centering a bowl with a vacuum chuck

Re: centering a bowl with a vacuum chuck

Joel Hunnicutt

>I was going to tell you to be sure and mark a center point on the bottom and use the tailstock. Not sure why that isn't working, unless the vacuum is pulling the bowl off center. The other thing to try is one of those morse tapers that is threaded to accept a faceplate. I just screw the chuck or faceplate onto it and fit the morse taper in the tailstock to center.

Re: centering a bowl with a vacuum chuck

Arch

>Hi Tom, One method is to buy or make a tailstock chuck adaptor threaded same as the head spindle with M.T. that fits the tail spindle. Remove the bowl from the headstock with its chucking device attached. Screw it to the tail-adaptor and bring the bowl up to the vacuum chuck. Remove the adaptor & tailstock from the bowl now centered on the vacuum chuck..... I hope, Arch

Re: centering a bowl with a vacuum chuck

Bill Howatt

>How perfect is your definition of perfect? I usually tolerate a small amount of a wiggle when finishing off the bottom.

Are you sure your tailstock is in perfect alignment?

Bill

Re: centering a bowl with a vacuum chuck

John Trant (aka Boxes-n-Bowls)

>The method you use is good enough. No bowl is perfectly round after you turn it and certainly not after being sucked onto a vacuum bell. As long as you are close to square at the base (don't worry about the rim wobbling) then you can remove the tenon, flatten the base, and sand.

John

Re: centering a bowl with a vacuum chuck

Robert Simmons, Atlanta

>I picked up a #2MT that has the same thread as my lathe spindle. Either a faceplate or chuck will thread onto this adapter when it's mounted in the tailstock making bowl centering on the vacumm chuck pretty easy. I think I paid about $20 for it at HH, worth every penny.

Robert

Easy way,or hard way?

Bob Hackett

>The easy way is to just use the corner of the toolrest to act as a pointer and watch the gap.If you turn the vac on lightly enough and just move the rounded and polished end of the rest up to the work as you spin it by hand then it can center it automaticly for you.

The hard way is to buy a dial indicator and a magnetic base.The indicator will do two things,it will tell you how may thousands of an inch you are out at any point on the work.The other thing it will do is to prove that nothing made of wood stays round across it`s exterior surface for long.You will be amazed to see how far off a bowl can be,especially when under the stress of the vac chuck.

I have used both approaches(the indicator only comes into play when a precision fit is required)and recommend using the toolrest at the point you intend to cut.If the foot is being worked,don`t sweat the rim being off,etc.

For a real treat,try putting a bowl you`ve used for a year or more in the chuck.Something about going thru a full cycle of seasonal changes puts the whammy on woods like apple and oak to name just two.

Mainely,Bob

Re: Easy way,or hard way?

Tom Blahnik

>Thanks for everyone's input. I like the idea of getting a #2 morse taper with a threaded end to match my shaft so I could flip the bowl and attach it on the tailstock with the faceplate. It seems that even with the reference point in the middle of your work, when you push it up against your vacuum chuck it can move a little. It makes since that with it still connected to the faceplate that you would get a true center.

Robert, what is the HH store and what sizes were available? The shaft on my lathe is 1 1/4".

Thanks everyone, Tom

Re: Easy way,or hard way?

John Lucas

>Tom

You can get the reverse adaptors from www.bestwoodtools.com Even with these the piece will be off little, probably due to the bowl changing shape after you turn it. That adaptor and bringing the tailstock up to the original center point have been the closest to perfect for me.

Re: centering a bowl with a vacuum chuck

Ric Erkes

>Another thing to consider is how thick the cushion is on your vacuum chuck. If it is too thick the cushion will allow the bowl to wobble off center.

Ric

HH

Robert Simmons, Atlanta

>HH is shorthand for Highland Hardware here in Atlanta. I live about 5 miles too close (or too far away, depending), so it's easy for me to drop in. YOu can check the catalog or website and probably find the adapters for several different spindle treads. Other folks sell them as well, but that's were I found mine on the shelf. No waiting - I like that.

Robert