Goblet and Hollowing Interiors

My preference is the Oneway Termite. Perfect for this application. Over on Woodcentral, Keith Tompkins recently had a tip about hollowing goblets. He suggested about putting a rubber band around the goblet to reduce the flexing and help avoid chatter (which it looks like you have a bit of on the inside). I'll try it next time I do goblets.

rr

Greg G. wrote:

What sort of problems are you having? Vibration? If so, are you hollowing a good portion before shaping the outside, especially cutting in at the stem?

I have the Termite and it's one of my favorites for boxes and this type of end grain hollowing. It takes a little practice to get the hang of it

- there's a web site one of the guys here posted a while back on how to use it (can't remember who that might have been... but google the archives and I'm sure it'll come up.)

I use a gouge for almost all the hollowing. It's ground waaaaay back relative to its width, until it's "pointy" in profile. Since the grind is fingernailed, you can pick your degree of aggressiveness by rolling to that section of the gouge. You can also keep the tip slightly elevated as you cut to get some shear, which, coupled with a light cut, can do wonders for chatter, and allows the shavings to run down the flute of the gouge rather than building up inside.

For the bottom it's tough to beat something like the Termite. It's a gouge at right angles, and responds best to being put to the wood as a gouge is, or would be if you were doing an end-grain platter and could get a gouge into the center.

We have a tool simalar to the Termite we call it the Cup hollowing tool. Advantages: It has a removable cup cutter which is easily sharpened and cheap to replace. 2) the cost is US$ 60.00 against $79.00 which will pay for a Stem sharpener to keep it sharp. Look at it on my site

Thanks for the info.

Very observant - I was hoping no one would notice the chatter marks, and would attribute them to a funky grain in the wood... ;-)

Yes, there was a bit of chatter at the top, below the rim. It happened when I was smoothing the interior using a light bulb shining through the wall of the vessel. The tool in use was a Sorby Hollowmaster with the round bit. When I got to the part where the diameter decreased, I apparently forgot to lessen the pressure or adjust the angle properly, and it chattered severely. It was the first time I used the tool. Heck, it's the first time I tried making a Goblet.

Greg G.

Not vibration as much as difficulty in hollowing deep interiors, and general slowness. This piece took about 30 minutes to rough out the interior, and another 10 minutes for finish shaping. 30 minutes seems to be an exorbidant amount of time for the rough hollowing process.

I am careful to leave sufficient (generally ALL) stock while hollowing interiors, partially due to paranoia about pieces exploding off the lathe, but also due to vibration concerns.

I have a standard Crown bowl gouge, but it only cuts to a certain depth and then control becomes a handful. I'm sure it's great for bowls (haven't tried it yet!), but not so much for deep vessels. Examining the profile and how it contacts the piece, I would hazard a guess that a heavily modified fingernail grind would be necessary to use a bowl gouge for deep interiors.

Basically, I roughed out the outside of the "cup" portion, then hollowed out the inside almost to completion. I then finished off the outside, working the the profile to get the lines I wanted, shaved the interior to the desired wall thickness, then final cut the stem and base. Getting that chuck tenon off the base was a bit problematic, as I only have one set of chuck jaws, and they were too small. I turned a jam chuck from scrap for this, and used the tailstock while parting it off. Still ended up with a small nub in the center which had to be removed with a sharp chisel.

Thanks for the info, I guess I'll have to give it a try. I came up with three pictorial tutorials concerning the Termite. I sure hope it works faster than what I am doing now!

Greg G.

I tried a standard bowl gouge, but beyond a certain depth, it just didn't work. I'm new to all this, and haven't mastered the finer points of grinding custom profiles, but I guessed that this would be necessary.

I've studied the pictorials and text of the Raffan book section on hollowing, but didn't find it very helpful - the pictures are terrible.

I'm probably going to try the Termite or something similar. I sure hope it's faster than what I am doing now. 30 minutes seems a long time for rough hollowing.

Thanks,

Greg G.

I looked at your cup cutter. There are no dealers in my area that carry your products, and the pictures on the site are not that helpful. I can physically go to Highland Hardware and actually handle the Termite to know what I am getting.

Have you considered posting extreme close-up photos, and/or links to the .PDF user manuals for your products?

Greg G.

Greg, why the need for speed? You say you are just beginning to do goblets and then talk about deep hollowing. A goblet is not deep hollowing, compared with other vessels. A Termite is great for hollowing end grain and will work to about an 8" depth. Remember to keep the rest further away from the rim and adjust the height so the cutting tip is at center. Take your time and throw the clock away. I have spent 2-3 hours hollowing some of my pieces and regard it as "learning" time. Above all learn to be consistent in how you turn and the techniques you apply. Speed will come eventually, but somewhere someone else will always be quicker.

Uhh.. I'm a speed freak and have to fit limited amounts of woodturning in between two jobs and 6 other hobbies, including reef aquariums, re-siding and re-roofing our house, and keeping SWMBO happy ? ;-)

Seriously, however, it took longer to hollow the interior than to finish the entirety of the outside. Is this really normal? This is only my fourth turning, so pardon my ignorance of turning parlance.

I turned this a few weeks ago, surely this constitutes 'deep'? The same obstacles arose during the making of this project:

I imagine the definition of 'deep' is a matter of semanticsand relativity. It is deep compared to a bowl, but not so deepcompared to the pencil cup. In my mind, anything deeper than it iswide constitutes 'deep'.

Thanks for the info.

It's not like I'm 'watching the clock' while turning, but with limited amounts of time available due to a hectic lifestyle and the heightening economic pressures of living in this failing modern U.S. Republican economy, it would be beneficial to maximize my productivity in the limited amount of time available to spend in the shop. I do other woodworking things as well, the current project being a huge, arched top garden arbor for the better half... It's not a profession for me, it's a hobby. The need to reach a comfortable compromise between an objects relative net worth vs. time expended is, unfortunately, a reality of life in these modern times.

We live in a huge southern metro city, and if I had my d'ruthers, we would be living in the middle of rural nowhere - where time and production pressures are vastly reduced, and there are far fewer hands trying to pick our pocketbooks clean faster than we can keep them filled.

Greg G.

Greg, that's a very reasonable time for many professional turners, unless you're Richard Raffan! No intention of dissing your artistic talent, but if you can produce marketable items at that speed, it will be time to quit your regular job ;-)

Ken Grunke

Hmm.... I guess my guesstimations of time are in error. Of course, that didn't include the cutting and truing of the blank.

I didn't have a plan for a goblet when I started, it's just what

*happened* as I worked at it.

Boy, wouldn't THAT be nice... I wouldn't think that something like this, properly finished, would be worth much more than $25 or so... But again, I could be wrong...

And how many of these could you possibly sell in a year? Just 'cause you can turn 'em doesn't mean you can sell 'em!

If the demand were very high, they would be pumping these things out of China faster than all the other crap we import. I have already been displaced from several technology jobs because of fricken Chinese imported crap. If this happens one more time I'm going postal... or to parasite... errr... law school.

Little would make me happier than to leave this filthy city, abandon the pathetic technology related work I do, move to the woods, grow herbs, and turn stuff for a living. :-o

Thanks,

Greg G.

for straight sided work, Soren Berger makes an excellent hollowing tool - much faster and smoother than the termite - you can roll 1/2X1/4 inch shavings off the inside of a wet box blank with that tool, so it will give you the speed you want - the tool is visible on Soren's web site

Greg, don't know if you got mine. just in case, here is it:

Pascal

Yep, it's a ten-minute job, really. And that's with sanding. Otherwise you pay with time what you didn't in tools.

I'm not sure what a "standard" bowl gouge is anymore. I own four, from 1" to 3/8", and they're ground differently so they can do different work. I'm also lucky enough to have an old Delta iron rest, which I can use to support a gouge for an inch or so inside the piece itself. Never give leverage you don't have to.

Yep, a round nose shear scrapes like Ken's cup tool or Sorby's of similar function, but for my money, the hook or ring tools are the proper ones for the job.

Good point Greg we are working on that at present and will soon have video on most products working as well

Greg, what struck me when reading your reply was that perhaps your gouge isn't as sharp as it could be... I don't recall others commenting on this, but if it's not really sharp then hollowing with it is a punishing experience. You'll notice a more difficult time when hollowing with a dull tool than using the same dull tool on the exterior.

Others have given suggestions, but I thought I'd offer my centavo... with a short overview of end grain hollowing done by the Lowe Technique:

Only rough shape the exterior around the bowl of the hollow portion - don't remove much, if any, of the stem area. You need as much solid wood for support as possible.

Drill a 1/2"-ish hole into the center of the goblet to nearly the depth you want the hollowing to go.

Set the lathe speed at about 1000ish rpm. Not fast and not slow. You can speed up later as you get more proficient. Position the tool rest about

1/2" from the end of the wood, perpendicular to the lathe bed and at a height so that the cutting edge of the tool is at about the center.

Working from the center toward the rim with the gouge (either spindle or bowl gouge works fine), place it on its side so that the flute is facing

9:00 - 9:37 (PM, not AM) and the shaft pointed straight towards the stem with the tip maybe 1/4" inside the drilled hole. Gradually sweep the handle away from your body, using your left hand as a pivot point. This will cause the cutting edge to make a small arc from the center to the left and out of the wood. (If the gouge doesn't cut easily, either try rotating just slightly more "open" - 10:00ish - or raise/lower the tool rest a tad. You really *don't* want to "open" the tool to 10:30 or more

- it'll seriously startle you with a catch.)

Reposition the gouge at the center and a little bit deeper. Do the sweep away movement again. The arc will get larger and larger the deeper you go. Cut in about an inch or so and then if you still need to open the hollowing more toward the rim, reposition the starting point with the gouge to the left of center and again pointing straight in. Repeat the sweep. When you get the diameter of the hollow wide enough at 1" deep then return to center and go another inch from the center outward. Continue working your way inward and out toward the rim in small amounts. When you get to the end of your drilled hole you know you're nearly to finished depth.

One more thing that I didn't want to throw into the gouge cutting mix above. As you clear two depths out to the rim there will likely be a ridge on the wall marking the change of depth. Use a side scraper very, very lightly to just skim off the ridges. Do this every time you complete a cutting sequence to the rim - if you wait until the end to clean them all up at the same time you can get some majorly disasterous chatter because of all the missing mass that hollowing removed as well as the wood will often warp and lose it's roundness as you hollow and it dries.

Please feel free to ask any questions that pop to mind or if I've confused you.