Segmented turning questons

[Christopher Hunter]

Hi,
I have been wanting to try turning a segmented bowl and have not thus far because I know that accuracy is the key
I made a couple pens that way and used a belt sander the get the pieces flat but on gluing rings together I find that this would be a challenge ...
Basically --working one ring only
if I cut all the pieces at say for example 30* on the table saw what should I do after they are cut to make sure they are flat without gaps ---
or will the table sawed pieces be ok to glue together like that...
I thought about sanding them by hand but I wouldn't want to mess up the angles ---
any advise is appreciated

Thanks
--Chris

[Stephen Hibbs]

Even on a mitre saw I have trouble getting perfect angles, so I glue up the two halves of the ring seperately, then sand the ends flat on a table before gluing the halves together.

[Christopher Hunter]

Yea I thought that would be a problem too, but my question was angled more on even two pieces within a single ring...
I have a miter saw as well and I'm looking for the best way to even start the cuts;;;;;
I sound so much like a newbie don't I, LOL
well on this segmented stuff I guess I am

[Ron Sardo]

Malcom Tibbets has a great book on this
http://tinyurl.com/y6s9df

[Stephen Hibbs]

hmm, I'm not entirely sure what the issue is, but I'll go through what I do. I cut strips on the table saw so that they are completely square, then cut the trapezoids on the mitre saw. I then put a liberal amount of glue on a piece, and rub it with another piece until it creates some suction. I put the pieces on some paper on a flat surface and get them flat on the surface. Each hour I combine pairs and groups until I have a half. When the halves are dry, I sand the end on a piece of sandpaper glued to a board so the ends fit together. Then I use a clamp to hold the ends together while the glue dries on them.
Then I sand the top and bottom flat on the sandpaper board.

[Christopher Hunter]

So let me get this right---
from the trapezoid pieces sitting in front of you -- you just glue them up... right from there or do you need the flatten the trapezoids first on some sandpaper--
I just think that after I cut the trapezoids on a saw the saw marks will create holes in the two pieces and thus preventing them from fitting tight ----
In general woodworking I have found that making a 45* mitred frame, (like in a picture frame) that the angles still need to be sanded a little to make them line up tight..
should I need to do that for every piece that I cut???
--Chris

[Lee DeRaud]

In general woodworking I have found that making a 45* mitred frame, (like in a picture frame) that the angles still need to be sanded a little to make them line up tight..
should I need to do that for every piece that I cut???Nope, just two (or maybe four) of them. To maybe clarify what Stephen is saying: glue up two half-circles from your raw trapezoids. See how the two halves go together and trim/sand/whatever until those two joints are tight. You can't do this with a picture frame because it would end up out of square, but here it doesn't matter because you're going to turn it round anyway.

And if the saw marks are bad enough to show in the finished piece, it's way past time for a new/better saw blade.

[Joyce Baldauf]

Christopher,

There is a very good DVD available titled Introduction to Segmented Turning by Curt Theobald. Our club just got it for their library. It is very clear and detailed and I'm certain you will find it extremely helpful.

There is a second DVD in the series but the first will take you a long way.
Probably available at any of the woodturning retail outlets.

Joyce

[Paul Engle]

Picture framing slicing tool at Rocklers, 194$ , perfect angles , perfect surfaces. I have used one for over 10 years making dispaly case bases with mitred ends and they have to be perfect angle and dead flat and this tool works great.I can shave .010 inch at a time with it, and use my Delta wet grinder to sharpen the blades. cuts right and left up to 90 degrees.
try this link to see the trimmer.

http://www.rockler.com/product.cfm?page=6533

[Lee DeRaud]

Picture framing slicing tool at Rocklers, 194$ , perfect angles , perfect surfaces. I have used one for over 10 years making dispaly case bases with mitred ends and they have to be perfect angle and dead flat and this tool works great.I can shave .010 inch at a time with it, and use my Delta wet grinder to sharpen the blades.How well does it handle the very short (typically less than 1") pieces used in segmented turnings?

[Bob Way]

Hi Chris,

You've gotten some really good advice that should help you out. There are a couple of things I might add for your consideration. It sounded to me like your concern was for 1) the kerf marks left when you cut your segments, and 2) a gap that might be caused if the angle cut on the miter saw is off a tad bit.

While I tend to cut all my segments on a table saw, much of this will apply to a miter saw as well. I tend to be a proponent of setting up for accuracy right at the start. So, I will check the squareness of my blade to the table, and the squareness of the cut it makes to miter gauge (saw fence in the case of a miter saw). Leaving kerf marks on a cut usually means one of the moving parts is not running quite true, or there may be an tooth on the blade a little out of kilter. Anyhow, checking for an accurate and clean cut at the beginning, and correcting it until it is should help with getting a cut that could be gluable from the saw.

The gap caused if the angle is a tad bit off follows a similar process. I will either use plastic drafting squares for the common angles (30, 60, 45), or paper templates I make by drawing a line to the proper miter angle, and setting the miter cut to that template. I don't usually trust the scales or the autostops on the saw to do that. The thing to keep in mind, is that the error in the cut gets multiplied. So, if the cut is off by .1 degree and it takes 24 cuts for a 12 segment ring, then the error in the ring will be 2.4 degrees. That can be corrected by following the advice to glue pairs of segments together until a half ring is built up, then sanding the edges of each of the half rings until they are flat.

I strive to glue whole rings together at one time, or if they have a lot of segments, then half rings. So, I'll take the setup one step further and cut 1/2 of the number of segments in the ring out of scrap, dry assemble them, and hold a straight edge across the ends of the half ring to see if, and how far, I might be off. Then tweak the miter setting.

Man, this is long, and I apologize for that. I am attaching a photo of a salad bowl I turned some time ago. The rings were made from segments cut on the table saw with the finish that came off the blade. Each ring was assembled by gluing all the segments at the same time. Bowl is composed of 12 segment rings, and measures 11" diamenter by 5" high.

Have fun with your project.

Bob Way
Canton, MI.

[Richard Madison]

Chris,
What they said. Get Malcolm Tibbetts" book, about $18 on Amazon. Cuts made with a sharp 80 tooth carbide blade on whatever saw are sufficiently smooth to glue as is. Watch for the little burrs on bottom edge of the cuts and try to remove same before gluing segments two by two.