• It's time to cast your vote in the January 2025 Turning Challenge. (click here for details)
  • Conversations are now Direct Messages (click here for details)
  • Congratulations to Alan Weinberg for "Elm Burl Bowl" being selected as Turning of the Week for January 27, 2025 (click here for details)
  • Welcome new registering member. Your username must be your real First and Last name (for example: John Doe). "Screen names" and "handles" are not allowed and your registration will be deleted if you don't use your real name. Also, do not use all caps nor all lower case.

Tear out on one side

E

Edward Olson

Joined
Jan 9, 2019
Messages
22
Likes
15
Location
Matthews, NC
What are the possible reasons for tear out on one "side" only of a piece. I have nice a smooth surface going all the way around a small 4 inch'ish dish/bowl except this one "side" I've tried all tool to smooth it out but I can't get it to go away? It's green wood, if that helps.
 
Most of the time, there is tear out on two opposite sides, which reverse on the inside of a bowl. This is the end grain, which comes around twice each revolution. For 1/4 turn, you are cutting with the grain, for 1/4 turn you are cutting against the grain, and repeat... This can be greatly reduced by high shear angle cuts or shear scraping. A flat scraping cut generally makes it worse. Oh, sharpening on a finer grit wheel, like 600 grit can really help some times too. Honing works some times also.

Some times it is the wood. If your bowl is standard bowl grain orientation and you are getting tear out on only one side, it can be funny grain, or if the piece is spalted, then one side could be softer than the other which can cause more tear out in one spot rather than the others.

Picture???

robo hippy
 
Wood sealer can sometimes help overcome a difficult piece of wood that has end grain tear out. If the wood is "punky" from excessive spalting or decay you could harden the wood with a resin if it is worth the time, effort and cost.
 
Edward Olson said:
What are the possible reasons for tear out on one "side" only of a piece. I have nice a smooth surface going all the way around a small 4 inch'ish dish/bowl except this one "side" I've tried all tool to smooth it out but I can't get it to go away? It's green wood, if that helps.
Click to expand...

A photo would be useful.

Tearout Is almost always is due to cutting an unsupported fiber.

Take a bundle,of broom straws and cut them with a machete whack. The first straws cut cleanly because there are longer straws to back the cut. As you cut most of the way through the straws begin to bend and get torn rather than cut.


When you cut from foot to rim on a hemispheric bowl each fiber ( except the last ones) have a longer fiber behind them supporting the cut. This means you cut parallel to the lathe bed toward the rim location.
If you cut perpendicular to the lathe as the endgrain comes around the fibers in the front side are cut cleanly because they are supported by the longer fibers. As you cut the back side of the endgrain the fibers tear because they are not supported and have only air behind them. The cutting edge will raise the fibers and tear them rather than cut them.

I highly figured wood is often a problem as it has fibers going in different directions.
 
Last edited:
Here's a pic. The tear out is only occurring on the "trailing edge" if you will, where normally it would be both the leading and trailing edge experiencing the tear out. All tear out I have experienced has been as mentioned before every half rotation. You can see in the pic on the right side where the tear out occurs along both the leading and trailing of that "side". But farther into the the piece and to the left the tear out occurs only on the trailing edge.
 

Attachments

  • tear out.jpg
    tear out.jpg
    305.1 KB · Views: 57
The tear out is on the back side of the end grain what you may be calling the trailing edge and at the rim.
These are where you are have unsupported fibers.

It looks like you are scraping or not riding the bevel.

I get a similar or worse surface when I use a roughing cut without the bevel riding.
Then I shift to a bevel riding cut to take off the last 1/4” of wood leaving a smooth surface

Sharp tool, bevel riding cut from foot to rim.
The nose of the tool needs to point towards the tailstock.

The video below of a demo I did the in Sarasota shows how I do the push cut.
The bowl is mounted backwards from yours with the rim to the headstock until I put it in the chuck then the rim faces the tailstock.

If you fast forward to 26:50 you will see the push cut with an explanation.
I do the cut at about 3 rpm so you can see the shaving being taken.
Also the wood is a bit punky and you can still see tearought from the roughing.
I clean it up pretty well. Wi a few minutes of nice bevelmriding cuts.

View: https://m.youtube.com/watch?v=A6XccQl_0BY
 
Last edited:
I agree with Al, but there are a few species of wood that when green are especially prone to shredding if you bowl gouge isn't perfectly sharp or, as Al said, you are scraping rather than riding the bevel.

I tried enhancing the image to look for clues, but I don't see anything specific. My best guess is that the wood is green and possibly Manitoba maple or cottonwood. I would also guess that the tool might be dull and scraping

image.jpeg
 
As everyone stated....I keep my bowl gouge razor sharp and that helps a lot on tear out. I also take very light cuts which also helps....However, most of my wood is dry.
 
I have turned some green cottonwood that had the same issue, the grain varies in these trees as the branches twist and turn in many directions as they grow which makes it challenging to address the grain with the proper tool angle to cut it cleanly. You could try some wood sealer to stiffen the wood fibers or let the wood blank dry some more before trying to make clean cuts.
 
Thank you everyone, it's as I expected..more of user error than not I'd have to say. I'll keep grinding away at the metal so I'll stop grinding away at the wood. unfortunately I haven't become very well adept yet in identifying tree species but live in NC, so lots of Oak and Pine for sure. As of now I really think I only have three types of wood in the pile waiting to be turned.
 
Edward Olson said:
Thank you everyone, it's as I expected..more of user error than not I'd have to say. I'll keep grinding away at the metal so I'll stop grinding away at the wood. unfortunately I haven't become very well adept yet in identifying tree species but live in NC, so lots of Oak and Pine for sure. As of now I really think I only have three types of wood in the pile waiting to be turned.
Click to expand...

If you have it, Red and silver Maple are good woods for learning. For crack free drying it is less demanding of even walls and nice curves than other wood and it cuts cleanly.

Cherry & sweet gum are good woods

Walnut and poplar are good to but they are soft and more prone to tearout with less than proper bevel,riding.

Stay away from willow until you have lot more experience.
 
I am guessing, from the tool marks, that you were using one of the square carbide tipped tools. They work fine on most woods for roughing cuts in a scraping mode, which is flat on the tool rest and the wood spins at about 90 degrees to the cutting edge. If you have a good bowl gouge, the clean up cuts would be with the handle dropped low, and pulling from the bottom of the bowl to the rim. The 'shear' angle can make a huge difference in how clean your cut is. If you intended to have the top of the bowl curve back in (closed form meaning opening is smaller than the largest part of the diameter of the bowl), you want a dropped handle pull cut coming from the edge to the bump/largest outside diameter. Play date with mentor needed!!!!

robo hippy
 
Edward, I'm not familiar with exactly what's in your woods, but be aware that there are two different varieties of tree called poplar, and if I understand correctly, they have somewhat different turning properties.

Out here in the wild west, we have cottonwood/poplar, which are members of the Populus genus and tend to have a shaggy surface when turned. I believe this is the variety of tree that produces the poplar wood you find in big box stores.

Then there is the Tulip Poplar/American Tulipwood which is found in the southeastern US, is also a soft hardwood, and sometimes called Rainbow Poplar as it can be various colors. It is not a member of the Populus genus, is not a true poplar, and, as far as I understand, is a more desirable turning wood.
 
Last edited:
Dean Center said:
Out here in the wild west, we have cottonwood/poplar, which are members of the Populus genus and tend to have a shaggy surface when turned. I believe this is the variety of tree that produces the poplar wood you find in big box stores.

Then there is the Tulip Poplar/American Tulipwood which is found in the southeastern US, is also a soft hardwood, and sometimes called Rainbow Poplar as it can be various colors. It is not a member of the Populus genus, is not a true poplar, and, as far as I understand, is a more desirable turning wood.
Click to expand...

I think you may have it reversed Tulip or tupelo is the tree that the lumber comes from and will usually have at least some green color which sometimes permeates the entire tree. It has small branches making it easy to mill into lumber with few knots.
 
After reviewing the US Forest Service wood book, I suspect you are correct. They don't mention the greenish color, but I've never seen that in any of the western or horticultural poplars around here. The basic answer from the USFS suggests that tulip poplar is used for somewhat more sophisticated purposes that are true poplars. Both types grow in the south and southeast, are turned into lumber and other wood products, so it's kinda fuzzy.

For other nerds out there, here's a summary of the government info:

Eastern and swamp cottonwood grow throughout the eastern half of the United States. Greatest production of lumber is in the Southern and Central States.
Cottonwood is used principally for lumber, veneer, pulpwood, excelsior, and fuel. Lumber and veneer are used primarily for boxes, crates, baskets, and pallets.

Yellow-poplar (Liriodendron tulipifera) is also known as poplar, tulip-poplar, and tulipwood.
Yellow poplar grows from Connecticut and New York southward to Florida and westward to Missouri. The greatest commercial production of yellowpoplar lumber is in the South and Southeast.
The lumber is used primarily for furniture, interior moulding, siding, cabinets, musical instruments, and engineered wood composites. Boxes, pallets, and crates are made from lower-grade stock. Yellow-poplar is also made into plywood for paneling, furniture, piano cases, and various other special products.​
 
You must log in or register to reply here.
Back
Top