Cherry cracking

[Johnny65]

This is a cherry log that I just roughed out the outside, and it's split all over the place and deep cracks.
It was felled 6 months ago and has been kept dry since then.
How do I stop this horrendous cracking, I've got a dozen pieces 12 inch diameter and about 15 inches long.

 

[Sgian Dubh]

This is a cherry log that I just roughed out the outside, and it's split all over the place and deep cracks.
It was felled 6 months ago and has been kept dry since then.
How do I stop this horrendous cracking, I've got a dozen pieces 12 inch diameter and about 25 inches long.

In truth you're essentially asking for something that's pretty much impossible to prevent. What you're witnessing is, as the wood dries, the difference between the shrinkage factor of the growth rings that encircle a stem or limb (tangential shrinkage) and the radial shrinkage factor, i.e., from the pith to the circumference of the stem/limb. Typically tangential shrinkage in wood is somewhere near double radial shrinkage which means that radial shakes are almost inevitable.

In an effort to prevent this occurring you might research, as one strategy, the use of replacement bulking chemical to stabilise wood and are quite popular with turners. Pentacryl is one such chemical, and another is PEG (polyethylene glycol). Slainte.

 

[Johnny65]

Thanks, how do you use this pentacryl stuff ?

 

[Wood4me]

View attachment 137700This is a cherry log that I just roughed out the outside, and it's split all over the place and deep cracks.
It was felled 6 months ago and has been kept dry since then.
How do I stop this horrendous cracking, I've got a dozen pieces 12 inch diameter and about 25 inches long.

Since you have a few pieces there are sone options you could try.
I have had success with turning bowls with high moisture content or ‘green’ by roughing them out to about 25 mm thick in one quick session then putting it initially in a plastic bag with most of the damp shavings and seal it for about a week, then put a slit in the bag to allow slight air exchange, over the next few weeks enlarge the slit but cover with paper. You can if interested weigh it accurately and calculate the mc. Eventually you will end up with an oval, but dry bowl. As long as you left it thick enough initially you should then be able to turn it back to circular but maybe about 10mm thick . That’s the principal and you may get varying degrees of success .
I have also turned and finished a walnut bowl the same day as the tree came down in a storm. This time by roughing it to about 25mm then drying in a microwave. Very gently on low in short bursts for several hours ( I made a timer unit that was adjustable for how many seconds on an off)
When dry I completed the turning , oiled and polished it,
I gave the bowl to the lady that was so upset that her lovely tree had blown down the same day .

 

[Johnny65]

Hi wood4me,
I've done as you suggest with various other types of timber successfully, but cherry, I just can't stop it cracking

 

[Wood4me]

Same day walnut bowl re. previous post

 

[Stigmorgan]

Unfortunately cherry seems particularly prone to cracking, I have a few pieces that are 2 years old, kept dry and ends sealed that have still cracked, as soon as I see the cracks I put more sealer on to close the cracks but it just keeps going.

 

[Johnny65]

Stigmorgan,

As they are 12"dia 15"long I just might make some garden ornament mushrooms out of them, the cracks will be home to a myriad of insects.

 

[Wood4me]

There is the option of accepting the cracks a filling with brass powder and CA glue

 

[Sgian Dubh]

Thanks, how do you use this pentacryl stuff ?

I've not needed to use it myself, so I can't offer the best advice nor report on its effectiveness. But here's one supplier. That's a link to a turner's retailer, and turners tend to be the most common users, so I'd suggest you start your research with that group of woodworkers and perhaps ask them about PEG too. Try the Turner's forum here to go on with. Slainte.

 

[Adam W.]

Show us a picture of the end of one of the un-turned rings.

 

[Steliz]

Cherry is renowned for cracking more than other woods but you also only roughed the outside which exposed a new layer of high moisture content wood to the air which started drying more rapidly than the inside. When rough turning green wood you should rough out the inside as well to keep the moisture content at the surfaces more balanced. Not that it will make any difference with Cherry though as it will still crack.

 

[gog64]

I’m not sure what your process was here, ie did you 1st turn as soon as it was felled, then store it for 6 months then try to 2nd turn or something else, so can’t give specific advice. However, a couple of points. You’ve left the pith in. Notice that your largest crack started in the pith. I always remove the pith (based on bitter experience!).

Second, FWIW My process is (for large branches or thin trunks):

1. Cut into rounds, a couple of inches longer than the diameter.
2. Anchorseal the end grain as a “holding” method until I have time for (3). If you skip this step you have firewood. BTW your wood will take roughly forever to dry out if you leave it like this.
3. Cut in “half” on the bandsaw, taking out the pith.
4. First turn wet. Lots of fun. Leave the walls nice and thick. Leave a tenon inside & out. ANCHOR SEAL ALL END GRAIN. If you skip this step you have firewood.
5. Stick it on a shelf and forget about it until the mc gets down to an acceptable level.
6. Laugh at all the funny shapes & pick out the best for second turning.

Works for me, but there are plenty more experienced people who will have better advice.

BTW, as others have said, cherry loves to move!

 

[Orraloon]

As said above leaving the pith in is the biggest mistake for any timber as thats where cracks usually start. Fruit woods are more prone than most for cracking and there is never a guarantee even if you do everything right but with the pith in they nearly always crack. Most turners would have been there so look at it practical learning experience. The few times I have been tempted to keep the pith in order to get a bigger blank have usually failed.
Regards
John

 

[Adam W.]

Judging by the colouring in the rings (lower right), I reckon you're trying to tame reaction wood. A photo of the whole un-turned piece will help a lot in identifying what's up.

 

[Bob Chapman]

Cherry sapwood (the pale outer wood in your photo) is notorious for shrinking more than the heartwood and this inevitably leads to cracking from the outside inwards as your photo shows. Also you have cracking originating in the pith which is common to most timbers. Not much you can do about it other than remove the sapwood and the pith centre before you start turning.