CNC cut Longworth chuck

Ever since I got my X-Carve I’ve been thinking about making a Longworth chuck for my lathe. If I could do it quickly I could offer to make them in a get together of my woodturners group. One challenge is to accurately align a faceplate after the disc is cut on the CNC, so my solution was to design and 3D print an alignment tool that threads into the faceplate and registers in the center hole of the plywood disc. Tonight after learning how to create a toolpath for slots in Fusion 360 I cut this prototype disc (two are needed for a chuck). I need to tweak some fitting and dimensions, but it’s on the right track. I may also end up 3D printing the soft grips for the front and some hand friendly knobs for the back. Kinda neat having such manufacturing capabilities in my basement.


I like it. I could have used one 15 years ago when i was doing a lot of turning but my lathe right now is buried under a pile of lumber.

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Dig that lathe out. Put it to work. I love mine

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I would but i just don’t have the time.

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That’s a good problem. (I think). Lol. Good to be busy

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I do have the Beall tap so I’ll probably go that route in the end. I’ve only done a couple of them and wasn’t totally sure whether I should use a couple of pieces of plywood or solid wood for the wood plate - what’s the best combination of wood stability vs thread holding ability?

Oh OK, that sounds easy. Thanks!

A little late to the party, I know. My lathe is a DVR-XP, as well. I love that thing!!
Steve, is there any chance you would share that file? I only use Easel and very rarely, so I don’t know how to design this. Any help you could offer would be appreciated.
Thank you,

I’d be happy to share, but I didn’t do it in Easel - it’s in Fusion 360. The other issue is that it didn’t work smoothly and I haven’t gotten back to it to do a final version. The original prototype was cut in 3/4" ply which I wonder if it was too thick, but also I’ve made a bunch of stiffening mods to my X-Carve with other improvements on the way (Z axis, screwdrive) in case the issue was smoothness of the curves. Or it could be the way I designed the arcs of the chuck - maybe they’re too steep or shallow.

If you’re comfortable in Fusion I can share it with you.

It’s not shown in the pictures above, but I didn’t just design the 2 plywood discs in Fusion. I also designed a 3D printed alignment guide which threads into a faceplate and then has a locating pin for the center of the plywood discs - the idea was this would allow me to cut the discs on the CNC and then get the mounted and running true. The other thing I modeled and then 3D printed out of semi flexible TPU filament is the cushioned grippers which are meant to have a good angle to grab the wood and an appropriate height, but also have a recess in the top so the head of the bolt is maybe a little less exposed and dangerous. I even experimented with the infill percentage of the gripper so it would have the right amount of give.

This multi-material full 3D capability is why I use Fusion for anything non-trivial.

Thanks for the offer, Steve, but I’m not using Fusion 360 and at the moment don’t want to take the time to learn to use it. Also, I was given a file by Phil Johnson - remember him? - so I should be good to go. Thanks again!

Sounds like you’re all set.

I just run across your posting. My woodworking club here in Reno is in the process of purchasing a CNC Router. A few of us are working on learning Fusion 360, I do a lot of turning, but really enjoy segmenting. I started to try and figure out how to make a four post longworth chuck for aligning segmented ring under my ring press. Since i am just attempting to learn Fusion 360, it is a struggle to get this figured out, CNC is all new to me.
If i could get your plans that would be super great. I really like your six post chuck.
Stan Merrell