Microwave wood drying
#10
Have a request from son for a mothers day present for his wife. Wants a simple weed pot. White birch with the bark left on lower part. Arlin has posted a picture of one he did. Very simple turning, but my problem is all I have axcess to would be fresh cut. Sap is now up in the trees. 4" diameter and 12" high. I want to dry as much as possible before turning. Has anyone dried something like this in a microwave, and any sugestions on the best way to do this would be appreciated. Fortunatly I have a microwave in my shop I could use. Could save me a lot of problems with the wife. Don't think I would even want to sugest using the one in the kitchen.
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#11
I have only tried it twice and both were with bowl about 1/2" thick.  Even then I nuked it for about 30 seconds, removed to cool, then nuked again (several times).
4" diameter is going to be a tough one.  Maybe if you drilled out the pith and then inset a contrast such as walnut in the base when finished it would help.  Keeping the bark on may be another problem especially now.  Birch bark is used a lot for baskets and canoes because it is though but very easy to peal off the log.  You may have a problem keeping the bark on as it dries.
I would go slow and easy with the nuking to prevent cracking.
Good luck and hope you get it made....that day is not far off.
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#12
2 rules

1. Don't use a microwave for drying wood

2. If you do, don't use your wife's microwave
If it don't hold soup, it's ART!!

Dry Creek Woodturning

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#13
Trying to dry a solid length of branch will likely guarantee that it will crack.

If you do hollow forms, then your best bet is probably to turn the weed pot as a hollow form with relatively thin walls and let it warp as it dries.

You could also drill out the pith all the way through and use a glass or metal insert as the weed pot stem holder. You can do that even if you do the hollow form approach.  Craft Supply has a good selection of inserts with and without rims.

Drill the hole a bit snug in the green form and then let it dry without the insert. After the wood dries, use a standard twist drill bit to make the hole round and fit the insert.
"the most important safety feature on any tool is the one between your ears." - Ken Vick

A wish for you all:  May you keep buying green bananas.
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#14
Drilling out the pith would be my suggestion too, Any blank left in "log" form is very likely to crack as it dries, no matter what  the method. A "hollow log" is better able to shrink and deform, and leave the outer shell intact. 

Then as long as it's not the wife's M/W, and you take your time zapping it (too hot and it catches fire) you really have nothing to loose by zapping a few chunks of wood. After an hour you will either have some dry blanks, or some kindling. 

BTW, sap up and down has little effect on the core wood moisture content. That sap is moving in the cambrium layer just under the bark. It may move faster, and sugar content will vary, but I deal with lots of evergreen hardwoods, and there is little difference in the wood between the seasons. The "harvest with the sap down" does have some merit, but it's usually to do with easier drying in the cooler weather when bugs and fungus aren't an issue. Then once the weather warms up, the wood is drying enough that it wont mould or get eaten by bugs, You can harvest the wood any time, IF you can control the drying, in this case with your mini RF dry kiln.
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#15
Another benefit of microwaving wood is that it kills the critters.

GM
The only tool I have is a lathe.  Everything else is an accessory.
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#16
Birch.  Lots of varieties.  To leave the bark on, shrink/Saran wrap and tape before you cut the shoulder.  It'll keep the bark from peeling, flapping and skinning your knuckles as well as anything I've found. 

Radial cracks come from the outer, wetter wood trying to shrink more than the inner, dryer heartwood will let it.  Microwave inside a plastic bag (wrap off) for at least the first few cycles.  Should go a long way toward equalizing heart/sapwood differences.  Go with the defrost type cycles where there are good pauses between power and no power time.  If you apply energy/heat continuously for too long, you can ignite dense spots, so longer and lower power will allow them to readsorb some moisture from surrounding wood. 

Help yourself by concaving the bottom a bit, so the edges have room to move inward without splitting, and when you take the wood out of the bag with your gloved hand, don't set it on the base, set it on the bark to let the moisture exit.

Sorry, almost forgot. Bark will probably lift away from sapwood, because it's pretty thick and dry. No real sweat, fill the visual gap with a splinter of the waste wood, displaying the grain orientation properly.
Better to follow the leader than the pack. Less to step in.
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#17
I would be most happy to send you a couple of mine if you pay the shipping.

Also remember that I put tape around it.  First with the sticky side up for a few wraps and then with the sticky side down.  I do the whole thing and just cut off what is not needed.

Send me a pm if you want some.
As of this time I am not teaching vets to turn. Also please do not send any items to me without prior notification.  Thank You Everyone.

It is always the right time, to do the right thing.
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#18
I have been out of town for a few days and will drill out the pith today and see what happens. Notmuch to lose. I can always make her a new one if it fails. Arlin. Thanks for your very generous offer, but keep what you have and sell them to help you out with extra cash for your needs.
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