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How do you do that?

underdog

underdog

Joined
Oct 5, 2005
Messages
451
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Location
North Georgia
I've seen several beautiful natural edge bowls (well - three) that incorporate a hollow section of tree in the design. I've been so intrigued that I've shared these photos with a co-worker and we've been puzzling over how to mount such a section on the lathe.

We can envision faceplate mounting for the base, but seemingly, there's no good way to mount from the top so as to turn the base.

What mounting method has been used to turn both the inside and outside?

Allen Alexopulos first posted this one:
http://tinyurl.com/pdl3u
And then entered it's cousin in the contest:
http://tinyurl.com/leb59

Robert Davis also entered his in the contest:
http://tinyurl.com/nsj2k
 
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Jim,

Would be pretty straight forward to start between centers with the TS at what will be the base, adjust the points to center the grain after initial roughing of the outside profile and a few cuts on the bark section to show ring placement. When the rings run true on both "ends," cut a tenon on the base which runs concentric to the rings for conpression chuck mounting. Reverse and hollow. Reverse again and either vacuum mount or use a jam chuck. At least that's how I would do it.

There are, I'm sure, other ways.

M
 
Unless you've got a really long drive center, I don't think the headstock center will go into the hollow log that far, for the initial turning, Mark.

I'm wondering if you mean to put the tailstock ram into the top.... 😕
 
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Appears to be straightforward interrupted edge turning for the first. Just that overgrown scrape produces the ears. Pin chuck or jaws, turn the outside, reverse to do the in.

I've set up hollow stuff crosswise with pin chuck and tailstock. If you want to do it lengthwise, you can use a bumper in one of the live centers like the NOVA that allow you to turn a cone or jam chuck and mount in the tail.

Where you have more spaces than places, a jam ring is a real good idea to use while turning the inside. Or maybe two. Tighten up for circular, tack with hot glue and the wall pieces won't fly away.
 
Just a quick reality check. Underdog, do you know what jam chucking is? Alot of folks don't. Especially when starting out. If not, let us know and you'll get a more detailed description.

And, yes, between centers initially until you can cut a tennon, chuck it up and turn outside and inside of bowl, and then reverse onto a jam chuck to touch up the base. Sand off the nipple and done.

Dietrich
 
I'll try again.

I have a log that has been ripped in half through the pith. In this instance I want a NE bowl and want to use the partially healed scar to get max interest in the rim. I therefore ripped the log so that my pith cut leaves the two sides of the scar symetrical and centered vis-a-vis the pith line. I then put my drive center in the middle of the bolt's scar and put the ts point in the pith line. If the scar is too deep to drive from, and I need, but don't have, a MT extender on the headstock side, I'll switch and mount with the spur set in the pith and the TS extended into the scar; makes it a bit dicier to do the initial rough because I'll be using pull cuts toward the rim. Mounting between centers is important here because it allows me to adjust both points to balance the annular rings. Once I have the rings balanced, I can form a tenon on the pith side to put in the chuck while I do the serious hollowing. Care is the word here, especially when putting the tenon in the chuck. Since the tenon corresponds to the rings and it may have grip on only a few of them, and it's very easy with a DT jaw to split the tenon right off with too muich compression pressure.

Maybe Alexo or Robert will jump in here, maybe even with a couple of pics to illustrate?

M
 
Hey Mark,

Quick fix for when the gaping hole scar is just too darned big to handle either the live or drive spindles. Mount up that chuck, open the jaws till extend past the hole (or into the hole), and jamb chuck the whole piece against the open chuck, hole side to drive. As long as you get at least three solid points of contact and some good compression, it holds well enough to rough out a tennon. Be gentle though cause, if it slides loose, it will come off the lathe. Low speeds are good and keep footsies out of line of fire. That way, you just have a falling chunk, rather than a flying one.

How's dat?

Dietrich 😀
 
That works for me Dietrich. One might want to be careful with that type of roughout though since there is no point driven into one of the sides. There could be a potential loss of contact or slippage out of the jaws. If the piece is sufficiently convex it would fit into the jaws pretty well.
 
dkulze said:
Hey Mark,

Quick fix for when the gaping hole scar is just too darned big to handle either the live or drive spindles. Mount up that chuck, open the jaws till extend past the hole (or into the hole), and jamb chuck the whole piece against the open chuck, hole side to drive. As long as you get at least three solid points of contact and some good compression, it holds well enough to rough out a tennon. Be gentle though cause, if it slides loose, it will come off the lathe. Low speeds are good and keep footsies out of line of fire. That way, you just have a falling chunk, rather than a flying one.

How's dat?

Dietrich 😀
Click to expand...

I've used my jaw chuck as a jam chuck, especially with retruing the tenon on a dried rough-out befor second turning. But I think in this situation it would limit my ability the adjust the grain orientation. To check for concentricity I have to be able to make a cut on the driven face and as close into the center as possible. Chuck with expanded jaws would, I think, limit that cut too much. I believe I'd still prefer a spur drive from the pith-side since I know that I'll be close to the center line by definition.

M
 
The making of ....

You've all got the general idea of the process that I used to do the "Sleigh Runner" pieces. I photographed the entire journey through the sequence and am going to work it into a "The making of ..." article. Stay tuned.

One tricky aspect of SRII was the quandary that I was confronted with by the off-balanced relationship between the slot running down the side of the tree and the pith. I had to decide on whether to balance the rim with the important "runner" features or to place the foot as close as possible to the center of the growth ring sequence. There didn't appear to be any way to accomplish both goals given the hand that I was dealt. Since I chose the former in SRI, I chose the later in SRII. The image with the inset shows the result of this approach.

Three images from the SRII turning sequence are included below. The first illustrates the end grain of the sassafras chunk that I started with. The second shows the initial placement of the drive center while the third shows how I adjusted the position of the live center to accomplish the prime directive for the piece.

I'll post a note on this thread as soon as I get a chance to write the article.

Best Regards,
-Allen
 

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The light came on!

Hey guys,
thanks for the great replies. And thanks for that picture Allen. That helped quite a bit.

I was envisioning an actual hollow log. When I realized that this was just a surface scar on the tree the light bulb lit up.

You will notice that Mr. Davis used a partially hollow log for his... I wonder how he did this?


PS. Yes Deitrich, I know what a jamb chuck is. I ran into a book the other day at a discount book store called, Work holding methods for the lathe, or something like that. It pretty much covered the spectrum, but here's a new one I found - ever hear of a String Steady?
 
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String Steady

underdog said:
Hey guys, Here's a new one for you - ever hear of a String Steady?
Click to expand...

Oh Yeah! That's one of them deals that you use when you're turning string so it doesn't flop around, right? 😀 😀

M

ps: Actually tried one, once. Decided that spindles that thin were not really my thing. 😉
 
Hi Allen,

Great pictures and I'm looking forward to the article. What the first two pictures clearly show, for me anyway, is a different way of looking at a piece of wood and taking the greatest advantage of what nature has given.

Doug
 
Allen and everybody. If you want to make a large pdf of the article I'll get it onto the forum. If anyone else wants to write a larger item (an organized article) the same offer applies - we'll find a way to get it on the forum.
 
Hey Dawg,

Tried a string steady but, no matter how good l lined up the tiny little wheels on the string, it still wobbled all over the place. Also, I couldn't get good compression on the string between centers. Waste of time as far as I'm concerned.

heh. heh.

We had a club member last year demo string steadies. He does goblets with 1/8 stems up to 18". Uses waxed dental floss and tapes the stem so that it doesn't burn or stain from the wax. Believe it or not, he primarilly uses a scraper, so those steadies must work pretty well.

Dietrich
 
A Scraper!

A scraper! 😱 Man.

Either they work well or he's very good at getting a perfect burr on the scraper. 🙄
 
dkulze said:
Tried a string steady but, no matter how good l lined up the tiny little wheels on the string, it still wobbled all over the place. Also, I couldn't get good compression on the string between centers. Waste of time as far as I'm concerned.
Click to expand...

Dietrich,

The "trick" is using your tailstock in "expansion mode" rather than "compression". That keeps tension on the string by "steadily" pulling the turning away from the headstock. Does, however, require a specially drilled tailstock collet appliance.
😉 😉

ps: [nudge, nudge] no, not really.
 
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Dietrich,

I recently watched Ernie Newman demo a tailstock mounted string steady that seemd to work quite well. He was turning a long flower stem to about 1/16 of an inch. (it was insanely thin) He did not just loop the string around the posts, he did a figure 8 which caught the stem of the piece much more securely. He also had a small spring on the string so that it was always being pulled taught. Seemed to work very nicely.

I have a photo of it I will send later tonight. I have it with me but have no way to transfer it from my camera till I get to the hotel tonight. It was a very simple rig and because it is tailstock mounted would work on any machine with the same taper size.

More later when I can get to the photo.

Dave
 
Allen Alexopulos said:
One tricky aspect of SRII was the quandary that I was confronted with by the off-balanced relationship between the slot running down the side of the tree and the pith. I had to decide on whether to balance the rim with the important "runner" features or to place the foot as close as possible to the center of the growth ring sequence. There didn't appear to be any way to accomplish both goals given the hand that I was dealt. Since I chose the former in SRI, I chose the later in SRII. The image with the inset shows the result of this approach.
Click to expand...

I have roughed a few pieces with similar defects in the wood and found that it was much easier to position the wood the way I wanted it and secure with larger drive centers. I have a 2" 4 spur which i can hold in my chuck jaws as well as a 3" and a 4" 2 prong mt2 drive (unfortunately the guy who makes and sells these on ebay has been absent from there for over a year).
 
Spur Drive Selection

Good suggestion. In order to balance the piece I eventually had to reposition the spur drive about an inch into the rough part of the bark. A larger 2-prong spur drive would have eliminated the need to carve out a flat for the 4-prong spur drive to seat on.

Regards,
-Allen
 
Allen,

Suggest you get a spin-on spur drive such as those made by bestwoodtools; either 2 or 4 spur. The advantage of the spin on is that it doesn't depend on either the morse taper or the chuck for the driving stability. I have a 4-spur spin on for my Stubby and it is IMO unmatched for rough wood. I would not use the chuck mounted variety as I would not wish to put that much stress on the jaws.

M
 
Why not use a large diameter Forstner bit to drill down through the lightning strike scar to a good spot in solid wood? This method also has the advantage of "capturing" the wood, especially if done on both ends so that it doesn't leave the lathe.

Bill
 
Promised photo of the string steady

David Somers said:
Dietrich,

I recently watched Ernie Newman demo a tailstock mounted string steady that seemd to work quite well. ...............I have a photo of it I will send later ......................Dave
Click to expand...

As promised, here is the photo of the string steady. This has a #2 Morse Taper on it for mounting in the tail stock. Most others I have seen were made to fit the bed rails. He also looped the string in a figure 8 to provide a closer fit to the wood it held as opposed to the simple loops shown here. Hope this helps.
 

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Mark Mandell said:
Dietrich,

The "trick" is using your tailstock in "expansion mode" rather than "compression". That keeps tension on the string by "steadily" pulling the turning away from the headstock. Does, however, require a specially drilled tailstock collet appliance.
😉 😉

ps: [nudge, nudge] no, not really.
Click to expand...


Well, intended as a joke or not, it seems that this tailstock mounted string steady almost does what you joke about...
 
underdog said:
Well, intended as a joke or not, it seems that this tailstock mounted string steady almost does what you joke about...
Click to expand...

Yup, but somewhere along the line you need a good "board stretcher" or your string's gonna come up more than a bit short.

He he

M
 
Yep, I got one a those.. It's right over there with the sky hook. Look over there and get it fer me willya? 😉
 
Now you guys....this one actually works. I watched it myself in a demo in Hilo just 1 week ago. The gentlemen turned a flower with a loooooooong 1/16" diameter stem on. The picture that follows is what he turned with it. Reallly!!!!

Now having said that.....I haven't met any of you folks yet....normally you should not trust anything I say without verifying it least 6 times from reputable sources. But since you don't know me I have been scrupulously honest and not attempted to yank anyones digital leg (yet).

Dave <grin>
 

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