Printable View
Needed to flatten the base of bowl using a donut chuck, and having trouble centering it wishing I had ordered an adapter.
Here was my solution. I removed the chuck, and move the tail stock to support the DC after centering. Did not and would not run the lathe with this setup.
Attachment 434262Attachment 434261Attachment 434260
It took me quite a while to puzzle out what I was looking at, but I think I've got it-- you leave the chuck attached to the workpiece and then center it using the cone center on the tail stock? If so, great idea-- I always forget to be sure to mark the center when making my tenons; perhaps someday I'll learn! Still don't know what a donut chuck is though.
It also took me a while to figure out what Bob was describing.Quote:
Originally Posted by roger wiegand
BTW, a donut chuck is a device which clamps and holds the work, usually for turning the bottom of a bowl. You can make a simple one with two pieces of plywood - fasten one to a faceplate or chuck and fasten the second one to the first with bolts through holes spaced around the outside edge. Turn both round and turn a hole in the top one big enough to expose the base of the bowl but small enough to clamp the bowl. Then use longer bolts to clamp the bowl for finishing. (the head of one of these bolts is visible in the lower corner in Bob's third picture.) It's an alternative to a vacuum chuck or a fully supporting jam chuck to expose the entire base for final turning without the tailstock in the way, or supporting with the tailstock to turn most of the bottom and finishing up the "nub" by hand.
The problem with all of these methods, of course, is the trial-and-error sometimes needed getting the piece centered. I personally use a dial indicator and can can usually center a piece in just a few tries.
BTW2, this book by Doc Green has lots of ideas about holding things, including the donut chuck.
https://www.amazon.com/Fixtures-Chuc.../dp/1565235193
Google gives instructions and videos.
JKJ
For folks without a large cone for the tailstock, like myself.
Yours is easier if you do have a cone.
Here is a possible solution for the center. Yes, I know, I inserted from the wrong size when I took the picture.
Turn an insert for your faceplates or chucks; they should be the same.
Drill the center hole, I used a 16p nail to start with but now use a metal skewer from the kitchen.
If you don't want to leave a dimple in the wood you can do two things.
a. Drill the hole to fit a pencil so that you can just mark.
b. Cut a small (nickle size?) piece of 1/4 wood and tape into the recess. You now have a dimple to bring your tailstock up to. When complete just peel off the sacrificial center.
Stick Fast (Hold fast vacuum chucks) makes a chuck reversing adapter that has either 1x8 or 1.25x8 threads that holds your chuck in the #2 MT on the tailstock. It centers perfectly every time. Don't lock down the tailstock and the vacuum draws the piece nice and tight, centered. Not cheap. 35 buck or so.
I also turned a #2 MT and threaded the other end to fit the chuck, but that is not perfect. Pretty close after turning 3 of them. First ones were pretty badly centered. Solution, thread first, then turn the taper. If close is good enough, this can save you a few bucks. Assuming you can already do threading and have the correct die. Die is not cheap either.
I think I will get Roger and John to review the next post I make. Thanks for clearing up my "design".
Nova sells one too, but with a short 2MT. It was about $30 but looks like it's gone up: https://www.amazon.com/5016-Tailstoc.../dp/B0064JJ49YQuote:
Originally Posted by Kyle Iwamoto
Seems to work fine with the short taper.
A lot cheaper than the one from Best Wood Tools, but his stuff is always well made. https://bestwoodtools.stores.yahoo.n...pihetachr.html
I also have a less expensive one made from aluminum which works fine. I wish I could remember who made it.
JKJ
I have the Nova one JKJ mentions. It is ideally designed for the Nova live center, but I guess it could be used straight in the tailstock. I have never tried it that way though. In the live center, it is especially nice because you can spin the work piece to check true. Just be careful you don't unspin the work piece in the process. I like it.
Oneway has an adaptor so you can mount your chuck on the Oneway live center. It's part #3941-222 and runs about $45. I use it to center bowls perfectly in the donut chuck. Just remove the chuck from the headstock with the bowl still attached. Put the appropriate size donut over the tailstock, screw you chuck on to the adaptor and live center. Then move your tailstock up to mate up with the faceplate of the donut chuck. Secure the donut ring with bolts and remove the chuck. The bowl is now centered in the donut chuck. This technique would also work great with a vacuum chuck, if I had a vacuum chuck.
I also use the adaptor for turning segmented hollow forms in two halves and then joining them together but that's another discussion.
Vermec sells a dedicated threaded live center. https://www.vermec.com/store/p33/Thr...evolving_.html
I purchased a live center from PSI and it works great.