How to deal with severe tear out. Chunk out?

[Nathan Roper]

I've got some box elder that is ready for its second turn and it seems it is "chunking out" on the inside of the bowl. Like real bad tear out in the end grain. I assumed it was from technique and/or dull tools so I sharpened and tried a couple times to clean it up. Its now happened on a couple other pieces from the same tree. I've got "lots" of experience first turning green wood but a lot less on final turning and could use some pointers. What techniques can I try to get a clean cut so I don't need to start sanding with 15 grit?

I've tried a bowl bottom gouge, regular bowl gouge, and a scraper.

 

[Darryl Fective]

That's got to be frustrating. I'm no expert, but I'll offer my ideas...

A scraper is probably not ever going to give you good results on soft wood that tears out easily. What kind of grind on your gouge(s)? Maybe a sharper point and slow light cut would help. Also, rim to center when cutting inside (center to rim outside) for grain support. (cutting downhill)

I try (but don't always) to remember to make some "practice" finish cuts before I'm at the desired thickness, especially with wood that I haven't turned. If you get in a hurry and hog out until you're close, then find the wood is ripping more easily than cutting, there's not much room for experimenting and correcting the issue.

Best of luck with it.

 

[Dave Landers]

As Darrel said, scraper probably isn't going to help. Maybe once you get most of it cleaned up with a gouge, a light pass with fresh bur at a shear angle might clean up the last of it (or could make it worse).

Freshly sharpened gouge. Very light/shallow cuts. Will take multiple passes to get to the bottom of the tear out (and multiple sharpenings). Might need some experimenting with grinds or tool presentation angles (every piece of wood is different).
Often a smaller diameter gouge helps - less metal bumping into the wood (heel of the bevel) and a smaller edge engaged in the cut.
Wetting the wood can help - swells the fibers and helps them support each other thru a cut. Also sorta lubricates the gouge which also helps.
Similarly, shellac or sanding sealer or even oil can stiffen the fibers (use something compatible with your planned final finish - shellac is pretty universal).
Problem woods like this sometimes take a bunch of experimentation to find the thing that works. On your next one(s) start that experimentation/practice early, before you get too close to final shape.

 

[robo hippy]

I haven't turned much box elder, but I believe it is one wood that tears out more than many. A flat scraper would most likely make it worse, not better. A shear scrape would work better, and I have one video dedicated to that on You Tube. If the wood is dry, try spritzing a little water on it, let it soak in for a minute, then, taking very light cuts, turn the wet stuff off. I used that technique with some very dry koa. It took a couple of times to remove the tear out to 'sandable' level.

robo hippy

 

[Gary Beasley]

Ive fought off tearout in semi punky wood by soaking in several coat of lacquer and allowing it good dry time. After that a good sharp gouge and a negative rake finished up.

 

[hockenbery]

I've got some box elder that is ready for its second turn and it seems it is "chunking out" on the inside of the bowl. Like real bad tear out in the end grain. I assumed it was from technique and/or dull tools so I sharpened and tried a couple times to clean it up. Its now happened on a couple other pieces from the same tree. I've got "lots" of experience first turning green wood but a lot less on final turning and could use some pointers. What techniques can I try to get a clean cut so I don't need to start sanding with 15 grit?

I've tried a bowl bottom gouge, regular bowl gouge, and a scraper.

I assume this is a bowl hollowed through the face grain.
It’s all about sharp tools riding the bevel(floating it over the cut surface.
I grind the heel off a gouge to let it ride the bevel easier

Using a small gouge on the first inch inside is a big help.
I return a dried, warped, sycamore bowl in my green wood demo. It is a similar density to box elder.
You can see how I do it. Look at the dried wood demo

Working with green wood

The August 2015 AAW JOURNAL has great article by David Ellsworth on working with green wood. This is followed by 11 marvelous ways turners turned cracks into features. One of David's themes is that the deck is stacked against newer woodturners successfully working with wet wood. Might be a nice...

www.aawforum.org

 

[odie]

Another consideration, is to keep the tool rest close to the wood, where better stability and control is more inherent. This usually means getting a curved "inside" tool rest for this purpose.

-o-

 

[hockenbery]

One other thought. Don’t let the tool bounce around. Cutting the uneven surface needs to be done slowly taking off the high spots first then gradually cutting a wider region as the high spots are gone.

My first step in returning a dried bowl is to flatten the rim.
This balances the piece a lot for weight and gives you a flat surface to begin the entry cuts for hollowing.

 

[Rusty Nesmith]

Another thing I didn’t see yet is direction. You will get a lot less tear out cutting from the rim to the base inside and the base to the rim on the outside. I always sharpen my tool before the final finish cut.

 

[Nathan Roper]

Thanks for the thoughts and ideas. Yeah, its a face grain bowl and I have been cutting from the rim down to the center. The problem areas are closer to the rim than the center on the one medium size bowl I've been thinking about. I intended to take a couple pictures last night but didn't get to the lathe.

I will try spritzing with some water to see if that might help. I've also got some shellac I could test out. That dries real fast so it wouldn't be horrible to wait on. I would like to get this technique figured out so if I end up losing one of these bowls to do that I'm okay with it. Sacrificing one for the greater good... I do feel like my tool rest is pretty close to the wood, its as close as it's going to get. I do pretty good at keeping the tools from bouncing around so I also don't know that is an issue on this one but is something I've had to figure out in the past.

As far as my gouge grind, I'm not sure what its considered but I have the wolverine set up and use a 2" protrusion on the vari-grind and 50* set up angle. I use that "set up" for all my bowl gouges. I probably ought to be more consistent about grinding down the heal afterwards. On my bottom of bowl gouge I have the platform set to 50* and then just lay the tool flat on the platform and touch up the end.

 

[hockenbery]

problem areas are closer to the rim

. I do pretty good at keeping the tools from bouncing around so I also don't know that is an issue on this one but is something I've had to figure out in the past.

If you have a small bowl gouge (3/8 bar) try that.
Light cuts are needed here. A big cut will pull some fibers attached to that big shaving before they are cut.
If you look closely at my video you will see me back off on the out of round hollowing to find a shallower cut.
The tool want to start bouncing with the bigger cut.
The smaller gouge can only take smaller cuts.

 

[hughie]

The Blackwood I turn often has a multi directional grain structure, and it can be prone to divot out. So for me it's time for some serious sharpening of the gouge instead of the usual touch up, small cuts at high speed and on occasion CA to most trouble some areas and leave to thoroughly dry. I have a tungsten gouge tip that I keep for the difficult pieces as its edge holding capability is brilliant. But often its all about technique more than anything else.

 

[odie]

One other thought. Don’t let the tool bounce around. Cutting the uneven surface needs to be done slowly taking off the high spots first then gradually cutting a wider region as the high spots are gone.

My first step in returning a dried bowl is to flatten the rim.
This balances the piece a lot for weight and gives you a flat surface to begin the entry cuts for hollowing.

^^^^^These are two good points.....

My S.O.P. is very nearly the same thing, with the following differences: I first bring to round the waste block, and then the side of the rim. As with Al, what's left usually gives less inherent vibration, plus it gives a round running surface at the rim with which to apply the Oneway bowl steady. For me, I find the Oneway bowl steady almost always makes a difference in bringing to round the rest of the interior and exterior specifically because of reduced inherent vibration......plus pays additional benefits for shaping and finish turning as well.

-o-

 

[Roger Wiegand]

Sharp from the grinder may not be adequate, try honing with a ~600 grit diamond. Then make super light cuts while holding the tool very firmly downward on the tool rest. Think "floating" not "rubbing" the bevel, as a couple of our pro demonstrators are fond of saying.

 

[Mike Johnson]

About as much pressure you put on your face when shaving with a sharp new blade.

 

[Alan Weinberg]

turning faster may help also. In addition to the other ideas such a shear scrape, sharp tools, and lacquer. Supported cuts.

 

[Scott Morgan]

Another thing to try is to go with a smaller gouge (1/2") with a 45 degree bevel. You will only be able to use this angle of bevel from the rim to where the side starts to transition to the bottom. Take light cuts moving down in 1-1.5" sections. Try it when wood is dry first, then wet. If it still doesn't work use oil to soak into the wood. If you use oil you will also have to wet sand with oil, which can be good as the scarf you get from sanding will fill small tear out sections. Dale Larson has an excellent video on youtube of how he turns his bowls. He oils everyone of them on the lathe.

View: https://www.youtube.com/watch?v=ELpJ0_9NOok

Good luck!

 

[Peter D'Attomo]

I'm familiar with box elder and it is soft. What worked for me is a coat of wood hardener which stiffens the grain. Sanding is also an issue. Again with light cuts and shear scraping.