Problem with Centers of Solid Segmented Rings

I tried many things, none worked. Leave a 2-3" diameter hole in the bottom ring, turn it into a round hole with a 5-10 degree chamfer, and turn a solid plug for it. Er, turn the plug first is what I did. Anyway, plug the hole with a solid 2-3" plug. Do this before turning the rest of the bowl, as you'll need to turn the glue squeeze-out off anyway.

In my case, I glued the plug blank to a waste block and turned the bevelled edge. Then, I glued the bottom ring to a waste block with the bottom exposed, turned the hole for the plug, and glued it in. When it dried, I turned the bottom shape, then reversed the ring onto it's mounting block, trued the plug flat (I was using it as a reference for thicknessing the other rings) and started gluing on the other rings.

The first photo clearly shows the plug in the bottom. The sixth photo shows the underside of the plug.

Thanks, I was afraid of that. I considered using a contrasting plug, but thought that 12 or 18 perfect joints would be cool. Of course, if cool were dollars, I'd be pretty well off. :-\

Neat stuff. I noticed on your web site, which I'm embarrassed to say I have only just looked at, your daughter(?) Rebecca turning a bowl on the lathe. That's amazing - it's almost bigger than she is, and the tools handles are as big as her arms! How old was she? 10? I see she has 'the grip' on the rest end...

I also noticed a 386 Compiler - neato. That would go very well with my Data General 386/16 with the four huge-ass 1mg memory cards. That throbbing ST-251a could use a good extended-mem compiler. ;-)

I've written stuff like Java eye-candy for my obese old web site, and a C/ASM based multiuser (semaphores), multitasking (limited) relational database for DOS many years ago. Dynamic Overlays eventually did it in, however. Kept adding stupid features, like network chat and a technical reference repository, until it was so bloated it wouldn't fit into memory... It even had pop-up windows, before Windows was a wet-dream! What's amusing (to me, anyway) is that after all these years, it still runs properly under Windows 2000. Oh, yeah - hooking those vector tables in assembly.

Anyway... Thanks,

Greg G.

It's a platter, she's my daughter, and yeay, she was 10 at the time. She's also demonstrated at our local turning symposium and our annual craft fair.

> I also noticed a 386 Compiler - neato. That would go very well with > my Data General 386/16 with the four huge-ass 1mg memory cards. I designed and built one of those. The DG 386/16 that is. Not the one that shipped, but the later one that didn't.

I finally did get one that sanding dust and glue did a nice job but normally that doesn't do the trick. One thing that I have done that look great is to drill through the center into the waste block and then fill it with contrasting epoxy. I'm working on a bowl now that will have a 1-1/4 or 1-1/2 inch hole drilled and filled. Once dry I'll re-drill a 1 inch hole about 1/8 inch deep and add a metalic button. When the bottom is finished I'll do the same thing. I dye my two part expoxy with regular Rit dye.

Jo-Ann's is a good place to find all sort of buttons to use for this purpose or for bottle stoppers.

Stuart Johnson

Just curious.

Owen Davies

First a question: Are you sure the degradation of the points is not due to the softwood characteristics of your test piece?

This disk is down in the bottom of the vessel where it's dark? What if you glued up 1/2 disks and sanded the flat edge to cut back to clean up the points? (This would distort the point where the points converge which is why I asked about it being dark down there.)

What if you make the four pieces, that join the 1/2 disks, with lopped off points larger than the others and then sand back to get the points at the edge?

(This diagram only shows 2 of the wedges - the other two would be on the other 1/2 disk. The tips are cut at 90 degrees to the bottom edge.)

Just thinkin'...

Oooooo. Let me guess first. General Mini? (I think the pulley cover laying to the side (!) was my clue - and the green color of the lathe.)

DJ - good to see her hair pulled back - now get that pulley cover back on. (Not usually a fear monger, but given my new turnin' tip in my sig block, I'm getting pretty aware of potential hazards.)

It was on when I left her, she says someone else removed it to help her change the lathe speed and didn't put it back on. She's a bit more paranoid these days. She puts her hair in a bun too.

General Midi.

As I recall, that was about the time the boards started coming from Taiwan. I repaired computers for the military way-back-when... I still have the manuals and boxes of BIOS EPROMs - ugh, reminds me, it's time to clean out the basement again. I hate computers...

Greg G.

Thanks, Stuart. I guess I'll use a contrasting plug. With a veneer wrap. With a zig-zag pattern. Thus making it _waay_ harder than it has to be.

Greg G.

I'm a relative newbie myself...

No, it's pretty crappy wood - and very dry.

Actually, now that I think about it, running the grain radially would probably work better. But it would change the appearance. That would work great with black palm - if I ever get any...

Good possibliities. Throws off the symmetry a little, but for a deep vessel it wouldn't matter because, as you say, it's dark down there. But if it's THAT dark, might as well fill it with a plug.

And after looking at other turnings on the web, I have yet to see one with a perfect center. And what about tearout while turning? I'd hate to go through all that and end up ripping it out anyway. I guess that's where experience helps - and I have little at this.

Thanks, Owen,

Greg G.

Oh, yeah. I forgot to mention this in my previous post. That picture is disgusting - you should be ashamed... Learned as a mechanic that you never wear anything that conducts electricity or encircles a body part. I've seen wrist watches do a similar thing around heavy machinery. As well as rings melted off with the finger from 200 amps. And eyes poked out while peering into shaft bores, while another guy is hammering on the far end of a Caterpillar track drive shaft. "Is it there yet?" Ouch!

That's why I do my woodworking in the nude...

Greg G.

You're not sanding glued up half-disks in prep for making the completed ring? Maybe your jig is absolutely perfect to .000001 degrees and you don't need to. ;)

Most segmenters glue up halves, sand the mating edges on a disk sander and then glue the two halves together. Eliminating any errors from cutting the angles - or at least masking them to the point where it's not noticeable. I guess I assumed you were doing the same and if you made those four wedges oversized and sanded back you wouldn't be adding much extra effort.

If you aren't aware of these two guys, I'd venture to say they're at the top of the segmenting game these days: Curt Theobald out of Wyoming; and Malcolm Tibbetts from Lake Tahoe, CA. Theobald has two videos that are well worth the $20 ea and Malcolm has a book that's equally as valuable. I've seen Curt's work in person as well as heard him speak at a chapter demo, his assemblies are absolutely flawless - and with as much attention as he pays to details it's not hard to understand why.

I forgot to reply to this part of your message in my previous post.

I think you should try a test with a hard wood that's not prone to chipping or splintering - perhaps Hard Maple or Cherry. You may find your problems disappear with a suitable wood.

I don't think going radially would be much of a solution as you don't want to be restricted that much in your choices of finished appearance.

Hi Greg,

You can cut very sharp pointed segments with a table saw or miter saw if you use good hardwood. Some very dense hardwood is too brittle and the tips can break off. Softwood usually doesn't work very good because the wood is too soft. You could use a sanding jig to re-point the damaged segment tips, then it probably wouldn't matter if you were using hard or soft wood.

To change the subject a bit, I have found that making a solid segment base using this pattern usually has problems down the road. The tips tend to pull apart over months or years, leaving a nice that will not look good even if you fill it. Wood humidity changes is probably the culprit. Glue will not hold the sharp tips together because there is almost zero surface area for the glue to bond to.

I like segmented bases on my bowls and have found two methods to solve the problem. The first method is to make a hole in the center of the disk and plug it with a solid disk. Small solid disk plugs work best because the disk will get a bit oval over the years and can break your base. Small solid disk plugs, say less that 1" diameter, get less out of round and cause less of a problem. Personally, I like using larger solid disks and these would definitely cause problems down the road. So, for larger disk plugs, I make a disk sandwich of thin baltic birch plywood between two disks of thin hardwood so the final thickness of each hardwood disk, after I finish turned the bowl inside and out, is about 1/8". Also, it's probably a good idea to not make the disk plug fit too tightly.

The second method is to not plug the center of the segment disk. Instead, the segment points are strengthened from the inside using a small hidden baltic birch plywood disk. A recess is turned onto one side of the segment disk for the plywood disk. The plywood disk and a suitable cover is glued into the recess. After final turning, the thickness of the segment disk wood on the outside of the plywood disk would be about 1/8".

Both of these methods are a bit of trouble but they have stood the test of time for me.

Kevin Neelley

In article , Greg G. says... >

Hello Kevin,

Whoa - the man himself! It's _your_ fault I got into this. I ran across your web site last year and just _had_ to make some of those neat looking segmented turnings. So, $2300 later, here I am...

Yes, the walnut seems to hold a sharp edge far better than the soft pine I was using as a test piece. I have wondered about expansion/contraction/humidity effects and issues over time. I know what to do on a flat job, but this is a whole new realm for me.

Thanks for the great tips and caveats! I would hate to put a lot of time into these and have them pull apart or deform over a long period of time. They should outlast me... and then some...

Suppose I should buy a book or two, but looking at the pictures and text on your site was enough to get me started. I even designed my own version of a cut-off jig.

Thanks,

Greg G.

Kev>Hi Greg,

Greg G.

Well, after jointing and planing the S2S Walnut picked up earlier this week, I used my newly designed segment jig to create this.

Straight off the saw, no sanding at all. It is _not_ glued. And as suggested by others, the denser wood was better able to retain a sharp edge. Whether it will remain this way over time now seems to be another concern. But at least I know it can be done...

This are parts for a simple platter I have designed. Walnut & Maple.

9 1/2" diameter, 2 1/4" tall. Rolled lip and beaded base.

This is the outer ring - the pieces are just lying there, no glue, no rubber bands, so don't take the gaps seriously...

I may recut the piece with the small exposed knot - I have no idea where it will end up after turning, but you can bet it will be in the worst possible spot. I hope it turns out OK, but I fear the end result after the surfacing operations. The grain is pretty prone to tear out, and I'm a rank newbie at this segmented stuff...

The hardest thing for me right now is the initial rough out, while turning off the flats. It's hard to know just how to approach a new piece comprised of new (to me) kiln dried woods. It'll be my luck to shatter it off of the lathe at the first touch of a tool.

Green wood is so much easier to turn...

Thanks,

Greg G.

It will be interesting to see if it's still a tight fit like that after you glue it. In my case, the moisture from the glue caused some minor swelling, but it was enough to destroy the ring.

Hmm... just had a thought for a base. Cut the wedges with a slightly

*higher* angle, so that the outside touches but the points don't. Or a compound angle (pentagon vs triangle). Spray glue it to heavy paper (having a computer print a pattern helps) and pour epoxy into the gaps. When set, remove the paper and use that face as the initial "flat" to work off of. Or, I suppose, glue the wedges to a mounting blank then turn your flat afterwards.