Longworth Chucks vs. Segmented Turning

[Pat McDermott]

I have been doing some segmented turning. Once I glue up a segmented ring I use a 12" disc sander to flatten 1 side to glue it to the previous ring. I just purchased are larger lathe and want to go beyond a 12" diameter. The issues the size of my disc sander. Has anyone ever used a longworth chuck (homemade or purchased) to flatten a segmented ring. I know that keeping the ring captured is an issue so I'm sure being gentle is key.

Any other methods out there? For the immediate future the purchase of a drum sander might generate a divorce so that isn't a viable option.
Thanks

 

[Jay Fluegel]

Just make a disk that you can mount to your lathe. I made a 12" disk out of 1/2" MDF mounted to hardwood faceplate I made. I sprayed the MDF with about six coats of shellac so the adhesive backed sanding disks hold fast. It works very well for flattening segment rings. I just got a larger lathe so I will making a 20" version this weekend. I've seen a few that people made out 1/4" aluminum plate but I don't see any advantage over MDF, besides I can buy five or six sheets of MDF for a 20" plate of aluminum would cost.

 

[Pat McDermott]

Jay,
Good idea.
Thanks - Pat

 

[hockenbery]

Just make a disk that you can mount to your lathe. I made a 12" disk out of 1/2" MDF mounted to hardwood faceplate I made. I sprayed the MDF with about six coats of shellac so the adhesive backed sanding disks hold fast. It works very well for flattening segment rings. I just got a larger lathe so I will making a 20" version this weekend. I've seen a few that people made out 1/4" aluminum plate but I don't see any advantage over MDF, besides I can buy five or six sheets of MDF for a 20" plate of aluminum would cost.

Just saw a demo by Ron Browning. He used Formica sink cutouts. So he skips the prep.
Sink cut outs are likely to be free if you can find a source. Should be able to find some suitable for 20" diameter.
If you get lucky you can color code them.

I am big fan of MDF for lots of jigs. Big advantage is it is cheap. Don't try to hold it with a tenon it will shear off.
Needs a recess chuck mount.

Have fun
A

 

[Col Smith]

. I've seen a few that people made out 1/4" aluminum plate but I don't see any advantage over MDF, besides I can buy five or six sheets of MDF for a 20" plate of aluminum would cost.

I can see the advantage. I made mine from 19mm MDF trued it up & after a couple of months it has gone out of true.
Now making one out of 30mm marine ply.

HTH
Col

 

[pete marken]

I have used several methods for flattening rings and all seemed to work, some better than others. Sanding dust was always a problem. A couple years ago I bought a Jet 16-32 drum sander and have been using it to flatten rings ever since. The drum sander does a great job using 80 grit paper to flatten the rings. On the final pass I run it through 4 times and rotate the ring 90 degrees each pass ath the same height setting. It has become a very important tool in my shop. Don't know how I got along without it. I ues it to surface all my lumber. I usually use 8/4 lumber and resaw as needed.

 

[john lucas]

I have used the cole jaws to flatten one side of the rings. There are problems but it does work. The little buttons tend to lift the ring so after I tighten it I put a block of wood behind the ring and then tap on the front side with a dead blow hammer. that flattens the ring onto the aluminum. I made some custom buttons that are shorter and some that are longer buy putting plastic tubing around the right size metal and drilling and tapping the metal. This helped reduce the lifting and the shorter buttons work for thinner rings.
Usually what I do now is to glue the rings together using band clamps. Then place the ring on a perfectly flat board that I put formica on. Then hammer the segments with the dead blow hammer. Then flattens the bottom side close enough that it only takes a few rubs on a piece of sandpaper layed on my flat board. If that doesn't look like it will work then I go to my new (to me) Performax sander.