The Jumbo Jaws kit contains everything you need to start turning the bottoms of your bowls. Click image to enlarge

Oneway Jumbo Jaws

Getting to the bottom of the bowl

Text & Photos by Tom Hintz

   Scroll chucks like the Oneway Talon (see our review) have made turning bowls fun and safe. However, finishing the bottom where the bowl is secured to the chucks jaws remained a kind of no mans land.
   Oneway Jumbo Jaws provide a safe, non-marring way to grip the lip of a nearly finished bowl so the bottom can be turned and finished on the lathe.
   The Oneway Jumbo Jaw system consists of four pie-shaped plates that replace the jaws on the chuck. The plates have a series of threaded holes in which rubber buttons are secured that grip the edge of the bowl. This is a reasonably simple concept that Oneway has refined to maximize safety, accuracy and versatility.

Initial Impressions

   The Oneway Jumbo Jaw system looks very well made with fine machining and a complete package of quality components necessary for use.

The difference between unfinished and finished is dramatic. This jaw set makes that transition easier than you might think! Click image to enlarge

   Oneway machines the Jumbo Jaws from solid aluminum bar stock rather than use a cheaper casting. Though considerably more costly, this process results in precisely machined jaws that are exceptionally well balanced, strong and true running.
   The thick rubber buttons and hardware are all high quality and will last forever with a little common sense care.

Instructions

   Using the Jumbo Jaws set is very simple and does not require extensive instructions. Oneway provides an instruction sheet that in addition to clearly written text includes well-done illustrations that clearly show setup and use procedures completely.
   In addition to using the Jumbo Jaws in the standard configuration, the instructions also describe using the buttons without the plates and with shop-turned false wooden jaws for special applications. This greatly expands the capabilities of the Jumbo Jaw set.

Versatile Plates

   The Jumbo Jaws are more than simple flat plates with holes in them. Thoughtfully designed and CNC (Computer Numerically Controlled) machined, the Jumbo Jaw plates lock directly into keyways machined

The plates are easy to install on the Talon chuck and the array of holes and slots mean virtually any bowl within the size range will be secured and centered. Click image to enlarge

in the base jaws that automatically aligns them perfectly with the chuck. The jumbo Jaws are mounted using the factory-installed screws that secure the original jaws.
   The back of the plates is extensively routed to reduce rotating weight without compromising rigidity.
   All four plates are identical with the exception of one that has the Oneway safety pin that must be installed into the corresponding slot on the chuck. The remaining jaws can be installed in any order.
   Each plate has two lines of 8 holes into which the buttons are secured. Between the scrolling action of the chuck and the array of holes, the Jumbo Jaws have an internal grip range of 4 ¾" to 11 ½." The external grip range is 2 ¾" to 10 ½."
   A slot is located between the lines of holes on each plate and makes gripping out-of-round bowls easy and secure. This is an important feature; especially if you turn bowls from wet wood that tends to "go oval" as they begin to dry.

No-Mar Buttons

Gripping bowls on the outside (Top) or inside (Bottom) edge is easy and secure. Click images to enlarge

   The buttons that contact the bowl are made from a non-marring rubber compounded to provide a firm grip without damaging the wood or finish.
   The rubber buttons are bonded to a machined steel inner core that allows them to be fastened to the plates securely without distortion.
   The kit includes 8 buttons and mounting hardware that accommodate most bowls. Additional buttons can be purchased separately, along with long screws that allow stacking two buttons. This additional reach can be necessary with some bowl shapes.
   The buttons can also be installed directly on the inner jaws to grip objects as small as ½"-diameter. This is an interesting feature that allows turning small boxes, goblets and other small projects.

In the Shop

   Installing the Jumbo Jaw plates is simple and accurate because they "key" on the same machined keyway that the chucks jaws do. This eliminates misalignments that could be disastrous even when spun in the recommended speed range of 900 to 1250 RPM.

Turning the bottom of a bowl (Top) is safe and easy with the Jumbo Jaws. (Bottom) The rubber buttons can be installed directly in the Talon base jaws to grip objects as small as 1/2"-diameter. Click images to enlarge

   While the range of holes allows installing the buttons to fit most bowl diameters within the listed range, I managed to turn a couple that simply would not fit. That is easily solved by removing a few of the buttons, setting the bowl in the remaining button pattern and then installing the remaining buttons. The grip is even, secure and takes only a little longer to set up.
   I was pleasantly surprised at how closely centered each bowl was held. This auto-centering made turning the bottom to the shape I wanted quick and with minimal material loss.
   While the specified RPM range of the Jumbo Jaw system sounds low, I found there was plenty of speed for turning, sanding and finishing the bottom of every bowl I tried.
   Overall, using the Oneway Jumbo Jaws proved to be very easy, surprisingly fast and allows the turner to be creative in an area of bowls that used to do little for the look of the project.

Conclusions

   The Oneway Jumbo Jaws set is a quality product that brings a new dimension to your bowl turning. The ability to finish the bottom of your bowls reduces frustration while increasing your satisfaction and the value of the project itself.

   With a street price of $79.99 (3-15-2005) the Oneway Jumbo Jaw set is an effective, economical tool that lets you get to the bottom of the bowl with your creativity intact.

Note: Oneway also offers the Mega Jumbo Jaw set designed for use with their Stronghold chuck.

Visit the Oneway web site.

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