hi, alan stratton from as wood turns dot com.the holy grail, if you will, for woodturning is a hollow form or hollow vessel. now thinkof a hollow form as being a hunk of wood revolving at high speed and you take a bent tool andjam it in there and hope to hollow out the inside. now, never mind if you get a catchon the inside of that and blow up your bowl, blow up your shoulder, your arm, whatever.how about another way to do a hollow form?
wood joints worksheet, how about a segmented hollow form, completewith the narrowest opening you could ever imagine, or ever want in a hollow form. so,how about an easy way to do a hollow form. let's make it.for a solid turning, i could simply mount a hunk of wood on the lathe, start turning,and let the shape emerge. in contrast, segmented
turning must start with a plan. i'm usingpowerpoint. i've drawn a grid on a master layout. then on a slide, i draw my shape ontop of the grid. having the grid on the master avoids accidently selecting a grid elementwhen drawing. after drawing the shape, i overlay rectangleswith my expected segment cross section. in powerpoint, it is possible to specify theexact width and height of the rectangle. from this overlay, i estimate the outer diameterand segment width that i'll need for the hollow form.this i enter in a worksheet which then calculates the segment length for each ring. this onewill have five rings each with eight segments for only forty pieces of wood plus one smallplug in the base. the cutting angle is 22.5
degrees.then off to the miter saw to cut the segments. i always use a piece of wood to hold downthe segment instead of a finger. my fingers are not a renewable resource. i try to alwayscut with the long side against the fence. this is especially important with very shortsegments that may tend to tilt on a very tiny side.to glue the half rings, i lay out a double layer of masking tape with the sticky sideup. after placing the segments on the tape, i tear off the ends that tend to get in theway. then spread titebond original extend on the segments and clamp with a band clamp.i purchased these long band clamps at an automotive parts store. these have a screw mechanismthat tilts up for quick adjustment so i can
use a long clamp for very short pieces. i'musing small bolts as spacers between the half rings.after the glue dries, i'll sand one face of each half ring slightly so that it will sitflat. no need to be perfectly flat -- i'll do that later after the ring is complete.then with the flat face down, i'll sand the mating surfaces for the final glue joint.this eliminates the accumulated error from cutting angles, the twists, and turns of thewood. finally, i glue the half rings into full rings.after the glue dries, i'll sand one face perfectly smooth. i'll tool the other side flat andparallel on the lathe since right now, i don't have access to a thickness sander.now with the top ring mounted to a wood faceplate
with hot melt glue, i'll round it off justa little then true the face. after making sure the face is flat, i can glue on the nextring. i've mounted the next ring to another faceplate with a couple of dabs of hot meltglue. the faceplate has concentric rings drawn on its surface to help position the ring oncenter. then i can use the tail stock to clamp the two rings together.with this glue joint dry, i'll rough trim the top section. most importantly, i'll trueup the face that i'll glue to later. meanwhile, i followed the same process to build the bottomsection of my hollow form. this is where i appreciate multiple faceplates. since i makeand thread my own wood faceplates, i can have as many as i want in any size that i want.now i've switched over to the bottom section
of the hollow form. i'll do a rough hollownow just to get the interior uniform. i don't want to do very much of the interior untili'm sure of the exterior shape. at this point, i still have the upper andlower sections separate. i'll reverse the top section onto the tail stock with a conecenter on the live center. i'll tool the two pieces together with only tail stock pressurewhile i establish the exterior profile. now with the exterior completed, i'll hollowout the bottom section. my gouge works good enough for this task.then switch to finish hollowing the top section. finally, i can glue to two sections together.the tail stock supplies the clamping pressure. with the hollow form now glued together, ican refine its exterior. but, i have to be
careful. i know i have about 3/8" wall thicknesson the sides and a little more on the top. it will be plenty. i'll use a gouge both incutting mode and shear scraping mode -- whichever fees right at the time.with the timber sanded thru 400 grit and walnut oil applied, i'll part it off from the faceplateaiming to be a little concave. by the way, i had glued the base section to its faceplatewith standard yellow glue. i'll clean up the bottom by mounting a small sanding disk ina jacobs chuck and sanding off any remaining marks. i usually do this in a drill presswhich is safer than using the lathe. voila, a completed hollow form without anycatches or shoulder injuries. no blind tool work. it has a smaller opening than i've everseen in a solid work. in fact, i drilled it
out a little more so it can receive a flowerstem or whatever. what possibilities do you see?please click the like button on this video and subscribe to bothmy website and youtube channel. always wear your face shield. until next time, this isalan stratton from as wood turns dot com.