Chatter/vibration in bowl turning

Re: Chatter/vibration in bowl turning

TDaniel

>Greg, you really need a lesson to get a handle on this problem. You need someone to watch what you are doing and help you make an adjustment. A few dollars spent f

Re: Chatter/vibration in bowl turning

TDaniel

>Greg, you really need a lesson to get a handle on this problem. You need someone to watch what you are doing and help you make an adjustment. A few dollars spent for some coaching will put you way ahead.

TD

Re: Chatter/vibration in bowl turning

Peter Teubel

>I have found that the Oneway bowl steady works very well at reducing the vibration. Its always parked on the backside of my lathe, ready to swing into action whenever I turn dry bowls.

Re: Chatter/vibration in bowl turning

bill hale

>Greg

I turn mostly dry wood and have very little problem with chatter. As said get a lesson and address your problem. Consider your tool angle and how you address the tool to the wood. Do not over reach a small tool and loose control of the cutting edge. Most of all slow yourself down and be sure you are holding the tool tight against the rest. Holding the tool tight to the rest and the tool handle tight against your hip may solve most of your problem. Good luck.

Good turning and be safe

Bill

Re: Chatter/vibration in bowl turning

Barry Turner

>Greg, I'm having the same problem you are......as recently as last Saturday. I was turning a small (4"H X 7"D) bowl from Jatoba (Brazilian Cherry) and was having problems with smoothing the bowl's interior. I was using a Crown extra heavy (1/2"thick) half-round scraper to clean up after my 3/8" bowl gouge. I was getting chatter. I sharpened the tool. Didn't help. I honed the tool. Still didn't help appreciably. I was getting whispy, feathery shavings, but still chattering. I finally settled on using a razor-sharp Sorby half-round scraper in a smaller size, held at about a 45-degree angle so that I was shear-scraping. Then I power sanded with 80 & 100 grit and switched to a progression of grits in regular sandpaper. I'm still not sure of the exact source of the problem, only that I found a solution that worked for me. This time.

Re: Chatter/vibration in bowl turning

e

>in addition to all that other's have offered, i'll include one more 'vibration story'.

i don't know when it begain but i also started to experience chatter when attempting the final cut, or at least that's when i most noticed it. i checked the lathe, the gouge, the wood, the grinder, my technique, etc. but couldn't figure out what i was doing wrong. finally, i just thought it was me ... senility or something ...

however, i had a chance to turn on a friends lathe (exact setup as mine) and had no chatter. this gave me the idea to start checking my equipment AGAIN!

long story=>short. it was the chuck ... the adaptor wasn't fully seated ... i've always increased the speed for the final cut and, thus, this also increased the vibration from the unseated adapter.

it still amazes me how long it took to discover this simple explanation...

Re: Chatter/vibration in bowl turning

Duane

>I find that chater as you discribed may come from one or more of these problems #1.Not having thick enough wood to suport the type of cut you'r trying to make.#2 Using to big of cuter (gouge or scraper)on thin walls will produce chater.#3Using dull tools.#4 Tool at the wrong angle.Best advice.Take lessons from a pro,or ask someone at next months club meeting to help. Good luck. Be safe.

Re: Chatter/vibration in bowl turning

John McAtee

>Greg, once a bowl is roughed out, the wood is going to move and the bowl will go out of round - more so if turned wet. The out-of-round condition can cause tool chatter and vibration if not dampened. If you have the base in a chuck or face plate, you can affix a waste/scrap piece covering the entire bowl opening with two-sided tape and then run the tailstock into the scrap to lessen the vibration. After truing up the outside of the bowl, having a bowl steady such as the Oneway will dampen or eliminate most of the vibration while you finish the inside. Having very sharp tools, a steady hand and making careful cuts is also key.

Re: Chatter/vibration in bowl turning

Doug Trembath

>Greg, TD has the best advice, in that it helps to have a good teacher help you understand and eliminate the technique errors we all develop as we try to learn on our own.

This phenomenon is one that I include in a bowl turning lesson, or demo, by purposely creating this type of result by using the wrong technique, then demonstrating the proper method to remove it. Then I have the student do the same thing. This approach shows them both how the problem is created, and then how to fix it.

As the bowl turns, you encounter the transition point from end grain to face grain, and if you apply too much bevel pressure, the tool is forced away from the plane you want to achieve, leaving a bump of material higher than that you desire. As it goes around, the cumulative cut/bounce becomes a series of bumps, and results in your chatter and vibration.

Here's the solution:

1. Anchor the gouge by pressing down onto the rest, not allowing the tool to rise or scoot laterally, and maintaining a controlled path through the cut.

2. Assuming you are using a swept back grind on a bowl gouge, rotate the gouge just a little more to the left, and orient the cutting edge to just above the center of the flute on the left wing. (As you gain proficiency, you can rotate the gouge until the flute is level, and use the side of the swept back edge, ala David Ellsworth.)

3. Back up and start your cut prior to the initial point of chatter. You must remove the initial bump without creating another. The key is to cut out the bumps and leave a nice even surface.

4. Take a very light cut with almost no bevel pressure, since this is the primary cause of the problem in the first place, but remember you must cut deeply enough that you remove the bumps entirely. Control the gouge with the downward pressure on the tool rest, and a steady but light grip on the handle. I've heard some teachers recommend you hold the gouge handle like it was a bird. White knuckles are a no-no.

5. As the cut progresses, concentrate on not "levering" the wood out, but float the tool through the cut, and allow the cutting edge to do it's job, that of cutting and wasting the wood away in it's own time, instead of horsing the tool through the cut. Once they understand and apply this technique, everyone I have shown it to has improved their ability to reduce this problem greatly.

When applied correctly, the bowl gouge can take a very aggressive cut and still float through the cut without bouncing. It's all in allowing the tool to make the cut instead of forcing it along.

Bowl steadies are one way of reducing and or eliminating the problem, but better technique wins every time, impresses your friends, and allows you to use the extra money for other things.

Again, just my opinion, and your mileage may vary. Email me if this isn't clear enough.

Doug Trembath

Studio in the Woods