Segmenting Have you ever made a blank you’re scared to turn?

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KenB259

KenB259

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That's how I'm feeling about this one!!
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I've made a bunch of the little "illusion" blanks which I should have been more afraid to turn. There are little pieces strewn all over my shop from blanks which started out with over a hundred glue joints!
 
If I were you I wouldn't be afraid to turn it. I've seen your work. Although I don't see any thing wrong with this blank I think if it goes haywire you can make another just as good if not better.
 
Good idea waiting . Probably not an issue for you over there but over here keeping in a warm place to generate a stronger epoxy cure is a good,idea. I must admit I would be tempted to apply some thin CA to the outside as well just to ensure as you turn to round it stays in one piece or maybe even sand it to an octagon first??

Good luck

Ian
 
howsitwork said:
Good idea waiting . Probably not an issue for you over there but over here keeping in a warm place to generate a stronger epoxy cure is a good,idea. I must admit I would be tempted to apply some thin CA to the outside as well just to ensure as you turn to round it stays in one piece or maybe even sand it to an octagon first??

Good luck

Ian
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Blanks like this, that I deem fragile, I typically apply some CA, as I go.


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Reduces the impact and shock loading on the blank. Wise in this case I think given the intricate nature of the blank , which looks incredible by the way. 👍
 
KenB259 said:
Mark, that second picture, what is that?


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Jarrah Burl. My wife swiped it and we still have it. The finish is not especially good, but it is interesting visually, and I do remember it being "fussy." I basically encased it with popsicle sticks, gauze and CA before drilling. Then glued in the tube, turned close, glued in the turquoise sand and etc. I did use CA liberally at all stages.

The last blank that splattered; I wanted to turn a bit off, then cut into slices and then rotate the slices for this kind of a pattern: "Rubic's Cubix with dots". I actually believed it was poor tool control that doomed it. I had spent a lot of time to size the color dimensions that when I eventually cut the slices, they would be close to square after turning it down to bushing size. The dots were another pipe dream element. Alas, it was a dust pan/shop vac finale. Feel free to give it a shot.


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I had a few over the years and still have one I made at least 10 years ago and still have not turned it. It is a celtic knot in aluminum and brass. Could not find the photo but I know I have shown it here before.

Here is one I knew was going to give me a problem when I made it and the third time was a success. Learned from the other two failures and will someday revisit it because I should have done something different.
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Got the photo. This is the one that I know will fight back. Have not really figured out what I want to truely do with it.
 
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Many years ago, a guy named "Eagle" made extraordinary segmented blanks (by the standards of the day).

I was privileged to be one of his "experiment turners". Over time, I learned to douse liberally in CA (he used CA to make the blanks) before starting.
Then, turn the two ends one night (don't touch the middle) and douse liberally with CA when finished. The NEXT night, turn the middle and again douse liberally when finished. That way either the ends or the middle would hold as you put stress on only one section.

Still blew up a couple, but my batting average went up considerably!!

FWIW,
Ed
 
KenB259 said:
I may sand the corners down on this before I put it in the lathe.


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If I were you I would not sand it. I would use bandsaw to cut corners off if you are not good with tool control. Sanding just adds heat. But do not forget to drill for tube first. Then CA the sides and then epoxy the tube. Then turn after another 24 hours. If you drill after turned not much support. I always drill before turning.

Do as Ed said too as you turn every so often add CA to outside. To me I would be looking at sharp skew and honing it quite abit as you turn.

Should be an interesting design.
 
ed4copies said:
Many years ago, a guy named "Eagle" made extraordinary segmented blanks (by the standards of the day).

Still blew up a couple, but my batting average went up considerably!!
FWIW,
Ed
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I was just about to mention Eagle. He is the one that taught me that there was nothing wrong with being overly cautious on delicate blanks. I have made several delicate ones over the years and no blow outs thanks to Eagle.

Today, the method is Wrap the blank three or four times fairly snug with gauze and CA it. Eagle would wrap it with string and CA it and this is what I began to do at his suggestion. I would turn 1/2 the length to round; use string (gauze) around the turned end and CA the heck out of it; Turn the other end to just round even with the first end. (This was also Eagle's suggestion to me). From this point on, make sure the tools are exceptionally sharp and keep a hone beside the lathe and swipe it a couple of times every minute or two.

This way, you are eliminating much of the danger points.

Oh, and use polyurethane glue for the tubes. Polyurethane will have 100% adhesion for the full length of the tube/blank, and that alone will add strength unlike CA or Epoxy that might have gaps between the tube and blank.
 
jttheclockman said:
If I were you I would not sand it. I would use bandsaw to cut corners off if you are not good with tool control. Sanding just adds heat. But do not forget to drill for tube first. Then CA the sides and then epoxy the tube. Then turn after another 24 hours. If you drill after turned not much support. I always drill before turning.

Do as Ed said too as you turn every so often add CA to outside. To me I would be looking at sharp skew and honing it quite abit as you turn.

Should be an interesting design.
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Great idea about sawing the corners off, I already have a small jig to do just that. I use it to cut the pieces fir my pool cue blanks. Will be prefect for this.


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Well I decided to buckle in and give it a try. Had a small tear out within the first minute and thought " here we go", but I held my tongue just right and here's the result. I'll say right off the bat, it's not my favorite design, but it's not too bad. I would have liked the design to be a little better centered. As you know, designs can move some when you are turning it down. Extremely hard to know where they will end up.
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Related question: How DO you center a segmented blank when you drill it? For my solid blanks, it's no big deal if the hole doesn't go perfectly down the center as long as there's enough to turn to round afterward, but with a segmented blank, I imagine it's pretty important.
 
I prefer to 'build' my designs from the center out (not very practical). So the center is established from the start. After that, it does not matter for me what extends out from the center, it all will be turned round. But, I will also say that my process is not very typical.
 
I am very meticulous about my segmented blanks being square. That way the center of the blank is the center of the design. Not that hard to do, just takes careful measurements.
 
Both KenB's and Mark James methods. From the center out solves a lot of problems, but some do require very precise squares or octagonal blanks. This last one does sometimes require several trials in a steep learning curve, which is not much more than practice, practice, practice, and it gets better after several trials, in my opinion.

One gift is the ability to "see" and notice with your eyes - very minute' distances of portions of a mm, and off centers by similar amounts.

Another method for some situations is to make the blank round first and have some very precise jigs to cutting. This works with stripes and indexing.
 
All depends on the design. Many of my blanks are done in the round and I segment with a router and the lathe. Drill holes using a collet chuck and a pointed live center to line things up. The center points are already there from the making of the blank round. When building on a tube then drill holes in pieces and build that way keeping things straight and true. Any slanting of the build will show. This can happen when the holes are slightly larger than the tube. when doing scallops and knots then square is the key and keeping that squareness helps. Here is a couple examples. The 3 top left all have center holes when rounding the blank. With the blank rounded and trued to same size entire length I can drill the ends for tubes as mentioned and cut off the length I need using my sled on tablesaw. The guitar pick blank was built in a jig that held all picks 90 degrees to tube.
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mark james said:
I prefer to 'build' my designs from the center out (not very practical). So the center is established from the start. After that, it does not matter for me what extends out from the center, it all will be turned round. But, I will also say that my process is not very typical.
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When you say from the center out, do you mean constructing the blank on top of the tube?
 
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KenB259 said:
I am very meticulous about my segmented blanks being square. That way the center of the blank is the center of the design. Not that hard to do, just takes careful measurements.
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I guess I'm a little ahead of myself here. Assuming you've created a blank where, as you say, the center of the design is the center of the blank, what methodology do you use to then ensure the center of the hole you drill stays at the center of the design? I ask because I know I'm not drilling "straight down the middle" right now with the pen jaws on my chuck, jacobs chuck, and square-ish blanks. As I mentioned, it's not a big concern when dealing with most single-material blanks.

jttheclockman said:
Drill holes using a collet chuck and a pointed live center to line things up. The center points are already there from the making of the blank round.
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What's the setup here? The bit in the collet chuck in the headstock, the live center in the tailstock, and hold the blank stationary with your hand?
 
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