In Segmented Turning: How to do it. Part 1, we were introduced to segmented turning, and how to set up your stock and tools for creating consistent rings that are ready for putting together. Continuing on, in this article I will show you how to cut and glue your pieces together, and look into the typical issues often faced during these processes. We will finish with an example of a finished piece, and discuss how you can take your new-found skills in segmented turning further.
Cutting the segments
You’ve planned your design, selected and prepped your materials, and checked and set your saw appropriately. Time to cut segments. To cut matching segments, you’ll need to set your outside length stop block and keep it clean. Regardless of how accurate you’ve set things, dust and debris preventing the stock aligning with the table, fence and stop block will set in errors. Once you’ve cut your first segment, flip the stock to make the second cut, with the stock against the stop block. The first cut was created when you separated the last segment. It’s wise to start with your shortest length segment first.
Check for gaps
After you’ve cut enough to form a half circle, check again that the stack up gives you a 180° semi-circle. Any gaps will only cause you more work later. If there needs to be adjustment, now is the time to do it, since you haven’t wasted too much stock. If all is well, complete cutting the lengths needs. Once the length is complete, reset the stop block to the next dimension and cut those. When you run out of stock and need to start using the next piece, you will need to make that initial establishing angle cut.
Sanding the segments
Cut each group of segments until you’ve finished cutting everything. Set aside the extra material should a replacement piece be needed. Depending on the quality of the cut, you may need to lightly sand any fuzzies off the segments if they will interfere with the gluing process. It isn’t often needed if you’ve used a sharp blade and good techniques. If you do need to de-fuzz, just a light scuff across the offending area will make gluing easier.
Gluing the segments
With your favourite wood glue in hand and a flat surface work area properly covered, the glue up process can begin. I’ve never had a problem with any fresh wood adhesive. If it is out of date and stringy, get rid of it and buy a replacement. PVA is a good choice. Avoid using epoxies or cyno-acrylate adhesives for gluing segments. There are a variety of techniques for applying glue, spreading it, mating the pieces and clamping. For the clamping process use tape, rubber bands or hose clamps. The simplest and fastest method I know of is called the rub joint.
Rub joining
Dispense adhesive so you can coat both surfaces to be mated. Once evenly coated, place the two pieces flat on the work surface, put them together and rub them for a couple of moments. The glue will tack up and they will stick. The trick is to have them properly positioned to each other when the bond moment occurs. At that point, continue applying pressure by squeezing the two pieces together. Usually 10 seconds or so is sufficient. Practise on scraps until you get a feel for it – don’t waste your cut segments learning. Glue pairs of the proper ring segments together and let them cure. With care, you can continue to glue pairs of pairs together after a few minutes. Once you’ve glues half of the rings, let them cure well by leaving them overnight. Once the half rings are cured well, glue them together to make full rings.
Making corrections
If there are any inconsistencies in angles, now is when to make a correction. The two halves need to mate perfectly with no gaps between the gluing surfaces. If they don’t, you’ll need to sand away the offending areas. Remove a bit from both halves until they meet perfectly. Minor errors can be ameliorated with a piece of sandpaper on a flat surface. More pronounced errors may need a trip to the disk or belt sander. Once corrected, you can glue the two halves together. The rub joint will work here. I put a rubber band or two around the perimeter to hold things in compression.
Gluing the rings into a blank
With the rings completed, they need to be flattened. The excess glue needs to be removed and any uneven joints need to be sanded flat. Carefully created rings can be prepped on a sheet of sandpaper attached to a flat surface. Attach your base to the waste block using adhesive and clamp. The glue will set well enough after a few minutes to continue with the next ring. I use my lathe as an assembly clamp, but you can use a table and set weight on top of the ring for clamp load. Rotate each ring so the segment joints are staggered between rings. Putting them all in line reduces overall strength. Staggered joints create a much stronger assembly.
Turning, sanding and finishing
Once you’ve created your segmented bowl blank, or any other segmented blank, turn, sand and finish as you usually would. Good practices, such as tailstock support, sharp tools and light touch, and cutting downhill are always valuable. Sanding and finishing are likewise identical to usual turning practices. The only difference is that you won’t run into end grain, other than at our solid base. As such, you can use a scraper almost everywhere. You won’t have the end grain coming around twice a rotation on the sidewalls as in the traditional bowl blank.
Summary
Perhaps this was simplistic for an entry into segmented turning. I hope not. The goal was to show you how to give it a try without big investment and lots of study. If you feel it easy to create a turning blank of any size and proportion without the worry of cracking, checking or availability, I have succeeded. You now have the basics, and can grow your segmented turning techniques from here. The ability to create artistic feature rings from different wood species to make intricate patterns will be a valuable addition to your segmented turning repertoire. No table, band or mitresaw? You can always use a mitre box and hand saw to cut segments. It is slower, but once the segments are cut properly, nobody will know whether you used a mitre box or Felder table saw. You’ve got all you need to know to dip your toes into segmenting. Give it a try. It’s great fun.
One Response
Enjoyed your article. Belong to Pembroke wood turners guild. Have seen many demo by you. Learned a lot from you. I’m still turning and learning. Thanks for info. John Marshek