# Just another way to extend the Chuck Jaws



## CHJ (25 Mar 2007)

__________Finishing off one of the small pots today, raised the thought
__________that someone may be interested in my solution to extending the Chuck Jaw range.

_________ 

___ 

___ 

___ _click on images for larger view_ 
___________Eight 7/8 x 1/4" pieces of steel, 48 Holes, 32 of them tapped 6mm.

__________Not something you would want to poke a finger in, but no worse than a square or natural edge bowl.


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## Paul.J (25 Mar 2007)

Blimey Chas,you been watching to much Dr Who.  
Did you make this yourself,very impressive if so,any chance of making me one :shock: 
Paul.J.


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## CHJ (25 Mar 2007)

Only the adaptors are mine, the Cole Jaws are Axminster, would have cost me nearly as much to buy the ally'  says he who once used to order the stuff in the tens of sheets, not that I would have borrowed any of course :roll: 

I'm generous Paul, but if you think I am volunteering for drilling and tapping another 48 holes in the near future, lets just say I have a lot of away days this year. 

I get most of my metal supplies from GLR in Daventry, make a detour that way now and again whilst visiting Leicestershire.


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## Paul.J (25 Mar 2007)

*Chas wrote*
I'm generous Paul, but if you think I am volunteering for drilling and tapping another 48 holes in the near future, lets just say I have a lot of away days this year.
Sorry Chas,i was just kidding.
How does this actually work.Do you have to make the bowl fit those sizes :?: 
Paul.J.


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## CHJ (25 Mar 2007)

Paul.J":zp9a8t6r said:


> How does this actually work.Do you have to make the bowl fit those sizes :?:
> Paul.J.



The Rubber covered buttons are positioned in the appropriate holes so that the PCD (inner or outer) of the bowl fits within the range of the chuck jaw travel.

Having said that, the Axminster precision chuck is bad in this respect because it has a smaller safe jaw travel compared with say the Nova chuck, this combined with the button diameters can leave you a few mm short of travel at times. I am in the process of turning some differing diameter buttons to overcome this.


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## Paul.J (26 Mar 2007)

Chas.
I am thinking of doing one of these but using ply. :shock: 
Do you think this Would be acceptable. :?: 
Paul.J.


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## CHJ (26 Mar 2007)

Paul.J":2wyudpsc said:


> Chas.
> I am thinking of doing one of these but using ply. :shock:
> Do you think this Would be acceptable. :?:
> Paul.J.



Ply would be fine, try and get a good quality 13 mm 5ply if possible. 
*EDIT:* Strike reference to MDF it is not strong enough I checked.

If you fit a doubler, say 100mm diam' on the rear you can turn a socket in it to take your chuck dovetail jaws before fixing, then mount the assembly on the chuck to clean up the disc and mark the PCD's for the holes on the lathe.

Then when it is all neat and tidy and chuck jaw fixing holes sorted chop it into four segments. At a minimum fit washers under the jaw fixing screws, I would prefer to see a brass or ally' ferule in the jaw fixing screw holes.

Two choices really re fixing buttons.
1: just plain holes and bolt right through
2: fit pronged tee nuts to the rear face


*Edit:*, keep RPM below 250-300 Alloy ones are rated at 600 or so.


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## Paul.J (26 Mar 2007)

Chas.
Not to sure what you mean,Doubler-pcd,s,-brass ally ferrule :?: 
I was going to mark the dia out on ply,segmented into 4,mark holes to fix to chuck,use t-nuts to fix rubber fittings,i was going to use a couple of large tap washers :?: 
Or have i got it all wrong :roll: 
Paul.J.


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## greybeard (26 Mar 2007)

I have no engineering knowledge, repeat, no engineering knowledge! 

But I have a suspicion that the fixing holes in the ply (to secure it to the chuck) may be subject to too much wear for safe use more than a couple of times?

Or have I just made a complete canines evening repast of myself?

Ooops - forgot to say - nice one CHJ - simple but jolly effective.


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## CHJ (26 Mar 2007)

greybeard":2b3jhp3c said:


> I have no engineering knowledge, repeat, no engineering knowledge!
> 
> But I have a suspicion that the fixing holes in the ply (to secure it to the chuck) may be subject to too much wear for safe use more than a couple of times?
> 
> ...



No *greybeard*, your reservations are valid, hence my comment about ferule in holes.

I have added an amendment after some tests since posting.


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## CHJ (27 Mar 2007)

Paul.J":1gnifry9 said:


> Chas.
> Not to sure what you mean,Doubler-pcd,s,-brass ally ferrule :?:
> ...snip...
> Paul.J.



*Doubler:* another smaller disc on the back to thicken the area taking the fixing hole loads.

*PCD: *Pitch circle diameter. the circles you can see on the alloy plates, makes it easier to align your button fixing holes.

*Ferules:* small pieces of tubes with a bore to suit your Jaw fixing bolts, to protect the wood and reduce the crushing effect of the bolts on the wood (should find some suitable in a B&Q Warehouse or model shop.)Epoxy them in.

An alternate would be to make a Longworth Chuck See this Thread

A Google will throw up several versions but this is as good as any for how to mark it out, mine has a doubler on the back with a socket to suit my chuck jaws.

Yet more ideas on the bowl chuck front


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## bobham (27 Mar 2007)

I sometimes use plywood jaws, BUT:

- You definitely need to use longer screws than the ones that attach your metal jaws. Do not counterbore the hole in the plywood deep enough to use the short screws or there will not be enough material left under the heads to support the load.

- I generally consider them consumeables, like a glue block on a face plate. Rather than attempt to drill holes for buttons I simply turn a recess into the face of the jaws to grip the rim of the workpiece. There must be enough material on the outside of the recess to provide support. I would consider one inch to be the minimum. Any narrower and you risk having the ply delaminate.

- A far better option for mounting the jaws is to use the Oneway flat jaws, which mount on to the chuck in place of profiled jaws. They provide countersunk holes that allow mounting wooden jaw faces from the back, similar to a screwing on a faceplate. They are flat on the back side so they will fit on any chuck that has the same hole spacing for the mounting screws as a Oneway has. I am not sure what that spacing is, but I do know that the Oneway basic and Talon chucks have the same spacing as my Supernova II chuck. 

- A plywood doughnut chuck mounted on a faceplate will give a more secure mounting than a plywood 4 jaw chuck and if you make a few different outer plates with different sized holes it should be just as versatile.

- I would not go too big or turn too fast with plywood jaws because all the stress is on that little area around the mounting screws which does not have much material around it to support it.

Good Luck!
Bob


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## CHJ (27 Mar 2007)

Thanks for the input *bobham*, as you say the jaw fixing is the major 'risk' area, hence my comment about doubler piece and ferules.

You make a valid point about longer screws, I did assume, I know I should not have, that long screws would have been used through the extra thickness. just shows how careful one should be giving advice.

As for the "*wood jaws"* they are relatively expensive over here for a new starter and are not available for all makes of chuck, one of the problems as you are aware is that the 'safety groove' location and form differs between the makes preventing cross brand use.

Your confirmation that the Oneway, Tallon and Nova have the same location form is useful info.

The Axminster chuck example above for instance has a proud safety ridge on the scroll jaw which makes for difficulty in fitting a flat adaptor.


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## NickWelford (27 Mar 2007)

CHJ":10fe0ms7 said:


> Your confirmation that the Oneway, Tallon and Nova have the same location form is useful info.



This is an interesting thread.
Between us we ought to compile a chart of which jaws/chucks are interchangeable......


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## CHJ (27 Mar 2007)

NickWelford":l993rbrq said:


> CHJ":l993rbrq said:
> 
> 
> > Your confirmation that the Oneway, Tallon and Nova have the same location form is useful info.
> ...



I would have thought so, and annotate reservations relating to restricted use because of lack of 'safety groove' non compliance etc.

I tried to get some info. way back in sept.2005 but did not have much input.


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## Bodrighy (27 Mar 2007)

That Longworth Chuck looks really useful. I don't have a router and as it isn't something that I probably wouldn't use much it seems silly to go and buy one for just one job. Does anyone have any ideas how to cut those curves accurately some other way. I have a jigsaw but find it really hard to get a good line with it. 

Pete


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## Paul.J (27 Mar 2007)

Thanks for the help chaps.
I have now made one :shock:
Here it is.What do you think.Is it safe enough to use. :?: 
Sorry about the wip piccys but i get that involved that i just carried on.Just missed the marking out.
No1 piccy shows bolts fitted to the steel straps to strenghten the back.





No2 piccy shows the chuck fitted.




No3 piccy shows it on the lathe.




No4 piccy shows brackets closed up using chuck.




No5 piccy shows a pilot hole for the T-Nuts these must be spot on.





No6 piccy shows countersinking for the T-Nuts so they're nice and flush on the back.




No7 piccy shows drilliing holes to tale the T-Nuts.





No8 piccy shows fitting the T-Nuts.




No9 piccy shows the whole chuck on the lathe.





No10 piccy shows the back of the chuck.




No11 piccy shoes some 6mm leather washers that i might try,as the rubbere seems a bit too soft.Any thoughts on this antone.




Most the materials i had lying around just bought some 50mm bolts that cost £2.00,which were cut down to suit.
Used 1/2" birch multi ply,M6 T-Nuts.
Haven't used it yet,but when i sort some decent buttons out i will and let you know.
Paul.J.


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## CHJ (27 Mar 2007)

Looks like you are almost there Paul, as long as you take into account the cautionary comments about the chuck fixing and watch for any 'pulling out' of the fixing holes you should be OK.

On that score do you have room to put a couple of short csk wood screws through your metal strips into the wood? may help spread the forces. There again the extra screw holes may just weaken the ply along the stress line anyway.

On the button front, you may find it an advantage to have some smaller diameter short dowel collars on the bolt stems between the button and your chuck face, thus allowing most bowl rims to sit behind the button top.


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## Paul.J (27 Mar 2007)

Thanks Chas.
I did set the 8 fixing bolts back an extra 10mm from the centre to give me that much more strength in the ply.
I let it run for about 10 mins with that scrap piece in and it seemed fine.
Fingers crossed  
Paul.J.


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## CHJ (27 Mar 2007)

Be prepared to run with the tailstock brought up for support if in doubt.

Even if not actually applying any pressure it will stop the piece falling away from the chuck face until you can stop the machine if the grip loosens.


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## bobham (27 Mar 2007)

Looks like you have done a good job. I am a little curious about why you put the metal reinforcement strips on the back of the jaws rather than the front, though. I can't see where they will do any good back there. If they were on the front under the screw heads they would spread the load of the screw heads over a wider area. On the back they will just act as spacers between the plywood and the chuck slides,

Oversize jaws, even the metal ones designed for the purpose, are intended only for light cuts and sanding at low speeds. Please use them with caution, because I know of one turner who sustained a life threatening injury when his home made jaws failed.

Take care
Bob


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## Mark Hancock (28 Mar 2007)

For those on a budget a simpler way of achieving the same is to reverse turn between centres with a friction drive.
1. Attach a disc to the headstock with a faceplate, screw chuck or chuck jaws - I use offcuts of various sheet material such as MDF
2. Turn a groove in the disc to centre the bowl - as I've used this method for many years there is usually a previous disc with a suitable or nearly suitable step already on it.
3. Place the bowl in the groove on the disc and bring up the tailstock and apply light presure.
4. Turn away the spigot or reshape the base of the bowl as you wish.

Obviously with this method you are limited by the swing of the lathe. The wood plate jaws come into their own when working outboard or with a swivelling headstock.


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## Paul.J (28 Mar 2007)

*bobham wrote*
I am a little curious about why you put the metal reinforcement strips on the back of the jaws rather than the front, 
Hello Bob.
The reason for this is that i was trying to keep everything flush,and because i had c/s bolts.
If i'd have c/s the strips which are only 2.5mm thick,to take the bolts,i would have lost the little amount of strength they were giving.
The strips were also put on instead of me using ferrules as suggested.This i feel would also have made the ply weaker at those points,by drilling a larger hole to take them.
It made sense when doing it,but i have no engineering background either,and if you feel that it unsafe to use Bob,i would rather not use it.
Just something to try that didn't cost much so nothing to lose.  
Paul.J.


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## Paul.J (28 Mar 2007)

*Mark Hancoch wrote*
For those on a budget a simpler way of achieving the same is to reverse turn between centres with a friction drive. 
Hello Mark.
Thanks for that but i'm not really sure what you mean.
Is it like a Jam fitting but with the tail stock to support it
:? 
Something else to learn. 
Paul.J.


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## bobham (28 Mar 2007)

Hi, Paul:
Since you have the full thickness of the ply under your screw heads it should be fine. I just meant that I don't see where the strips on the back of the jaws are contributing any strength to the joint. If they were mortised into the front of the jaws and countersunk for the screws they would distribute the force of the screw heads over a larger area and also prevent wear between the plywood and the screws. 

Since you only have four gripping points rather than the eight that commercial jumbo jaws provide I think that Chas' suggestion about using the tailstock for support is a good one.

Take care
Bob


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## Mark Hancock (29 Mar 2007)

Paul

Yes that's exactly it - like a jam chuck with tailstock support. The problem with a jam chuck is that you can damage the rim of the bowl. With the method I described the groove is there just to help centre the bowl. Without the tailstock the bowl won't stay in place.
Hope that's a bit clearer


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## Paul.J (29 Mar 2007)

Thanks Mark.
Now i know what it is i will also give that way a go.  
Paul.J.


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## Paul.J (29 Mar 2007)

*Bobham wrote*
I don't see where the strips on the back of the jaws are contributing any strength to the joint.
Hello Bob.
I have now taken your advice,and Chas's,by putting ferrules in the holes where the bolts go through,and putting the metal strips on the front.It does seem better somehow :? 
I haven't set them in as i feel this will weaken the ply too much.So will try this for now.
Also what do you think of the buttons.They are 2 pieces of 6mm leather glued together with the bottom one being chamfered all round to give that bit of extra grip.They are fixed using kitcen cupboard connectors.
If you or anyone else can see any safety problems arising please let me know.










Paul.J.


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## CHJ (29 Mar 2007)

*Paul,* re: the buttons I am not sure that leather is firm enough, unless it is the good old shoe sole or horse harness variety.

They are also rather shallow and I think could do with some spacers underneath.

Try turning some buttons and spacers from old Plastic Kitchen Chopping boards. (will post picky shortly, need to go up the shed)

I usually pick some up from the local pound shop when passing if TLOML is reluctant to release any.


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## Paul.J (29 Mar 2007)

Chas.
The leather is from the old belts that used to drive our machines at work,it really is tough stiff stuff,try saying that when you've had a few :roll: 
How thick should the buttons be,these are 12mm.
Paul.J.


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## CHJ (29 Mar 2007)

Paul.J":1d89e5tx said:


> Chas.
> The leather is from the old belts that used to drive our machines at work,it really is tough stiff stuff,try saying that when you've had a few :roll:
> How thick should the buttons be,these are 12mm.
> Paul.J.



That should be fine, the thickness is more a matter of moving the gripping area a little further from the chuck to improve the leverage factor.

Here's some I use, the walking stick buttons are good, you can usually find then at a reasonable price in the local markets.


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## Paul.J (29 Mar 2007)

Thanks Chas.
I like the walking stick feet option  
Paul.J.


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## Hans (30 Mar 2007)

Hi all,

sorry I am late, my ISP had a little problem.
Couple of years ago I wanted to use cole jaws. I had plans to build them of ply, until I found this synthetic building material. 

Over here it is called TRESPA, no clue under what name and whether it is available in Britain.

I used 10 mm (3/8") for a diameter of 500 mm (20"), it drills and taps easily and is much stronger than plywood. I fixed them to Oneway flat jaws. Here they are used with Vicmarc buttons.





Hope this is still useful to someone.

Hans


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## CHJ (30 Mar 2007)

Thanks for that *Hans*,

The company is known here

http://www.ribaproductselector.com/docs ... al/cov.htm

http://www.trespa.com/uk/

http://www.trespa.com/


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## Paul.J (30 Mar 2007)

Hans.
That looks a nice neat job,shows my effort up by me using some old scrap ply  
How have you fixed yours to the chuck.Did you have to strenghten this material,and how did you cut the segments :?: :?: 
Paul.J.


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## duncanh (2 Apr 2007)

Here's the mod that I sometimes use with my cole jaws when I have a hollow form or shape that the normal short bolts can't hold...



_click for larger image_

It works well but you may want to wrap the exposed threads with something to stop anything straying into their path

Duncan


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## Paul.J (2 Apr 2007)

Good idea their Duncan.
What have you used for the buttons :?: 
Paul.J.


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## wood yew believe it ! (2 Apr 2007)

ive got a bit of a bone (daft/stupid) question guys, why is it that you feel the need to have these special jaws? is it just to carry large pieces, or is it so you can finish a piece with no visible "holding" method, my point being that ive turned some large pieces and not had any problems, or am i being REALY thick here? :?: :sign3:


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## CHJ (2 Apr 2007)

wood yew believe it !":ssifmkmy said:


> ive got a bit of a bone (daft/stupid) question guys, why is it that you feel the need to have these special jaws? is it just to carry large pieces, or is it so you can finish a piece with no visible "holding" method, my point being that ive turned some large pieces and not had any problems, or am i being REALY thick here? :?: :sign3:



In the main "so you can finish a piece with no visible "holding" method" such as removing a spigot as opposed to leaving a socket which may not be so obtrusive.


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## Paul.J (2 Apr 2007)

*WYBI Wrote*
my point being that ive turned some large pieces and not had any problems
How have you been doing it Dave.Tell us your secret :shock: 
It just seems a quicker and safer way to me to do it.Even though i haven't tried it yet.  
Paul.J.


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## wood yew believe it ! (2 Apr 2007)

cheers chas, was kind of what i thought! paul, dunno mate, no secret, standard face plate to start, but dead slow, maybe with a counter-weight if piece badly unbalanced, when switched, a fairly large recess for the chuck to get a good ol grip on, and again slow till piece is balanced and lost a fair bit of weight, job done. 
absolutely no detriment to you guys, but for me i cant see the point as when finished you cant even see the recess, and spigots can easily be parted off and judging by some of the major engineering some are going to(all credit there!) just seems that its all getting too complicated IMHO.
One of my motto's .... keep it simple,stupid!, not saying you are of course, if it works for you, crack on! gonna shut up now b 4 you guys start calling me a w**ker


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## Paul.J (2 Apr 2007)

*WYBI Wrote*
gonna shut up now b 4 you guys start calling me a w**ker 
Whats wrong with been called a walker.Nothing wrong with walking :wink: 
Paul.J.


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## wood yew believe it ! (2 Apr 2007)

:lol: :-$ sorry


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## NickWelford (3 Apr 2007)

Ah but, WYBI, show your piece to another turner and they will always pick it up and look at how well finished the underneath is. And areas not usually in view. (cabinet makers probably look at the back of cabinets too). Was a time not so long ago when the base was generally covered with green fablon suede effect stuff - things are getting better.


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## Bodrighy (3 Apr 2007)

I don't mind the recesses in bottoms, they can be enhanced and made into a feature. When you have to mount on a faceplate however, I don't like the holes from the screws. Being able to get rid of those is good IMHO. Someone mentioned this on another thread so I watched people looking at my work and it's true. every single person has picked it up to feel it and then looked at the bottom. The very nature of the thing makes it tactile and worthy of inspection all over. 

Pete


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## Alf (3 Apr 2007)

NickWelford":p9qd6eh0 said:


> Was a time not so long ago when the base was generally covered with green fablon suede effect stuff - things are getting better.


Speaking as someone who's slaved over finishing table tops, often I think things are getting worse. Potters are the main culprits for having bases just designed to dig gouges out of tables, but turners aren't always as careful as they should be. I'd rather have the green fablon every time, personally; however naff ( and yes, it is ghastly, I know).

Cheers, Alf

_Nine_...


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## Bodrighy (3 Apr 2007)

I suspect the when people who could afford fancy pottery and woodwork all had french polished furniture, baize or felt was a neccesity. I seem to remember my grandmother always having a bottle of Topps Ringaway, (or something like that) in the house and getting slapped for leaving a white ring on her pristine walnut veneered sideboard.

Pete


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## wood yew believe it ! (3 Apr 2007)

good point nick, but i always finish the base as well as i finish the "top side" and in general use the smallest and most shallow recess as poss and where possible have no recess at all (parted off and hand fin) and never ever have a piece with "holes where mounted"


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## duncanh (3 Apr 2007)

Paul.J - the buttons are the original ones that came with the jaws. You can buy them separately but I haven't got round to it yet. I really should though as it's a pain to keep swapping them.

WYBI - I use these jaws to remove the holding method, which for me is pretty much always a tenon with a dovetail or sometimes without. Parting off the tenon isn't really a good method as (for me) it generally doesn't leave as clean a finish as the spindle gouge I use with my method. 
Also, a decent concave surface with a good finish is easier to achieve with a gouge. You need the slightly concave base so that if the wood warps once off the lathe there's no chance of a high spot in the middle off the foot causing a rocking problem. (or so I've read). And if warping does occur and causes a high spot then you can remount the piece in the cole jaws (or just sand the base - easier when concave as there's less wood to sand).

If a piece has some feature on the rim or side (like a bead or a couple of groves) then I sometimes put the same feature on the foot as a surprise for whoever might pick it up and turn it over.

Duncan


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## wood yew believe it ! (3 Apr 2007)

fair point duncan, though you can do the same if you have a recess, though not as much as your method granted


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## Anonymous (3 Apr 2007)

Duncan, you could use the plastic 'corks' they use for wine bottles... downside is that you have to drink the wine first... if you need help you only have to ask :wink:


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## NickWelford (3 Apr 2007)

wood yew believe it !":7j0ri8v7 said:


> good point nick, but i always finish the base as well as i finish the "top side" and in general use the smallest and most shallow recess as poss and where possible have no recess at all (parted off and hand fin) and never ever have a piece with "holes where mounted"



Of course, as all good turners should.


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## Hans (3 Apr 2007)

Paul.J wrote:



> How have you fixed yours to the chuck.Did you have to strenghten this material,and how did you cut the segments



I got a piece of Trespa of 48 cm (19") square. Cut it in 4 equal squares on the tablesaw, glued these squares together with some strips of sacrificial wood. Marked, drilled and tapped M6 holes to fix the flat jaws to the Trespa. Then drilled the holes to fix the jaws to the chuck.
Cut out a circle with the bandsaw and turned the perimeter flat with a scraper. Drew the eight lines from the center to the rim at 22°30' from the sawlines. For the Stronghold chuck I wanted the distance of holes for the buttons 15 mm (5/8") apart. Marked out, drilled and tapped the holes for buttons. I prefer the Vicmarc buttons with concave-convex shape which use a M5 machine screw.

Maybe some of the above makes sense when you have the picture with it. 


 

The Oneway flat jaws for the Stronghold have three countersunk holes that will take an M6 machine screw. 

These jaws are meant to be used for light cuts and sanding. 
I don't think the Trespa needs further strengthening. Of course you could make the holes for fixing the jaws to the chuck 6 mm (1/4") and countersink the heads. You would need to use longer screws then to fix the jaws. I prefer to use to use the standard screws. I have a job to keep things together as it is. 

I doubt if much of this is applicable when building jaws like this for a different chuck and lathe, nevertheless I hope there is something you can use.

Hans


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## Paul.J (3 Apr 2007)

*Duncan wrote.*
the buttons are the original ones that came with the jaws. You can buy them separately but I haven't got round to it yet.Thanks Duncan.

Hans it does make sense and thank you.
Paul.J.


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## duncanh (3 Apr 2007)

Instead of having to tap all the holes you could just use longer bolts and fasten them at the back with nuts - locking nuts if you want to be extra secure.

Duncan


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## Paul.J (4 Apr 2007)

*Duncan wrote*
Instead of having to tap all the holes you could just use longer bolts and fasten them at the back with nuts 
Duncan,this is why i used t-nuts on mine.
Paul.J.


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