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robatman
30th March 2007, 10:53 AM
Just got the latest LV e-newsletter with an article on bowl foot design. (see http://www.leevalley.com/newsletters/Woodworking/1/3/article3.htm )

I know the foot is a critical part of the design, (see cliff's comments on most bowls!!) but i just seem to be hesitant about remounting the bowl to finish the foot. I tend to just put a few grooves in the recess before i mount the bowl for hollowing. I dont have cole jaws and have never made a jam chuck, though the method seems simple enough...anyway came across an article in April Pop WoodWorking outlining a "longworth chuck". ( also see a how to online at http://www.woodcentral.com/cgi-bin/readarticle.pl?dir=turning&file=articles_485.shtml )

Anyone tried this or came across any other simple methods for reverse mounting to finish the foot?

thanks
Robert

joe greiner
30th March 2007, 02:20 PM
One of the advertisers above (www.chickandduckmfg.com) has a product much like the Longworth chuck. [OK, it was above. Seems to come and go.]

I usually mount a piece of plywood (round optional but advisable), slightly larger than the bowl rim, on a faceplate. Face the region corresponding to the rim, and turn a groove to mate with the rim. Mount the bowl with duct tape wrapped around to the back of the plywood disk. Add a few staples to keep the duct tape from flapping around. This is usually robust enough to do some serious work on the bottom; light cuts recommended. It'll be somewhat fiddly on natural edge bowls, but so is everything else.

Joe

Rookie
30th March 2007, 02:39 PM
I bought myself a set of cole jaws to rework the foot after the hollowing was finished. This was primarily for one reason. It was continually mentioned to me that in a woodturning competitions, the first thing a judge looks for is no evidence of how the piece was mounted. Now while I am nowhere near good enough yet to enter competitions, it seemed like a sound principle.

The more I think about it though, it just sounds pretentious. If you can make the foot an attractive part of the bowl, particularly if its mounted with outward pressure, why get all uppity about seeing where the thing was mounted.

OGYT
30th March 2007, 02:50 PM
I have a 15.5" (395mm) dia Longworth chuck that I made. It works. Better than my cole jaws. There are some sizes... within the range of the cole jaws... that you cannot get a bowl to fit, without adding O rings to the buttons.
(I found out from T.Geist, that on the back of the Cole Jaws, there are cast circle/intentations between the button holes. All you have to do is drill these out and tap 'em to the right sized threads. They look like they'll overlap with the other holes, but they won't... there's room. Just haven't done this yet.)
The longworth is infinitely adjustable all along it's arcs. And I made mine with a piece of Walnut on the back, with a tenon to fit my chuck. That way I didn't have to have a dedicated faceplate.
In the pic it looks like three of the buttons aren't contacting the surface of the bowl. They're not. I just stuck it up there quick to get a shot of it.

Zedster
30th March 2007, 05:52 PM
Now the that's a damn good idea OGYT,

I have not got a router, and don't think I could operate it with my one hand anyway, but I like the longworth chuck, I will have to do some searching on the internet to see if I can buy one here in the UK, if not I shall have to plead for some kind hearted soul to take pity on me and make me one.


Chris

rsser
30th March 2007, 09:05 PM
Chris, yep, there are designs on the web. It's an Ozzie invention of course ;-}

I'm told that without very accurate cuts it won't work.

Chris, there are pro turners who do what you do. The challenges are wood holding, bowl thickness and foot width. On medium bowls and upwards recess holding can be made to work fine. On smaller bowls the foot width becomes an aesthetic problem.

Zedster
31st March 2007, 02:14 AM
[quote=rsser;487565]Chris, yep, there are designs on the web. It's an Ozzie invention of course ;-}quote]

Where would the world be without the Scots and Ozzies, still sitting around the campfire I suppose :2tsup:

I can turn ok, I can reverse chuck ok, but the longworth chuck idea that OGYT came up with is miles better than thos stupid cole jaws, I want something that you can just hold in the chuck without the need to bolt on the cole jaws, that would take way to much time, keep it simple my philosphy.

Just need someone to make me a set :2tsup:

OGYT
31st March 2007, 05:09 AM
I have not got a router, and don't think I could operate it with my one hand anyway, but I like the longworth chuck.

Chris, I used my jigsaw. Fast as it would run, and went slow along the lines. Just sawed the arcs out, and used a rounded course file to sand them smooth.
I have a router, but didn't have the bit I needed. Router would have been more accurate, but not absolutely necessary.

rsser
31st March 2007, 07:54 AM
Chris, maybe we have a common enemy, or dislike ;-}

Have you considered a vacuum chuck? Vicmarc makes one. I can imagine using it one handed if I could vary the amount of vacuum.

Or just soft jaws out of MDF fixed to something like the Vicmarc multi-purpose jaws. This is harder to imagine working with one handed but if you could lightly jam the bowl in to begin with and then tighten or bring up the tailstock ...

What part of Scotland are you in btw?

Zedster
31st March 2007, 08:12 AM
Chris, maybe we have a common enemy, or dislike ;-}

Have you considered a vacuum chuck? Vicmarc makes one. I can imagine using it one handed if I could vary the amount of vacuum.

Or just soft jaws out of MDF fixed to something like the Vicmarc multi-purpose jaws. This is harder to imagine working with one handed but if you could lightly jam the bowl in to begin with and then tighten or bring up the tailstock ...

What part of Scotland are you in btw?

Yes I have considered a vacuum chuck, but it's too expensive and fiddly, I like OGYT's idea of utilising the chuck by just fitting the longworth chuck into them and finishing.

I am on the west coast of scotland, very near Oban.

Chris

baxter
31st March 2007, 08:27 AM
I am on the west coast of scotland, very near Oban.
Chris

Oban, now that is a lovely piece of the world.:2tsup:

TTIT
31st March 2007, 10:23 AM
I'm a big fan of the Longworth as you'll see in this thread (http://www.woodworkforums.ubeaut.com.au/showthread.php?t=29038&highlight=longworth). A couple of pieces of perspex or ply and you're in business - but a router is handy too. I've since setup a vacuum chuck on the new lathe but haven't even had the chance to try it properly yet - too much happening at the moment to get near the lathe!:no:

Frank&Earnest
31st March 2007, 03:47 PM
It only works if the piece can fit between centres, but what I have found easiest, having previously flattened the bottom of the foot and left its rim a bit proud to ensure it sits even, is to

"mount a piece of plywood (round optional but advisable), slightly larger than the bowl rim, on a faceplate. Face the region corresponding to the rim, and turn a groove to mate with the rim", as Joe said, then mount the piece and push the tailstock against the foot, protected by a small disk of wood to take the spur. Solid as a rock and no need for fancy fasteners of any description. And no "evidence" left either!

The only risk I can see, although it has not happened to me yet given my minuscule amount of turning, is that on very thin bowls there is a risk of overdoing the pressure and breaking them. Not a major one given a bit of care and practice, IMO.

Cheers
Frank

WillyInBris
31st March 2007, 05:21 PM
I was thinking of buying a cole chuck but after seeing this thread I think the Longworth looks the better for me the only thing is I don't have a router to make one with.

Is anyone making them for sale in aus:?

hughie
31st March 2007, 07:46 PM
I

was thinking of buying a cole chuck but after seeing this thread I think the Longworth looks the better for me the only thing is I don't have a router to make one with.

Is anyone making them for sale in aus:?



Willy make your own out of plywood or whatever you have suitable to hand. These links will get you started

http://www.woodworkforums.ubeaut.com.au/showthread.php?t=41166&highlight=cole+jaws+part

http://www.woodworkforums.ubeaut.com.au/showthread.php?t=41169&highlight=cole+jaws+part

tashammer
31st March 2007, 07:55 PM
i was thinking that the Longworth looks rather like the iris on a lens. The American one puts me in mind of something else i have seen but buggered if i can recall what it was.

http://www.crwoodturner.com/longworth/
http://www.crwoodturner.com/longworth/views.html

The first url is materials and the second shows good pictures of both front and back of a Longworth chuck.

buzzby
31st March 2007, 10:50 PM
I have only recently got the supernova2 chuck with a set of cole jaws for it and am so far very happy with this system. I have also used the 50mm jaws with the cole jaws bolted at the same time with the longer screws supplied this makes for effortless changing between the two this makes for me easier finishing of the work and fairly cheep once you have purchest the chuck.