How wide can you open YOUR jaws?
Posted: Sun Mar 28, 2021 5:27 pm
Your lathe-chuck jaws, that is.
Thanks to the new WoodAnchor fixturing system, mine can now grip the outside of a 13” diameter bowl!
And those jaw extensions can also grip severely out-of-round bowls, no problem.
Note that I'm using a speed reducer with this setup. Nova specifies a max RPM of 600 RPM for the stock cole jaws, so either a speed reducer or a PowerPro headstock is required for use on a Shopsmith.
The bowl in the pics had been sitting around rough-turned for over a year. When you turn bowls from green wood, they warp as they dry, shrinking across the grain. This particular applewood bowl dried a full ½” out of round. The round tenon had also turned into an oval, so I wasn’t going to get a secure grip on it with my standard chuck jaws. The only way I could think of to true up the tenon was to try turning the bowl between some sort of jam chuck and a live center. Which sounded like a fussy setup to me, and I wasn’t looking forward to it.
So on to Plan B. I added a set of Nova JSCOLE Cole jaws for my Nova G3 chuck to my wish list. Per Nova, these jaws are for lathes with a minimum 12” swing. Mark V’s have a 15-1/2” swing over the way tubes, so I would have preferred larger jaws, but those are the biggest ones that Nova makes to fit a G3 chuck. And it sounded as if they’d be big enough for this 10-1/2” bowl.
My family bought the Cole jaws for me as a Christmas present in 2019. What I didn’t know until I opened them was that these jaws have a max outside gripping diameter of only 9.29”, when mounted on a G3 chuck. I eventually found that info buried deep in the product manual, but it isn’t mentioned on the product pages at either Technatool or Amazon. So my new jaws weren’t big enough for that applewood bowl.
The other problem I discovered is that Cole jaws are designed only to grip round things. Given that the threaded “buffer” mounting holes in the Cole jaws are spaced about 3/8” apart radially, they can’t be adjusted to properly fit an out-of-round bowl (unless perhaps you remove half of the buffers, and then orient the bowl just so). This is pretty obvious from the stock photo above, showing the included standard buffers. So my new Cole jaws just got stuck in a drawer to await a smaller bowl, and there they languished for the next year or so.
When I finally I pulled the Cole jaws back out of the drawer, I noticed a mention in the instruction manual of making your own wooden extenders (at your own risk, of course). And voila! I realized that my new WoodAnchor™ fixturing system could solve the problem quite nicely.
These simple Cole-jaw extenders increase the bowl-size capacity, and they can be adjusted as necessary to securely grip out-of-round bowls. This makes it a piece of cake to re-turn a warped bowl. They’re also a lot less expensive than commercial jaws with a similar bowl-size capacity. I did purchase the NOVA 6030 Cole Jaw Buffer Accessory kit, which comes with eight of the multisided buffers shown in the photos. These grip much better than the standard cylindrical buffers that are included with the jaws. The heavy-duty clamping ability of the WoodAnchor™ fixturing slots and sliding nuts ensure that the buffers stay put wherever you lock them down, and that in turn enables you to crank down tightly with the chuck.
As this is only my third bowl, I’ll be very interested to see what the real turners out there think of this solution.
Thanks to the new WoodAnchor fixturing system, mine can now grip the outside of a 13” diameter bowl!
And those jaw extensions can also grip severely out-of-round bowls, no problem.
Note that I'm using a speed reducer with this setup. Nova specifies a max RPM of 600 RPM for the stock cole jaws, so either a speed reducer or a PowerPro headstock is required for use on a Shopsmith.
The bowl in the pics had been sitting around rough-turned for over a year. When you turn bowls from green wood, they warp as they dry, shrinking across the grain. This particular applewood bowl dried a full ½” out of round. The round tenon had also turned into an oval, so I wasn’t going to get a secure grip on it with my standard chuck jaws. The only way I could think of to true up the tenon was to try turning the bowl between some sort of jam chuck and a live center. Which sounded like a fussy setup to me, and I wasn’t looking forward to it.
So on to Plan B. I added a set of Nova JSCOLE Cole jaws for my Nova G3 chuck to my wish list. Per Nova, these jaws are for lathes with a minimum 12” swing. Mark V’s have a 15-1/2” swing over the way tubes, so I would have preferred larger jaws, but those are the biggest ones that Nova makes to fit a G3 chuck. And it sounded as if they’d be big enough for this 10-1/2” bowl.
My family bought the Cole jaws for me as a Christmas present in 2019. What I didn’t know until I opened them was that these jaws have a max outside gripping diameter of only 9.29”, when mounted on a G3 chuck. I eventually found that info buried deep in the product manual, but it isn’t mentioned on the product pages at either Technatool or Amazon. So my new jaws weren’t big enough for that applewood bowl.
The other problem I discovered is that Cole jaws are designed only to grip round things. Given that the threaded “buffer” mounting holes in the Cole jaws are spaced about 3/8” apart radially, they can’t be adjusted to properly fit an out-of-round bowl (unless perhaps you remove half of the buffers, and then orient the bowl just so). This is pretty obvious from the stock photo above, showing the included standard buffers. So my new Cole jaws just got stuck in a drawer to await a smaller bowl, and there they languished for the next year or so.
When I finally I pulled the Cole jaws back out of the drawer, I noticed a mention in the instruction manual of making your own wooden extenders (at your own risk, of course). And voila! I realized that my new WoodAnchor™ fixturing system could solve the problem quite nicely.
These simple Cole-jaw extenders increase the bowl-size capacity, and they can be adjusted as necessary to securely grip out-of-round bowls. This makes it a piece of cake to re-turn a warped bowl. They’re also a lot less expensive than commercial jaws with a similar bowl-size capacity. I did purchase the NOVA 6030 Cole Jaw Buffer Accessory kit, which comes with eight of the multisided buffers shown in the photos. These grip much better than the standard cylindrical buffers that are included with the jaws. The heavy-duty clamping ability of the WoodAnchor™ fixturing slots and sliding nuts ensure that the buffers stay put wherever you lock them down, and that in turn enables you to crank down tightly with the chuck.
As this is only my third bowl, I’ll be very interested to see what the real turners out there think of this solution.