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Mobyturns
8th November 2013, 08:59 AM
Coffenup raised the matter of using bowl jaws to reverse and hold items for finishing. There are about as many ways to hold and to reverse a work piece as there are turners but I like to crossover between the face plate only brigade and the chucks only mob and use a range of hybrid options.

Most modern turners forget that turners a couple of centuries back were turning quite intricate pieces with out scroll chucks. So it really is a great skill to learn to safely use jamb chucks and non scroll chuck work holding methods.

One handy tip is to have a series of already prepared discs with tenons cut to match your preferred chuck jaws in a range of sizes. Then its only a matter of inserting them into the chuck, facing off and glueing them on as a chuck tennon to a blank you don't want to waste or cutting a recess for a jamb chuck when you require one. I have made up a series from Tas Oak, radiata pine, rubber wood etc and my favourites for the small lathe with kwilia face plates approx 40mm thick x 75mm dia, some with 1"x8 black nuts set into the rear, that I glue (hot melt or Titebond / AVXL Plus) sacrificial radiata pine face plates onto. When the pine is past its use by date face off and glue on another. Using these waste tennons and spacer blocks also give you more room to safely manoveure around the back of the bowl if you like to do pull / shear cuts.

These small temporary tennons, face plates and jamb chucks are really versatile. When used with a scroll chuck they really open up your options, but you must use tennons with sufficient surface area for strength and for sound glue joints to be formed.

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Scott
8th November 2013, 10:33 AM
Superb thread Moby. I'm the same a you, I have a drawer full of tenons and pieces of radiata etc that I use for jamb chucks or sacrificial pieces for hot glueing. I wish I knew of these simple and inexpensive options when I first started turning. This would of saved me from buying some more expensive solutions. By joining a woodwork club, I learnt of these options and was quick on the uptake. I must admit, it took a while for me to gain the confidence needed to use a jamb chuck or even hot melt glue. I only recently start using hot melt glue for making finials and small knobs.

Thanks for sharing this with us :)

artme
8th November 2013, 12:12 PM
Yes, a greatly informative thread Moby. Many thanks for posting!!!:2tsup::2tsup::2tsup:

NeilS
11th November 2013, 11:53 AM
Thanks Moby for your thoughtful contribution.

Waste blocks come into their own sooner or later. I don't use them for regular bowl turning, but opt for them with some more complex multiply re-chucked pieces.




Most modern turners forget that turners a couple of centuries back were turning quite intricate pieces with out scroll chucks. So it really is a great skill to learn to safely use jamb chucks and non scroll chuck work holding methods.



I'm feeling my turning age, having begun prior to scroll chucks for woodturning, but it doesn't feel like a 'couple of centuries'... :U

The scroll chuck for woodturners is a fairly recent innovation. The self-centring engineering chuck has been around for a long time (from mid-1800's), and some of us did make limited use of them prior to the introduction of the scroll chuck for woodturners by Teknatool some time in the 1980's. The jaw arrangement on the Teknatool chucks (ring dovetail grip) was the significant innovation and a quantum improvement on the jaws that were available for engineering chucks.

There were a couple of clamping/expanding ring-dovetail jaw grip chuck 'experiments' that came out at about the same time as the Teknatool scroll chuck was introduced, but they were limited in their function and performance and soon vanished from the market with the success of Teknatool's Nova chuck.

Some pre-scroll-chuck woodturners wear their continued use of waste blocks and jamb chucks like a badge of honour. I would never wish to go back to that time prior to scroll chucks and have to use waste blocks and jamb chucks any more often than I do; only resorting to them on the odd occasion when a scroll chucks can't do the job to my satisfaction.

However, it's good that we are keeping the knowledge of these techniques alive.

NeilS
11th November 2013, 02:27 PM
introduction of the scroll chuck for woodturners by Teknatool some time in the 1980's.

Just checked my 1979 edition of Peter Child's The Craftsman Woodturner to see if I had that right. Confirmed, not a hint of anything like a scroll chuck in that edition.

RETIRED
11th November 2013, 03:55 PM
The scroll chuck was brought out in 1988 by Technatool.

powderpost
11th November 2013, 08:54 PM
The scroll chuck was brought out in 1988 by Technatool.

The early models were fitted with bronze jaws to be used on green timber so as not to leave black marks caused by the reaction of tanins in the timber. This would leave black marks on the job.
I use waste blocks a lot. This allows me to determine the size of the bottom, instead being dictated to by a chuck manufacturer.
Cup chucks were used extensively by the old English turners. Some even made their own from wood to suit the job in hand.
Jim

Mobyturns
12th November 2013, 09:04 AM
Just checked my 1979 edition of Peter Child's The Craftsman Woodturner to see if I had that right. Confirmed, not a hint of anything like a scroll chuck in that edition.
Neil,

I guess I'm lucky I span the eras of imperial to metric & I'm only mid 50's. As a surveyor I started off in the pre hand held calculator era using a slide rule for crude calcs and Chambers 7 Figure Tables (Log tables) for the routine accurate calcs. (Start Googling young ones.) Up untill the hand held calculator arrived nothing had changed in more than a century.

The same has happened in woodturning - along came the scroll chuck. Now many turners do not know how to use jamb chucks for simple tasks.

I've researched the origins of scroll chucks, their genesis stems from the original three jaw scroll chuck patent registered in 1862 by Austin F Cushman, formerly a Colt Fire Arms pattern maker. Woodturners owe a great debt to him and to the wood turners who saw its potential and developed the four jaw scroll chuck. Early 1980's is correct, though it is doubtfull that Nova / Teknatool were the first. The most significant developments though in nmy opinion are the insert and the back & top jaw slide innovation, that really revolutionised how we turn.

NeilS
16th November 2013, 06:48 PM
The scroll chuck was brought out in 1988 by Technatool.

Thanks . As late as that, however, that's still 25 years ago now.


The early models were fitted with bronze jaws...

In which case, I wasn't an early adopter. My first one came with the standard black metal finish, so definitely later yet again. Never got to see any with those bronze jaws; they would have looked quite specy.


Woodturners owe a great debt to (Cushman) and to the wood turners who saw its potential...

Agreed, without the earlier refinement of the scroll mechanism by the metal turners I doubt if we woodturners would have ended up with the chucks that we have now.

powderpost
16th November 2013, 10:50 PM
Never got to see any with those bronze jaws; they would have looked quite specy.

Can't remember when this one was bought, but it would have been in the late 70's, maybe even early 80's.
Jim293892

NeilS
17th November 2013, 10:08 AM
Can't remember when this one was bought, but it would have been in the late 70's, maybe even early 80's.

Jim
293892



Thanks, Jim.

Can't be that many of them around.

In my mind's eye I had the jaws all shiny like the brass plates out the front of the doctor's surgery.

But then, I doubt that I'd be polishing mine regularly if I did have a set of those brass jaws and they would end up looking more like the old brass tap out the back of the house...:U

Mobyturns
17th November 2013, 12:38 PM
Can't remember when this one was bought, but it would have been in the late 70's, maybe even early 80's.
Jim

Jim I'm very interested in the age of that chuck. (will catch up & have a chat.)

Darlow says 1988 for the introduction of the Nova chuck, but there are instances of modified 3 jaw engineers chucks being modified for wood turning well before that. I started researching patents and the introduction of the "dedicated" woodturners scroll chuck quite a while back & I've found some patents so far (time is the issue). Darlow in "Woodturning Methods" says he had a patent (13/08/1985 #PCT/AU1985/000190) on the idea for accessory timber jaws for fitting to a 3 jaw scroll chucks back slides circa 1985.

chuck1
17th November 2013, 07:21 PM
at Tafe we learnt some great friction chucking methods for bowls, and using engineering chucks with a a steel pipe section making a Big ring, to insert into rebate of bowl and once on Chuck jaws it would expand and hold bowl with more surface area grip. I've got one of those old bronze jaw scroll chucks!

Tim the Timber Turner
17th November 2013, 07:30 PM
In the late 80's, I sent my first Nova chuck back (twice) due to realy bad run out.

It must have been a major problem with the early ones because they started including a certificate with each chuck stating the run out as measured in the factory.

From memory the insert used to bottom out in the chuck and didn't use a shoulder to mate up with the chuck.

When Carba-Tec released the Bonham chucks I changed over.

Later, Vicmarc released their key operated chucks which is what I use today.

Cheers

Tim:)

chuck1
17th November 2013, 07:42 PM
think this Chuck was before scroll chucks think it's a teknatool as the teknatool inserts fit it!

powderpost
17th November 2013, 10:46 PM
From memory the insert used to bottom out in the chuck and didn't use a shoulder to mate up with the chuck.
The scroll chuck in the photo does not have an insert, it screws straight onto the nose of the lathe. From memory again they were supplied in 30 x 3.8 and 1" x 10tpi, which was the Teknatool standard thread.
Jim

powderpost
17th November 2013, 10:57 PM
think this Chuck was before scroll chucks think it's a teknatool as the teknatool inserts fit it!

That was the first chuck that Teknatool produced. It was designed by a kiwi, ( I forget his name) for turning green tinber. THe timber was turned and let dry when it would assume an irregular shape. The four jaws had two gripping points and worked in compression mode or expansion mode. The "floating" jaws compensated for the irregular shape after drying. The jaws were also bronze to prevent staining on wet timber. It was fitted with an insert that, when screwed in tighter, would force the jaws into expansion mode. This insert when backed off allowed a chromed threaded ring on the front, to be tightened onto the dovetail on the jaws for compression mode. THe chuck held the job very firmly, but needed two pairs of hands to adjust. THe chuck was also supplied with two double ended "C" spanners. It was a good chuck, but a but complicated to use.

Jim