Force drying bowl blanks
#6
What can you guys/gals tell me about force drying rough turned bowl blanks. I have a kiln for other purposes that maintains about 95 degrees when running. Thanks, Bill
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#7
(10-10-2017, 07:19 AM)Herebrooks Wrote: What can you guys/gals tell me about force drying rough turned bowl blanks. I have a kiln for other purposes that maintains about 95 degrees when running. Thanks, Bill

What you have would work great and be done in a few weeks or I have heard others used microwave ovens with the wood in it for 15 to 25 seconds at a time.
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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#8
(10-10-2017, 07:19 AM)Herebrooks Wrote: What can you guys/gals tell me about force drying rough turned bowl blanks. I have a kiln for other purposes that maintains about 95 degrees when running. Thanks, Bill

Used to do it, don't any more.  Turn a bunch when green, shelve, and turn after 3-6 months (~1" thickness).  Idea is to maintain the outer endgrain at near saturation while the interior feeds it.  Microwave therefore more useful than other means, as it boils out.  The dry kiln works on relative humidity, not temperature, as you know, so you want to go to the tables in the Wood Handbook to get some idea of what temp air equates to MC, and then mind your venting to allow new, unsaturated air.  Tables exist for board drying, but not convinced their schedules are good for pre-turned items.  I'd give the ends a coat of starch or PEG to make them grab and hold moisture while the interior gives it up if I were going to try.

I turn a mortise in the bottom, so I can judge pretty well when drying is ~ 10% by measuring along and across the grain to compare.  When I lose 1/8" in 2, it's a go.
Better to follow the leader than the pack. Less to step in.
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#9
(10-10-2017, 11:15 AM)MichaelMouse Wrote: Used to do it, don't any more.  Turn a bunch when green, shelve, and turn after 3-6 months (~1" thickness).  Idea is to maintain the outer endgrain at near saturation while the interior feeds it.  Microwave therefore more useful than other means, as it boils out.  The dry kiln works on relative humidity, not temperature, as you know, so you want to go to the tables in the Wood Handbook to get some idea of what temp air equates to MC, and then mind your venting to allow new, unsaturated air.  Tables exist for board drying, but not convinced their schedules are good for pre-turned items.  I'd give the ends a coat of starch or PEG to make them grab and hold moisture while the interior gives it up if I were going to try.

I turn a mortise in the bottom, so I can judge pretty well when drying is ~ 10% by measuring along and across the grain to compare.  When I lose 1/8" in 2, it's a go.

I am turning tenons on my bowls with diameters of approx. 4". They seem to remount easier than dovetail recesses after they have torqued out. My kiln is a dehumidifier type so air is constantly being dried out. I'll have to do a few test pieces to see how likely they are to crack. I suspect the type of wood would be a factor. At present, I'm turning walnut and west Indian Mahogany which seem fairly stable thru the drying process. There is no way I can wait 3-6 months for these things to dry to a fairly stable condition. I'll amend this post as I proceed.
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#10
(10-10-2017, 11:40 AM)Herebrooks Wrote: I am turning tenons on my bowls with diameters of approx. 4". They seem to remount easier than dovetail recesses after they have torqued out. My kiln is a dehumidifier type so air is constantly being dried out. I'll have to do a few test pieces to see how likely they are to crack. I suspect the type of wood would be a factor. At present, I'm turning walnut and west Indian Mahogany which seem fairly stable thru the drying process. There is no way I can wait 3-6 months for these things to dry to a fairly stable condition. I'll amend this post as I proceed.

I take it you're buying your wood, rather than hitting the woods as I do.  In the time I would fuss with one blank through a cycle in the kiln, I could make another, so stacking them in for the future when a good log happens means no problem waiting for them to cure.  There's always a batch available.  No cracks since I started curving, either.

I don't do tenons for two reasons.  First, you lose some depth, second, to remount in a mortise you enlarge the constricted mortise, which I prefer to cutting a smaller tenon and shoulder.  Third reason no longer exists.  The first (Masterchuck) chuck I owned had to be jam threaded to hold (poorly) on a tenon. 

http://i35.photobucket.com/albums/d160/G...ne/Log.jpg

As to torqueing out, I assume you're using the bad information propagated by people who don't understand that it's not GRIP that counts with a mortise, but wedging into bottom of the mortise.  You don't do more than snug the wedge, you do nothing but hurt you cause by tightening.  Of course, I use two centers until the piece is at it's lightest, and most circular. Less strain, though even there, "catches" are rare, so sometimes I do without. 

http://i35.photobucket.com/albums/d160/G...ne/Log.jpg
Better to follow the leader than the pack. Less to step in.
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