Need help with unstable lathe/blank: Updated with pic!

[Aaron Buys]

I have a nice piece of dried cherry on the lathe right now. Its about 7 inches thick and 9 inches in diameter. I'm presently shaping the outside but the bowl doesn't seem to be "settling" on the lathe allowing me to make nice easy cuts. I've got about half the diameter gone on the base of the bowl as I work my way up the sides but I still feel like I'm fighting to keep the tool steady even on areas that are obviously round already. The top of the bowl blank which will eventually be turned away is a bit lopsided as one side is maybe half an inch higher than the other. I'm guessing I'm getting movement of the lathe as a whole due to the out of round area at the top but I can't seem to stop it and I can't go any slower. I'm running this in a midi lathe mounted to a heavy wood stand with a weight rack underneath. I've tried adjusting the speed up but this just causes the whole thing to shake even more. On the weighted bench I have a 60 pound bag of cement mix along with about 6 large bowl blanks and a few cans of paint. I am getting close to having the outside shaped how I would like but the blank is really fighting me. Any suggestions on how to get rid of this? More weight?

Thanks!

[Kyle Iwamoto]

Ned a couple bits of info. Between centers? You can adjust the blank to be more "balanced". I usually use a parting tool and lop off the ends, if the length differs a lot, making it lopsided that way. If the length is lopsided, no amount of turning the outside will get rid of the unbalance. If you're using a faceplate, turn off the end. Use the tailstock to help keep things tight.
Is the wood punky? if it's punky in spots, that's tough.
Tool nice and sharp? Should have put that first.

I feel for you. I turned a bowl that size on my Jet Mini. The wood has got to be balanced when turning something that big on a small lathe. Take your time. It will get balanced.

Good luck!

[David E Keller]

Not sure I completely understand your situation, but if the top of the blank is out of balance, I'd sneak up to the top and get rid of some waste to bring things more into balance. Doing that also allows you to see what will be the top of the form, so you can plan your curve a little better. Photos might help if your struggles continue. Good luck!

[Scott Hackler]

I would also start to do a rough hollowing. By removing a lot of the inside, you will reduce the mass and the movement should slow down or stop all together. I would guess that the moisture inside is denser on one side than the other.

[Aaron Buys]

Sorry I should have been more clear. The piece is mounted to a faceplate but the faceplate surface is uneven and therefore poorly balanced the best I can tell. I had to mount the faceplate a little cock-eyed but made it as flush as possible. Apparently I should have had a flatter surface to begin with. The bottom of the bowl (outside) is all well rounded with a tenon in place ready for placing it in the chuck. The wood is very dry and there are no punky sections or odd grain/knots. Tool is sharp sharp.

Should I remove the faceplate, mount it in the tenon and try to true up the top, and then reattach the faceplate?

[Bill Bolen]

I've run into this a few times. I believe it has a lot to do with how it has been stored. Both of my trouble pieces were fresh cut from logs stored outdoors. I believe that the wood in contact with the ground held more water than the upside. In both cases I gave up, anchor sealed the end grain and stored in the shop for a month or two. Once evenly dried they turned just fine.

[Kyle Iwamoto]

If you have a tenon turned, mount it in the chuck and go! Once you got it in the chuck, you don't need the faceplate. I use spur drives to avoid this problem. Start between centers is a little easier, IMO.

[John Keeton]

Aaron, you have received some good replies, and I will offer a suggestion not really related specifically to your question. The dimensions you stated - 7" deep x 9" in diameter - are going to produce a very odd shape and may be difficult for you to achieve a fair curve on the bowl. I would think cutting the blank in half - 3.5" deep - might produce a better form, and may give you two bowls! I would probably reduce substantially, the off balance issue.

Just a thought.

[Bernie Weishapl]

Aaron if you faceplate is not sitting flat you are going to have problems being out of balance. I always mount between centers and face off where the faceplate will mount. If you have a tenon as was said mount it in the chuck. True up the outside and then start hollowing the inside.

[Steve Schlumpf]

I agree with turning the blank around and get rid of the uneven top of the bowl! Make sure that you use your tailstock for support!

Also agree with John - once you have the top cleaned up - check to see if it wouldn't be feasible to create 2 bowls out of the blank!

[Reed Gray]

Not having it flat on the face plate is the most likely problem. With the lathe off, grab hold of the piece and see if you can shake/move it. If it moves at all, that is the problem. Some times if the mounting surface is just slightly off (less than 1/8 inch) and you have lots of screw holes in your face plate, you can mount it securely enough to get a good grip. Tighten up the screws like you do lug nuts on a tire rim. 12 o clock, then 6, then 9, then 3, then go around and tighten them up again. To get a flat surface, I have used a large forstner bit and my drill press. I have also used a small forstner bit and the depth stop on the drill press. Drill the center one first, then drill around it.

If you have it mounted between centers (drive spur on both headstock and tailstock, or face plate and tailstock) keep it there just long enough to form a tenon or recess, then reverse it, tighten the chuck first, then bring up the tailstock to steady it.

robo hippy

[James Combs]

...Should I remove the faceplate, mount it in the tenon and try to true up the top, and then reattach the faceplate?

Aaron these guys have given you lots of good advice but this may not be real clear from what has been said. You should NOT have to go back to the face plate after you have the tenon cut and have reversed the blank into a chuck. Leave it in the chuck and turn the rest of it from there. Even if you cut it in half for two blanks you only need to re-chuck up the half with the tenon and finish the vessel. Chuck up the second half between centers, cut a tenon on one end and then put it into your chuck and finish it like the first one. I save myself some time by chucking my spur center up in my Nova chuck, I don't have to remove the chuck, the center fits nicely in the small center hole formed by the chuck jaws, I then turn a tenon between the centers, on occasion if balance is real bad I will round the blank and even face off the ends to improve balance. I then remove the spur from the chuck, re-chuck the new tenon into the chuck jaws and finish the vessel from there. I will use the tail stock to steady the blank as long as I can. Hope this is helpful.

[Aaron Buys]

Well it was indeed the extra mass on the top of the bowl. I turned it around in the chuck and took off the excess and it smoothed right out. Lesson learned =). Here is what I am left with after all my struggling. Completely opposite of what I had in mind originally but I suppose its something. Any suggestions on how to finish this off?

[John Keeton]

Aaron, is it hollowed out any? If not, and if you want this form, I would suggest smoothing out the concavity of the curvature. There appear to be a couple of areas on either side of the middle that flatten out a bit.

Should make into a nice vase form!

[Aaron Buys]

Aaron, is it hollowed out any? If not, and if you want this form, I would suggest smoothing out the concavity of the curvature. There appear to be a couple of areas on either side of the middle that flatten out a bit.

Should make into a nice vase form!

Nope still solid all the way through. I like your idea. Would you leave the base the size it currently is and just deepen the concavity then?