Chattering gouge problems

[Prashun Patel]

I'm turning a green sugar maple crotch bowl now that is giving me an odd problem. I've rough turned it to completely round, but the gouge continues to skip and chatter a little as if I'm still out of round.

My theory is that the wood is so green and wet that it's easy for the gouge to dig in for a portion of the cut, and then to subsequently follow the irregularity. I've tried all kinds of speeds.

I've also been using a heavy bowl scraper to clean up the irregularity, but even IT seems to chatter. I've not had this problem with other, more dry bowls.

As a result, I have to take extremely light, shearing passes which is becoming tedious.

Any ideas why this is happening?

[John Keeton]

Prashun, I would say the wood is still moving, and I would touch up the edge on my gouge. I sometimes get a little chatter when my edge starts to fail.

[Michelle Rich]

If the wood is wet it is changing shape. I don't know if you have it on a faceplate or a chuck, but I would CHECK IT FOR TIGHTNESS. Screws come loose in wet wood. Chucks lose their grip..the wobble could be from this..also as John said, sharpen your gouge...Did you change anything else? If so check that too.

[Prashun Patel]

Thanks.

I am using a faceplate with 1" spax screws. It's tight. That was the 1st thing I checked for.

It does get a little better with my gouge just off the grinder. The thing that gets me is the SCRAPER does this too. I never (as if I've done this a million times) have this prob with the scraper.

[Bernie Weishapl]

I have had this happen with green wood and certain species are worse than others. The wood is moving even as you cut. I am guessing that is your problem if everything else checks out. I don't worry about it. I get it roughed, round over the rim edges and put away to dry after coating with anchorseal.

[Kim Ford]

I agree with what has been said, and have experienced this condition when I have a blank that has hard and soft spots, some times from knots or whatever.

My theory is that the pressure you are applying to the chisel cuts deeper in the soft section than in the hard which starts an unevenness that then maginifies.

If this is what is happening then make sure the tool is sharp, the presentation is correct, (I usually change to a shearing cut), try not take too much of a cut untill it is round again, and then focus on pushing or holding the tool down on the tool rest while moving it during the cut. It seems to work for me.

I had a blank on last night that had a very soft spot and it started to happen and this fix worked very well. Hope this helps.

[Prashun Patel]

Thank you everyone.

[Reed Gray]

There is always a little 'bounce' when turning bowls. Mostly, I think, it is the difference between when you are cutting end grain and side grain. The tool cuts each grain type slightly differently. The more you fight the bounce (as in white knuckle death grip) the worse it gets. With crotch wood, the grain goes in more directions than just end grain and side grain. Look at the tear out to see what I mean. It does take a lot of practice to 'feel' the wood and tool as the cutting progresses. Your hand on the tool steel and/or tool rest does nothing other than gently hold the tool down (a job the spinning wood does very well actually), and your hand on the handle does all the work. Like my martial arts instructor told me, "10,000 more times!" "But teacher, that is what you said last time!" He smiled and walked away.

As to the wood moving, any wood will 'adjust' to having mass removed, no matter how dry it is. Movement isn't too much of a problem when turning green wood till you get to less than 1/4 inch, and then it can move a lot, and move really quickly. This is when you use the turn in stages method, where you finish turn the inside in stages or maybe 1 to 1 1/2 inches, then go another 1 to 1 1/2 inches. You can not go back to the rim for a final cut because it has moved too much.

If you are rough turning to dry and then return, then don't worry about it. Rough turning doesn't have to be pretty.

robo hippy

[Ken Fitzgerald]

Reed,

My martial arts instructor in Bend, OR said the same thing and if you said, "I've already done it 10,000 times".....he'd look at me and say "So? 10,000 times more".:o


There is always a little 'bounce' when turning bowls. Mostly, I think, it is the difference between when you are cutting end grain and side grain. The tool cuts each grain type slightly differently. The more you fight the bounce (as in white knuckle death grip) the worse it gets. With crotch wood, the grain goes in more directions than just end grain and side grain. Look at the tear out to see what I mean. It does take a lot of practice to 'feel' the wood and tool as the cutting progresses. Your hand on the tool steel and/or tool rest does nothing other than gently hold the tool down (a job the spinning wood does very well actually), and your hand on the handle does all the work. Like my martial arts instructor told me, "10,000 more times!" "But teacher, that is what you said last time!" He smiled and walked away.

As to the wood moving, any wood will 'adjust' to having mass removed, no matter how dry it is. Movement isn't too much of a problem when turning green wood till you get to less than 1/4 inch, and then it can move a lot, and move really quickly. This is when you use the turn in stages method, where you finish turn the inside in stages or maybe 1 to 1 1/2 inches, then go another 1 to 1 1/2 inches. You can not go back to the rim for a final cut because it has moved too much.

If you are rough turning to dry and then return, then don't worry about it. Rough turning doesn't have to be pretty.

robo hippy

[Prashun Patel]

Reed, I see exactly what you mean. There is definitely a lot of grain switching in this piece vs. the few others I've turned. Anyway, I'm able to compensate with lighter touches. I love the learning curve!

Ken, I love my two-handed sword - er EHD Sorby scraper. Weilding that tool makes me feel like a real man.

[Ken Fitzgerald]

Prashun,

I am a rather good size guy and yet, I typically use two fingers on the handle.....and very little pressure to hold it to the tool rest.

The extra mass in that thing makes it a real dream to use compared to some of my other thinner, smaller scrapers.

I hope you find it easy to use.

[John Keeton]

.....and very little pressure to hold it to the tool rest.I think this is the key. When I first started turning, my tendency was to hold the tool to the wood. The wood moves, and thus the cut moves. That is when "the bounce" starts!

The wood is still going to move, and some bounce may be unavoidable. But, if the effort is directed toward keeping the contact edge of the tool in constant position as it moves around the curve of the piece, one is far more likely to get a smooth and concentric cut.

[Scott Hackler]

Ken, I love my two-handed sword - er EHD Sorby scraper. Weilding that tool makes me feel like a real man.


I have one of those and use it quite often. I nicknamed it the "butter knife". :)

[Prashun Patel]

But, if the effort is directed toward keeping the contact edge of the tool in constant position as it moves around the curve of the piece, one is far more likely to get a smooth and concentric cut.

I hear you. Grumbine's video was great for hammering this point home. I concentrate on finding the invisible line. It's been especially important on this live edge bowl because of the hollow space between the wings.

[Jake Helmboldt]

I hear you. Grumbine's video was great for hammering this point home. I concentrate on finding the invisible line. It's been especially important on this live edge bowl because of the hollow space between the wings.

Everyone has said what I was thinking, but I'll say it too. Richard Raffan describes it as "letting the wood come onto the tool". Pushing hard, cutting with a dull edge, white-knuckling it results in the lumpy turning. When I started out I was convinced the chuck or lathe spindle were out of round so I checked runout; everything fine. Quickly realized it was technique. Cherry seems to be really bad in this regard (or at least has been for me). But just keep working on relaxing as you move through the cut and follow Raffan's mantra.

[Ken Fitzgerald]

When you are cutting on a NE bowl or a winged bowl or a square bowl, it is especially important. You have to have faith and keep the tool moving allowing the wood to come to the tool. There in also lies the importance of those tools being sharp! Dull tools are more likely to catch and tear wood fibers rather than shear cutting the wood.

When I am using my Sorby EHD bowl scraper....I am thinking "lightly".......because that's the type of cuts I want to take and I can do it by using very little pressure on the handle and taking very light......shavings....lightly.....

At that point you are not "hogging" wood.....you are finish cutting it....light gentle cuts....

[Prashun Patel]

Amen to all of that, Jake and Ken. I turned the outside wings quite thin last night by 'letting the wood come to the tool'. This was been a great a-ha moment for me. By doing this, I was able to take longer continuous sweeps in each of the sections, and to slow down the sweep. So, I'm actually able to take as aggressive cuts on each pass as before; it just takes more revolutions... Clear as mud?

Ken, the EHD scraper is dangerous for me on the green wood. It takes no prisoners and digs in easily. I'm tempted to soften the edge, but I think I just need to practice my technique with it.

[Ken Fitzgerald]

Prashun,

Using that scraper is a matter of two things. Like all turning tools it must be sharp and presentation.

I use mine with the handle higher than the cutting tip and I want the tip to be cutting at or just above center of the bowl. This means the tool rest is a little high.

Literally I hold it with my thumb and forefinger from below the handle. I am think light cuts the whole time.