Piece cracked

[Robert Dicke]

Newbie here- I just got my first lathe up and running and was playing around with a chunk of ash. I turned a rough vase shape and when I came back to it these cracks had opened. Is it because the wood wasn’t dry or just internal pressure in the wood? I have a lot of ash from a tree I took down in my yard and would start again but want to avoid it cracking again. Thanks for your advice.

415762

[Bert Delisle]

Turning green wood is fun but can lead to cracking if the wall thickness and base mount are thick. One could consider turning to finished wall thickness in one go then the object can warp rather than split.

[John Hart]

Welcome to the vortex Robert. You've just experienced the nemesis of wood turning.
When the green wood is thick like that and the end grain is not sealed, the ends immediately start to form cracks because the wood is drying. Those cracks quickly gravitate through the wood.
There are many ways to prevent it and it is something you'll always be conscious of.

[Robert Dicke]

So next time put a clean cut in both ends and seal the chunk of wood before turning. Then make sure I have enough time to turn the vase inside as well in one session.

as for this piece could I fill the cracks with resin and keep going? If so what kind of resin do you recommend for turning?

[Chris A Lawrence]

If you cant turn the inside right away you can put a plastic bag over it and while still one the lathe and wrap it around the chuck. Only do this if you plan on returning later that day or the next day. Anything longer then that just seal the entire piece with anchor seal.

[John Hart]

Nope...that piece is officially firewood.
It will fly apart regardless of any filler. Not to mention it'll continue to crack now

[Dave Mount]

Those are some impressive cracks. . .reminds me of most of my attempts to dry roughed out redbud bowls (even with Anchorseal).

It appears that piece had a boxed heart -- i.e., the pith of the tree running down the center. That makes it even more prone to cracking. Though you will still need to seal the ends and/or turn thin right away, you will likely have more success with a piece that does not contain the pith.

Don't let it discourage you.

Dave

[John Hart]

Oh yeah....don't let it discourage you. Beating the cracks is all a part of the game. Turning dried wood is nice because you don't have to fight the movement in the wood and go start to finish. But green wood is nice because it's a bit easier to turn. But then you have the drying process after rough turning before finish turning. It's all fun though

[Edward Dyas]

Wood cracks when it dries too fast. What people normally do when turning green wood is to roughly turn the wood and put it in a paper bag and put it away somewhere cool and let the wood season. Then finish the turning. Still a certain amount of turnings will crack on you. Myself I prefer to glue up kiln dried wood for that reason.

[Alex Zeller]

One thing I started to do when I can't rough out the inside of the blank, and I'm no expert, is to collect all the wet wood shavings and put them in a plastic garbage can. I'll then bury the blank in the middle to keep it from drying out. I've never left a blank like this for more than two days.

[Brice Rogers]

If I'm roughing a green piece, I will (sometimes) spritz it with some water as I'm turning to keep the outside from drying - - AND more importantly - - to keep the outside from shrinking. If I need to take a break for an hour, I'll wrap the piece with a thin plastic grocery bag and either tape it or tie it.

When I rough out the inside, I try to make the wall thickness about 10% of the diameter to account for shrinkage. This usually works but sometimes it doesn't with really shrinkable wood.

If I'm doing a hollow form, when I'm done roughing it, I'll wrap the outside with plastic with the theory that I would prefer it drying from the inside out rather than vice-versa.

But some pieces will crack no matter what you do.

[robert baccus]

Everyone that turns green fights this--green wood is usually free and comes in any size. There is a lot of witchcraft out there concerning this--after 30 years I have found the only foolproof method is standard twice turned methods. Turn the outside completely, never leaving it uncovered to dry, coat with a good endseal, reverse and hollow the inside to 10% of the diameter. Leave it open if a vase. For bowls coat the inside as well and toss it on the shelf for months. Always consider the hard/soft of the wood, humidity, draft, temp. ect. when doing anythng with wood. This is not fast or quick to season wood but very easy and foolproof--also very cheap. All wood must be seasoned at the mill or home or else.

[Glenn C Roberts]

Robert, I'm trying to figure out what your blank looked like before turning. I get the grain pattern on the left, but the pattern on the right is baffling to me. Was the blank a curved branch? That may explain the weird grain and also the excessive cracking. Had a 9/4 walnut slab split 3' right off the mill because it was branch wood - internal stress I was told.

[John K Jordan]

Newbie here- I just got my first lathe up and running and was playing around with a chunk of ash. I turned a rough vase shape and when I came back to it these cracks had opened. Is it because the wood wasn’t dry or just internal pressure in the wood? I have a lot of ash from a tree I took down in my yard and would start again but want to avoid it cracking again. Thanks for your advice.

415762

As others mentioned, wet wood drying too fast will crack - it's the nature of wood since wood shrinks in certain ways and has to crack when given no other choice.

There are lots of things you can do to prevent this. I recommend a very basic - learn about the nature of green (wet) wood and how it shrinks! There is an excellent book by a guy who is not only a craftsman but a wood expert: "Understanding Wood: A Craftsman's Guide to Wood Technology" by R. Bruce Hoadley. https://www.amazon.com/Understanding-Wood-Craftsmans-Guide-Technology/dp/1561583588 Hoadley explains clearly why and how green wood shrinks and what to do about it.

A solid thick piece of green wood that is not hollowed out inside is almost sure to crack badly as it dries.
A thinner piece of green wood is more likely to survive.
Tall forms are more difficult than bowls or platters.

Several things to do, some mentioned.
- Turn it thin in one setting.
- If taking a break, keep it wet
- Don't leave the pith in the blank (there are exceptions)
- Hollow to a relatively uniform wall to final thickness, especially don't leave the bottom thick
- Hollow to a uniform but thicker wall and dry very slowly before turning to the final wall thickness
- Turn as end grain rather than side grain (grain running down the lathe axis). This won't prevent cracking but can minimize cracking and out-of-round warping.
- Turn dry wood

Turning green wood is fun and so easy but I almost always turn dry wood. I cut green wood into turning blanks and let them dry. I rough out the green wood from the log with a chain saw then cut in to nice turning blanks on the bandsaw. If you process a little wood on a regular basis you will soon have more perfect turning blanks than you can possibly use! The method:

- Cut around any existing cracks and defects and be careful to not allow the pith of the tree in the blank.
- Coat at least the end grain with at least one coat of AnchorSeal or Green Wood Sealer (the same thing)
- Weigh the blank and write the date and weight on the side
- Put the blank in a place that's not too hot or dry and wait. I stack them on wire shelves
- The slower wood dries the more likely it is to dry without cracks
- After a month or so I examine each piece and either cut away or mark minor defects that have shown up, re-seal as needed.
- Every few months weigh again. When it quits changing weight it's dry.
- Cut away any defects that have developed
The wood is now dry and you can turn anything, solid, thick walls, thin.

Here are some examples of the wood I've dried and am drying:

415804 415805 415806 415807

And at the bandsaw:

415808 415809 415810

Some species take longer to dry and some are more stable than others But with this method it is extremely rare to lose a piece to cracks.

Since you are new to turning, let me pass on what many experts recommend about getting started. Many (Richard Raffan, Mike Darlow, Jimmy Clewes, Frank Penta, Kieth Rowley, and more) say to start with spindle turning before you go to bowls, platters, forms, etc. Spindle turning will teach you the fine tool control that will allow you to turn anything but it doesn't always work the same way in reverse. When I teach a new student the first tool in their hands is a skew chisel. We master the basic cuts with the skew then the spindle gouges before going to face turning (bowls and such).

BTW, this method is NOT popular with some since most want to immediately turn bowls and the bigger the better.

Oops, I just noticed you are listed as a "Member" and may not be able to see the photos. For a $6 minimum you'll have "Contributor" status and can see the photos and enhance your forum time in other ways: https://sawmillcreek.org/payments.php

JKJ

[Prashun Patel]

I wish someone had given me this advice when I started turning green wood:

Don't try to salvage cracked wood.

There's 2 reasons:

1) it's not safe. Cracked wood - even glued or filled - is being held under force either with your chuck or between centers. You are removing thickness as you turn it, and eventually it may break. It's just not safe and not worth it.

2) Most green wood turners have access to plenty of wood, so don't get precious about saving punky or cracked wood. Turn extra blanks, seal them, and plan on losing half when you start out.

I've turned plenty of cracked bowls to completion - maybe 50. Only 2 have cracked. But it's dangerous enough that I don't do it any more.

[Edward Weingarden]

As you can see from the prior posts, there are a number of methods to try to prevent cracking. Here's what I do for my twice turned hollow forms. When I harvest green wood, I always seal the ends (Anchorseal) right after it's cut. When it's time to turn, if there is any checking on the ends, I cut them off first; start with a defect free blank. In contrast to others, I usually turn with the pith in the center ( I'll get back to my reasoning at the end). When I turn the rough form, the bottom is turned with a 1.5" diameter (approximately) "drive shaft". The drive shaft runs between the tenon in the chuck, and the bottom of the HF. This eliminates the mass of wood at the base that would otherwise dry slower than the rest of the piece. If it's a tall HF, I use a steady rest for the hollowing process. Once the outside shape is completed, I coat it with Anchorseal, including the drive shaft and exposed area of the mounting tenon. I hollow leaving a 1/2" wall thickness, including the bottom. Once the piece is off the lathe, I coat the tenon area that was in the chuck with Anchorseal. I weight it and record the date and weight on a piece of paper that I leave in the top opening of the HF. I then put it in a paper bag and hang it upside down. I'll leave the paper bag on for about a week, and then let it hang exposed to air, and weight it once a month. Usually takes 3 - 4 months for the weight to stabilize.

And now for the issue of the pith. My theory is that the rings around the pith are somewhat concentric and they should shrink down in a somewhat uniform fashion. A blank that is taken out of the log to the side of the pith now has rings that are somewhat "C" shaped. When the wood shrinks, it will tend to pull in opposite directions from the open side of the "C", possibly resulting in a crack. As I say, this my theory. As long as I slather all external surfaces with anchorseal, have a uniform wall thickness, and dry slowly, I have been very successful in having crack free rough turned HFs.

[John K Jordan]

...

And now for the issue of the pith. My theory is that the rings around the pith are somewhat concentric and they should shrink down in a somewhat uniform fashion. A blank that is taken out of the log to the side of the pith now has rings that are somewhat "C" shaped. When the wood shrinks, it will tend to pull in opposite directions from the open side of the "C", possibly resulting in a crack. As I say, this my theory. As long as I slather all external surfaces with anchorseal, have a uniform wall thickness, and dry slowly, I have been very successful in having crack free rough turned HFs.

The piece with centered pith will definitely shrink without the lopsided warping you get when off center. But sometimes juvenile wood around the pith will have higher rates of shrinkage than the older rings, depending on the species and how fast the young tree grew. This can leave the sides perfect but star cracks in the center. Anchor sealing all the way around is a great method.

JKJ

[robert baccus]

A few comments on wood problems-- Wood shrinks more across the grain-far less with it. Dense, fine grain woods are strong and pull themselves apart when drying Soft weaker woods are far less likely to split While drying. Wild grain patterns in wood will move and split without great precautions. Species in both catagories vary greatly. We are raised in a culture that is taught uniformism as in wood is wood. Nature never read that book. Try to never be surprised by anything. End seals and time cuts my losses to < 5% of pieces. Piths and roots can be seasoned with little extra effort and endseal. I just finished out a E. Indian rosewood 10" bowl with 1/4 " flared sides with the pith and tight knots radiating running longgrain through the side---lucky too. Pith and the juvenile wood around it are sorta hairy--on hollow forms and vases ect. you can drop CA unto the bottom. Soaks in nicely--try 2 doses also. I use glueblocks and thick CA to mount pieces and leave them until after finishing and have no problems from pith and juvenile wood.