microwaving or CA green wood?

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txbatons

txbatons

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I have a customer who wants an item for Christmas using wood from her fiance's childhood home.

I know I can use the microwave to dry the wood, but is it full power and for how long?
If not the microwave, can using CA during the turning stabilize it enough?

The pieces I am using are 3/4" round by 3 1/2" long.

Thanks for any help! I told her that by using green wood I could not guarantee that it would not crack. Didn't matter to her, but it matters to me and I want to get it as correct as I can.
 
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I am assuming this is from a tree on the property.

1. Cut it a bit longer than the tubes.
2. Drill with smaller bits than what you will need (you will need to re-drill later). Smaller bit is needed to compensate for possible warping.
3. Wrap each of the drilled blank in paper.
4. Microwave for 10 seconds (full power is okay). Take the blank out and feel it/observe. If it is boiling, you need to reduce the time next time. If it is still cool increase the time.
5. Let it cool down.
6. Repeat step 4 until dry.

My test is to do the cycle then stand the blank on a plate. Remove after a few seconds, if the place where the center hole was has mist/sweat like moisture, it is not yet dry.

Hope this helps.
 
HA! Sorry. Yes, the wood is from two TREES from his childhood home. One cutting from (limb) from pecan and one from ash.

Dario...thanks for the tips. I'm using these for a baton handle, so there's no pre-drilling done. I drill the hole (3/16") after the shape is turned. I probably should rough turn the piece to take off the bark and then start the microwaving. I might even do a half/half segment for the baton handle to further minimize movement.
 
General Agreement with Dario's method but what I do is:
1. Cut blanks at aabout 20%-30%larger and longer.
2. Weigh the wood on Weight Watcher's scales.
3. Drill holes as dario says
4. Wrap each end and place in microwave. I always put mine across a couple of thin scraps or pencils to hold them off the platter.
5. My approach now becomes mor conservative. I set power level to 10% for 2mins
6. Feel for heat etc. If not really hot repeat.( imight do this 4-5 times depending on heat/moisture.
7. Remove paper and weigh.
8. Repeat step 6. As wood gets drier and lighter it will tend to get hotter.When this happens you will need to let it sit until cool to touch before more stints in microwave. When the wood loose no more weight you can safely assume it is dry.At this stage let it air for a couple of days.
This process is more tedious than Dario's but I have found that I haven't ruined a blank for along time.[:p]
 
I have gradually learned to make green cuts considerably larger than I would have guessed. I have had several 7/8 inch square blanks "twist" as they were dried in the microwave. For that reason, I make mine 1 to 1 1/8 inch square before drying.

Green ash will shrink approximately 8% tangential and almost 5% radial (cross section - not length wise) and has moderate tendencies to warp or twist. Pecan has almost 9% T. and 5% R. shrinkage in size and also has intermediate tendencies in warp/twist. (Taken from Hoadley's Understanding Wood, pages 117 and 123.

The shrinkage itself (as it dries) is not your main specific problem (IMO) but the allowance for moderate warping. For this reason cut the blanks with allowance for this.

DON'T DRILL First:
I used to think that drilling a hole would help but I found that it can render the blank totally useless. If you have lots to play with, then practice, it might work. If you don't have but a few pieces - DON'T drill the hole first it. IF the blank warps the warped hole can be so far out of alignment between ends that you can't use it.

Besides that, the differences in the tangential and radial shrinkage will cause the hole in these woods to become egg shaped as they dry. Learned that from a book and didn't listen - then learned that for real from Mr. Experience, a wonderful but sometimes harsh teacher. [:D]

Forgot to add my 2 yen on the CA finishing:
NO finish will totally stabilize <u>green</u> wood. That is an almost absolute. It "can" probably be done, but you would need a millionaire's lab to do it consistently. There are a few woods that do not move (shrink) with moisture loss or humidity changes but pecan and ash are not in that small group. However, finishes, including CA do not prevent mother nature from doing her work.

CA does stabilize but only as far as it soaks in. Moisture in cells do not let CA go in under normal atmospheric conditions. IF the cells are "dry" CA can penetrate and stabilize it for a layer or two or three.
 
Good post Hank.

I probably am lucky that all the local wood that I used to microwave dry are "stable" and warp minimally.Like R2, I think I only lost one blank since I got it down. I did lost a batch once because I turned it into charcoal. That is what high power and long settings can do [:I].

As a follow up...wood with un-equal shrinkage (tangential vs. longitudinal) affects those that are figured/burl, biased cut, cut near crotch, etc. more than regular straight cut.
 
The idea behind microwave drying is to excite and heat the water molecules. if you heat them to the point they turn to steam they will split your wood. Ask how I know that. so very short 10 sec. cooking times and then let them completely cool. I use low setting to lessen the chance the blank will act like pop corn. wrapping them in paper gives the water a place to go as it moves to the surface. if the wood is going to warp as it dries it is going to warp no matter how you dry it. spliting is anouther matter. knowing how wood warps and why goes a long way towards minmizing it when you are cutting your blank. still cut it oversized. I do not pre drill my blanks as the water is being heated from the center of the blank anyway. it is basically being vibrated out of the wood from the center out.
 
Thanks for all the help. Lee...these limb cuttings are as straight as arrows, about 1 1/2" in diameter and not much of it. This whole order is doomed to fail anyway, especially since the customer requested something dark...and then sent me some of the lightest colored woods known to man! [:0] Now to have it split or check months later because she sent me green wood is just another aggravation. I tried explaining all of this to the young lady, but she's been relentless.

Regardless, once LOML leaves for the malls here in a bit I will take control of the microwave and give it a go.

As a related follow up - is there a resource list somewhere that arranges types of wood by how much they do/don't move as they dry?
 
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