Black cherry wood

[Gerard Uebbing]

I have retired and am now pursuing my bowl turning. We moved to the Upper Peninsula of Michigan where they use black cherry for firewood ( the horrors ). I bought a load and found out the dealer had a yard full of B. Cherry burls. I worked a deal and purchased 10 burls ranging from 14 to 37 in.diameters. 1: how long should I let the burls air dry under cover? I have sealed the ends. 2: As far as the rounds I have sealed the ends to cut down on cracking and stored with the burls. I have tried turning green, but all but 1 have cracks from hairline to 1/8 in. Have tried both rough turn, and let dry, and dry blanks to under 10% rh then turn, and still they crack. I know to remove the pith. Have tried many ways to dry. Air, microwave, dehydrator and even burying in a bucket of desiccant, and still they crack. I hate to see them end up in the fireplace like what everyone else does around here. It’s such a beautiful wood. Help please!
The burls, once they dry enough, will probably be cut to size then epoxied and put in a pressure pot to hopefully help save them from blowing apart when I turn. Any and all ideas will be appreciated.

 

[hockenbery]

Welcome to the forum. Hard to get classes and mentors until COVID is over.

drying thick wood takes a long time a year per inch of thickness. Longer when sealed.
Burls can usually be dried without getting big cracks because they don’t have concentric growth rings.

I encourage people to turn green wood.... so much more fun than dry wood.

There is a strange phenomenon in woodturning. New turners have a high percentage of bowls crack. Experienced turners rarely loose a bowl. To some extent the deck is stacked against the new turners because they can’t do the things needed for success as well as the experienced. Good news is you won’t be a beginner long if you keep turning bowls. I like to turn green wood.

Drying rough turned bowls without cracking is most successful when:

The bowl blanks has even grain cut parallel to the bark
The blank has no pre-existing cracks (firewood usually has pre-existing cracks)
The bowl has even wall thickness ( can be a little thinner at the bottom)
The bowl has nice curve that can move with the warping
The bowl does not dry out on the lathe( big difference in roughing out a bowl in 20 minutes vs. 3 hours)
The drying of the finished bowl is controlled.​

check out the thread on working with green wood below. It is taken from a demo I do. There’s are slides I use as an overview, a video of rough turning a bowl, and a video of mounting a dried bowl and finish turning it.
https://www.aawforum.org/community/index.php?threads/working-with-green-wood.11626/

 

[Dean Center]

One of our former frequent contributors (Gretch Flo) was periodically flying to the UP and bringing home cherry wood. She has a lot of experience with the wood, and if I recall correctly, had similar problems. She might respond to a direct communication if you look her up here on the forum and send one.

Fruitwood of most sorts tends to crack early and badly. Al mentions that experienced turners have less trouble with cracking than beginners, and one major factor is that experienced turners have lots and lots of wood available and are very selective about what they turn. They just don't spend any of their limited time on troublesome wood, unless there is something extremely special about it.

Good luck with your gnarly wood.

 

[Gerald Lawrence]

I turn lots of cherry and rarely lose a bowl due to a crack. Just do as Al suggested , turn to even thickness or a little thicker at the rim. I do not seal but place in bag with shavings and open that bag every other day for two weeks. Then in bag till drying slows.A book could be written on the many ways and details on drying wood successfully but no time or space for that.

 

[Roger Wiegand]

Cherry is pretty much my favorite wood, for everything-- it's my primary furniture wood, I did all of our interior trim in the house with it, and I love turning it. I don't seem to have particular problems with cracks (unlike, say, apple, which cracks when you look at it crosseyed). With your burls I'd suggest getting them as thin as possible as soon as possible if they are prone to cracking. So turn green to final thickness; they won't be quite round when they dry, but that's part of the fun! Burl won't go as out-of-round as regular wood, so if you are twice turning you can leave them a little thinner than you would on a plain wood blank.

Working quickly to get the whole blank down to uniform thickness seems important. Uneven thickness promote cracking. Whenever I've left a piece half done overnight it has cracked.

I would guess that 80% of cracks I get in bowls are due to pre-existing cracks in the wood that I didn't notice. If the piece of wood is really nice and you want to use it despite the cracks plan on making the crack a feature rather than a bug. Inserting pewas or stitching the crack are ways that people do this (sign up for Emiliano's online demo of calabash turning and pewa repairs!) If you know the wood is cracked you need to take precautions against it flying apart and clocking you in the head as you turn. (Many folks will tell you to never turn a cracked piece, which is probably good advice. Other folks make spectacular pieces that seem to be more air than wood.)

Burl is almost inevitably have some small fissures that open up. Filling with CA or epoxy (black or with wild colors), or just leaving them in the final piece is fine.

 

[hockenbery]

Currently most of my wet wood turning is HFs or NE bowls. I finish turn these from green wood, let them dry p, then sand off the lathe, and apply finish.

one exception I sometimes make is burls. These I sometimes sand with abranet while wet.
The surface when dry gets wrinkly and wonderful to hold.
If I wait until dry I sand the wrinkles away - I do this if I plan a glossy finish or have lots of burl eyes to show off.

 

[Gerard Uebbing]

Thanks for all the reply’s. It seems everybody turns their wood green. I thought by drying 1st you could avoid it drying to quick and cracking. I was figuring it would be 5 years before I could start on the smaller burls. I look at that giant burl ( it’s well over 100 pounds and an almost perfect ball ) and want to open it up and see what’s inside, but figured it would be 10 years before I even try. I was looking forward to my next tax refund to put on a 18 inch band saw to tackle them!

 

[Russell Nugent]

I doubt the giant burl will ever actually air dry.

 

[Dean Center]

Gerard, one other thing to keep in mind when you compare your wood drying results to others, is the climate in which we live. Northern Michigan indoors in the winter is going to be drastically different than Hawaii. Then in spring when all that lake effect snow melts, you'll be in the temperate rain forest, and it'll be different. Wood cut during the tree's dormant season in the winter will be less likely to crack than wood cut in the summer, except that when you bring it indoors to a super dry environment, it's going to dry very fast, too fast.

Similarly, when you get recommendations on how to coat or bag or otherwise dry wood, your personal circumstances and the local climate will dictate what of the many methods work best for you. Getting local advice in these areas might be quite helpful. There are AAW affiliated clubs in Marquette (no web site) and Moran Township https://hiawathawoodturningclub.blogspot.com/, and one of the online remote demo instructors lives near Traverse City (which also has a club, but I can't imagine doing the bridge in winter) While these clubs are probably not meeting in person these days, they almost certainly have members who would be happy to help answer questions.

 

[Gerard Uebbing]

Dean, sounds like you know the weather here. I assume the wood was cut this summer due to the moisture content. Definitely not seasoned. The burls I have no idea. I paid him $25 a burl. Won’t know until I open them who got the better deal. (I am expecting me). I will take advantage of the clubs and have already joined the Hiawatha club blog. I have my shop in a room in my pole barn so not quite as dry as the house in the wintertime but dry none the less in winter. Summer months are devoted to fishing and the garden/ mowing. Definitely like retirement better than working

 

[Dave Delo]

One thing with cherry burls that I've found is the bugs really love it too. I process outside before bringing into the shop and get rid of the shavings immediately.

 

[Dean Center]

Dean, sounds like you know the weather here. I assume the wood was cut this summer due to the moisture content. Definitely not seasoned. The burls I have no idea. I paid him $25 a burl. Won’t know until I open them who got the better deal. (I am expecting me). I will take advantage of the clubs and have already joined the Hiawatha club blog. I have my shop in a room in my pole barn so not quite as dry as the house in the wintertime but dry none the less in winter. Summer months are devoted to fishing and the garden/ mowing. Definitely like retirement better than working

I misspent my summers near Watersmeet. If I recall, the seasons are Tick, Mosquito, Fly, Firewood, and Stuck Snowmobile.

 

[Gerard Uebbing]

Dean, you pretty well nailed it...lol

 

[Karl Loeblein]

You can store wood in a barrel of water and RV antifreeze (for potable water systems to prevent freezing) until you figure out what is best way to process them.

Below are a few methods I use for non burl bowls that you could experiment with:

If you have room you can also cover some rough turnings in plastic wrap, and then toss them in a freezer for several months. The plastic can come off after they start to freeze dry some. I seem to get less cracking this way, but I haven’t done this enough to say for sure.

Cover a rough turning with plastic wrap and then microwave at half power for a few minutes. Allow the piece to cool down. Repeat several cycles with turning completely covered. Next cut a small hole in center of the plastic wrap for steam to escape as you continue more bake/cool down cycles. Goal is to drive the water out of the middle of the wood while keeping the outside from drying too quick.

Use an outdoor turkey fryer to boil the rough turnings for a couple of hours. Oddly enough, doing this could cut your drying time in half. Although you might keep the turning in a paper bag for a while in order to slow down the outside from drying to fast.

Search for ways to turn an old dishwasher into a small kiln. Get it fully loaded before turning on the heat. A fully loaded kiln will keep the moisture level high enough during initial drying so the outside doesn’t dry too quickly.

 

[Gerard Uebbing]

Thanks Karl, when I tried the microwave I didn’t have the piece wrapped. I can see how having it wrapped would slow down the outside from drying to fast and hopefully stopping the cracks. How long do you do total. Do you weigh the turning between cycles?

 

[Roger Wiegand]

Anyone ever tried freeze drying difficult wood? I've always been curious, but no longer have access to a big lyophilizer. Almost certainly impractical, you'd probably have to leave it in there for a month, but it should pull all the moisture out without changing the shape of the wood at all. Question is what happens when the blank is returned to air and water vapor.

 

[Mark Jundanian]

I have been doing some reading on homemade vacuum kilns. The block or rough out is placed in the evacuation chamber, wrapped in and warmed by an electric heating pad and the vacuum applied. The chamber itself is costly as is a good enough pump so I haven't gotten past the musing stage, but if you had the apparatus you could try placing a deeply frozen block in the chamber without the heater (vacuum being a good insulator). Just an idea. Now all we need is a government grant.

 

[Karl Loeblein]

Thanks Karl, when I tried the microwave I didn’t have the piece wrapped. I can see how having it wrapped would slow down the outside from drying to fast and hopefully stopping the cracks. How long do you do total. Do you weigh the turning between cycles?

My process is very time consuming so I only do this when I am in a big hurry. Microwave a rough turning fully wrapped around half power for about 2 or 3 minutes at a time in order to get it hot enough to relax the wood. Do this 3 to 5 times. Then continue the heat/cool cycles with a small hole on top to let some of the moisture out slowly. Also stick paper towels inside to wick up any excess moisture, but swap out the wet paper towels as needed. When there’s a lot less moisture being driven out from the middle of the wood then poke another hole in the bottom and continue the cycles. Keep enlarging the holes a little until piece is mostly dry. Try not to get the wood so hot that you can”t hold onto it.

Regardless of your drying method, remember the end goal. Don’t let the outside get significantly dryer than the middle.

 

[Mark Jundanian]

Has anyone ever tried microwaving an un-turned block?

 

[Karl Loeblein]

The main reason for using the freezer is it gives me time to turn a green piece of wood several times without having to coat it with anchor seal between turnings. Also, there’s no worry about mold and no cracking between turning sessions if covered in plastic wrap. If the piece is left in long enough in the freezer then it seems to have less cracking problems when I’m done with the final turning.

 

[Roger Wiegand]

I have been doing some reading on homemade vacuum kilns. The block or rough out is placed in the evacuation chamber, wrapped in and warmed by an electric heating pad and the vacuum applied. The chamber itself is costly as is a good enough pump so I haven't gotten past the musing stage, but if you had the apparatus you could try placing a deeply frozen block in the chamber without the heater (vacuum being a good insulator). Just an idea. Now all we need is a government grant.

I've seen some decent used ones that would be big enough selling for $20-30K. Perhaps a group purchase.... or perhaps we could just pitch the blocks of wood that crack.

 

[robo hippy]

For furniture making, it is difficult to find air dried wood, which is best. Tied for second place, by a very small margin are vacuum kiln dried, and solar kiln dried. With all 3, if you rip a board on your table saw, you get shavings and not dust. If you rip a 2 inch thick board on your bandsaw, at least with the pieces I have used, there is no cupping, warping or twisting. I think there are still problems with drying thick blanks, just too much wood in the way for it to dry evenly.

I am wondering if using the stretch film in the microwave is a good idea.

If I had some really prized logs, for long term storage, I would want a mill pond to sink them in, preferably one that has water flowing through it so you don't get slime build up. They will keep there for ever...

robo hippy

 

[Mark Jundanian]

I've seen some decent used ones that would be big enough selling for $20-30K. Perhaps a group purchase.... or perhaps we could just pitch the blocks of wood that crack.

I'm guessing those might be sized to do pallets of boards. I'm talking about something table top using a laboratory vacuum oven or homemade from very large diameter PVC pipe, but it would still be in the 2k region. Hard to think up the business model for that, but I haven't entirely given up the idea yet. After all thinking doesn't cost much.

 

[GRJensen]

Anyone ever tried freeze drying difficult wood?

Steve Sinner freezes wood ... some folks say it doesn't work, but Steve has been doing it with great success for years.