Is there a difference between a "Scroll Chuck" and a "Woodturning Chuck"?

[Jesse Tutterrow]

Some people refer to any woodturning chuck (i.e. SuperNova2) as a Scroll Chuck. Other times / people refer to a chuck using Tommy Bars to tighter as a Scroll Chuck.

In precise terms is a SuperNova2 a Scroll Chuck?

What is the more generic term for all chucks?

 

[Michael Mills]

I believe all of the the ones you mentioned are scroll chucks. All of the jaws move in unison as you looser or tighten.
In metal work (mainly) there are independent jaw chucks where each jaw is moved individually in order to turn something such as a cam shaft.

 

[Clifton C]

I think the generic term is "chuck" unless you have so many that you've misplaced the one you want, and then it's called, where is that "##@$#$%$ chuck"
If you look here https://www.teknatool.com/wp-conten...va2-Maunal-full-version-for-CD_8-Feb-2005.pdf
Page 6 item #4 you can see the scroll ring, hence the name. Other chucks have used clamping action with independent jaws, the scroll allows the jaws to work together to center the work.

 

[John Torchick]

Interesting. Clifton, thanks for the link.

 

[hockenbery]

The scroll mechanism in chucks is controlled it two basic ways:
Tommy bars
Or a chuck key.

Most people prefer the keys but I know several professionals that prefer using one Tommy bar because they are faster to lock and unlock. They lock the spindle then operate the scroll ring with one hand and hold the work in place with the other. They also use a Tommy bar with a 12-14” handle to make it easy to find and add leverage.

 

[Jesse Tutterrow]

So then a "scroll chuck" is any chuck where the jaws move together which automatically centers the piece?
Would you then say a "scroll chuck with Tommy Bars" vs. "scroll chuck with key"?
Are all woodturning chucks self-centering or are there woodturning chucks were each jaw moves independently?

 

[hockenbery]

Are all woodturning chucks self-centering or are there woodturning chucks were each jaw moves independently?

The modern ones are all self centering.
There are old chucks and many metal working chuck with independently moving jaws.

I have a circa 1990 precision chuck where the jaws are free floating and locked in place by a floating collar.
It is possible for them to lock off center on something not round

 

[Martin Groneng]

I have about 6 chucks and some with multiple jaws and some of these chucks are "older fellows" but all work well. Every one has a key and I hate tommy bars. I find the key faster as once I tighten the piece, I go to the other hole and tighten a little more and often go back to the first hole. Thus, the piece is snug and never to move. Last action is to draw a pencil line against both the #1 jaw and the #4 jaw. Thus, if for some reason you want to remove the piece at some point and rechuck it, you know "exactly" where to replace/put the piece back in the chuck. This system/approach has worked for me for over 35 years. Try it, you might like it!!

 

[john lucas]

There are also Collet chucks where a sleeve is tightened over a sloped shoulder and tightens up the inner jaws that hold the work. These are also self centering. What we refer to as scroll chucks are self centering chucks using a scrolling mechanism. 4 jaw (or sometimes 6 or 8 jaw) independant chucks as mentioned above are not self centering although my machinist friends use those when they absolutely need a perfect center. You have to use a dial indicator to truely center something on those types of chuck.
There is also a difference in jaw shapes for metal chucks vs wood chucks. Wood chuck jaws are cut from a circle and when closed all the way form this size circle. metal lathe chucks have stepped L shape jaws that are really terrible to hold wood because they tend to crush the wood and then it gets loose and flies out of the chuck.

 

[Bill Boehme]

As already mentioned, not all woodturning chucks are scroll chucks. We could also say that not all scroll chucks are woodturning chucks because some scroll chucks are designed for metal turning. A scroll chuck has a scroll gear (AKA, scroll plate which has a nautilus like spiral that engages teeth on "dogs" that slide in radial slots. In woodturning parlance these dogs are known as "lower jaws" , "base jaws", etc. depending on the manufacturer. As already mentioned, scroll chucks are self centering ... collet chucks are also self centering, but with a much smaller gripping range. There are two types of scroll chucks used in woodturning:

• Those that use tommy bars to rotate the scroll gear. This is the older design that has mostly fallen out of favor.
• Those that use a ring and pinion gear to rotate the scroll gear. On Oneway chucks, the pinion gear is part of the key and on Vicmarc chucks the pinion remains in the chuck body and a hex key is used to rotate the pinion.
• There are also a couple hybrid scroll chucks that combines the best of both types in a single body.

For all practical purposes, four-jaw scroll chucks have become the defacto standard woodturning chuck.

 

[RichColvin]

On metal lathes, both 3-jaw and 4-jaw scroll chucks are common.

Also common are 4-jaw chucks that are not scroll chucks. Instead each jaw can be moved in or out separately. This allow for centering irregular pieces (especially for drilling / cutting holes).

Rich

 

[Perry Hilbert]

This shows how a scroll chuck is constructed inside and with some cutouts, how a scroll chuck works. The scroll refers to the interior flat plate that is a ring gear on one side and a machined spiral shaped thread on the other.

View: https://www.youtube.com/watch?v=F8XhqqHtF88

 

[Michael Mills]

In his discussion on chucks.... just a tidbit to show how much thing have changed.
"Mr. Thomas Hark received an award from the Society of Arts... for a variety ..having four jaws."
"Mr. Alexander Bell about the same time contrived a chuck with three jaws...."
"...upon turning the back plate about one third round, by a key or plain lever;"
"The Universal chuck, now sometimes called the Scroll chuck...."
From Hand or Simple Turning by John Holtzapffel published about 1881 and rewritten from his fathers (Charles) book of the same about 1850. pages 230 -231.

 

[Perry Hilbert]

tommy bar chucks are thinner in silhouette because they do not use a geared system behind the scroll. The wheel for the tommy bars is the scroll. And BTW, I have an independent jaw 4 jaw wood working chuck.. (came with a used lathe) I still see them offered on some sites, yet their advantage is lost on me.

 

[john lucas]

I use a 4 jaw independant chuck for special things but I thoroughly understand it's holding ability so I never push it. When you need to turn something off center it's very easy with that chuck.

 

[Jesse Tutterrow]

I use a 4 jaw independant chuck for special things but I thoroughly understand it's holding ability so I never push it. When you need to turn something off center it's very easy with that chuck.

if an independent chuck had the same jaws as a self-centering woodturners chuck would it not have the same holding ability?

 

[john lucas]

The indenpendant jaws on a metal chuck have the same jaws as a self centering metal turning chuck. These are usually stair step shaped and fairly narrow. Excellent for holding metal. Terrible for holding wood. A self centering woodturning chuck has jaws that form a circle when completely closed.

 

[RichColvin]

John is right !