatten the fourth face, resulting in a blank that was mostly 1 ¹/₁₆" square. I think I can work around the narrow spot where the bandsaw still shows.

Using a combination square with a centerfinder head and a scratch awl, I marked the centers of both ends of the blank.

I chose a drill bit to match the diameter of the tool that I expect to mount in the handle. I carefully aligned the blank so the hole would be drilled parallel to the faces of the blank, and drilled a ⁵/₁₆" diameter hole about 1 ¹/₄" deep. If you suspect I may not be using a hand cranked post drill, you would be correct. All the posts holding up my shop's roof are already taken up with other stuff. The Grizzly cross slide vise is far from a precision instrument, and I aligned the blank in the vise by setting my combination square on top of the vise jaw. If you follow the Adam's Challenge protocol, a wooden try square and wooden hand screw instead of the vise would work well enough. I do not think a hand-held brace and bit would get you the required accuracy, but I'm always looking for more effective techniques.

There are other ways to get your hole precisely centered. For example, you could drill the hole at the lathe either before or after you have finished the rest of the turning, or you might be able to drill the hole first with a brace and bit in a rough block, and then align all four surfaces to the pre-drilled hole. I do it the way I show because I think it makes it easier to mount my preferred compression nut ferrules. How ever you want to do it, precision is important to the quality of your results. I won't go into any more details of the alternatives. There are experts on the Turning Forum who can help you out.

I mark all four faces with two lines that will show me how much of the corners to remove to convert this square into a regular octagon. Bob Smalser posted an article a while back on making oars with an octagonal cross section. In the resulting thread, we discussed various ways to get the proportions correct. The easiest way is to use 5:7:5 ratios. The precise ratios are one to the square root of two to one. If you consider Pythagoras' Theorem and do the math, you will realize that the width of the facets (the hypotenuse) left when you remove the corners should be the same as the width of what is left of the original face. 5:7:5 is off by a factor of about 0.07, or .0004", which is a lot less than you will remove with the final pass of your card scraper.

In this case, I chose units of ¹/₁₆", which results in a ¹⁷/₁₆" diameter handle. This is a little smaller than I prefer for a high torque tool like a screwdriver. It will work fine for most people, whose hands are smaller than mine, or for tools like files, paring chisels or burnishers, that do not need a lot of force. I set the marking gauge at ³/₄", but could just as easily have set it at ⁵/₁₆".

⁵/₁₆" + ⁷/₁₆" = ³/₄"

⁵/₁₆" + ⁷/₁₆" + ⁵/₁₆" = 1 ¹/₁₆"

"Ohmygawd, he's using a ballpoint pen in a plywood stick!" A pencil or even a quill pen will work. Just don't use a sharp marking or cutting gauge, because the cuts will show in the finished handle. With an octagon gauge, you could mark two lines at once, even if you started with a tapered blank.

I clamp it between dogs on the face vise, on edge, and plane off a corner right down to the lines. You could start with a small drawknife, and proceed to a spokeshave if you prefer. As you will see later, getting it flat the whole length is not critical, but anything you take off with the plane you don't have to take off with a roughing gouge, and flat helps you know how much to turn off later. I like the shape of the plane shavings.

I've got one corner flat, and three more to go. It's interesting how the more coarsely tuned block plane makes the curl disappear. I knew I had the right block of wood when the smoother I used to finish squaring it up revealed the figure. I won't get a good view of it again until I put the oil and shellac on it.

Now I have a regular octagon, and I'm ready to take it to the lathe.

I can't walk and chew gum at the same time, much less operate a treadle lathe, so I'm going to have to kill some more electrons. Still, anyone who has experienced a catch understands the concept of the workmanship of risk.

I mounted a ⁵/₁₆" diameter mandrel in a Jacob's chuck in the headstock of the lathe, slipped a brass compression nut and the handle stock onto the mandrel, and brought up the tail stock. After turning a tenon and threading the ferrule (which will be the subject of another article), using a parting tool and some open end wrenches, I filed down the hex and polished it. Instead of the signature Loxahatchee Toolworks ferrule with the hex-to-round transition, I decided it would look better to turn the whole ferrule round. The hexagonal and octagonal facets fought like cats and dogs. I then turned the fancy beads and coves, that will remain round, on both ends of the wood.

Now, the whole plot seems to have come completely undone. That beautifully executed octagon ends up in shavings on the floor under the lathe, but there is method in my madness, with just a hint of the original lines remaining. I work very carefully with the skew chisel, to not completely obliterate the arises of the octagon. As I'm shaping, I carefully watch the profile defined by the newly turned surface where it intersects the arises, but ignore the profile 22 ¹/₂� away, where the turned profile meets the original flats. I think I quit working on the head end of the curve a little too soon. If you didn't get the hole for the mandrel centered, it will show up now. The photo shows that my flat ovals are not quite the same size, but I can easily compensate for this small error in the next steps, so the risk paid off.

Now for the fanciest jig you're going to get in this project. I raise the tool rest even with axis of the lathe, and move it right up to the handle, rotate the handle with the chuck, and then hold it steady while I extend what is left of the lines on the arises to both ends, holding the pen horizontally.

Now, the handle comes off the lathe, and back to the bench where I shaped the original octagon. I clamp it between the dogs, and using a pair of half round files, an 8" bastard followed by a 6" finish file, I reflatten what I just turned, right down to, but not beyond the new lines. It helps to clamp it with the face you are working horizontal, and then turn it 45� to work on the next face. A little touch-up by eye with a card scraper is all that is needed to build new smooth, symetrical facets between sharp, straight arises. I stop scraping just as the lines disappear.

Finally, back to the lathe, to touch up the beads, to blend them into the facets, sand, apply some Frog Polish�, complete the shaping of the butt end and part it off, sand it smooth, ebonize it, and apply more finish.

The mounting of various and sundry tools to the handle would be the subject of one or more future articles. In the meantime, you can search the WC or OldTools archives.