twisted goblet

[john lucas]

I'm been working like crazy reorganizing my man cave that masks itself as a garage. I still have a lot of work to do but simply had to stop and turn something. We had a demo at our club on turning twisted boxes and that was the presidents challenge. I figured I could turn a goblet and not take up too much time away from the shop rebuild.
For those who have never done something like this the process is quite easy. The tool control however is quite challenging to get clean cuts without ridges since your only hitting the wood for 1/3 of the revolution. I should have tried a scraper just for the heck of it but doubt you could do it. I think it would tear the trailing corner and the corners on these need to be very clean to show off the twist. you have to be very light on the bevel of the tool for good control of the cut.
what you do is simply turn a cylinder. Then draw a circle about 5/8" from the center on each end. Mark off 120 degree dots. These will be your off set centers. Mark the dots 1,2,3. Do the same on the other end making sure 1 aligns with 1 etc. Now mount it between centers using number 1 on one end and 2 on the other. turn this. Then mount it between 2 and 3, then 3 and 1. Then mount it between centers and turn a tenon on what will be the bottom of the goblet.
The trick is to get the off center sides exactly the same width. I had forgotten that step since it's been probably 10 years since I did one of these. That throws the goblet opening off center so one side is thin compared to the other 2. You can't see that in this photo (because I'm a good photographer and know how to hide things like that)
Anyway it was fun so now I have to get back to doing flat work and finish the shop redo.

 

[Tom Sherman]

That's cool John very nice. I did a box the same way back in 2006 for an auction on SMC. Had a great deal of fun with it. Turned it on a midi Rikon, was almost too much for it had to strap it down to keep it on the bench. I have been entertaining the idea of doing another soon. Nice job.

 

[wwlewis]

John
What tool did you use to get clean cuts? I have been using a heavy spindle roughing gouge and hand sanding to keep the edges crisp.

Do you have another technique?

 

[hockenbery]

John What tool did you use to get clean cuts? I have been using a heavy spindle roughing gouge and hand sanding to keep the edges crisp. Do you have another technique?

One tool that works really well for me is a side ground gouge in a shear or a pull cut.
The cut is on the wing with the wing edge at 45 degrees to the wood or higher with the bevel floating over the cut surface.
It is the same cut I use on the outside of natural edge bowls.
A clean cut on the interrupted surfaces. It is close to using a skew with the point down.

I do quite a few multi center turnings with this tool. One great feature is you can start the cut at the edge.

On each face there is usually one direction that gives the cleanest cut. Most times I can sand with 220 on the face.
The less sanding the sharper the edge. I use 3" Velcro discs carefully.


John, interesting piece with the ring.

Al

 

[Shawn Pachlhofer]

I tried to do a twisted piece once. once.

I didn't pay close enough attention to Barbara Dill at SWAT and numbered the top clockwise, and the bottom clockwise - and ended up with something "kinda" twisted. 😀

still on my list of things to figure out...someday

 

[john lucas]

I used a spindle roughing gouge and played with a skew and spindle gouge. All worked but my spindle roughing gouge has a 35 degree grind and it was easier to control. The trick I found was to control the tool with your body. That keeps the tool from bouncing so much since your only cutting 1/3 of it at a time. Then you have to force yourself not to feed into the cut too rapidly. When I cut at what felt like a normal speed I got lots of tearout. I assume that's because since your cutting mostly air the tool wants to cut too fast so I simply slowed down my feed rate and let it cut. Much better. I still found it very hard to get a really clean cut. Usually on spindles I can easily start with 220 paper. Had to back down to 150 for this because of a few tearout lines.

 

[hockenbery]

Using the sideground gouge

John,

I have found the side-ground bowl gouge with the Ellsworth grind to be the most effective for me in the interrupted cut be it spindles, natural edge bowls, or roughing an irregular blank. works great for multi-center spindles which becomes great practice for turning natural edge bowls.
I have been doing a demo and some workshops turning 3 sided napkin rings. In 90 minutes near beginners have made 3 napkin rings they can sand with 220.
the wing of the tool is similar to a skew cut with the point down. the gouge has support for entering the cut from off the wood. a great advantage.

Here is a video clip from a demo showing the side ground gouge used to cut 3 sides of a multi-center spindle which has been divided into profiled napkin rings.
There is some bounce with the tool but it is hard to see in the video. probably more a felling than tool movement.
The handle is held against my side and I just shift weight from one foot to the other to make the cut.

video cutting the three faces
https://www.youtube.com/watch?v=rJ4xZ3nx11E

I also put up a video of turning the cylinder. Anyone wanting to improve their bowl turning should do some spindle work with the sideground gouge.
in this clip I show the relationship of the push cut on spindles to the push cut on bowls
https://www.youtube.com/watch?v=I05IYkb06Jc

Have fun,
Al

 

[Bill Weaver]

Just some simple questions

John,
I get or understand the method of doing the twist, which I'll call it bar stock to keep clear in my mind. after you have the twist to where you like it you then drill the center out for cup (correct). Then you do the smaller stem spinal turn. So next how are you anchoring the foot? Are you leaving extra stock on the foot for a chuck or a face plate. Then using a jig in a live center at cup end? Just give us some of your tricks too clear up how this would work best.

Thanks John for posting this
BTW I really like it.😀

 

[john lucas]

Bill I turn the twist. Then drilled and turned the inside of the cup. Then turned the stem partially and turned and released the captured ring. Then turned the rest of the stem and the goblet bottom. I left enough rough to use a parting tool and cut a concave on the bottom. Then I sanded the bottom using a sanding disc in my drill press.