Tapered hollow vessels

[Bombarde16]

Haven't turned anything in decades but got myself pulled into a thought experiment and wanted to poll the collective wisdom of the group.  In brief, I'd like to make a set of hollow, tapered spindles.  They'd be turned in two pieces and then glued together.  Viewed in cross section at the widest point, the two pieces look like this:

 

 

The dimensions would be gradated across the set, but 12" long by 2" diameter gives you an idea of the maximum size I'd be working to.  i.e. No spindle piece would be any bigger than this.  In perspective, the piece on the left would look like this:

 

 

I know there exist tapered drill bits, particularly in metal shops, but nothing this size.  To acheive such a slender taper, I envisioned shaping and sharpening a flat steel bar into a custom hollowing tool such as this:

 

 

The workflow would then be as follows:

1. Bore a 1/4" center hole in each end of the blank.  Doesn't have to go all the way through, just enough to get things started.
2. Turn between centers to get the ends of the blank round and concentric to the starter holes.
3. Chuck one end in jaws, remove the tailstock and fix a center steady around the turned portion at the other end.
4. Rig up a support system such as the Hollow Roller and feed the tapered hollowing tool into the workpiece to get the internal taper.
5. Turn the exterior between centers.

Thoughts?  Given the length of the taper and the fact that the tool is cutting on both sides (i.e. making contact over nearly two linear feet) would this tax the abilities of a lathe?

[wdwerker]

Yes, it would tax most wood lathes. Chip removal would also be a challenge . Why an internal taper? Weight? What about using Forstner bits and make it a stepped bore.

[TRBaker]

Just out of curiosity, Rob, what are you making with these?

[duckkisser]

you will have a lot of catches the larger the cutting edge the more surface you have to cut.  so you will need rock hard arms, or some way to lock it in place and edge it forward.  maybe mount it in a drill mandrel and use the tail stock to move it forward a little at a time. I would also have a steady rest on it to keep it centered.  I would also use forester bits to remove as much as possible before you start turning.  better to shave off a little then try boring it out.  I think you might have a problem with the cutting edge you have no way for your cutting edge to cool off or clear out your wood chips.  maybe when you make your cutting edge put some gaps in like a  resaw band saw blade.

 

http://www.pennstateind.com/store/LCCAP.html maybe buy one of these to help hold your blade steady I know when im making a bowl and im only going a few inches when it catches badly my tool almost flys out of my hands even light catches can gouge my wood realy bad.

 

when you start go slow and back out often to clear out. I would think this would be more of a shaving the center out then cutting it out so light cuts.

[Bombarde16]

Thanks guys.  Wasting out most of the inside with a set of Forstners is certainly a good way to go.  Moreover, I have no intention of holding a big, flat spike barehanded without a big, sturdy set of bars to hold it captive.

 

Just out of curiosity, Rob, what are you making with these?

 

 

Ahh, but why spoil it?  If the project ever goes beyond the theoretical stage, you'll see.  Until then, let's leave it as the woodworking equivalent of a Rorschach test.  Right now, I need to finish a set of boxes and get them out of my shop.

[duckkisser]

damn you and your secrets ..........first the alter with little tidbits of info.  ......then the 1ft challenge where you show just a little bit to get us wonderings and now this.

[Tpt life]

Why not section the piece in the other axis and work hollows and rounds rather than conical cylinders?

[Bombarde16]

Why not section the piece in the other axis and work hollows and rounds rather than conical cylinders?

 

The thought did occur to me.  Can a core box plane run on sides that aren't parallel?

[Tpt life]

I have not operated a core box plane but I do not foresee my suggestion to be an easy way out, but rather a successful way to get the form you want. I envision a rotary cutter like a router sled or the cutter Marc used to work his fluted column as a way to hog material with something like a core box or spoon carvers and scrapers to fine tune your shape.

[Byrdie]

Have you seen the "Frank makes" 4 part video on the desk he built? (Same guy who did the stop motion lawn chair video.)  What about a segmented turning like the legs he did for that desk?

[sbarton22]

Frankly, in concept, I don't see what you are doing being any more difficult than making a pepper mill. 

 

I also question the need for tapered interior walls. I read, maybe in a Richard Raffan book, that consistent walls are an exercise in self gratification if you do not plan on penetrating the walls to reveal it. So, if you think about a pepper mill, the hole (peppercorn storage) is made the simplest way possible (forstner bit) and the form is what you make of it.

 

Now, there is the aesthetic question of how does the weight of the object feel in your hands. If you feel that a middle heavy form is not in line with the design, then there are other adjustments you can make. IF you wanted to lighten the middle, I would just use a larger bit for a depth and then use a gouge to reconcile the step.

 

I do recommend the center steady...makes life so much easier!

[sbarton22]

One other suggestion. If you can live with a consistent hole size, do that first. That leaves you with a very simple and easy spindle turning to finish your form and your piece is held between centers.