I've been looking through a book by Malcolm Tibbetts called "The Art of Segmented Woodturning". He makes some absolutely wonderful pieces and I wouldn't mind having a go at segmented turning myself. Only trouble is that he uses a veritable arsenal of tools - and due to a combination of space and budgetary restrictions I try and get by on as little as possible. This means, for example, that my disk sander is a piece of abrasive stuck to a plywood disk attached to the scroll chuck on my lathe! He advocates use of a
12" disk sander, a mitre saw for cutting the segments, a jointer and a whole host of other stuff. He certainly seems to make good use of his tools but quite often you find you can produce perfectly acceptable results with a minimum of equipment. I'd be interested to know from any segmented turners out there how much tooling is necessary to produce good quality results - for example, do I need to shell out on a "proper" disk sander and a mitre saw. I have a good quality bandsaw and wonder whether I can get away with that. Your experience and advice is welcomed.
Hey, I just got that myself but haven't had a chance to really read it yet.
Mine is on my faceplate. So? I built a plywood table that sits on the bed of the lathe that lines up with the center of the disk, too.
12" disc on the lathe.
Table saw and incra.
Ok, I've got one of these. You can use a belt sander or your disc sander along with a "safety planer" on a drill press to thickness wood.
I use a jointer/planer to prepare my stock, and a tablesaw to cut it and match half-rings. Disc sander for facing the rings.
I think the thing to do is try try try! Pick an inexpensive hardwood (maple around here) and see if what you've got is accurate enough for the results you want.
I have the incra 5000. However, even after aligning the angle with feeler gauges to within a few thousanths of an inch over the 18" length, it still wasn't accurate enough to get it "just right" for wide rings, so I use the half-ring-trim technique.
The flip stop comes in handy for segments, though. I use a two-phase technique for cutting segments:
Phase 1 - rough cutting. I use a drafting triangle clamped to the waste-side sled (the one that doesn't slide, for incra) as if it were a rip fence. To set this up, I measure a segment on the stock, position it for the cut, and use a t-track clamp to clamp it to the sled. Then I position the sled so that the point of the stock is at the near edge of the waste side sled, and clamp the corner of the triangle at that point. I push the sled forward so that the point of the stock is now near the tip of the triangle and clamp the far corner down. Now I have the triangle clamped along the leading edge of the waste side sled, and one edge is parallel to the cut and the right distance away. Note: the triangle is short enough that the stock leaves the triangle before beginning the cut, like any good crosscut.
Ok, now that I have a stop, I cut a dozen blanks. Cut, flip, cut, flip, etc. Now I have a dozen trapezoids slightly longer than needed. I run a pencil line down all the angled edges of the trapezoids so I know which ends I've trimmed.
Now I set up the flip stop. I set it for 1/32 long and trim one end of each rough trapezoid. Set four of them aside. Move the stop to
1/16 long (note that the incra stop makes this easy - it's moved one notch each time) and trim the other end of the remaining 8.
The reason for this trimming step is that the trimming is done with the SAME long edge against the SAME part of the fence each time, and I don't have the rest of the stock influencing the angle at all. It results in fairly precise cuts that way, and I don't have to worry about how parallel the long edges of the stock are.
Ok, so now I have parts for two half-rings with slightly long ends. Use one of the short trapezoids to mark the long ones with a marking knife so you know where to trim them to later. Glue up the half rings, leaving the marked ends unglued. Lightly sand. Use t-track clamps to clamp the half rings to the crosscut sled, aligning the marks you made with the edge of the sled, and trim them. Note which side is "up" for each half, when you glue them together keep one half up and the other half down, so any inaccuracy in the blade's angle is cancelled out instead of doubled.
Now, sand the whole rings on the disk sander. I make pencil marks on that side first so I know when I've sanded just enough.
As I glue each layer on to the form, I let it dry enough so that I can true it up and thickness it on the lathe. I use a ruler across the ring as a reference, and a second ruler from that to the bottom of the form to check the "height" of the ring, since in my cases I'm usually following a plan and it's the absolute height of the ring that's important and not the relative thickness of it; I can't allow for accumulated errors in ring thickness.
I use a long block and sandpaper to do the final flattening and use a straightedge to test for flatness.
When clamping each ring on, also, I turn the ring relative to the form after the tailstock is brought up to squeeze out any excess glue. This seems to get rid of the dark glue lines, since bubbles of excess glue can keep the rings apart.
A while back, I found a jig for a tablesaw that will help you cut the segments-- I find it much easier than using a chopsaw & safer. The only problem is that you have to make a jig for each type of segement- ie. 8, 10,12 segments. I don't remember the website, but it may be on the woodworking webring at
formatting link
Also, Kevin's woodturning has some neat ideas. If I remember the link, I'll repost. I think I still have the plans in an excel spreadsheet that you can have (assuming I didn't erase it when I reconfigured my harddrive this week) good luck, Phil
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