bottom of bowls

[0zwood2003]

i have a supernova 4jaw chuck wich i use to turn bowls with(abviously). does anybody know how to get the grip marks out of the bottom of bowl.the bowls look good but when you turn them over and see the round raised bit(the piece used to hold bowl) full of divets looks crap. any idea's please

[arose62]

There are a few ways:

1) glue a scrap bit of wood to the bottom of the bowl, with a piece of paper between the two pieces of wood (many suggest using brown paper).
Grip and dent the scrap in the jaws, then, when the bowl is finished, split the scrap piece off.

2) make the diameter of the spigot the same as the diameter of the jaws. The jaws divot worse the more they are open, as they only make a circle at one sized opening, and are just 8 contact points at all other openings.

3) turn a groove in the bottom, and expand the jaws into this. Expanding the jaws doesn't give the same denting problem as contracting the jaws onto a spigot.

4) turn a scrap to the inner diameter of the bowl, and jam the bowl over this, with friction holding it in place. Then, turn (or sand) the bowl to take the jaw marks out.
Search for "jam chuck".

5) buy or make bowl jaws (or Cole jaws) for your chuck. These grip around the outside rim of the bowl, and let you turn and finish the bottom of the bowl.

Cheers,
Andrew

[Jim Carroll]

As you have a supernova chuck the easiest way is by using the Cole jaws.
http://au.store.yahoo.com/cws-store/jscolecolejaws.html
These allow you to hold a bowl safely and give you the chance to redress the foot or blend in the outer shape to create a new foot . If the bowl has a different shape that does not allow the jaws to fasten onto the edge there is riser kits available to allow you to raise the rubber bushes to fit over the sides of the bowl . I always try to work with a spigot as this gives better grip than a recess that has a tendency to split the base if you overtighten a bit. I like the thought of being able to get a firm grip on the timber and not get any nasty surprises.

[foool64]

I am a novice turner and have found turning an internal "spigot" as in your first reply stated is the best option, expanding the jaws outwards to grab your work-piece, or inwards depending on wall thickness....no need for an external spigot as i too have learned, they are crappy..lol but in some cases probably needed. the only problem with turning bowls is, in my case, the wife pretends to admire them but has no place to put them all, its great fun. Its very addictive, i luv it...good luck m8

[clawdee]

Hi Ozwood

Here goes for my first post at WWF. I also started out with a supernova chuck and had a preference for internal spigots but soon came to the view that the foot detail could be as important as the rest of the bowl for those "special" pieces. I reversed bowls after finishing them inside and out and either used jam chucks, a home-made vacuum chuck or a Longworth chuck (also home made) to hold the pieces while I finished the feet. Mostly worked OK but did have a few notable disasters with dig-ins and all-but-finished bowls skidding across the workshop floor. Nowadays I stick to external spigots then reverse bowls against scrap timber or MDF faceplates and use my tailstock to support the bases while i work away at the feet with a fine detail gouge, generally at slower speeds.

[jhunt_2000]

Hi Ozwood, firstly good luck, I've been working on that very problem for a while, compounded by a complete lack of funds. Having had a few goes at reinventing the wheel while keeping my eyes the best idea I've tried is one I picked up through a link posted here. It's simple and effective. http://www.enter.net/~ultradad/bowljig.html
Have fun.

[Little Festo]

My wife used to always comment that my turnings were nice BUT the didn't have very nice "bottoms", so I bit the bullet and bought a set of cole jaws. Now my bowls boast nice smooth bottoms as well finnished as the rest of the piece. So, if you can justify the cost, a set of cole jaws is definatly worth while.

I have been turning some vases and other pieces that I cannot mount on the cole jaws or a jam chuck, so I've been using a belt sander/linisher to somooth them out, only problem is that if i'm not carefull they can develop that Leaning Tower Of Piza look. What I do now is put a sanding disk in my drill chuck in the lathe and do it that way. My lathe, a Vicmarc, seems to do this quite safely and not want to eject the drill chuck, as can happen, I still exercise care when doing this. Does anyone have any other methods for smoothing out the bases of vases etc. I suppose I should lean to be more accurate when using the belt sander.



Peter

[Jim Carroll]

This is the cole jaws holding a bowl that is not able to be held by the normal rubber inserts or with the traditional jam fit system. I have used the extensions and the larger bowl rubbers to hold this bowl and redesign the foot. it was originally a spigot which I find to be the more secure way of holding a bowl .
This way you can hold a bowl with either the rubbers themselves or with the extensions which can be either 14mm or 28mm or together 42mm. You are able to run the lathe a bit higher speed to acheive a better cut and still feel secure .

[clawdee]

Hey Jim, that's a sweet looking base. :) :) Must admit, if I had all that hardware to hold the bowl to the lathe, I'd crank the Vicmarc up and rip into it without any fear whatsoever. Good work, my man!