Too green for once turned?

[Ross Berning]

I’m on my third neighborhood tree that’s going from growing to lathe in a few days. The blanks are so green they’re throwing water and are often visibly wet. Rough turning goes great but for blanks over about 6” the blank is going out of round while still shaping the outside. This has made once turned bowls very difficult. Bowls are mounted on a vicmarc screw chuck. Vibration is not an issue.

Does this sound right? Should I let the wood dry a bit more before trying a once turned or am I missing something?

 

[Lou Jacobs]

Sounds perfectly normal to me. You’re dealing with wood that was cut in spring/summer so it’s full of water. Turn the outside quickly, sand and then don’t go back. Then turn the inside and do the same. It’ll keep moving, but hopefully you’ll like the final shape. Be sure to get walls even thickness to minimize the chance of cracking.

 

[robo hippy]

No such thing as "too green for once turned bowls". I mount my bowls with a drilled recess, on my bigger Vicmark chuck, it is 2 5/8 inch diameter. Never have problems with the outside moving as I turn it. For the inside, with larger bowls, like 12 inch diameter or so, I turn it down in stages. Having the ability to turn the inside with one hand on the gouge is huge here. Too much bevel rub, and the bowl can go out of round. Some times I think that if I am turning at very high speeds, that can elongate the bowl as I turn.

robo hippy

 

[hockenbery]

blank is going out of round while still shaping the outside. This has made once turned bowls very difficult.

As you progress you will be working faster. And see less movement
Also concentrate on light bevel pressure
You can cut an out of round shape with too much bevel pressure, too fast a feed rate, wrong cut angle.


What I do with NE bowls is to get the rough shape out side.
Put it in the chuck
Do some hollowing a couple inches below the rim but leave the wall 3/4 thick
This hollowing releases sone tension which can cause movement too
Finish turn the outside - I use a pull cut.
Then cut an even wall 3/16” thick or so.

 

[Jarrod Dahl]

Hi, new here on this forum. For side grain, green is mostly what I turn and I don't think it can be too green. I have this problem sometimes too but mostly on the inside. I suspect that the tool is not sharp enough (or cutting angle is not right) or moving too fast across the surface. Side grain and end grain cut differently and when face turning you will have both to deal with. I'd start by sharpening and slowing the tool down as you cut across the surface and take thinner roughing cuts. See if that helps.

 

[Darryl Fective]

A blank shouldn't go out of round while still solid, so if it's while you're still shaping the outside, it's likely you need a sharper edge. Rough it down to (near) shape, then sharpen. Then make a final pass (or 2) with a light cut and slow feed rate.

 

[Dean Center]

No such thing as "too green for once turned bowls". I mount my bowls with a drilled recess, on my bigger Vicmark chuck, it is 2 5/8 inch diameter. Never have problems with the outside moving as I turn it. For the inside, with larger bowls, like 12 inch diameter or so, I turn it down in stages. Having the ability to turn the inside with one hand on the gouge is huge here. Too much bevel rub, and the bowl can go out of round. Some times I think that if I am turning at very high speeds, that can elongate the bowl as I turn.

robo hippy

Reed, can you explain what you mean by 'turn the inside with one hand on the gouge'? Obviously, one hand on the gouge is pretty plain, but which hand, why, what's the other hand doing, how does that make a difference, etc?

Also, I'm assuming you and Al mention too much bevel pressure and high speeds because it's generating heat. Is that correct?

 

[Jim Reynolds]

I highly recommend the book Turning Green Wood by Michael O'Donnell. He mentions wetting down the surface if it is getting dry.

 

[Rusty Nesmith]

Sounds normal to me.

 

[Brian Gustin]

Reed, can you explain what you mean by 'turn the inside with one hand on the gouge'? Obviously, one hand on the gouge is pretty plain, but which hand, why, what's the other hand doing, how does that make a difference, etc?

Also, I'm assuming you and Al mention too much bevel pressure and high speeds because it's generating heat. Is that correct?

I'd assume he means one-handed as in you hold tool handle in whichever , usually dominant hand that you usually use to control tool, with no pressure applied to tool on tool rest - It forces you quite literally to take fine, slow, smooth cuts with no bevel pressure whatsoever (applying bevel pressure one-handed, tool is going to bounce all over the place!) I taught myself to do that when I start the inside of a natural edge bowl other than I do have my left hand hovering above the tool to stop it bouncing out of control if I do happen to push a little too hard on bevel. You just position tool to let the cutting edge do its job and cut as fast or as slow as it wants to. Takes a lot of practice to do when you're doing interrupted cuts like natural edge bowls, but mastering it can go a long ways to not only knowing when the tool is already too dull to cut nicely (it'd otherwise seem to cut fine if you applied pressure though) , but also forces you to learn the finesse cuts. as for bevel pressure it isn't so much generating heat as it is the tool bouncing off the wood - Higher speeds can help a lot on interrupted cuts also as it leaves less time for the tool to be cutting air, so you aren't tempted to push the tool in to make it cut faster. At least that's my take on it, and what I've learned myself through trial and error (No mentor to tell me otherwise!)

 

[Roger Wiegand]

What everyone else said, but just to emphasize, do the inside in stages. No more than an inch at a time, take it down to final thickness and finish surface and then don't go back.

 

[robo hippy]

I think I explain the 1 handed push cut in my videos some where. A quote I use a lot is from some unknown skew master who said, "the bevel should rub the wood, but the wood should not know it". With the 1 handed push cut, you can't put too much pressure on the cutting edge. When turning both the insides and outsides of bowls, the handle hand does all the work. The other hand just rests on the tool shaft. When you use a lot of pressure on the shaft, you start to get a lot more bounce in your cuts, and your surfaces get a lot more bumps and humps in them rather than the smooth line. This may also be part of the difference between roughing cuts and finish cuts. With roughing cuts, you can use a lot of force. After all, you are just removing mass. However, for the finish cuts, you can be pushing too hard. This can make the bevel rub too hard, and also cause more tear out. There is no way to measure the difference other than lots of practice. With side grain bowls, you always get some bounce as you go down the walls, both inside and outside. This comes from going with and against the grain, 2 times each revolution. If you have a heavy hand, you get a lot more bounce, which is part of why if you stop and restart a cut half way down a bowl, you frequently get a line. Having a light touch greatly reduces this run out. Kind of like a hard axle on a wagon and every bounce from the road goes straight to your butt. If you have shock absorbers, then the shock is greatly reduced. Hope this makes sense. That 1 handed push cut is essential for bowl turning. Well, all turning actually.

robo hippy

 

[Dean Center]

Thanks, Reed. Good information, clearly shared.

 

[Ross Berning]

Thank you all, after going over everything that’s been said I looked differently at what I was doing wrong. Suspecting the bowl was not steady enough on the screw chuck I brought up the tailstock which greatly helped. The face of my blanks are straight from the chainsaw and apparently sometimes are not flat enough. I’ll pay more attention to that and use the tail stock more as needed.

I appreciate everyone’s time, and as robo hippy mentions I’m almost certainly using too much force on inside finishing cuts. I’ve been rough turning dozens of blanks and need to learn more finesse when switching to finishing cuts.