Thread: Couple questions about Segmented Turning.

g/day Michael
I use sandpaper glued onto a piece of glass to with a spray adhesive just to make sure the surfaces glue face is tight and right to each other . But as I am still learnin my self I don't know if this is correct but it works for me. I leave the glue to dry at least 12hrs to fully dry before I start turning it just to make sure it's fully dry. I learnt this when I inserted a dowel into a segemented base I making I inserted 6 dowels around the base and I ony left it a couple of hours 2 of the dowels came loose so i had to insert & glue new ones in and wait again
good luck with your turning
Regards Michael

Hi Michael...

You might just be able to squeek by not sanding if your using a real quality blade like a Forrester Woodworker II that is sharp, but why take a chance on having an "open" joint.
Coffenup's advice is sound...using sandpaper on a piece of plate glass will smooth out any inconsistencies....I usually use 220, others prefer 120.

A real good miter sled plan can be found at Kevin Neely's web site:

http://www.turnedwood.com/index.shtml

Go to the "Segmented" tab, then click on "Sleds". He also has a wealth of other info on segmented construction on the site.

Also check out my previous post on flattening a ring face:

http://www.woodworkforums.ubeaut.com...ad.php?t=77631

Good Luck,

Ed

Where in the Panhandle? I was in Milton.

Thanks for the tips and links guys!!!!
I live just down Hwy 87 from Milton!
I'm exactly 3 1/2 miles west of Hurlburt Field in Florosa. My back yard is on Hwy 98.
When were you down here Ed, I moved here in 88.

I use the saw cut as is for all glue joints and have no problem. I believe the more critical thing is precise angles. If the cut angles are not right you won't be able to fix it with sanding. IMHO
Re: Stave sled. If that is what I think it is then I can forward pictures of mine which works very well for segmented work as well as "staves".

Quite so (precise angles), but for your first efforts, you can cheat on some rings using open segments, like this: [media]http://n-fl-woodturners.org/images/2005-12/2005-12-19.jpg[/media]
The turning itself can be an adventure, though, with all the air to be cut. Not one of mine, BTW, and the link may not be permanent forever.

Joe

Good saw joints will be fine for strength, but what is more critical about getting a perfect joint is so that you don't get a noticable glue line. It is difficult to get this just by sawing.

DAMHIKT

Interesting question and interesting answers. The obvious next question is how do the proponents of sanding (either on a disk sander or a piece of glass, the technique is slightly different but the issue is the same) overcome the difficulty of holding the piece exactly flat by hand? Maybe it's just me being un-coordinated, but the risk of rounding the edges of the surface by applying uneven pressure seems to me more than offsetting the advantages of sanding. Please tell me it's not just my problem!

(btw, holding the piece flat under a drill press and revolving the sanding disk with the press solves the problem for parallel surfaces, but requires jigs for angled pieces etc... a rather cumbersome solution)

Buying Malcolm's book is still on my "bucket list," but here's some thoughts gleaned from him and others on the weird wild web:

End-grain to end-grain glue joints are very weak. Aim for alignment instead, as Alastair says, and rely on overlap with the segments of adjoining rings for strength. Don't sweat about all perfect sizes and alignments for all segments in a ring. Assemble half-rings as best you can, allowing the final diameter to be slightly off-planar. Take each half-ring to the sander (disk, or belt, or plate glass with paper), to make the diameters planar. Then glue the two half-rings into a full ring. Half-segment overlap with adjoining rings, like running bond in masonry, is stronger, and makes imperfect sizing of the segments of little consequence.

Assemble each ring with its bottom on a flat surface, and mark that edge for reference. The top alignment is less important, and can be worked on later, e.g. on the drill press, as suggested by F&E. If handled delicately, all the rings can be finished to thickness this way. Alternatively, the stack can be built up piecemeal, with each top surface sanded in sequence.

The first ring of segments, relying only on end-grain to end-grain glue joints, should be handled delicately for sanding a flat surface for the next ring. Attach the next ring at the edge you marked in the previous step, which you already know is flat. Sand the top to a new flat surface. Continue this loop until the blank is finally assembled. It may take several days to complete a single blank; production turners like Malcolm will have several blanks under construction at the same time.

Joe

Following on from Joe above,

Unless you have graduated to the very precise multi-segmented work, the need for accuracy and symmetry is overstated, except WRT the integrity of the glue line, as above. Small differences in alignment, segment size, thickness etc vanish into the mix, when you are talking the "vanilla" Seg piece, in one or a mix of timbers.

While the endgrain joints are weak, in all the seg pieces I have done, I have only had an unsupported single ring break up once. That was a roughly prepared one for a demo, and happened when I had a dig hard enough to pull the piece from the chuck..........'nuff said.

a la Joe, forget the perfect circle. I cut segments on a bandsaw jig, then sand on disc sander. Target is a flat glueing surface, not maintaining perfect angles. I don't clamp up my rings. After sanding, I rub joint in pairs, on a melamine surface, using yellow glue. Then rub joint pairs int 4's, then 4's into half rings. These are then refaced off on the sander, and rubjointed to give whole rings.

I don't sand rings. Using hotmelt, I spot-glue ring to (faceplate; base; part bowl) on the lathe, roughly centered by eye. Using light cuts, and checking with a straightedge, I true up the ring. "Pop" it off the hotmelt with a chisel or screwdriver, reverse, and glue to piece in chuck, using tailstock to clamp and a platen to spread the load. Once glue dry, true up as above, and repeat with next ring.

I tend to do all this on a production line through the weekday evenings, (30 min 2ce per evening), and have an assembled piece for turning at the week end.

HTH